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GENOTYPE-ENVIRONMENT INTERACTIONS
AND GENETIC PARAMETERS IN
NEW ZEALAND ROMNEY SHEEP
A t he s i s submi t t ed f o r the d e g r ee o f
Doc t o r o f P h i l o so phy
at
Ma s s ey Un iv e r s i t y
New Z e a l and
SUBHASH CHANDER CHOPRA
1 978
ii .
ABSTRACT
P e r forman c e r e cords o f 1 , 1 1 3 New Zealand Romney ewe hogge t s f rom
two sub f locks ma i n t a ined on con t ro l (CSR) and i n t ens ive (HSR) s t o ck in g
r a t e s were ana lysed .
The d a t a r e p r e s e n t e d the progeny o f 34 s i r e s and
we r e co l l e c t e d b e tween 1 9 6 7 and 1 9 74 inclus ive wh ich cove r ed four
cons e c u t ive two-year s i re p e r iods .
The t r a i t s inve s t i ga t ed were hogge t l ive-we i gh t ( HLW ) , greasy
f le e c e we igh t ( GFW) , c l ean wo o l we ight per un i t a rea (WA) , c l ean s c oured
y i e ld (Y) , s t a p l e length ( SL ) , me an f i b re d i ame t e r (MFD ) , s t andard
d e v i a t ion of the f ibre d i ame t e r ( S FD ) , qua l i t y numb e r (QN ) , c r imp s p e r
c e n t ime ter ( CP C ) , t o t a l cr imp numb e r (TCN ) , char a c t e r ( CHG ) , t i p p in e s s
( T G ) , hand l e ( HG ) , lus t r e (LG ) , greasy co lour (GCG) , s c oured c o l o ur
( S C G ) , d i s c o l oured area ( DAG ) , cot t i ng (CG) , co t t ed area ( CAG ) and
s oundn e s s ( SG ) .
S tocking r a t e had s i g n i f icant e f f e c t on a l l the t ra i t s exc e p t ing
MFD , SFD , TCN and HG .
H S R depre s s ed the t r a i t s inve s t iga t e d excep t i ng
Y , S FD , QN , CPC , HG , GCG , S CG , CG and CAG .
w e r e an imp o r t a n t source o f va r i a t ion .
e x c e p t on
l�W,
SFD , CHG and HG was sma l l .
Year e f f e c t s exc e p t in DAG
The inf luence o f b i r t h- r ank
S t ocking r a t e x year
i n t e ract ions except in CPC , TCN , CHG , TG , HG , GCG and CAG we re
imp o r t an t .
S i r e x s t o c k i n g r a t e in t e rac t ions we re s i gn i f i c an t in HLW ,
MFD , SFD , TCN and GCG only , whe r e a s s i r e x y ear i n t e r a c t ions we re
s i gn i f icant in HLW , GFW , HG and SCG .
S ire x s t ocking r a t e and s i r e
x
year i n t e r a c t ions we re i n c l uded in
d i f f e rent way s in some f o rmu lae for c a l c u l a t ion of he r i t ab i l i t y e s t ima t e s .
The s e e s t ima t e s we re c a l cu l a t ed f rom p a t e rn a l h a l f - s i b analy s e s in C S R ,
iii .
The various e s t ima t e s f o r t h e d i f fe rent t ra i t s
HSR and comb ined d a t a .
we r e i n the f o l l owing ranges : H LW 0 . 2 1 - 0 . 7 2 ,
y
GFW 0 . 3 8 - 0 . 6 1 ,
WA 0 . 3 1 - 0 . 4 9 ,
0 . 87 ,
0 . 53 ,
SL 0 . 54 - 0 . 6 3 ,
MFD 0 . 3 4
S FD 0 . 3 5 - 0 . 6 6 ,
QN 0 . 4 6 - 0 . 7 2 ,
CPC 0 . 4 8 - 0 . 8 8 ,
TCN 0 . 6 5 - 1 . 0 9 ,
CHG 0 . 2 4 - 0 . 3 4 ,
TG 0 . 1 3 - 0 . 2 7 ,
HG 0 . 2 3 - 0 . 6 6 ,
LG 0 . 3 2 - 0 . 4 2 ,
GCG 0 . 2 2 - 0 . 4 4 ,
0 . 19
SCG 0 . 1 0
-
--'
0 . 39 ,
DAG 0 . 04
0. 21 ,
CG 0 . 1 2
-
0 . 67 ,
S G 0 . 00 - 0 . 2 2 .
CAG 0 . 1 8 - 0 . 53 ,
No s i gn i f i cant d i f f e renc e s b e t tve en the e s t ima t e s in the two
s t o cking r a t e s exc e p t in CG and SG were ob s erved .
t h e s e comp a r i sons
iS
The r e l evance o f
d i s cu s s e d i n t e rms o f s i re x s t ocking r a t e and
s ir e x year int erac t ion s .
In t ra- t r a i t gene t i c c o r r e l a t i ons be tween t h e two s t oc king r a t e s
w e r e c l o s e t o un ity exc e p t in HLW ( P < 0 . 0 5) ;
Y , SFD , GCG , SCG ( 0 . 0 5< P < 0 . 1 ) .
Gene t i c c o r r e l a t ions b e twe en t r a i t s we re cal c u l a t e d by the p a t e rnal
h a l f - s ib me thod .
The c o r r e lat ion coe f f i c i e n t s sugge s t t h a t t h e HLW
s e le c t ion r e s u l t s in h i gh e r f l e e c e we igh t , longer s t ap l e s , b e t t e r
f l e e ce charac t e r , inc r e a s e d va r i a t ion i n f ib r e d i ame t e r , h i ghe r q ua l i ty
S e l e c t ion f o r f l e e c e we igh t would
numb er and c r imp ing and mo r e lus t re .
r e s u l t in longer s t ap l e s , less cot t ing and less s u s c e p t Jb i l i t y to b r e ak
and increased mean f ib r e d i ame t e r .
Co r r e l a ted re s p on s e s exp e c t ed w i t h
s e l e c t ion f o r f ineness a r e reduced s t ap l e leng t h , more c o t t ing an d l e s s
s ound wo o l .
S e l e c t ion ·fo r TCN resul t s in f avourab le changes in H LW ,
GFW , TG , co t t ing , co lour and soundn e s s .
Favourab l e changes in y ie l d ,
c r imp ing , d i s c o loured area are exp e c t ed f o l l owing s e l e c t ion f o r whi t ene s s
o f a mid s ide samp l e , whe r e a s GFW could d e c l ine .
iv .
App l i c a t ion s o f the r e s u l t s are d i s c u s s ed w i t h par t i cu l a r re f erence
t o the role p l ayed by s i re
x
s t o cking r a t e and s i re
x
year i n t e ra c t ions
in the gene t i c imp roveme n t of cha r a c t e r s of economic imp o r t an c e in New
Zea l and Romney sheep .
v.
AC KNOWLEDGEMENTS
I t is with s p ec i a l gra t i t ud e that I acknow l ed ge my s up e rvi s o r s ,
Pro f e s s o r A.L . Rae and Dr G . A . Wi c k h am f o r t h e i r immense h e l p , cons t an t
encouragement , c on s t ruc t ive c r i t i c i sm and able coun s e l t hroughout t h e
course o f this s t udy and t he p r eparat i o n o f t h i s t h e s i s .
G ra t e f ul a cknowled gement i s made t o t h e s t a f f o f Sheep Husb and ry
Dep a r t men t and No . l Sheep Farm , Mas sey Un ive r s i t y who were invo lved wi t h
t h e c o l l e ct ion o f t he d a t a u s e d .
Thanks are due t o Mr R . P . Lewe r , Mr A . B . P l easan t s and Mr C . J . Dodd
f o r the i r as s i s t ance dur i n g t he p e r i o d of comp u t er f ami l i a r i z a tion .
They and o t he r c o l l e agu e s and fe l l ow s t uden t s h ave p rovided a sou r c e o f
s t imu l a t ing d i s cuss ion o n many o c c a s i ons .
S incere t hanks are due t o Mr s A . F . Barton for ski l l f u l ly typ i n g
t h e manus c r ip t .
I wish t o exp r e s s my utmo s t app r e c i a t ion and s p e c ia l t hanks to my
w i f e , Re e t a f o r provid i ng t h e i n s p i r at ion .
Wi thout her r e s o l u t e
s up p o r t and encouragement t he t a sk may neve r have b e en comp le t ed .
The a f f e c t ion r e c e ived f rom t he Chopra and Varma f ami l i e s encouraged
me in the a c c omp l i shmen t of t h i s t a s k .
Th i s the s i s wa s made p o s s ib l e t h rough the awar d o f a C ommonwe a l t h
S ch o larship .
The grant o f s t udy leave by the Ind i an Coun c i l o f
Agr i cu l t u r a l Re search i s g r a t e fu l ly acknowl edged .
v i.
T ABLE O F CONTENT S
Chap t e r
ii
AB STRACT
AC KNOHLEDGEMENTS
V
L I ST OF T ABL ES
X
L I S T OF F I GURES
xii
ONE
INTRODUCTION
1
TWO
REVIEW CF
4
LITERATURE
CLAS S I F I C AT IONS OF GENOTY P E- EN V I RONMENT INTERACTIONS
FALCONER ' S CONC EPT OF GENET I C CORRELAT I ONS BETWEEN
P ERFORMAN C E IN DIFFERENT ENV I RONMENTS
Exp e r ime n t a l ev i d e n c e f o r Fal coner ' s c o n c e p t
GENOTYPE- ENVIRONMENT INTERAC T I ON S IN SHEEP
12
13
20
Growth charac t e r is t i cs
21
C ar c as s ch a r a c ter i s t ics
29
F l e e ce chara c ter i s t i c s
32
Re p roduc t ive t r a i t s i n
O t hers
GENET I C PARAMET ERS
THREE
4
ewes
41
45
46
He r itab i l it y
4 fi
Gene t i c c o r r e latio n s
60
GEN ERA L CONCLUSIONS
78
SOURCE OF DATA
79
THE D AT A
81
v i i.
TAB LE
OF
CONTENTS
(continued)
Chap t e r
FOUR
STATI STICAL HETHODS
86
PRESENCE OF INTERACT I ON
86
ANALY S I S OF VA RIAN C E
88
Le ast s q u a r e s and computing methods
88
F i t t i ng models t o the data
90
Es t imat i on o f mean s quare s , variance and
covarian c e components
96
LEAS T SQUARES E S T IMATES
98
POOL ING OF TH E S I RE GRO UP P E RIODS ANALY SES
98
PART I T I ONING THE VARIAT ION
99
VARIANCE CO NPONEN T ESTH1ATES
99
GENET IC P A RANETERS
FIVE
101
H e r i t ab i l it y
10 1
Gene t i c c o r r e l a t io n s
103
RESULTS AND
DISCUS SION
E S T I NATES OF NON- GENET I C FACTORS , I NTERACT I ON S
AND VARIANCE C ONPONENTS
1 05
105
Ho gge t l i ve -we i gh t
1 10
Greasy f l e e c e w e i g h t
115
Clean w o o l we i g h t p e r un i t a r ea
1 18
Clean s c o u r e d y i e l d
1 20
S t ap l e l e n g t h
12 1
Me an f ib r e diame t e r
124
S t anda r d d e via t i on o f t h e f i b r e d i ame t e r
125
Qua l i ty number
127
C r imp s per c e n t ime t e r
128
To t al c r imp numb e r
1 30
vi i i .
TABL E O F CONTENTS
( c on t inued )
Chap t e r
Charac t e r grade
131
T i p p i ne s s grade
1 34
Hand l e grade
135
Lus t re grade
1 37
Greasy c o lour grade
138
Scoured colour gr ade
140
D i s c o l o ured area g r ade
14 1
Co t t in g grade
143
Co t t e d a rea grade
144
Soundne s s grade
146
HER ITAB I L I TY ESTIMATE S , INTRA-TRAIT GENETI C
CORRELAT IONS AND INTERAC TION VARIANC E COMPONENTS
148
Ho g ge t l ive-we i gh t
152
Greasy f l eece we i gh t
155
C l e an woo l we i gh t p e r u n i t area
1 56
C l e an s c oured y i e l d
15 7
S t a p l e l en g t h
158
Me an f i bre d i ame t e r
159
S t andard dev i at ion o f the f i bre d i ame t e r
161
Qual i t y number
162
C r imp s p e r ce nt ime t e r
163
To t a l c r imp numb e r
1 64
Chara c t e r grade
165
T i p p i ne s s grade
1 67
Han d l e grade
168
Lus t r e grade
169
Greasy c o lour grade
1 70
S c o u red c o lo u r g r ad e
171
D i s c o l o u red area grade
172
Cot t ing grade
173
Co t t ed area grade
1 74
S o undne s s grade
1 76
INTER-T RA I T GENET I C C ORRELATION S
177
ix.
TABLE
(continued)
Cha p t e r
SIX
OF CONTENTS
CONCLUDING DISCUSSION ON PRACTICAL
U1PLICATIONS
BIBL10GRAPHY
185
1 94
x.
LIST OF TABLES
Table
1
2
3
4
5
Some published estimates of heritability of
live-weight, wool quantity and quality traits
in s heep
48
Some published estimates of genetic correlations
between various characteristics for live-weight,
wool quantity and quality in sheep
64
Combined stocking rate analysis.
Calculation of
reductions in sums of squares and expectations of
mean squares
94
Within s tocking rate analysis.
Calculation of
reductions in sums of squares and expectations of
mean squares
95
Percentage of total variance attributable to each
factor for each variable from the combined stocking
rate analysis pooled from the different Sire group
periods
106
6
Least squares estimates and standard errors of
environmental effects for HLW and GFW
111
7
Least squares estimates and standard errors of
environmental effects for WA and Y
119
8
Least squares estimates and standard errors of
environmental effects for SL and MFD
1 22
Least squares estimates and standard errors of
environmental effects for SFD and QN
126
Least squares estimates and standard errors of
environmental effects for CPC and TCN
1 29
Least squares estimates and standard errors of
environmental effects for CHG and TG
132
Least squares estimates and standard errors of
environmental effects for HG and LG
1 36
Least squares estimates and standard errors of
environmental effects for GCG and SCG
139
Least squares estimates and standard errors of
environmental effects for DAG and CG
142
Least squares estimates and standard errors of
environmental effects for CAG and SG
145
9
10
11
12
13
14
15
xi.
OF TABLES
( continued )
LIST
Table
16
Heritability estima t es
o f v a r ious tra it s
analyses by diffe ren t
17
Intr a-trait gene t ic
erro r s o f t r ait s
18
t raits
me t h o d s
14 9
co r rela t ions a n d s t anda rd
in two s t o cking rates
Gene t ic c o r relatio n s
various
and standard er ro r s
o b t a ined f r o m t he p o oled
and s t anda rd e r r o r s
from the pooled analysis
v a r iance and covariance
151
among
of
178
xii.
LIST OF FIGURES
T i t le
Fig.
1
2
(A, B) x enviro nmen t
(X, Y ) int er ac t ions as sugge s t ed by Haldane ( 19 4 6)
(af t e r McBride, 1 9 5 8 )
Illu s t ra t io n of geno t yp e
Typ e s of heredit y x environment int erac t io n
(af t er Dunlop,
3
5
9
19 62)
A cla s s ific a t io n of geno t yp e x environment
int e r a c t io n s
s pec ially de signed for
animals, s t udies
(af t e r Pani,
19 71)
use in farm
11
1.
CHAPTER ONE
INTRODUCT I ON
Geno ty pe-envi ronme n t i n t e r a c t ion ( GE l ) o c curs wheneve r a chan ge
f rom one envi ronme n t to ano ther resul t s in d i f f e r en t e f f e c t s on the
geno t y p e s i n the popula t ion .
Thus if changing f rom environment 1 to
environment 2 add s 10 un i t s t o one geno type and 15 un i t s t o ano the r ,
GEl w i l l be presen t .
GEl imp l i e s that genotypic and envi ronme n t a l
e f f e c t s a r e no t ad d i t ive , i . e . , i n s t ead o f being able to a s s ume that a
t r a i t x i s t he sum o f a geno t y p i c component and an environmen t a l
compon e n t , i t i s ne c e s s a ry to ad d an e f f e c t due to the j o int i n t e ra c t i o n
The p r esence o f GEl could r e s u l t in a
o f gen o t yp e and envi ronmen t .
change o f ranking o f the anima l s or at le a s t in the ma gni tude o f t h e i r
d i f fe r en c e s .
The l a t t e r t ype w i l l bri ng a chan ge o f he r i t abi l i t y and
so w i l l i n f luence e f f e c t ivene s s o f s e l e c t i o n .
Th i s leaves no doubt
that p l anning o f a b reeding p rogramme depe n d s o n the magn i t ude of GEl
as we l l as the e s t ima ted val ues o f o t he r gen e t i c p arame t e r s .
A maj o r p rob lem o f p rac t i c a l imp o r t ance posed by the p o s s i b l e
p re s en c e o f GEl is the cho i ce o f envi ronme n t a l c ond i t ions un d e r wh i ch
t o p r a c t i c e s e le c t ive b r e e d in g .
b reeder has t o de c ide
In p l an n ing a s e le c t io n p r o gramme , a
the envi ronmental c i r cums t an c e s und e r wh ich
the p ro gramme is conduc t e d .
Th i s is a very imp o r t an t d e c i s ion wh ich
b e c ome s mo r e c r i t ical as the range o f envi ronments in wh ich the imp roved
s to c k are used comme r c ial ly , in c r e a s e s .
Should t h e breeder subj e c t t h e an imals among wh i ch s e le c t i on i s t o
b e made t o a ' good ' environme n t wh i ch give s maximal exp r e s s i o n t o t h e
d e s i red cha r a c t e r o r shou l d he rat h e r sub j e c t them t o c o nd i t ions , whe ther
2.
' go o d ' o r ' b ad ' und e r wh ich the imp roved g enotype i s des t ined
sub s e q uen t l y t o l ive and p e r f o rm?
Fa l c on e r ( 1 9 5 2 ) and F a l c oner and
Lat y s z ewski ( 1 9 5 2 ) have d i scussed s ome a s p e c t s o f the gene r a l p rob l em o f
env i r onmen t and s e l e c t ion .
In p a r t i c u l a r they have c r i t i c i z e d views ,
e xp r e s s e d by Hammond ( 1 9 4 7 ) , that env i ronmen t a l condi t ions i f un f avourab l e ,
w i l l p r ove t o b e a fac t o r l imi t in g the r e s ponse t o se l e c t io n .
In t he New Ze aland Romney b r e e d , i t is common for r am- b r e e d ing
f l o cks t o b e l o c a t ed in areas of favourable env i ronme n t a l cond i t ions
whe re rams are s e l e c t ed and bred und e r adequate leve l s of nu t r i t ion and
in above-ave r a ge husbandry and manageme n t t o a l l ow h i gh individual·
pe r fo rmanc e t o b e achieved ( S t evens ,
1946;
Rae , 1 9 6 4 ) .
The p ro geny
of t he r ams b re d in t he s e f l ocks , however , are exp e c t e d to p roduce
s a t i s f a c t o r i l y over a wide range of environme n t al cond i t io n s , usually
much l e s s f avourab l e than t ho s e o f t h e ram-breeding f locks .
In a farming
sys t em wh ich r e l i e s on pas ture f e e d i n g , chan g ing the s t o cking r a t e is the
maj o r me thod b y wh ich the lev e l of n u t r i t ion supp l ied to the sheep can be
var ied .
The r e fo r e , as long as the c u rrent sys t em o f s e l e c t ion o f
b reed ing r ams rema ins in p r a c t i c e , t here i s an obvious n e e d t o inve s t i ga t e
the imp a c t o f geno t y p e o f s i r e s x s t o cking r a t e and o th e r imp o r t an t
i n t e r a c t ions on the e f f e c t ivene s s o f selec t ion .
C le a r l y , i f n ut r i t iona l
l eve l s f lu c t ua t e v i o lent ly , as t h e y do , f rom low s to cking r a t e s t o h i gh
s t ocking r a t e s and i f t he r e are imp o r t an t geno type o f s i r e s x s to cking
r a t e i n t e r a c t ions , the e f f e c t ivene s s o f s e l e c t ion may be s eve r e l y
p re j u d i ce d .
L i t t l e c r i t i c a l in f o rmat ion is ava i l ab l e on the impo r t ance
o f t he s e in t e r a c t ions in sheep and on woo l t r a i t s .
The p urpo s e o f t h i s s t ud y was to inves t ig a t e t he p o s s ib le
in t e r a c t ions b e twe en the geno t y pe s o f s i res w i t h in t he New Zeal and Romney
b re e d o f sheep and d i f f e re n t levels o f s tocking r a t e .
Thus, the wo rk
3.
was p rimarily c o ncerned with detecting and evaluating the r o le played
by the sire x stoc king rate inter a c tions with regard to the str u c tu r e
of h er itability estimates i n hogget live-weight,
clean wo o l weight per unit a rea,
mean fibre diameter,
number,
c r imps per
h andle,
lustre,
greasy fleece weight,
clean s c o u r ed yield,
staple length,
standa rd deviation o f the fibre diameter,
c entimeter,
greasy c o lour,
total c rimp number,
sco ured c olour,
c otted area and so undness o f wo o l.
c h a r a c ter,
quality
tippiness,
discolo ured a rea,
c o tting,
S ir e x year inter actio ns were also
c o nsidered.
In o rder to
o btain information and assess the p r a c ti c a l implications
of the observed inter a c tions under investigation,
the estimation of th e
genetic p ar ameters and some environmental effects was co nsidered to be
necessary.
As an outline of the sc o p e of the thesis,
th ree major
top ics may be mentioned.
1.
Estimation of no n-genetic f a c to rs and inte r a c tion effects
on e a c h
char a c ter so th a t th e a p p r o p riate adjustment of
the
data fo r the differences in the known environmental fa c to r s
a n d inter a c tions c a n be made p rio r t o the genetic studies of
v a riation and cova riation.
2.
Estimation o f herita bility estimates in different sto cking
r a tes and of intratrait genetic
c o r relations to p r ovide
statistical evidenc e of sire x stoc king r a te inter a c tions
in the flo c k under study.
3.
Estimation of inter-trait genetic
c o r relations to describe
what other c h a r a cters a r e likely to change in futu r e
gener ations i f o ne p a rtic ula r
c h a r a cter i s under selection.
4.
CHAPTER TWO
REV I E\.J OF LITERATURE
CLAS S IF ICAT IONS OF GENOTYPE- ENVIRONMENT INTERACTION S
C l a s s i f i c a t ions o f GEl have b e en made b y Ha ldane ( 1 9 4 6 ) , Ma t h e r
and Jones ( 1 9 5 8 ) , Mc B r ide ( 1 9 5 8 ) . Dun l o p ( 1 9 6 2 ) , Pan i ( 1 9 7 1 ) a n d o t hers .
A t t e mp t s have been made by s eve ra l wo rke r s t o t ake into a c c oun t the
e x t e n t of the change s i n rank ing o f the s a me genotypes in d i f f e r en t
env i ro nmen t s and t h e s i ze o f the d i f f e r en c e s between the envi r onment s
and b e tween the ge ne t i c e f f e c t s .
Hald ane ( 1 9 4 6 ) c l as s i fied the GEl wh i ch may o c c u r when gen o t y p e s
d i f f e r ing a t
a
s in g le locus are exposed t o c o n t r a s t i n g environmen t s .
Con s i de r ing two geno t yp e s (A , B) a nd two envi ronme n t s ( X , Y ) a s an
examp l e , he tabu l a t e d s ix d i f f e r e n t t y p e s of inte r a c t ions w i th the
c r i t e r ion that gen o t y p e
rank .
A
in a n envi ronment X has a lway s the h i ghes t
He gave no a t t e n t ion t c the types o f d i f f erences b e tween the
envi ronments and b e tween geno types .
are p r e s e n ted graph i c a l ly in Fig .
The s i x types o f in t e ra c t i o n s
1.
_Ma t he r and Jon e s ( 1 9 5 8 ) de s c r ibed t h e d i f ferenc e s a mo n g t h e f o u r
phen o types g iven b y two genotypes i n each o f the two env i ronme n t s i n
t e r ms o f t h r e e p a r ame t e r s , d a me a s u r ing the a ver age e f f e c t o f gen i c
d i f f e rence s , e 1 me a s u r ing the ave r age e f f e c t o f d i f ferences in
env i ro nmen t and g l me asuring the GEl .
The q uantity g 1 , the s t a t i s t i ca l
int e r a c t ion o f d a and e 1 i s e s t i ma t ed by (A : X + B : Y ) - (A : Y
+
B : X)
wi th s ign ignored , i . e . , taken a s the a mount added by the i n t e r a c t i o n to
the pheno types of A i n env i ronment X and B in envi ronmen t Y , a nd
dedu c t ed from the pheno typ e s of A in Y and B in X.
5.
1 (b)
1 (a)
Ax
1
Ax
~
2
A
3
X
4
�
By
By
2
3
Ax
1
Ax
Ay
2
Bx
�
z
�
3
4
Ay
/
By
By
4 (a)
4 (b )
Ax
1
Ax
By
2
3
Ay
4
X
A
Fig .
Bx
1:
B
Ay
A
B
I l l us t r a t ion o f geno type (A , B ) X environment (X, Y )
i n t e r a c t ions as sugge s t ed by Haldane 0. 9 4 6) ( a f t e r McBride, 1958 ) .
\
6.
McBride ( 1 9 5 8 ) p ropos ed t o c l as s i fy GE l on the f o l l owin g b as i s :
1.
Gene t i c d i f f e r ences a s int ra-popul a t ion geno types and
i n t e r-popu l a t ion ge no t ype s .
2.
Env ironme n t a l d i f f e rences as micro-environme n t s and
ma c ro-envir o nmen t s .
Type A ( in t ra-popul a t ion , mi cro-envi ronmen t a l ) :
Th i s wou ld i nvo lve
i n t e rac t ions be tween those envi ronmen t al f a c t o r s wh ich o c c ur whe n a l l
an imals appear t o b e t r eated a l ike ( i . e . , are i n a s in g l e gene r a l
e nvi ronmen t ) and are f rom a s ingle popul a t io n gene t i c a l ly s u c h a s a
s ingle h e r d o r f lock .
Type B ( in t ra-pop u l a t ion , ma c ro-environme n t a l ) :
Th e s e are in t e rac t i on s
wh ich migh t o c cur i f the gene t i c d i f f e rence s o f anima l s f rom a r e l a t ive ly
homo genous gene t i c group we re e xposed t o large environmen t a l d i f ference s .
The pre s ence o f type B i n terac t i ons is o f imp o r t ance t o p l ant and animal
b re e d e r s concerned w i t h s e l e c t ion wi t h i n b r e e d s or s t rains .
o f type B in t e ra c t ion s has f o l l owed two l ine s ;
Th e s t u dy
the s t a t i c and dynami c .
The s t a t i c approach c o n cerns the behavi our o f d i f f e r e n t fami l ie s w i t h in
the normal r ange o f geno types c omp ared in two o r mo r e c on t ras t i n g
environme n t s .
Wh ile t h e i nve s t iga t i ons o f t y p e B i n t e ra c t ions in s t a t i c
popula t i ons may g ive s ome ind i c a t ion as t o wh e ther the enviro nmen t i s
impor t a n t i n s e le c t ion p rob lems , the s e que s t i o n s can b e answe red
conclus ive ly by sel e c t ing und e r d i f fe ren t envi ronmen t a l cond i t i on s ; i . e . ,
by the dynamic appro ach to the prob l em .
Fal c o ner ( 1 9 5 2 ) , Falconer and
La t y s z ewski ( 1 9 5 2 ) , Fa l c oner ( 1 9 6 0) , Korkman ( 1 9 6 1 ) , Fowler and Ensminger
( 1 9 6 0) , Da l t o n ( 1 9 6 7 ) and o t h e r s cond u c t e d s tud ies of t h i s type .
7.
Typ e C ( int e r-popu l a t ion, mi c ro-environmen t al ) :
Such interac t ions c o u l d
b e illus t r a t e d by an inte r a c t ion o f se veral l i n e s , s t ra in s , bree d s o r
c r o s s e s wi th env ironme n t al variab i l i t y wi t h i n f l o cks .
The ideas on
h e t e ro s is put f o rwa rd by Rob e r t s on and Reeve ( 1 9 5 2 ) sugge s t tha t the
h e t erozygous geno types are comp e t ent t o h and le a wider r ange o f micro­
envi ronmen t s than the h omozygous geno t ypes and a r e thus l e s s subj e c t to
environme n t a l var iat ion .
In t e rp re t i ng the re s u l t s in v i ew o f t h e above
sugge s t s that the mi c ro- envi ronmen tal f l uc tuat ions c ause some popula t i ons
( the pureb r e d s ) to vary , y e t they produ ce no e f f e c t on o ther popula t i o n s
( the h yb r i d s ) .
in t e r a c t ions .
He t e ro s i s , in t h i s sense , is an examp le o f type C
However, type C intera c t ions are no t generally th ough t t o
b e impo r t ant i n the f i e l d o f a p p l ied gen e t i c s .
Typ e D ( int e r-popu l a t i on. ma c ro-environmen t a l ) :
Ty p e D in t e ra c t i o n s are
f o und in gene t i c gro ups t h a t show large va r i ed responses t o the dif f e r e nt
e nv i r onmen t s .
The p re s en ce o f type D i n t e r a c t ions wou l d i n f l u e n c e
i mpor t an t d e cis ions i n a nimal and plant breed ing .
Before the animal
b r eeder can locate the b re e d o r s t rain t h a t wi l l p e r f o rm b e s t in h i s
environme n t , h e mus t t e s t for the pr e s ence o f type D i n t e rac t i ons .
Having f o und the b e s t s t r a in for h i s p a r t i c u l a r cond i t ions , he mu s t t hen
d e c id e whe ther the c ond i t ions und e r wh ich h i s se l ec t i on is to b e c a r r i e d
o u t a re i mp o r t ant ;
i . e . , whe t h e r any type B i n t e ra c t ions are p r e s en t .
Ha ldane ( 1 9 4 6 ) c l a s s i f i ed the
GEl
wh i c h may occur wh en gen o typ e s
d i f fe r in g a t a single locus a r e exposed t o c o n t r a s t ing envi ronmen t s , and
Dunlop ( 1 9 6 2 ) extended Hal dane ' s c l a s s i f i c a t ion t o c over the t y p e s o f
in teract i on wh ich may o c cur wi t h groups o f anima l s d i f f e r ing at many l o c i .
A simi lar approach was adop t ed by McBride ( 1 9 5 8 ) .
Dun lop ident i f i e d
f o ur types o f intera c t ion a c c o r d ing t o magn i t ud e o f d i f f erenc e s in
8.
geno t y p e and envi ronment .
He arbi t r ar i ly c lass i f ie d gene t i c
d i f f e r e n c e s as e i t her large o r s ma l l , d e f in ing s ma l l gene t i c d i f ferenc e s
a s tho s e occurring among in d iv iduals o f a s ingle pop u l a t ion s u ch as
s i n g l e f l ock or the related f l ocks of a breed or s t r a i n and large gene t i c
d i f f e r e n c e s as those be tween s t r a ins , b reed s , s p e c i e s o r even wider
gene t i c d iv i s ion .
S i mi la r l y , h e de f i ned s ma l l env i r onmen t a l d i f fe rence s
as th o s e o c curring f r om ind ividual to individual in a s in g l e general
env i ro nment whe re d i f ference s due to such d e f i nab le e l e me n t s in the
envi ronme n t as f i e l d , age , sex, e t c . are ei ther non- e x i s t en t o r have
been c o r r e c ted f o r , and large environme n t a l d i f f e ren c e s as tho se b e tween
d i f fe re n t d i s t r i c t s or regions or widely hu s b andry or nut r i t ional
regime s .
His me thod of c l a s s i f icat ion is i l lus t ra t e d in F i g . 2 .
In t e r a c t i on o f type
l:
s ma l l x small -
Th i s may o c cur in the us u a l
mod e l o f sources o f va r i a t ion in a pop u l a t i on where g e n o t y p e s and
envi ronme n t s are uncorre l a t ed .
e s t ima t e ;
The s e interact ions are d i f f i cu l t to
i f p r e s en t , a so u r c e o f va r i a t ion o f unknown s i z e co u l d l ead
to a f a l l in the h e r i t ab i l i ty and hen ce hind er p rogre s s by s e l e c t ion .
Th i s t y p e o f inte rac ti on c o r r e s pond s to type A o f Mc B r i d e ' s ( 1 9 5 8 )
c l a s s i f i c at ion .
In t e ra c t i on o f type 2 :
la rge x sma l l -
The s e may o c c u r when there are
large d i f fe rence s b e tween geno types and sma l l d i f f e r en c e s b e tween
env i r onme n t s , s u ch as several b r e eds in one are a .
The s e i n t e rac t ions
are s e l d o m imp o r t ant and are d i f f i c u l t t o e s t imat e .
In t e r ac t ion o f type 3 :
s mal l
x
large -
Th is c l as s o f i n t e r a c t i on
co r r e s ponds t o t ype B of McBr id e ' s c l a s s i f i c a t ion .
Large int e r a c t ions
o f th i s t ype are a h indran ce t o sele c t ion as the sma l l gene t i c
9.
TYPE OF
I NTERACT I ON
ENV I RONMENTAL
D I FFERENCES
Fig . 2 :
1
G ENET I C
DIFFERENCE S
Typ e s o f Hered i t y x Env ironmen t In t er a c t ion
( a f t er Dun lop , 1 9 6 2 )
10.
d i f f e rences are s e p a r a t e d by large env i ronme n t a l d i f ferences .
In many
coun t r ie s , s ir e s a re produced in s t ud f l o c k s wh ich are usua l ly s i t u a t e d
in good areas , t h e an imals b e ing t r ea t e d t o above- ave rage husbandry
p ra c t i ce s ;
mal e s a r e then d i s t r ib u t e d fo r use over a wide r ange o f
envi ronmen t s .
Inve s t i gat ion of the magn i t udes o f type 3 intera c t ion i s
If a common founda t i on s t o ck we re
the re fore o f cons i d e r able imp o r t an ce .
randomly d iv id e d i n t o two d i s t r i c t env i ronme n t s and then s e l e c t e d und e r
the s e enviro nmen t s , t he d i f f e r ences in the geno types deve l oped und e r
t he s e re g ime s wou l d s t em o r i gina l l y f rom t h i s type o f i n t e ra c t ion , b ut
i t may we l l deve l o p into type 4 in t e ra c t ion by the end o f the exp e r imen t ;
i . e . , gene t i c group s showing large d i f ferent ial response t o the d i f f e rent
environmen t s .
Th i s has been reco rded by Fa l coner and La t y s z ewsk i ( 1 9 5 2 )
i n s e l e c t i on fo r b ody we igh t i n mice .
In t e ra c t ions o f type 4 :
large
x
la rge -
i n t e r a c t ions o f grea t e s t ma gni tude .
Mo s t l i kely to f i n d
Int e r a c t ions o f th i s type are o f
imp o r t ance in choo s i n g the c l a s s o f o r gan i sm suited t o a p a r t i c u l a r
envi ronmen t .
Type 4 can b e desc r i bed a s s t rain
x
envi ronme n t .
the
s t ra in b e in g ex i s t in g or sp e c i f i ca l ly deve loped .
Re cen t ly , Pan i ( c i te d by Pan i and La s l e y , 1 9 7 2 ) a t temp t e d t o
c las s i fy t h e inte r a c t ion in the context o f b r e eding o f anima l s f o r
d i f f e rent env ironme n t s .
He b a s e d the c l a s s i f i c at ion on whe the r the rank
of genotypes und e r c on s iderat ion change f rom one env i ronme n t to the
o t he r and also i f the intera c t ion e f f ec t s a r e s t a t i s t i c a l ly s i gn i f i c an t .
His c la s s i f i c a t ions ( t ype 1 - 4 ) are p r e s e nt ed in Fi g . 3 .
Type 3 in
this case r e f l e c t s t he kind of in t e r a c t ion whe re a d i f fe rence in
h e r i t ab i l i ty ( d i f f e r ence in the ma gn i t u d e of genet i c width ) b u t no change
in rank was n o t ed .
In type 4 , the e s t ima t e o f he r i t ab i l i ty ma y o r may
no t a ccompany the change in ranks .
11.
Ay
By
Ax
Bx
Ax
Bx
No
Type 1
change in ranks
s i gn i f ic ant interaction
No
No
Type 2
Ch ange i n ranks
sign i f i c a n t in t e r a c t i on
Ax
------
By
Ay
A:v:.
Bx
Bx
Type 3
change in ranks
S i gn i f i cant in t e r a c t ion
No
Type 4
Ch ange in ranks
Si gn i f i c ant in t e r a c t ion
ENVIRONMENTS
Fig . 3:
Ay
(X, Y)
A c l a s s i f i c a t i on o f geno t yp e x environment
i n t e ra c t ions spec i a l ly d e s i gned f o r use in
f a rm an imal s t u d i e s ( a f t e r Pan i , 1 9 7 1 )
12 .
FALCONER ' S CONCEPT OF GENETIC CORRELATIONS BETWEEN PERFORMANCE IN
DIFFERENT ENVIRONHENTS
Gene t i cis t s and b reeders a re p r ima r i l y in t e r es t e d in the
t r a nsmi t t i ng ab i l i t y of an ima l s and p l an t s .
Th i s i n t e r e s t is n o t
confine d to j us t o ne t r a i t but to seve r a l t ra i t s wh ich t o g e t h e r make up
t o t a l p roduc t ion and not j u st fo r the expres s i on o f t h e s e t ra i t s in one
environment but in a range of environmen t s .
Fa l c oner ( 1 9 5 2 ) made a con s i de rab l e con c e p t u a l �d vance i n h a nd l i n g
o f th i s s ubj e c t when h e con s i d e red t h e p rob lem o f p e r f o rman c e un d e r two
envi ronme n t s as a case o f two d i f f e rent cor r e la t e d char a c t e r s , thus
extending the conc e p t o f gene t i c c o rre l a t ion (Ha ze l ,
s i tu a t ion .
1 9 4 3 ) to t h i s
Th i s con cept a l l ows one t o e s t ima te the r e l a t ive progre s s
th a t can b e mad e f rom d i r e c t s e l e ct i o n fo r p e r fo rman c e i n a g i ve n
enviro nment or from ind ire c t s e l e ct i o n p r a ct iced i n a d i f f e r e n t
e nvi ronmen t .
He a r gued tha t s in re p e r f o rma n c e i n a f avou rab l e
envi ronme nt h as a dif ferent genetic bas i s f r om p e r f o rma nce i n an
unfavourab le envi ronmen t , a supe r i o r genotype in one envi ronment c o u l d
no t b e expe c t e d t o b e a su p e r io r i n
a
dif ferent envi ronment .
Th e
ma gn i t ud e of the c o r re l a t ion c o e ffi c i e n t ( r G) i s a me a s ure o f t h e
prop o r t ion o f t h e genes wh i ch are common t o bo th cha r a ct e r s .
t he n a l l o f the genes are c ommon t o b o t h and two ch a r a c t e r s c an b e
regarded as one and n o GEl o c c u r r ing .
Fa lconer ( 1 9 5 2 ) de sc rib e d t h e ab ove conc e p t by an a p p li c a t ion o f
t h e r u l e s o f path c oe f fi c i e n t s a s f o l l ows :
Let cha r a ct e r s
l
and 2
s t a nd f o r p e r f o rman ce ( e xp r e s s ed i n s t and a r d devi a t i o n s ) of s ome t r a i t
un de r two envi ronmen ts.
D i re c t s e l e c t i on f or J will p roduce gain
p rop o r t ional t o h f ( s ince �G 1
=
ih 1 0 1 ) .
S e l e c t i o n for l on t h e b a si s
13.
o f 2 w i l l be ( al l e l s e b e ing e q ua l ) p r o p o r t ional to h 2 r 1 when 6G
2
gen e t i c change , h
deviat ion uni t s ,
2
a
he r i t ab i l i t y , i
=
=
s e l e c t ion d i f f e r en t i a l in s t andard
gene t ic s t andard d eviat ion ,
r
=
gene t i c c o r r e l a t ion .
When t he quan t i ty h 2 r 1 2 excee d s h 1 i n d i r e c t s e l e c t io n i s mo r e e f f i c i ent
t han d irect s e l e c t ion .
However , GEI reduces r 1 2 and may mak e s e l e c t ion
in o ne env i ronmen t for p e rforman ce in ano t her ine f f i c i en t .
Jame s ( 1 9 6 1 )
d eveloped the s t a t i s t ical a s p e ct o f the p rob l em by ext ending Falconer ' s
( 1 9 5 2 ) t reatmen t t o the case wh ere gene t i c gain in b o t h env i ro nmen t s is
d e s ired , t hough the two environme n t s may d i f f e r .
Fal coner ( 1 9 5 2 ) p o in t ed out tha t i f con t ro l of the env ironment
invo lved on ly a reduct ion in envi ronme n t al variance , the g ene t i c
co rre l a t ion wou l d be un i t y .
I f h 21 and h 2 a !e r e s p e c t ive l y t h e
2
he r i t ab i l i t ie s o f p e r f o rmance in cont r o l l e d and uncon t ro l l e d e c onomi c
environment and r G is the gene t i c c o r r e l a t ion b e tween t hem , then i f
h 1 r G i s gre a t e r than h 2 , s e l e c t ion shou l d b e c a r r i ed o u t und e r the
cont r o l led env i ronment .
Exp e r imental ev idence for Fa l c oner ' s con c e p t
T h e s t udy o f GEI based o n the t heory p r epo unded by Fal coner ( 1 952 )
and further d eve loped by D i ckerson ( 1 9 6 2 ) in gene ral , has f o l l owed two
l in e s - t he dynam i c and the s t a t i c .
In the dynamic app roach to GEI , the p o s s ib l e accumu l a t ions o f
d i f f e rent ial r e s ponses are me asured when s e l e c t ion i s p r a c t i s e d in
d i f f e rent environmen t s .
I t i s po s s ib le t o con t ras t t h e d i f f e r e n t
b ehaviour o f t h e geno t yp e s in d i f f e r e n t envi ronments when t hey a r e
0
s e l e c t e d not only in their environment o f s e l e c t ion b u t a l s o in o t he r
env ironmen t s .
The p ub l ished exp e r imen t s in mammal s are r e s t r i c t e d
14 .
a lmo s t exclus ively t o growth r a t e on ad libitum and res t r i c ted f e e d i n g
r e gi mens f o r ra t s and mice .
Es t ima t i on o f GEl , as und e r t aken by
Fal coner and Latys zewski ( 1 9 5 2 ) i s imprac t i cable in l ive s t o ck b e c a u s e o f
the number o f genera t ions required and the n e ce s s i t y for avo id ing t e mpo ral
var i a t ions in envi ronme n t .
S ince the e s t ima t ion of the pa rame t e r s w i t h
t h e requi red pre c i s ion ne c e s s i t a t e s t he me a s u r e ment o f a large numb e r o f
ind ividua l s i n each o f t h e alt ernat ive envi ronmen t s , t h e cos t appe a r s t o
b e prohib i t ive in farm an i mal s .
One such s t udy r epo r t ed so f a r by
Fo,v l er and Ensminger ( 1 9 6 0 ) in p i gs des erves men t ion .
An a l t ernat ive to the dynamic approach is the s t a t i c approach in
wh i ch the relat ive pe r f o r mances o f d i f f e r e n t geno t ypes are me asured
unde r d i f f e r en t environmen t s in fac t or i a lly d e s i gned expe r i me n t s and
t h e in t e r a c t ion var iance e s t i mat ed .
Ideal ly , one would wish t o c o mpare
the p e r f o r man ce o f the s ame geno t ype ove r d i f f e re n t environmen t s .
is usually not p o s s ib l e w i t h dome s t i c an i ma l s .
Th is
Hence groups o f r e la t e d
i n d i v idual s , i . e . , p a t e rnal ha l f - s ibs , b reeds , s t rains are c o mmonly
cho sen f o r s t udy .
Con s id e rab ly less r e s ou r c e s are requi red f o r t h e
s t a t i c approach and a numb e r o f worke rs have appl ied i t t o the farm
a n i mals .
Wh i l e the i nve s t i g a t ions of GEl in s t a t i c p opula t ions may give
ind i c a t ions as t o whe th er t he envi ronmen t i s i mp o r t an t in s e l e c t ion
p rob lems , t he s e q ues t ions c an , in f a c t , only be answe red conclus ive ly
b y s e le c t ing unde r d i f f e r e n t envi ronme n t al cond i t ions .
Falcon e r and Lat ys z ewski ( 1 9 5 2 ) repo r t e d the r e s u l t o f a s e l e c t i on
e x p e r i me n t in support of Fal cone r ' s ( 1 9 5 2 ) con t e n t ion .
The e f f e c t o f
t h e p lane o f nut r i t ion on improvemen t in body we ight a ch ieved b y
s e le c t ion w a s s t ud ied in mic e .
Two s t ra in s d e r ived f rom a s ingle
15.
fo unda t ion populat ion were s e l e c t e d in exac t ly t he s ame manner for
we i gh t at 6 weeks o f age:
one s t rain was fed ad lib .
and the o th e r was
r e s t r ic t ed to ab out 75% of the no rma l food i n t ake b e tween t h e ages o f
The
wea n i n g and we i gh ing - t h a t i s , b e tween t h e ages o f 3 t o 6 we eks .
r e s ul t o f s e l e c t ion was however, d ifferent in each env i ronme n t .
inc r e a s ed und e r s e l e c t ion i n b o th s t ra ins;
We i g h t
t h e ave rage increase per
gene r a t ion in t he full d i e t s t rain was 1 . 5 % o f the un s e l e c t e d we i gh t ,
and 1 . 3 % in t he,r es t r i c t e d s t rain .
The h e r i t ab i l i t y was h i gh e r in t h e
re s t r i c ted d i e t s t rain b e in g 0 . 2 9 o n res t r i c t ed d i e t a n d 0 . 2 0 on fu l l .
Exchan g e s o f n u t r i t ional leve l we re made be tween the s t rains a f t e r 5 , 7
and 8 gene r a t ions o f s e l e c t ion .
When reared on the r e s t r i c t e d d i e t ,
t he re s t r i c t ed d ie t s t ra i n was sup e r i o r in 6 week we i gh t , t h e fu l l d i e t
s t ra in showing n o improveme n t over t h e uns e l e c t e d leve l .
When reared
on f u l l die t , the full d ie t s t rain was supe r i o r but the r e s t r i c t e d d i e t
s t r a in d id no t f a l l far s ho r t o f i t and showed a ma rked imp roveme n t
over t he uns e l e c ted leve l f o r full d i e t .
It i s concluded t h a t t h e
r e s u l t s do no t support H arnrnond ' s t h e s i s .
Ano t he r e xp e r iment w i t h m i c e se l e c t e d on op t i mal a n d subo p t i ma l
d ie t s wa s rep o r t e d b y Falconer ( 1 9 6 0 ) .
Two -way s e l e c t i on was app l i e d
t o one p a i r o f l in e s for grow t h rate when ind ividuals were r e ared o n
a
h i gh p l ane o f nu t r i t ion and t o ano ther pair o f l ines when ind ivi d u a l s
we r e r e ared on a l ow p l ane o f nu t r i t ion .
The s e l e c t e d t r a i t s were high
and l ow b ody wei gh t gain from 2 1 t o 42 d ays of age .
n o rmal and h i gh f ibre .
o f age by 2 0 % .
The d i e t s were
Th e l a t t e r reduced grow t h f rom 2 1 t o 4 2 days
Re s ul t s o f t h i s exp e r ime n t showed t h a t 2 1 t o 4 2 days
body we i gh t whe n me asured on the op t imal d i e t , was increased almo s t as
muc h b y s elec t ion on the s ub o p t i mal as on t h e op t imal d i e t b u t g rowth
on the s ub o p t ima l d i e t wa s n o t incre a s ed at all by s e l e c t i on on t h e
16.
In
op t imal d i e t .
this and t h e p rev ious exp e r ime n t by Falconer and
La t y s z ewski ( 1 9 5 2 ) s e l e c t ion on op t ima l d i e t s imp roved only growth on
th e o p t imal d i e t s but s e l e c t ion on s ubo p t imal die t s imp roved growth on
bo th d ie t s .
Re s u l t s o f t he two exp e r ime n t s ind i c a t e that i t may b e
be t t e r t o s e l e c t under t h e wo r s t cond i t i ons rather than the b e s t
cond i t ions i f the s e l e c t ed p o pula t i on is e xp e c t ed to p e r form over a
range o f envi ronmen t s .
It
i s al so o f i n t e r e s t that the mice s e l e c t e d
f o r in creased grDwth o n the s ubopt ima l die t were less f a t a n d we re
be t t e r mo thers than tho se s e l e cted on the o p t imal d ie t s .
Falcon e r
s t a t ed tha t t h e resul ts i n h i s exper iment wh i ch r e f e r t o t h e final
out c ome of th i r t e en gener a t i o n s o f s e l e c t i on , d o not a c cord we ll with
the t h e ory o f s e l e c t ion f o r c o r r e l a t e d charac t e r s .
Over the f i r s t f ew
gene r a t ions the resul t s we r e in reasonably good agre ement wi th the
theo ry .
The d is c repan c i e s p r obably arose from chan g e s o f the gene tic
p ar ame t e rs wh i ch took p l a c e duri ng the course of s e le c t io n .
Th e re are
o th e r s tudies o f GEl on mi c e , Drosophi la and Tribolium, s imilar to th a t
o f F a l c oner and Latys zews ki ( 1 9 5 2 ) an d Fa l c one r ( 1 9 6 0 ) .
Mo s t o f the work on m i c e i s based on s e l e c t ion w i t h in d i f f e ren t
d i e t s and on s i r e pro geny g r o u p s s t udied in re l a t ion t o the d i f f e re n c e s
i n q u a l i t y and quan t i ty o f f e e d ( Youn g , 1 95 3 ;
al.
1966 ;
1972 ) .
Da l t on , 1 9 6 7 ;
Ko rkman , 1 9 6 1 ;
B a t ernan 1 9 7 1 and 1 9 7 4;
Park e t
Kownacki and Geb l e r ,
Young ( 1 95 3 ) exam in e d the s t r a in x d i e t i n t e r a c t ions and
o b s e rved the s l ower growth o f C5 7 s t ra in o f mice on c rushed o a t s than
the CBA s t rain .
The her i t ab i l i ty e s t imat e s o f body weigh t was l owe r
( 0 . 0 6 6 ) in a s e l e c t ion on a l ow p lane and h i gher ( 0 . 2 1 8 ) in a s e l e c t i on
on a h igher p l ane o f nut r i t i o n ( Korkrnan , 1 9 6 1 ) .
17.
Park et a l .
( 1 9 6 6 ) inve s t i g a t e d the inf luenc e o f f e e d i n g r e g ime on
t he e f f e c t s of s e l e c t ion for p o s t -wean ing gain in the rat and p o in t ed to
the d e s irab i l i t y of s e l e c t ing under the c o nd i t ions in wh i ch it i s
e xp e c t ed the d e s cendan t s are t o be kep t .
When compared in e a c h r e g ime ,
t h e s e le c t ion l ine devel op e d i n t hat r e g ime t ended t o give a l a r g e r
r e s p o n s e than t h o s e devel oped i n o t her r e g ime s .
Dal t on ( 1 9 6 7 )
o b s e rved that t h e i nd i r e c t responses o n e i t her p l ane ( fu l l d i e t and
d i lu t ed d i e t ) were equal to the d ir e c t r e spon s e s on the s ame p l an e .
Howeve r , Dalton ' s f ind ings do not so much contradict Falconer ' s
recommendat ions as remove the i r l imi t a t ions .
Other s t ud i e s c i t ed
by B a t eman ( 1 9 7 1 , 1 9 7 4 ) and Kownacki and Gebler ( 1 9 7 2 ) a l s o s up p o r t
Falconer ' s gener al thes i s .
W i l s on et a l .
( 1 9 7 2 ) ob s erved that there
wa s n o ind i cat i o n that s e le c t ion could b e increased b y subj e c t i n g m i c e
t o t emperature s t re s s dur ing the s e l e c t ive p r o c e s s .
Ext ens i ve s t ud ies r e l a t in g t o the p ro b lem o f GE l have b e e n mad e
w i t h the lab . i n se c t s .
In a s e r i e s o f s t ud i e s on the e c o l o g i c al
g e ne t i c s o f Drosop hi la Rob e r t s o n ( 1 9 59 ,
1 9 63 ) reveal ed t h e i n t e r­
dep endancy o f gene t i c and env i ronme n t a l f a c t o r s in d e t ermining t h e
n a t u r e o f q uan t i t a t ive variat ion .
Lines s e l e c t e d f o r large and sma l l
b o dy s i z e i n Drosophi la showed r e l a t ive l y lar ger we ight reduc t i o n when
g rown on subop t imal d ie t s than d i d ind ividuals f rom the uns e�e c t ed
populat ion .
Druger ( 1 9 6 2 ) found the magn i tude o f corre l a t ed r e s ponse
for wing- length unde r the t emp e r a t u r e o th e r than that of s e l e c t i o n was
i n f luenced b y b o th d i re c t i on of s e l e c t i o n and cul turing t empe r a t u r e .
However , the he r i t ab i l i t y e s t ima t e s ob t a ined under two d ivergent
cond i t ions ( l arval den s i t y ) were very c l o s e in an exp e r ime n t b y Frahm
and Koj ima ( 1 9 6 6 ) .
Th e ' corr e l a t ed ' r e s ponse o f a l in e was u s u a l l y
a s l arge as t h e l in e ' s p r imary r e sp ons e .
18 .
In s t ud i e s o f growth o f Tribo lium cul t ured in d i f ferent humid i t i e s ,
McNary and Be l l ( 1 9 6 2 ) and Bray et a l.
( 1 9 6 2 ) f o und G E l s i gn i f i c an t ly
i n f l uen c ing the responses t o s e l ect ion .
B e l l and McNary ( 1 9 6 3 ) however ,
found that sele c t ion for growth in t he subop t imal environment gave a
c o rr e l a t ed response in the o p t imum e qual in b o t h the r ep l i c a t ions t o t h e d i r e c t r e sponse o f s e l e c t i o n under o p t imum cond i t ion s .
Hard i n and B e l l
( 1 9 6 7 ) r eported t h a t the max imum p e r f o rmance in a c e r t a in env i r onmen t
r e s u l t e d from s e l e c t ion in t h a t envi ronmen t and the max imum average
p er f o rmances resul t e d from s e l e c t ion in the poor envi ronmen t .
Yamada
and Be l l (1 9 6 9 ) ob s e rved in a s e l ect ion expe r imen t t h a t the d ir e c t
s e le c t io n respon s e s exceeded c o r re l a t e d responses und e r b o t h leve l s o f
nu t r i t i o n (Good and Poor ) and average p e r f o rmanc e o f l in e s s e l e c t e d f o r
large l a rval s i z e und er ' Po o r ' e xceed ed ave rage p e r f o rman c e o f lines
se l e c t e d for large size und e r ' Good ' .
An e xp e r iment comparab l e t o those o f Falcon e r on mice was
cond u c t e d by Fowl er and En smi n g e r (1 9 6 0 ) wi t h swine and de serves
men t i on .
two l ine s .
They r andomly d iv i d e d a cros sbred populat i o n o f swine in t o
One was selec t e d f o r increased aver a ge d a i l y ga i n for
wean i n g t o 6 9 kg und e r a full f e eding regime (H) .
The o t her l ine was
s e l e c t e d for the s ame t ra i t at a feeding leve l of 70% that of f u l l f e e d
gr oup ( L ) .
The resul t s o b t a in e d were q u i t e s imi lar t o those o f
Fal coner i n tha t gain i n we i g h t o c curred i n l in e s s e l e c t ed wi t h in t h e
h i gh ( H ) a n d t h e l ow (L) nu t r i t i onal p l an e s .
Al s o , whe n the s t o ck s
s e le c t e d on t he o n e p l ane we r e t r an s f erred t o t h e o t h e r t h e L was
equiva l e n t in g a in t o H s t oc k in the H r e gime but the H s t o ck was
inf e r i o r to the L s to c k on t he L regime but apparen t l y superior to t h e
found a t ion s t oc k .
The L s t o c k had higher e f f i c iency i n t h e u t i l i s a t i o n
o f f e e d t h an t h e H s t o ck on bo t h regime s .
19 .
The ap p roa ch o f Falconer ( 1 9 5 2 ) to the p r ob lem o f GEI and the
r e s u l t s of the other exper imen t s reviewed above lead t o the f o l l owi n g
main i n f erenc e s .
One general p r in c i p l e wh i ch seems t o emerge from the exp e r imen t s
o n GEI i s that they are mo s t l ikely t o b e found whe re i n t e rpopul a t ion
geno t yp e s and mac roenv i ronmen t s are invo lved .
The genera l i t y o f
i n f e renc e s p o s s ib le f rom the above exper imen t s are l im i t ed b y the f a c t
t hat the magn i t ude o f d i f feren c e s b e tween t h e environme n t s and be twe en
t he gene t i c e f fe c t s vary in d i f f eren t s i tuat ions .
Th i s leads us t o
the n e c e s s i t y o f exp lo r i n g the i n f luence o f a varie t y o f env i ronmen t s
and gen o types on each o f the t r a i t s in wh i ch w e have in t e re s t .
The
f ind ings from the exp e r iment s reviewed above i n gen e r a l sup p o r t
F a l coner ' s the s i s .
The resul t s are in agreement in sugge s t i n g that
p r o gr e s s f rom s e l e c t ion under un f avourab l e cond i t ions approaches or
equals t h a t und e r f avourable cond i t ions when t h e obj e c t ive i s t o improve
p er f o rmanc e in a favour ab l e envi ronment .
Howeve r , s e l e c t ion und e r the
unfavourab l e cond i t ions c on s i s t en t ly p roduced mo re response than d id
s e le c t io n under favourab l e cond i t i ons when the obje c t ive i s improveme n t
i n the unf avou rab le o r average envi ronmen t s .
I n gener a l , exper imen t a l
i n f orma t i o n doe s no t i nd i c a t e that one c an exp e c t t o enhance p r o g r e s s
b y s e l e c t ing i n an env i r o nmen t d i f f e r en t f rom t h a t in which t h e
p o p u la t i o n i s t o b e p ro duced .
And f inally , the c o n s e q uences o f GEl e x i s t in g f o r two env i ronme nt s
c a n b e p r e d i c t e d f rom ( 1 ) the gene t i c correla t io n be twee n the two
environmen t s f o r a t r a i t ;
environrnen t s -;
environment s .
( 2 ) the her i t ab i l i ty e s t imat e s in t h e two
( 3 ) the phenotyp i c var i an c e s o f a t r a i t i n two
S ince the value o f the h e r i t ab i l i t y depends on the
20 .
magn i t ude o f a l l t he componen t s o f varianc e , a change in any o f t h e s e
w i l l a f f e c t it .
GENOTYPE- ENV IRONMENTA L INTERACT I ONS IN SHEEP
A remarkab l e d ive r s i t y i s obs e rved in sheep produc t ion s y s t ems
throu ghout the wor l d .
Sheep are exp e c t ed t o l ive and p ro duce a
cons i d e rable var i e ty o f produc t s ;
meat , wo o l and milk e t c . , over a
wider range o f environmen t s than mo s t f a rm an imals .
The preva i l i n g
f armin g p r ac t i c e s d o n o t permit as r i gid a c o n t rol o f envi ronme n t s i n
rais ing sheep as i s p o s s ib l e w i t h the dairy c a t t l e o r poul t ry .
S in ce
o p t imum produc t i o n i s c r i t ical o f any l ive s t o c k ent e rp r i se , the
exi s t en c e of GEl and p a r t icularly of gen o t y p e x nut r i t ion i n t e ract i o n s
and breed geno type x envi ronment f o r c omp onent s o f p roduct ion and
rep roduc t ion in sheep are l ikely t o be impo r t a n t .
Re l at ively l i t t l e c r i t i ca l in f o rmat ion i s available on t h e
imp o r t ance o f GEl i n sheep .
The s t at i c exp e r imental app roach , in
whi ch t he relat ive p e r f o rmance o f d i f f e ren t genotypes are me asured
under d i f f e rent envi ro nment s in f a c t o r ially d e s i gned e xp e r ime n t s and
the i n t e r a c t ion v a r i a n c e e s t imat ed , has b e e n a pp l ied i n mo s t o f the
s t ud i e s c ondu c t e d in sheep .
f o r t h i s approach .
Cons iderab ly l e s s resou r c e s a r e r e q u i r e d
The cho i c e o f the geno t y p e s and t rea tmen t s , h a s ,
i n gener a l , been arb i t r a ry c r e a t ing a body o f l i terature w i t h a wide
r ange o f gen o t yp e s and t reatment s comb ina t io n s .
Int e r a c t ions i nvo lving
d if ferences in nut r i t ional s t a t u s or l ev e l s have rece ived mor e a t t en t ion
t han r e search on any o t her env i ronme n t a l e f f e c t s.
A r ev i ew o f t h e
repo r t s on var ious t ra i t s o f e conomic imp o r t an c e i n s h e e p i s p r e s e n t e d
b e low .
21.
Growth charac t e r is t i c s
Gen o type x nut r i t ion
King and Young ( 1 9 5 5 ) condu c t ed an exper iment showing the r e sp on s e s
in b o dy we igh t a n d body me asuremen t s e xh i b i t e d b y young ewes o f the
Blackface , Che v i o t and
Wi l t shire breeds und er two nut r i t ional and two
temp e r ature t r e a tment s .
The d i lu t ion o f o a t s by cha f f was adop t ed a s
a c onvenient me thod o f r e s t r i c t ing the d i e t .
The warm e nvironment
°
cons i s t ed of p e n s in a hea ted a n ima l-house kep t at 6 0- 6 5 F .
The c o l d
env ironment cons i s t e d o f p ens e r e c t e d i n a very windy a l l e y exp o s e d t o
r i g o r s o f a c o l d winter .
Neither b r e ed x env i ronmen t nor b r e e d x p lane of nut r i t ion was
s i gn i f i cant in y e ar l ing we ight .
of h ind- c annon and t ib ia ;
Ske le t a l me asurement s s u ch a s l e ngth
width of h ind- c annon and heart - g i r t h sh owed
the p r e s en c e of marked s i gn i f i c an t i n t e r a c t ions due to mor e rap i d growth
of B l ackface sheep on the h i gh p l an e of n u t r i t ion .
The n e g a t ive resul t s
for c ha r a c t e r s wh i c h gave i n s i gn i f i cant i n t e r a c t ions were l e s s i n f o rmat ive ,
s in c e they may b e a r e f l e c t ion only o f the sma l l s cale o f the e xp e r imen t .
Th i s e xp e r iment c o r r e sponds t o Type 4 o f Dunlop ' s c l a s s i f i c a t i o n ; i . e . ,
when gene t i c and envi ronme n t a l d i f f er e n c e s are b o t h l a r ge .
Four breeds (Linco ln , Corriedal e , Polwa r t h and Fine Me r ino ) were
ma int a ined on two nut r i t ional r e g ime s by D a l y and Car t e r ( 1 955 ) .
Though the int era c t ions we r e not spe c i f i c a l l y s t ud i e d , they con c lu d e d t ha t :
"With f ew excep t i ons t he a b s o l u t e or r e l a t ive values o f the char a c t e rs
measured form a s mo o t h s e r i e s f r om the Fine Mer ino through the P o lwarth
and C o r r iedale t o the Linc o l n - e i th e r in t h e a s c end ing o r the
d e s cend in g order o r s how l i t t le o r no d i f f e rence b e tween t h e b r e e d s
( e . g . b o d y length and he i gh t , f o o d int ake p e r uni t ne t t l ive we i gh t ;
22 .
t o t al s kin produ c t s p e r un i t food i n t ake ) .
The re l a t ive p o s i t i on s o f
the breeds were gene r a l l y ma in t a ined a s f o o d was progres s ive l y reduced " .
However , t here was an ind icat i on o f the GEl whe n examining the ra t i o o f
body we i ght at unr e s t r i c t e d int ake t o body we i ght a t 2 0 % o f t h i s i n t ak e ,
t he Me r i no showin g the gre a t e s t percen t age r e s p onse t o changes in
nut r it ional level .
Mars t on , P i e r c e and Car ter ( c i t ed by Turner and Young ,
e xamined s t rain x env i ronment i n t e r a ct ions i n Austral i a .
1969)
Two Me r in o
s t r a in s ( s t rong wo o l and fine woo l ) were f e d a t two nut r i t ional l eve l s .
The s t rong wo o l s t rain s howed a grea t e r body we i ght r e s ponse to good
n u t r i t ion .
King et a l .
( 1 9 5 9 ) s t udied the d i f fer ent i a l response o f l amb s o f
The l amb s
var i ous b reeds and cros s e s t o d i f f e r e n t p l an e s o f nu t r i t i on .
o f two b r e e d s and f ive c r o s s e s of she ep we r e wint ered i n h i gh -h i gh ,
h i gh- low , l ow-h i gh and l ow-low nut r i t ional env i ronment s and s ub s e q u en t ly
b r ought t o the same we i gh t for s l augh t er .
I n b o dy we i ght , the ma i n
f e at ure o f the expe r ime n t was t h e simi l a r i t y o f t he res ponse t o
d i f f erent environmen t s .
Body me asureme n t s a l s o showed con f o rmi ty
b e tween b reeds in response to envi ronmen t s .
Morley ( 1 9 5 6 ) in an exper iment invo l v i n g the progeny o f d i f f e r e n t
Me r ino rams kep t on a h i gh and a l ow p l ane o f n u t r i t ion found no
i n t e r a c t ions in body we i gh t at 6 mon t h s but h i ghly sign i f i c an t
i n t e r a c t ions were evident a t 1 2 and 1 7 mon t h s b o dy we i gh t .
At the colle c t ive f arm in Al t a i , U . S . S . R . S t akan et a l .
( 1963)
found that t he heri t ab i l i t ie s were lower under p o o r than good
environme n t a l cond i t ions .
S t u d i e s were condu c t e d invo lving two group s
23.
o f l amb s reared on two p l anes o f nu t r i t ion , h i gh and l ow ;
her i t ab i l i t y
e s t ima t e s o f 0 . 1 5 and 0 . 0 5 r e s p e c t ive l y were found f o r we i gh t .
Var i a t i o n of t h i s charac t e r was l e s s i n high p l ane t han in low p l an e .
E f f e c t iven e s s o f s e l ec t i on o f sheep o f Ku chugury b r e e d group und e r
d i f f e r en t feed ing r e g imes w a s inves t i gated by An f ino genova ( 1 9 7 0 ) i n the
U. S . S .R.
ade q ua t e .
Ewes were fed on an adequat e d i e t o r a d i e t 2 3 % l e s s t h an
The g ene t ic var iance amoun t ed t o . 1 2 and . 3 0 r e s p e c t ively ;
t he p e r ce n t age o f lamb s c l a s s e d grade 1 rose f rom 42 t o 5 1 % f o r p ro geny
o f grade 1 or grade 2 dams and f r om 7 to 4 3 . 2 % for p ro geny or grade 4
dams when dams on inadequate d i e t we re p l aced on ade q u a t e d i e t .
E r c anbrack and P r i ce ( 1 9 6 9 ) s t ud i e d whe t h e r the e f f e c t s o f e arly
weaning on grow t h rate was the s ame in Rambo u i l l e t , Targhee and
Columb i a l amb s .
A l l lamb s we r e reared in the s ame f l o ck t o an ave rage
age of 75 days and hal f f rom e ach b reed were weaned and p l aced in a dry
l o t , the r ema in in g ha l f s t ayed w i t h t h e i r dams .
Amon g i nb r ed lamb s
( 3 3 % inbred ) , no s i gn i f i c an t i n t e r a c t ion b e tween breed and wean ing
respons e was ob s e rved t hough i n the non- inbred group t h e r e was a
s igni f i c an t in t e r a c t ion b e tween b r e ed and respons e .
I n t he non- inb r ed
gr oup T arghees we r e superior in d a i ly gain among lamb s n o t we ane d .
Targh e e s a l s o we r e sup e r io r among c e r t i f i ed lamb s b u t Co lumb i a s we re
s up e r i or among l amb s having a c ce s s t o p a s t ure .
In an inter im r e p o r t o f a long t e rm exper ime n t t o s tu dy the GEl i n
the c omp onent s o f l amb product i o n , J o y c e e t a l .
( 1 9 7 6 ) reported the
e f f e c t s o f mature b o d y s iz e a n d f er t i l i t y on t h e level and e f f i c i ency
o f animal pr oduc t ion .
Four geno t y p e s o f sheep ( Coopwor t h , Perendale
and two Romney s t rains ) were ma i n t a ined o n three d i f f e r e n t s t o cking
rates ( 2 6 ewe s / ha , 2 1 ewes / ha and 1 6 ewe s / ha ) .
There was no change i n
24 .
t h e r e l a t ive ranking o f geno types in t e rms o f ewe l ive we i gh t s .
Ewe
mor t a l i t y was s imilar f o r a l l geno types and a l l s t o cking r a t e s .
Increas ing s t ocking r a t e reduced lamb b i r t h we i ght by 5 % , the e f fe c t
b e in g mo re marked f o r mu l t ip l e born lambs t han f o r s in g l e born .
Geno t y p e x env i ronment i n t eract ions have n o t b e en analy sed as ye t .
The he r i t ab i l i ty e s t ima t e s o f b i r t h weight in two f l ocks we r e 0 . 5 8
t o 0 . 7 6 and 0 . 5 2 to 0 . 7 6 r e s p e c t ively on t he h i gher p lane o f nu t r i t ion .
Fo r sheep on the lower p l ane o f nut r i t ion the co rresponding h e r i t ab i l i t y
(Burd ukovskaya and T imashev , 1 9 7 1 ) .
e s t imat e s were 0 . 34 and 0 . 2 3
The s e ob s e rvat i ons were made in an exp e r ime n t t o d e t e rmine the e f f e c t
o f type o f s e l e ct ion and level o f nu t r i t ion o n t h e her i t ab i l i ty o f b i r t h
we i gh t i n Sovie t Me r ino sheep .
Breed x r a t ion concen t ra t e level on r a t e and e f f i c ieny o f l amb
growth was inve s t iga t ed by Gl imp ( 1 9 7 1 ) .
i n t e r a c t ion was observe d .
A s i gn i f icant ( P < 0 . 0 1 )
Su f f o l k and Hamp s h i r e lamb s showed
d i f f e r en t i a l response to e ne rgy l ev e l f o r l amb growth .
The t r i a l was
d iv ided int o t hree p e r i o d s and s ix t re a tme n t s r e p r e s en t i ng s ix f e e d i n g
s chedul e s .
Lambs f rom e ig h t breeds were randomly d ivided i n t o two l o t s
p er t re atme n t group .
S u f f o lk and Hamp s h i r e l amb s gained f a s t e r when
t h e r a t ion energy level was increased above the l eve l p rovided in t h e
f ir s t two t reatment s wh i l e n o d i f f e r en t i a l r e s p o n s e t o energy l e v e l wa s
o b s e rved among o t her b r e e d s .
T e s t ing and evalu a t i o n o f p ro geny o f s ir e s und e r d i f f erent
envi r onmen t s was carried out by Go l ' t sb la t and Budan s t ev ( 1 9 7 3 ) i n
U . S . S . R.
Three s ire groups t o t al l ing 7 0 young P r e c o c e r ams were e a ch
r e a r e d under d i f f erent s e t s o f management c o nd i t i o n s ;
group 1 on
p a s ture , group 2 and 3 a t t e s t ing s t a t ions on g r o up and i n d ividual f e e d
25.
r e s pe c t ively .
The r e were no s i gn i f ic ant GEl for growth o r food
conve rs ion and sires ranked i n t he s ame order on t hr e e s e t s o f t e s t
cond i t ions f o r their pro geny .
Hohenboken et a l .
( 1 9 76b) fo und no s i gn i f i c an t b r e e d x env i ronment
i n t e r ac t i o n s f o r b ir t h we ight .
Fo r weaning we igh t , s i r e x management
sys t em was h ighly s ign i f ican t .
Th ere were no sign i f i c an t d am b re ed x
management i n t eract ions .
�
The s e r e su l t s were obta ined f rom an exp e r imen t
invo lving d i a l l e le c ro s s among three b r e ed s r ep l i c a t ed over three years
and two graz ing management sys t ems .
Breeds were the S u f f o l k , Hamp s h i r e
a n d W i l lame t t e and managemen t sys t ems we re h i l l p as tu r e s v s i r r i ga t ed
p a s t ur e s .
The b as i c mathema t i c a l mo d e l included env i r o nmen t al e f f e c t s
(management sy s t ems , years , managemen t
x
year int erac t ions , a g e o f dam ,
sex and b i r t h and rearing typ e ) , breed and b r eed x environmen t
i n t e r a c t ion e f f e c t s .
In add i t i on , s ir e s ne s t ed wi t h i n b r eed ,
management sy s t ems and year we re inc l uded .
Genotype x l o c a t i o n
The Canada Depar tment o f Agr i c u l t ur e and the Vir g i n i a Ag r i cu l t u r a l
S t a t i on co-o p e r a t ively s t ud i ed G E l i n s h e e p ( Ca r t e r et a l . ,
1973 ) .
1 9 7 1 a , 1 9 71b ,
The e xp e r iment invo lved ewe s o f two breed cro s s e s , Nor th
Count ry Chev i o t (NC ) rams x Cana d i an Le i c e s t e r ( L ) ewes and Hamp shire x
(Hamp shire x Ramb ou i l le t ) b ackcro s s e s comp a red t hr ough f ive lamb c r o p s
( 1 9 6 1- 6 5 ) at two l o c a t ions ;
Virgin i a , U . S . A .
O t t a,va , On t a r i o , Canada and G l ade S p r ing ,
The d i f f e rence in la t i tude r e su l t ed in a cons i d e r ab l e
d i f f e rence in t h e r e l a t ive summe r-win t e r d a y length and l'onger c o l d e r
wint e r s a t O t t awa .
The s ame Su f fo l k r ams were u s ed each s ea s o n a t b o t h
s t a t ions a n d t he r ams w e r e rep laced annual ly .
Car t e r e t a l .
( 197 1a)
ob s e rved s igni f ic an t lo c a t i o n x b re e d c r o s s i n t e r a c t ions f o r we i g h t o f
26 .
lambs '"'eaned per ewe ma t ed .
The i n t e r a c t ion ap p ro a ch e d s i gn i f i c an c e
( 0 . 0 5 < P < O . lO) f o r body we ight o f t he ewe a t bree d i n g t ime .
The
s i gni f i c an t b reed x loc a t io n i n t e r a c t ion f o r we ight of l amb s weaned p e r
ewe mat ed may b e p o s s ibly d u e t o t he d i f f e r en t ial f er t i l i ty o f two kinds
of ewe s a t d i f ferent locat ions .
The magn i t ude o f t h e i n t e ra c t ion
component i n body we ight of the ewes was sma l l and p ro b ab l y not o f
e c onomic s i gn i f ic ance .
S ign i f i c ant ewe breed c ro s s x l o c a t ion intera c t ions were ev i de n t
for b ir t h we i ght and adj us t ed 1 2 0 d ay we igh t b ut not f o r aver age d a i l y
g a i n from b i r t h to wean ing ( Ca r t e r e t a l . , 1 9 7 1 b ) .
lamb s f r om N C x L ewe s
>N<�
B ir th we ight o f
:.eavi e r a t both l o c a t ions b u t t h e d i f ference
was much larger in O t t awa t han i n V i r g inia r e s u l t ing i n a s i gn i f i cant
breed x l o c a t ion interact ion ( P < O . O S ) .
resp e c t t o 1 2 0 d a y we i ght .
The s i tua t ion was s imilar w i t h
A l a r g e and highly s ign i f i c an t i n t er a c t ion
was ob served b e tween ewe breed c ro s s an d type of b i r t h f o r b ir t h we igh t .
Wh i l e s i gn i f i ca n t ewe breed c r o s s x l o c a t i on i n t e r ac t i o n s were pre sen t
f or b ir t h and 1 2 0 d ay we igh t , the d i f f e r ences invo lved were r e l a t ive ly
sma l l .
S train x l o c a t ion inter a c t ions in b ody t r a i t s we r e inve s t i ga t e d
b y Dunl op ( 1 9 6 3 ) .
In this exp e r ime n t f ive s t r a ins o f Aus t r a l i an Me r ino
were comp a r e d at three locat ions w i t h cont ras t in g environmen t s in New
S o u t h Wales and Queen s l an d .
Rams were r o t at e d b e tween t h e l o c a t ions
to ens ure s im il ar i ty i n the three s e t s of geno t ypes .
d a t a were anal y s e d by separate year-age o f ewe group s .
The r e s u l t ing
Ob s erva t ions
were made on body w e i gh t , body lengt h , w i d t h of h ip s , w i d t h of shoulde r s ,
d e p t h o f che s t and length of l e g .
No s i gn i f i c a n t s t rain x y e a r and
s t r a in x lo c a t ion int e r a c t ions were ob s e rved f o r adult we i gh t s .
With
27 .
one excep t ion i n t e r a c t ions among the ma in c l as s e s were not imp o r t an t
s o u r c e s o f var i a t ion in b o d y s i z e .
The excep t io n was year x l o c a t ion
int e r a c t ion wh i ch was s i gn i f i c ant in over 60% o f t e s t s .
The s e
i n t e r a c t ions b e tween year and locat ion were brought about by var i ab i l i t y
i n p a s t u re cond i t ion f rom one year t o the next i n any g iven l o c a t ion .
H i s f in a l co n c l u s ion was t h a t the s p e c i f i c a d ap t at ions are no t imp o r t an t
when c ho o s ing a n exi s t in g s t r a in , at l e a s t f o r the range o f envi ronmen t s ,
s t r a i n s and produ c t i on me a s u r e s s t u d i e d .
G E l and the e f f e c t s o f envi ronment s on pheno typ i c and gene t i c
var i a t i on was s tud ied by Osman and Bradford ( 1 9 6 5 ) i n a n exper ime n t
condu c t ed at two l o c a t ions w i t h Targhee- t ype sheep .
The d i s t an c e
between l o cat ions was no t g r e a t and t he main d i f ference a p p e a r e d t o b e
in n u t r i t ion with sheep a t Hop l and F i e l d s t a t ion hav i n g a l ower p l ane
o f nut r i t i on than at Dav i s .
E i gh t Targhee-type rams were used on a l l
ewes in b o t h loc a t ions i n order to ensure that t he d i f f e ren t grou p s in
the expe r iment we re gene t i c a l ly as s imi l ar as p o s s ib l e i n i t i a l ly .
Dav i s l amb s rece ived creep f e ed whe reas Hop l and l ambs d i d not .
The
chara c t e r s s tud i e d were b i r t h and 1 2 0 d ay weigh t , gain f rom we aning t o
f a l l and f r om f a l l t o shearing , 4 5 0 d ay we i gh t and con f o rma t ion s core .
For many t r a i t s me an level o f p e r f o rmanc e was muc h h igher a t Davis .
The pheno t y p i c vari ance was h i ghe r in t h e ' good '
(Dav i s ) t h an t h e ' po o r '
(Hop land ) environmen t wi t h t he r e s u l t t h a t the s e le c t ion d i f f eren t i a l
was a l s o h igher f o r t h e ' go o d ' env ironment .
Her i t ab i l i t y e s t ima t e s
ob t a ined f rom pat ernal h a l f - s i b f o r 1 20 d ay we i gh t and year l in g t r a i t s
were h i gh e r i n b e t t e r environmen t .
S i re x loca t ion int e ra c t io n was
ne g l i g ib l e in birth we i gh t t hough it was s i gni f i cant i n one of the
year s .
S ire x l o c a t ion e f f e c t s were f ound t o b e h i gh ly s i gn i f i c ant
( f rom p o o l e d mean square s ) for 450 days weight b u t were n o t
28 .
s i gn i f i cant f o r 1 2 0 day we igh t .
group geno t yp e s and l o c a t i o n s
by
S t ud ies o f intera c t ion i nvo lving u lo o d
S t an s f i e l d e t a l .
( 1 9 6 4 ) also i nd i c a t e d
t he ab s ence o f i n t e r a c t ion e f f e c t s on b i r t h we i g h t and wean ing we igh t in
s heep .
Radomska ( 1 9 6 5 ) inve s t i ga t ed s i re x f l ock ( con founded wi t h
l o cat ion ) i n t h e p ro g e ny o f Me r ino ra ms .
B i r t h we i g ht , we ight at l O O
d ays (weaning ) , d a i ly g a i n t o l O O days and body we i g h t a t s ix and 12
months were s t ud i ed .
In t e r a c t ions we r e f o und t o b e n e g l i gible f o r
b ir t h we i g h t b u t t h e p r e s e n c e o f s i re x s t a t i o n ( t e s t i n g s t a t ion v s
f l ock ) wa s no t ed f o r wean i ng we i gh t .
Genotype x sex
Vesely and Rob i s on ( 1 9 7 0 ) s t udied s i re x s e x i n t e r a c t ions
in
g rowt h
t ra i t s s u ch as body we i gh t , wean ing we igh t , ave r a ge d a i l y gain , f i n al
w e i gh t , t o t a l g a in and f e ed e f f i ciency in Romn e l e t and Rambo u i l l e t .
G E l were no t s i gni f i c an t f o r any o f t h e t ra i t s .
The he r i t ab i l i t i e s
t h e t r a i t s d id n o t d i f f e r s i gn i f icantly b e tween t h e two s e xes .
of
They
c on c l uded f rom the r e s u l t s t h a t no s i gn i f i cant d i f f e r en c e s in the r ank ing
o f s i re groups e xi s ted .
Gen e t i c c o r r e l a t ions b e tween t h e two s exes were
c a l c u lated t o ve r i fy the c on c l u s ions .
\vere o b t a i ned .
Very h i gh gene t i c corre lat ions
Only t h e c o r r e l a t ion f o r b i r t h we i g h t in Ramb o u i l l e t and
f e e d e f f i c iency i n Romn e l e t appeared to dev i a t e marked ly f r om uni t y .
Ab s e n c e o f s i gn i f i c ant s i r e - s ex in t e r a c t ions , s imilar i t y o f h e r i t ab i l i t i e s
i n two sexe s and very h i gh gene t i c c o r r e l a t ions s u gges ted t h a t t he geno t ype­
s e x i n t er a c t ions we re not imp o r t an t in the t wo p o p u l a t ions o f t h e s t udy .
Brown e t a l .
( 1 9 6 1 ) in t h e s tudy o f eva l ua t i o n o f f a c t o r s a f f e c t i n g
t he g rowt h o f s p r i n g lamb s f ou nd n o s i gn i f i ca n t l ine x sex i n t er a c t i on
in b i r t h we ight and 1 2 0 d ay we i ght and wean i n g we i gh t .
s igni f i c an t d i f f e r ences d ue t o s ex and l in e .
Ther e wer e n o
29.
Geno type x year and o t he r s
Rae ( 1 9 5 8 ) i n a s t udy o f gene t i c var i at ion and covar i a t ion in
p roduct ive chara c t e r s o f New Zealand Rornney sheep f ound the in t e r a c t ion
of s i res and years for body type o f sheep was no t s i gn i f i c a n t .
No s i gni f i c an t int e r a c t ion for body w e i g h t b e tween gene t ic o r i g in
and age we r e f ound by D i e z
et
al .
( 1 9 7 4 ) in C o r r i e d a l e s o f three
d i f f erent o r i g ins kep t in Peru a t a l t i t ude s o f 4 2 60- 5 0 0 0rn .
P e t e r s and Heaney ( 1 9 7 4 ) s t ud ied the int e r a c t ions i n fac t o r s
i n f luenc ing t he growth o f l ambs reared ar t i f i c ia l l y o r w i t h t h e i r darns .
I n c l uded in the exp e r iment we re the l amb s o f S u f f o l k and Sh ropsh i r e
b re e d s and the i r re c ipro c a l c r o s s e s and O t t awa synthe t i c o r i g i n .
The re
were s i gni f i c ant int e r a c t ions o f rearing sys t em wi th b r e e d s of l amb
( P < 0 . 0 1 ) , s e x ( P < 0 . 0 5 ) , t yp e of b ir t h up t o 7 0 d ay s and rearin g s y s t em
wit h year ( P < 0 . 0 1 ) in grow t h rate up to 1 4 0 d ay s of age .
C a r c a s s Charac t e r i s t i c s
Geno t ype x nu t r i t ion
No s igni f i cant i n t e r a c t ions we r e ob s e rved b e tween s i re x ra t ion
for c arcass t r a i t s ( c a r c a s s weigh t , d re s s in g p e r c ent , c a r c a s s grade ,
l o in e ye area and percent o f fat in carcas s ) by O srnan and Bradford ( 1 9 6 7 )
i n an exper imen t compa r in g g r ade Targhee l amb s a t two leve l s o f n u t r i t ion .
King e t a l .
( 1 9 5 9 ) o b s e rved no s igni f i cant in t e r a c t ions for c a r c a s s
we i gh t , che s t c i r c umf eren c e , eye mus c l e (wi d t h x d e p t h ) and dep t h o f
f a t ove r the eye muscle i n an exper iment t o s t udy d i f f e r en t i a l r e s p on s e
o f l amb s o f var i o u s breeds an d cro s s e s t o d i f f e r e n t p lanes o f nu t r i t ion .
30 ·
S i gni f i cant geno t y p e x nu t r i t ion and geno type x environment
in t er a c t ions we re repo r t ed for growth , s laugh t e r we i gh t , d re s s i n g
percent age , car c a s s c omp o s i t ion and meat cha r a c t er i s t i c s b y Budans t ev
( 1 9 7 3 ) i n an exper ime n t of me a t p rod u c t ion o f l amb s s ired by d i f f e r e n t
rams a n d fat t ened unde r d i f f erent cond i t ion s , i . e . , indoors vs p a s t u r e .
G E l e f fe c t s on l amb growth and c a r c a s s me r i t were repo r t ed b y
Hohenb oken e t a l .
( 1976b)
( s e e a l s o p 2 5 ) f ro m a dial l e l e c ro s s among
t hree b r e ed s rep l i c a t e d over three years and two graz ing management
sys t ems .
In this s tudy both geno type x env i ro nment and ma t in g s ys t em x
env i ro nment interac t ions for g rowth and c a r c a s s qual i t y wer e s t ud ie d .
For c a r c a s s wei gh t p e r d ay o f age , b reed of s ir e x management sys t em was
h i ghly s i gn i f i cant .
B r e ed o f s ire x management sy s t em were a l s o
s igni f i cant f o r f in i sh s core and USDA qua l i t y gr ade .
S i r e b reed x y e ar
i n t e ra c t ions were s i gn i f i can t for f in i sh s c o r e (P< O . O l ) , percent kidney
f at and fat thi ckne s s ( P < O . OS ) .
Imp o r t an t b re e d rank chan ges d id not
o ccur f o r any of t h e s e i n t e ra c t ions .
The only s i gn i f i cant d am b re e d x
year e f f e c t was percent k idney f a t (P<O . O l ) i n wh i ch b r eed o f dam e f f e c t s
were more var iable i n some years than i n o t he r s .
changes o c curred .
No imp o r t an t r ank
B r e e d o f s i re x b reed o f d am int e r a c t ions we r e
a b s e n t f o r a l l me asures o f c a r c a s s me r i t wh i l e b o th breed e f f e c t s and
s ire e f f e c t s w i thin b r e e d we r e s i gni f i can t .
No three f a c t o r int er a c t ion
of s ir e b reed x d am b r e e d with management sy s t ems or with year was
s i gn i f i c an t .
Geno type x l o c a t ion
Car t e r e t a l .
( 1973)
( s e e also p 2 5 ) examined the genotype-lo c a t i o n
i n t e r a c t ions i n t h e lamb c arcass t r a i t s and f o un d that t h e int er a c t ion
was h i gh l y s i gn i f i c an t (P< O . O l) f o r c a r c a s s we i gh t and carcass grade ,
31.
s i gn i f i c an t a t P < O . OS f o r we ight o f l o in and a t P < O . 1 0 f o r c a r c a s s
y i e l d ( d r e s s ing- o u t p e r c e n t a g e ) and we i ght o f shoul der .
In V i r g in i a ,
c a r c a s s e s o f lamb s f rom H x HR ewe s were s l i gh t ly h e av i e r ( 0 . 1 6 k g ) t h an
thos e from NC x
L
were 1 . 7 1 kg he avi e r .
L
Howeve r , i n On t a r i o th o s e f rom NC x
ewe s .
ewe s
B r e e d x loca t ion i n t e ra c t ions i n t h e s e t ra i t s
a r e another measure o f t h e d i f f e r en t i al response o f the ewe b reed c r o s s e s
a n d t he ir l amb s t o t he envi ronment s a t two l o c a t ions a s expre s s e d i n
l amb growth r a t e and s i z e .
Th ere was no evidence o f i n t e r a c t ion s in
any c a rcass me as u rement s wh en ca r c a s s we i gh t was he l d con s t ant .
I t was
conc luded that NC x L ewe s we r e c l e arly s up e r i o r und e r the envi ronme n t a l
c on d i t ions in O n t a r i o wh i l e t h e H x HR i s adap t ed t o V i r gi n i a .
Geno type x s e x
C r ame r and Marche l l o ( 1 9 6 4 ) s t u d i ed s ir e x sex int e r a c t i o n s
in
the
comp o s i t ion o f s u b c u t aneous f a t from f a t b i o p s i e s at 9 w e e k s o f age t o
1 8 mon t hs o f a g e i n Co l umb i a r am-ewe t\vin lamb s , b u t f o r t h e iod ine
numb e r int e r a c t ions were f o und not s i gn i f i c ant in any o f the o t her t r a i t s
(me l t in g point , laur i c a c i d , myris t i c acid , p a lmi t i c a c i d , s t eari c acid ,
o l e i c a c i d , l in o l e i c a c id and minor a c id s ) s t ud i ed .
I n another i nve s t i ga t i o n Kromann and Ray ( 1 9 6 7 ) obs erved
s i gn i f i cant l in e o f b r e e d i n g x sex (we t her and r am lamb s ) i n t e r a c t ions
for c a r c as s we i gh t , f a t p e r c e n t and p r o t e in p e r c en t but not f o r
f a t : p r o t e in rat io .
Geno type
x
ye ar and o t he r s
B r e ed x y e a r i n t e r a c t i o n s we re s t udied by Boy l an e t a l .
( 1976a)
wh i l e comparing t he f a t t y a c i d compo s i t ion o f c a r c a s s e s o f Finnish
crossbred ,
S u f f o lk , Ta r gh e e and Minne so t a l amb s .
I n t e ra r t i o n s we re
32.
not f ound s i gn i f i c an t exc e p t
for
h e p t adec ano i c a c i d amo n g the var i o u s
f a t ty a c i d s (myris t i c , pen t a d e c ano i c , p a lm i t i c , s t e a r i c , o l e i c , l i n o l e i c )
s t udied .
In ano ther s t u dy
Boy l an
et al .
( l 9 7 6b ) examined t h e b re ed x
y e a r and b r e e d x type of b i r t h and r e a r ing in t e r a c t i on s i n the c a r c a s s
t r a i t s o f Finn i sh c ro s s b r e d l amb s .
I n t e r a c t ions w e r e s i gn i f i c a n t on ly
f or the USDA yield grade and qu a l i t y g rade ( P <O . O S ) o u t of the var i o u s
c a r c a s s t r a i t s (hind sadd l e we i gh t , k i d ney a nd pe l v i c f a t , Lo n g i s s imus
a r e a , fat t h ickn e s s ove r Lon g i s s imu s ) s t udied .
F l e e c e char a c t e r i s t i c s
Few a n a ly s e s o f i n t e ra c t ion e f f e c t s o n wo o l t r a i t s have b e en
c a r r ie d o u t .
As the magn i t ud e o f d i f f e r e n c e s in the geno t y p e s and t h e
e nv i ronme n t s emp l oyed in the exp e r i me n t s wh ich have b e en c ond u c t e d
v a r i ed wide l y , i t i s wo r t hwh i l e t o c o n s i d e r e a c h s t u dy s e p a r a t e l y in
th i s p a r t o f the rev i ew .
Gen o t ype x n u t r i t ion
is
l.fu e t h e r the heri t ab i l i t y of a t r a i t
n u t r i t ion wa s s tu d i e d b y Mo r e l y ( 1 9 5 6 )
in
dependent on the p l a n e o f
a n exp e r ime n t on in t e r a c t ion
b e tween geno t y p e and p l ane of n u t r i t ion in f l e e c e t ra i t s of Aus t r a l i a n
Me r i no .
In t e ra c t ions were no t f ound s i gn i f i c an t in any o f t h e t r a i t s
s t udied ( gr e a s y f leece w e i gh t , y i e l d , c l e an f l e e c e we i gh t , s t ap l e len g th
a nd c r imp s / i n ch ) in the h al f -s i b p r o geny of d i f f e rent Me r in o r ams k e p t
on a h i gh a n d l ow p l a n e o f nu t r i t i on .
The r a t i o o f gen e t i c t o t o t a l
v a r i ance wa s no t a f f e c t e d b y the p l a n e o f nu t r i t i on i n t h e exp e r i men t ,
con tradi c t ing H ammond ' s ( 1 9 4 7 ) t he s i s t h a t " . . . i t is only p o s s ib l e t o
d ir e c t evo l u t i o n b y s e l e c t ion o f gene s f o r the s e charac t e r s un d e r
c ir cums t an c e s whe r e t h e envi ronmen t a l c o ndi t ions a r e o p t ima l f o r the
33 .
development o f t he chara c t e r i n que s t i o n " .
The i n t r a- c l a s s c o r re l a t i on
among h al f - s i b s f o r f l e e ce char a c t e r s were s imi lar in b o t h p l ane o f
nut r i t io n i n this e xp e r imen t .
S t akan e t a l .
( 1 9 6 3 ) ob t a ined h e r i t ab i l i t y e s t ima t e s o f f l e e c e as
0 . 2 0 and 0 . 1 9 in the
' h igh ' and ' low ' p l an e s o f nut ri t io n resp e c t ive l y .
An expe r ime n t invo l v in g s i res o f f i n e-woo led s h e ep and two p l anes o f
nu t r i t i o n was ca r r i e d o u t in t h e U . S . S . R . t o t e s t t h e e f f e c t o f
environme n t o n gene t i c charac t e r s and the i r h e r i t ab i l i t y .
Va r i a t ion
was l e s s i n ' h igh ' p lane than in ' l ow ' p l an e for f l e e c e we i gh t at
15 mon t h s of age .
Re s po n s e s in wo o l we igh t and some o f i t s comp onen t s exh ib i t e d b y
young ewe s o f t h e B l a c kf a c e , Ch e v i o t and Wi l t sh i r e breeds were s t u d i e d
i n two nu t r i t ional and two t emp e r a ture t rea tmen t s b y Kin g and Young
( 1955) .
Th e t ra i t s inve s t i ga t e d we r e c l ean we i gh t o f a l l f ib r e s on
t a t tooed area , clean w e i g h t o f wo o l f ib r e s on t a t tooed area , d en s i t y
( f ibres p e r un i t are a ) ; d e ns i t y ( non-me du l la t e d f i bres p e r un i t a r e a ) ;
average l e n g t h of a l l f ib r e s ;
average length o f woo l f i b re s ;
d i ame t e r o f al l f ib r e s and ave r age di ame t e r o f wo o l f ib re s .
e f f e c t s w e r e produced b y d i f f eren t env ironment s o n a l l t ra i t s .
ave rage
S i gn i f i c an t
Breed x
nu t r i t i on i n t e r a c t i o n was s ign i f i c ant o n l y f o r t h e f i r s t two char a c t e r s .
The in t e r a c t ion in woo l p r oduc t i on wa s due t o t h e ou t s t an d i n g ab il i t y o f
B l ackface t o inc rea s e t h e s i z e o f f i b r e s in t h e me dul l a t e d f r a c t ion o f
t h e f le e c e .
S imilar o b s e r va t ions we re r e p o r t e d b y Ke l ly ( 1 9 4 9 ) i n an
e xp e riment in wh ich s t rong woo l and f i ne woo l M e r i nos gave r e sp e c t i v e l y
8 . 0 and 7 . 3 lb on a ' l ow p l ane ' o f nu t r i t i on and 1 8 . 4 and 1 3 . 3 lb o n
a ' h i gh p l ane ' .
The i n c re ased d i f f e r e n c e b e tween the s t rains can b e
a t t r ib u t e d t o a gre a t e x t e n t t o changes i n t he c r o s s s e c t i ona l area o f
t h e f ib r e .
34 .
King et al .
( 1 9 5 9 ) examined d i f f e r en t i al reac t ions t o four
nu t r i t ional environmen t s (high-h i gh , h i gh - l ow , low-h igh and l ow- low) in
twin l amb s of two b r eeds ( B lackface and We l sh Moun t a i n ) and f ive cros s e s
f o r greasy wo o l we i g h t an d f ib r e len g t h .
Neither in t e r a c t ion o f c ros s x
p l ane o f nut r i t i o n n o r the twin pairs wi t h i n a cro s s x p lane o f n u t r i t ion
was s ign i f ican t .
Howeve r , Burd ukovskay a and T imashev ( 1 9 7 1 ) repo r t ed
e s t ima tes o f her i t ab i l i t y for woo l length in the pro geny o f r ams having
long wool as 0 . 30 to 0 . 5 2 , and 0 . 1 7 t o 0 . 2 5 in two f l o cks fed on h i ghe r
and l ower planes o f nu t r i t i o n re s p e c t ive l y ;
for rams w i t h wo o l s o f
mod e r a t e l ength , t h e correspond ing f i gu r e s were 0 . 30 t o 0 . 4 5 and 0 . 1 5 to
0 . 23 .
I n a s tudy b y O s man and Brad ford ( 1 9 6 7 ) grade Targhee ram and
we ther lamb s by d i f f e r ent s i res we re ob t a in e d and each s i re f amily was
d ivided at random in t o two group s .
One h a l f of each group wa s f e d a
h i gh energy ration and the o ther h a l f a l ow energy rat ion f o r 7 weeks
( Period 1 ) .
Sub s equently anima l s f rom b o th groups were f e d the h i gh
energy rat ion for ano ther pe r i od o f 7 weeks ( Period I I ) .
group s were thus d e s ignated a s HH and LH .
The t r e a tment
S i re x p l ane o f nu t r i t i on
was s ign i f i cant (P < 0 . 0 5 ) for s t aple length ( Pe r iod I ) in the c a s e o f
we ther l ambs and c l ean f l eece we ight ( Period I I ) in the ram lamb d a t a .
I f the magn i tude o f GE l b ears a relat ionship t o the magn i t ude o f the ma in
e f fe c t s , then the t r a i t s wh i ch showed s i gn i f i c an t s i re d i f f e re n c e s w i t h in
environments , s in c e r a t ion e f fe c t s we re l a r g e , would be exp e c t e d t o show
mo s t in t e r a c t ion s .
the case of rams .
Th i s was found to b e t rue for c l e an f l e e c e weight in
However , s t aple length o f wethers and car c a s s w e i g h t
o f rams showed s i gn i f i c an t interact ion even though t h e s ire d i f f e renc e s
were n o t s igni f ic an t .
35 .
Ewes f rom three f l ocks , one s e l e c t ed f o r h igh c l ean wo o l we ight ,
one s e l e c t e d f o r low c le an woo l we i gh t , and a random c o n t r o l group were
inve s t igated by Wi l l i ams and Win s t on ( 1 9 6 5 ) for relat ive e f f ic iency o f
c on version o f f e e d to woo l .
Three n u t rit ional leve l s were imp o s e d .
F l o cks x l eve l s o f nu t r i t ion was f o und s i gn i f i c ant f o r c lean woo l
product ion ( P < 0 . 0 5 ) t hough i t was n o t s ign i f i c ant f o r e f f i c iency ( g woo l :
g food ) .
On t h e high and int ermed i a t e p l anes the mean c l ean wo o l we i gh t s
o f t he high wo o l we igh t group , r e l a t ive t o con t rol (
=
1 0 0 ) were 1 2 6 and
1 2 0 resp e c t iv e l y , wh ile on t he low p l ane it was only 1 0 1 .
f i gures for the l ow we i ght group were 8 7 , 8 8 and 96 .
S imilar
The i n t e r a c t ion is
evident in t h i s c a s e , but only when t he nut r i t i onal d i f f e r e n c e s be come
extreme , i . e . , on the l ow leve l .
A group s e l e c t e d f o r high c l e an wo o l we i ght and a r andom control kep t
o n two p lane s o f nut r it ion , ma in t en ance and ad lib . sh owe d much sma l l e r
d i f f e rences i n t he exper imen t cond u c t ed b y Do l l ing and P i p e r ( 1 9 6 8 ) , t h e
woo l we igh t r e l a t ive to control (= 1 0 0 ) b e ing 1 1 4 on a d lib . a n d 1 1 0 on
ma inten ance .
No s i gn i f i c ant int eract ion s f o r e f f i c iency o f conv e r s ion o f f o dder
t o woo l was ob s e rved by Dunlop e t a l .
( 1 9 6 6 ) who fed three s t r ains of
Mer ino ( f ine woo l , medium wo ol and s t rong woo l ) on two leve l s of n u t r i t ion ,
ma in t enance and 1 . 4 x ma int enan c e .
The c lean woo l we i gh t in med ium and
s t rong wo o l s t r a in s was 1 2 2 and 1 3 7 o n ma i n t enance and 1 2 8 and 1 4 2 on
the h i gher rat ion r e la t ive to the f in e s t r a in (
=
1 00 ) .
South ( 1 9 6 5 ) s t ud ied the r e l a t ive e f f i c iency o f woo l grow t h in e a ch o f
t h e two group s o f s heep f e d on d i e t s o f cha f f and nut s i n Mer ino , Corriedale
and Romney breed s .
we i gh t .
One g roup was f e d t o gain we i ght and the o t h e r t o l o s e
The mo s t e f f i c ie n t group was t h e Merino group on low p l an e o f
nut r i t ion whi l e there was l i t t le d i f f erence be tween the o ther group s .
3n .
D i f ferent ial re spons e in wo o l growth was observed when two leve l s
o f f e e d in g ( l imi t ed and unl imi t e d feed i n g ) were imp o s e d on sheep f rom
f l o c k s s e le c ted for h i gh ( f l e e ce p lu s ) and low ( f l e e c e minu s ) c l e an
The re was
f le e c e we ight and a random-bred f l o ck (Will i ams , 1 9 6 6 ) .
grea t e r r e s pon s e in rate o f wo o l growth o f the rams of f l eece plus f l o c k
re l at ive t o th o s e o f random a n d f l eece minus f lo cks .
Flocks x leve l s
in t e r a c t ion wa s s ign i f i cant f o r woo l growth , e f f i c i e n c y o f conver s i on o f
food t o wo ol and f ibre cros s - s e c t ional area and e f f i c iency , but not f o r
f ibre leng t h .
The d e c r e a s e i n e f f i c iency o f f l e ece p l u s rams as f e e d in g
leve l increased was re l a t ively sma l l er than those f o r o t he r f l o c ks .
S i gn i f icant int e ract ion b e t ween gen o t ype and d ie t ary t r eatment s for
woo l p r oduc t ion wa s repor ted in a s t udy by Wi l l i ams ( 1 9 7 6 ) .
The s t udy
wa s co nduc t ed on 2 year old Mer ino ewe s f rom the f l e e c e p l u s and f le e c e
minus s e l e c t ion f l o cks kept on two diet ary treatmen t s .
The r e s u l t s were
in gen e r a l a gre emen t with Wi l l iams ( 1 9 6 6 ) that the woo l p roduc t i on per
un i t a r e a of s kin and woo l p rodu c t i on per sheep were g r e a t e r in the
f lock s e l e c t ed for high cl ean f l e e c e we i ght ;
the d i f f e ren ce be twe en the
f l ocks was mo re p ronounced a s leve l o f int ake of f ood increased .
Breed x environment int e r a c t i o n s for woo l p ro d u c t ion were examined
by Hohenboken ( 1 9 7 6 ) .
The env i r onmen t a l variab l e s were s y s t ems o f
pas t or a l man agement (dry l and h i l l p a s t ur e s and i r r i g a t e d p a s t ure s ) and
year s .
Gen o types were a l l p o s s ib le s t ra i gh tbreds and r e c i p rocal c r o s s -
b r e d comb in a t ions among Hamp s h i r e , S u f fo l k and Wi l l ame t t e .
Ewe-breed x
management s y s t em interact ion a f f e c t ed woo l produc t ion s i gn i f i c an t l y
(P<0 . 0 1 ) .
Ewe breed x mana gemen t s y s tem interact ion was e xpre s sed as
greater breed d i f ferences in the mo r e f avourab l e environme n t for woo l
produ c t i o n than i n the l e s s f avourab l e environme n t .
37 .
Geno type x l o c a t ion
Dunlop ( 1 9 6 2 ) reported the r e s u l t s of s t r a in x l o c a t ion in t e r a c t ions
(Type 4) exp e r iment in wo o l t ra i t s in wh ich f ive s t r a i n s of the
Aus t r a l i an Merino were run a s bre e d i n g group s in three woo l - growing
re gions o f Aus t ra l i a .
The s t a t ions we re cho s en to represent a range o f
envi ronment s and only one wa s sp e c i f i c a l ly the home environment o f one
s t ra i n .
He examined the imp o r t an c e o f int e r a c t ions o f s t rain and
l o c a t ion with y�ar a s the pr e l iminary analys e s s ugge s t e d var i a t ion in
in t e r a c t ion t e rms f rom year t o year .
Each ma i n e f f e c t was a s s umed t o
be a r andom var iable .
S t ra in x l o c a t ion interac t ions we re found to b e s i gn i f i cant i n
c le an f l ee c e we i gh t , greasy f l e e c e we i ght , p e r c entage c l e an s coured
y i e l d , c r imp s / inch , f ibre d i ame t e r , char a c t er , co lour and s t ap l e leng th .
S t r a in x lo c a t ion int eract ions in these t r a i t s were no d o ub t r e a l but
t h ey were gene r a l ly sma l l and a c coun t e d f o r only a sma l l f ra c t ion o f the
varianc e .
Such inter ac t i ons were not s i gn if i cant i n f ib r e s p e r mm2 ,
coun t , soundn e s s and hand le ,
S t ra in x y e ar was s i gn i f i cant o n ly for
c lean s coured y i e l d and f i bre d iame t e r .
He sugge s t e d t h a t the l a ck o f
imp o r t ance o f t he s t rain x locat ion i n t e r a c tion s result s i n p a r t f rom
the variab il i t y f rom the year t o year o f c l ima t i c cond i t i o n s w i thin
ind ividual l o c a t i o n s .
Th i s re s u l t e d in variation in quan t i t y and
qua l i ty of f o d d e r ava ilab l e .
The frequent s i gn i f icance o f s t r a in x
l o c a t i on x year , p a r t i cularly in s ubj e c t ive ly a s s e s s ed t r a i t s , suppor t e d
t h i s argumen t .
S o unle s s any addit ional e nvironment t e s t ed had a much
lower year t o y e ar v ar i ab i l i t y than t h o s e at Armidale , Cunnamu l l a and
Den i l iquin , s t r a i n x loc a t ion i n t e rac t io n might s t i l l rema in
undemon s t rated .
38 .
In cont inua t ion of t h e above experiment Dunlop and Young ( 1 9 6 6 )
anal y s e d sire x s t at ion and s i r e x year int e r a c t ions f o r cl ean woo l
During the
we i g h t in d a t a f rom f ive Me r ino s t ra ins at t hr e e s t a t ions .
exper ime n t s ome r ams were used i n mo re than one year and in s ome c a s e s
a t mo r e t h an one s t a t ion .
The o f f s p ring o f t h e s e r ams produced three
c l as s e s of d a t a , i . e . , sire x year ( and age ) , s ir e x drop ( and ye a r ) and
s ire x s t a t ion in whi ch s i re x envi ronment in t e rac t io n s were e s t imat ed
on an i n t ras t ra in b as i s .
S i r e x year ( p ro geny a g e ) and s i r e x drop
I n t e r a c t ion
inte r a c t i ons we r e f ound t o b e of negl igible impo r t anc e .
t e rms for sire x s t a t ion were f ound s i gn i f i can t only o n t wo o c c a s ions
and were s omewhat l arger ( on ave r a g e ab out half as large a s t h e r am
comp o n e n t ) .
They conclud ed t h a t when c l ean wo o l weight is und e r
s e le c t i on , t h e i n t e r a c t ion t erm o f this s i z e would be unimp o r t an t i n the
s e l e c t i on o f r am in one environme n t f o r use in ano ther .
The much
sma l l e r i n t er a c t ion in sire x y e a r and s i re x drop ana l y s e s ind i c a t e d
tha t s e le c t ion o f a ram in one y e a r for u s e in ano t he r i s unl ike ly t o
hinder g e n e t i c p ro g r e s s and t h e d e cre a s e o f h e r i t ab i l i t y
as
a result of
i t wi l l b e o f n o conse quence .
S t an s f ie l d e t a Z .
( 1 9 6 4 ) f ound no s i gn i f i cant b lood- group geno t yp e
( 7 l o c i ) x loc a t i o n int eract ion f o r various woo l t ra i t s ( s id e woo l grad e ,
t hi gh wo o l grade , s t ap l e length a t wean ing , greasy f le e c e we i ght , s t ap l e
l en g t h a n d f l e e c e grade o f y e ar l ing s ) .
Sheep represen t in g f ive gen e t i c
b ackgro unds and t h r e e d i f ferent env i ronme n t s we r e s t ud i e d .
The t h r e e
environm en t s were cons iderab l y d i f f erent in c l ima t e , t o p o g r aphy , s ea s on
o f lamb in g , p l an e s o f nutrit ion and leve l s o f animal car e .
C ar t e r e t a Z .
( 1 9 7 1 a ) in t h e s t udy r e f erred t o a l s o o n p 25 a t
Virginia i n U . S . A . and Que b e c i n Canada , found t h e l o c a t i o n x breed- cro s s
interac t ion in greasy f l e e ce we i gh t approached s t a t i s t i c a l s i gn i f i c an c e
39 .
wh i l e breed- c r o s s x year was of negl i g i b l e impor t an c e .
S t a p l e length was the only t r a i t
in
wh ich s ir e x f l o c k ( l o c a t i o n )
was f ound s i gni f i c ant ( f rom p o o l e d e s t imat e s ) i n t h e s t udy by O sman and
Brad f o r d ( 1 9 65 ) condu c t e d at Dav i s and Hop l and in C a l i f o rn i a .
Th e s i r e
x l o c a t ion in t e r a c t ions f o r greasy f l e e ce we i ght , f l e e c e grade and f a c e
s c o r e were not s i g n i f i c ant .
The h e r i t ab i l i t y e s t imat e s f o r g r e a s y f l e e c e
we i gh t , s t ap l e length and f l e e c e g r a d e code and face cover s c ore
were 0 . 84
±
0 . 33 , 0 . 53
±
0 . 2 9 , 0 . 70
±
0 . 3 1 and 0 . 2 1
wh i l e the correspond ing f i gu r e s at Hop l and were 0 . 5 0
0 . 58
±
0 . 1 8 and 0 . 4 3
±
0 . 1 6 r e sp e c t ively .
±
at
Davi s
0 . 2 3 r e sp e c t i ve l y ,
±
0. 17 , 0.42
±
0 . 16 ,
Resu l t s o f the s ev e r a l t r a i t s
s t u d i e d s howed a v e ry con s i s t ent p a t t e rn i n f avour o f hi ghe r h e r i t ab i l i t y
in t he more favo u r ab l e envi ronmen t at Dav i s and sugge s t ed s t rongly t h a t
th i s e nv i ronment was mo re favourab l e f o r the exp r e s s ion o f gene t i c
d i f f e rence s .
They con cluded that the int e r a c t ions , a t l e a s t the k i n d
leading to reve r s a l o f rank o f geno typ e s be tween env i ronmen t , were n o t
of maj o r imp o r t ance i n t h i s ma t e r i a l .
t h e r e su l t s repor t e d b y Dunlop ( 1 9 6 2 ) .
Th i s i s in f u l l a g r e ement w i t h
I t was sugge s t e d t h a t mo r e
gene t i c p rogre s s would be made b y s e l e c t ing in a mo r e f avourab l e
envir onment because o f highe r pheno typ ic var i an c e in good envi ronme n t ;
equal o r h i gher he r i t ab i l i ty in the good env i ronment and no l a r g e
geno t y p e -envir onment int er a c t i ons , a t l e a s t in the f i r s t f ew
gene r a t ions o f s e l e c t ion .
The p ro geny o f Mer ino r ams (each f rom d i f f erent f l ocks ) were
s tudied in f locks and a t a pro geny t e s t in g s t a t ion by Radoms ka ( 1 9 6 5 ) .
Obs e rva t i ons were mad e on woo l finene s s at t h e s e cond shear ing , f l e e c e
weight and o t he r f le e c e chara c t er s .
Int e r a c t i ons due to d i f f e r en t
l o ca t i on s was f ound s i gni f i cant o n l y f o r woo l f inene s s a t 2 n d s h e a r in g .
40 .
The l ack o f the i n t e r a c t ion i n the c a s e o f o t her chara c t e r s ind i c a t e d
that there was no d i s agreement between the p ro geny t e s t s on t h e s t a t ion
and i n f l ocks .
Dun lop and Hayman ( 1 9 5 8 ) f ound s t rong e v i d ence o f i n t e r a c t ion wh i l e
comp a r ing the incidence o f f le e ce-rot f o r a number o f s t r a i n s o f Me r i no
sheep and locat ions in Au stral i a .
In three l o c at ions ra i n f a l l was
s u f f i c ient ly h i gh to cause in c i d ence of f l ee c e- rot i n the mo s t
s u s c ep t i b l e sheep wh i l e i n t he o t he r two l o c a t i ons cond i t ions were s uch
t hat i t s oc curren c e was e i ther absent or negl i g ible .
They found that
i n the presence o f s u f f i c ient r a inf a l l t o c a u s e f l eece- rot , the s t ro n g
w o o l s t r a in w a s mo s t s u s c ep t ib l e and t h e f ine w o o l s t rain l e a s t
The f ine s t rain was thus we l l a d a p ted t o h i gh rain f a l l
s uscep t ib le .
e nvir onment s i n t e rms o f fleece-rot whe reas t h e st rong s t ra i n wa s n o t .
Geno type x s ex
Gen o type x s ex i n t eract ions and the gene t i c corr e l a t ions b e tween
s e xes f o r gr easy f le e c e w e i ght , c l e an f l e e c e we i ght , s t ap l e length , woo l
g r ade and woo l y i e ld we re evaluated by Ve s e ly and Rob i s on ( 1 9 7 0 ) in rams
No s i gn i f i cant in t e r a c t ion s
and ewe s of Rambou i l l e t a nd Romnelet sheep .
( P < 0 . 0 5 ) were d e t e c t e d in any o f the t r a i t s s t ud i e d in e i ther breed s .
Th e her i t ab i l i t ie s o f t he trai t s d id no t d i f f e r s ign i f i can t ly b e tween
the two s exes .
The he r i t ab i l it i e s in Rambou i l l e t mal e s and fema l e s
r e s pe c t i v e ly were ;
c l e an f l e e ce we i ght 0 . 2 8
0. 19
±
0. 13;
±
0 . 16 , 0 . 28
woo l grade 0 . 1 9
0 . 4 5 ± 0 . 1 7 respect ive l y .
greasy f le e ce we i gh t 0 . 2 8
0 . 46
±
0 . 1 8 , 0 . 29
±
g r e a s y f l ee c e we i ght 0 . 3 4
±
0. 17;
±
±
0. 15 ;
0. 15, 0 . 14
±
0 . 1 7 , 0 . 46
±
0. 17;
s t ap l e length 0 . 3 1 ± 0 . 1 6 ,
0. 13;
yield 0 . 5 6 ± 0 . 1 9 ,
The corr e s p onding f i gures in Romn e l e t were ;
±
0 . 1 6 , 0. 18
±
0. 15;
s t ap le leng th 0 . 3 6
c l ean f l e e ce we i gh t
±
0 . 1 7 , 0 . 36
±
0. 17 ;
woo l
41.
grade 0 . 7 6
±
0 . 2 1 , 0. 23
±
0. 16;
y ield 0 . 3 3
±
0 . 17 , 0 . 32
±
0. 17.
Th e
genet i c co rrel a t ions o f each t r a i t between two sexes were c a l c u l a t ed and
only t he correlat ions for greasy f l eece weight and c lean f l e e c e we i gh t
devia t e d markedly f rom un ity .
I t was thus concluded t h a t no s i gni f i c an t
d i f f erence s i n ran k ing of s i r e s e x i s t ed between the two s e xe s .
Gen o typ e · x year and o t hers
No s i gn i f icant interac t i on b e twe en s i re x year was o b s e rved by Rae
( 1 9 5 8 ) in woo l t r a i t s ( greasy f l e e c e we i ght , s t aple length , qua l i t y
numbe r or count and hairine s s ) exc e p t ing f l e e c e chara c t e r ( P < 0 . 0 1 ) i n a
f lo ck o f New Zealand Romney sheep .
Th i s s ingle s i gn i f i c an t r e s u l t could
be due t o g enuine non- l inear in t e r a c t ion be tween s i r e s geno type and
env ir onme n t a l cond i t ions p e cu l i ar to each year or to d i f f e rences b e tween
dam and s i r e x d am interaction or it could be an a r t e f a c t of the
subj e c t ive as s e s sment .
The e x a c t cau s e was no t e s t ab l i shed f rom the
d at a .
S i gn i f i c ant int eract ions b e t\v een gen e t i c ori gin and age i n
Corr i e d a l e s were o b s erved by D i e z e t a l .
( 1 9 7 4 ) f o r f l e e c e we ight , fi bre
d iame t e r and s t ap le length in a s t u dy invo lving sheep f r om three
d i f f e rent gene t i c o r i gins in P e ru .
Repro duc t ive t r a i t s in ewe s
Genotype x nut r it ion
Ewe s of two geno types whi ch d i f f ered with r e s p e c t to p o t en t i a l
f e r t i l i t y were s ub j e c t ed to three nutrit ional r e g ime s t o e s t imat e the
imp o r t an c e of GEl for various r e p r o duct ive t r ai t s (Mey e r ,
1974) .
The
two gen o t y p e s we r e T arghee (me d i um f er t i l i t y ) and Finn i s h Landrace x
42.
Targhee cha r a c t e r i s ed by h i gh pro l i f i cacy .
' Low ' ,
' Me d ium ' and ' H i gh '
f e e d int ake leve l s o f a l f a l f a we re the three n u t r i t ional t r e a tment s
invo lved in t h e experiment .
In t e ract ion app roached s i gn i f i can ce ( P � 0 . 0 9 )
f o r p re f lush in g , ovula t ion r a t e bu t was ab s ent f o r ovula t ion r a t e mea s u r e d
a f t e r one c y c l e o f f lushi n g .
N o inte r a c t ion ef f e c t s were found f o r
o e s t r u s c y c l e le ngth o r lamb i ng pe r f orman c e a l t hough t h e r e we re in d i c a t i ons
of b r e ed d i f f erences in t he i nc idence o f s i l ent he a t s and ova su c c e s s ra t e
o n t h e var ious t re a tmen t s .
The e f f e c t o f t h i s int e r a c t ion in general
've re of l imi t ed imp o r t ance f o r mo s t repro d u c t ive t ra i t s me asured
su g ge s t ing t ha t the int rod uc t i on of genes f rom this h i gh f e r t i l i t y b r eed
i n t o t he ex i s t ing sheep shou ld imp rove rep roduct ive r a t e ove r a f a i r l y
wide range o f l eve ls o f nut ri t ion .
Gene t i c imp rovemen t o r i gi na t i n g
in
o n e n u t r i t ional requiremen t i s l ikely t o be exp r e s sed at l e a s t in part ,
in o t her nu t r i t i onal envir onment s .
Geno type x p a s t ure int e r a c t i on in the f e r t il i t y o f Romn ey ewe s was
s t u d i ed by Ch ' ang ( 1 9 6 3 ) .
The d i f f e ren t i a l r e sponse o f ewe s born a s
s in g l e o r twins when gra z e d o n oe s t rogenic red c l over an d a rye-gr a s s /
wh i t e c l over as s o c ia t ion ( con t ro l ) was examined .
Ewe s grazed on
oe s t ro gen i c red c l ove r we r e l ower in fe r t i l i t y than ewes grazed on
c on t ro l p as t ur e s .
E f f e c t s due t o interac t i on we r e n o t s i gnif i c an t a t
5 % level for average d a t e o f l amb ing , but w e r e s i gn i f i cant i n o n e y e a r
f o r p ercent barrenn e s s ( as a measure o f lamb ing p e r c ent ag e ) .
Geno t yp e and mat in g sys t em x env i r o nmen t in t er a c t ions f o r
��
reproduct ion t ra i t s in ewe s were r ep o r t e d by Hohenboken ( 1 9 7 6a ) from a
d i a l l e l cross among t hr e e b r e e d s o f sheep r ep l i c at ed over
three years
and two graz ing man ageme n t sys t ems ( imp roved dry hill l and p a s t ur e s
ver s u s irrig a t e d and heav i l y f e r t i l i z ed low l an d p a s tures ) .
Breeds we r e
43.
Hampshire , Suf f o l k and Wi l l ame t t e .
S ir e b r eed x mana gement was no t
s i gn i f i c ant f or f e r t i l i t y , p ro l i f icacy and l amb survival .
S i r e b r eed
x
year approached s i gn i f icance for f er t i l i t y and was s i gn i f i cant f o r
p r o l i f i cacy .
B o th int era c t ions invo lved r ank changes amon g the s i r e
b r e e d s b u t i n n o c a s e were the d i f f erenc e s w i t h in years l a r g e o r
impo r t an t .
Dam breed x manageme nt int e r a c t ions invo lving chan g e s in
rank o f d am b r e e d s d id not d i f f e r , but there was a marked d am b r e e d x
environment in�e r a c t ion ( P < O . O S ) for f e r t i l i t y .
Dam breed x ye a r s was
not s ign i f i cant f o r any o f the chara c t e r s .
S igni f i c an c e t e s t ing for repr oduct ion t r a i t s is f raught wi t h
d i f f i cu l t y be caus e o f t h e d is t ribut ion p r o b l ems .
Dunlop ( 1 9 6 3 ) remarked
that even in we i gh t of lamb s born o r weaned per ewe ma ted , the und e r l y i n g
e f f e c t o f lamb numb e r s make t h e d i s t r ibu t i on p a r t i a l ly d i s c on t inuo us .
Car t e r et a Z .
( 1 9 7 1 a ) observed that the d i s c on t i nuous nature and c o a r s e
c l a s s i f i c a t ion o f b a r ren or l amb ing ( 0 or 1 ) as we l l a s o f l amb s b o rn o r
weane d p e r ewe ( 1 , 2 , 3 , o c cas ionally 4 ) b r ought about p r o b l em s o f
d is t r ibut ion and t e s t s o f s t a t i s t i ca l s i gn i f i canc e .
Geno type x l o c a t io n
S t r a in x l o c a t i on , s t r a in x s e x and s t r a in x age
int er a c t ions on
survival r a t e to weaning of Merino lamb s we r e examined in two s e t s o f
dat a b y Lax and Turner ( 1 9 6 5 ) .
Th e s t r a i n t r i a l invo lved f ive s t r a i n s
o f Merino run w i t h o u t s e l e c t i on a t e a ch o f t hree locat ions ( Cunnamu l l a ,
Arrnid a le and Denil i qu in ) wi t h s ix age groups of ewes .
The s ame f ive
s t r a in s were l a t e r in cluded in s e l e c t ion groups at Armid a l e wi t h s even
age groups of ewe s .
There was no s igni f i cant l o c a t ion x s t ra in
int e r a c t ion in the s t r a in t r i al .
S t r a in x age int eract ion (P<O . O l )
was f ound s igni f i can t , wh i l e s t ra in x sex was f ound n e g l i g i b l e i n the
44 .
However , Dun lop ( 1 9 6 3 ) in a s t ud y o f s t rain x
Armi d a l e s e l e c tion group .
l o ca t ion and s t rain x year interac t i o n s in reprod u c t ive p e r f o rman c e found
no s igni f i c ant i n t e ract ion in Me r i n o s for number o f l amb s b o rn , number o f
l ambs weane d , weight o f l amb s born and we ight o f lamb s weaned .
S t r ain x
year int er a c t i ons we re vir t u a l l y ab s e n t and s t ra in x l o c a t ions a c counted
for only a very sma l l fra c t ion of v a r i a t ion , wh ile s t r a in x l o c a t ion x y e a r
w a s o f s l i ght importance .
S imilar r e s u l t s were o b t a in e d by
De
Hass and Dun l op ( 1 9 6 9 ) wh i l e
e xamining the impo r t ance o f s t r a in x locat ion intera c t ions in t h e
reprod u c t iv e t r a i t s o f Me rino s .
S t r a in x l o c a t ion in t er a c t ions we re
n o t large enough to suggest any d i f f e rences in adap t a t ion o f s t r a ins t o
p a r t icular l o c at ions in repro d u c t ive t ra i t s o f s ingle b i r t h s and mu lt i p l e
b i r t hs .
Pat t ie ( 1 9 6 5 ) a l s o wo rking with Mer ino s , reported t h a t a r and om­
b red f lock and f l ocks s e l e c t e d in p o s i t ive and negat ive d i re c t ions f o r
weaning we i gh t d i d not intera c t s i gni f i c antly with y e a r s for we t ewes ,
l ambs mo ther e d , l amb s we aned ( a l l three e xpre s s e d as p e r c ent o f ewe s
j o ined ) , mul t ip l e b irths , ewe s l ambe d and l o s t (b oth exp r e s s e d a s
p ercent o f we t ewe s ) and lamb deaths ( mo t herin g t o wean i n g a s p e r c en t
o f l amb s mo t h e r e d ) .
Locat ion x b r e ed ( c ro s s ) o f ewe i n t e r a c t ion in sheep was s t ud ied
by Carter e t a l .
( 1 97 la)
( see a l so P 2 5 ) f o r numb e r of l amb s b o rn , l amb s
b o rn a l ive , l ambs weane d , l amb ing d a t e and we i gh t of l amb s weane d .
Th i s inter a c t i o n was h i gh ly s i gn i f i c ant (P<O . O l ) for ave r a g e lamb ing
d a t e s u gge s t ing a real d i f f erence in r e s ponse t o s e as on of breeding as
a part o f two env ironmen t s .
I t was a l s o s ign i f i cant (P<O . OS ) f o r
we i gh t o f l amb s weaned p e r ewe mat e d .
The two kinds of ewes were in
45 .
reve r s e rank at t\.JO l o c a t ions for I.Je igh t o f lamb s weaned p e r ewe ma t ed .
The i n t e r a c t ion app ro ached s i gn i f i cance ( 0 . 0 5 < P < 0 . 1 ) f o r ewe s lamb ing
per 100 ewes ma t e d .
None o f the other int erac t i on s were c l o s e t o
s i gn i f i cance .
Dun e t a l .
( 1 9 6 6 ) a l so ob s e rved t h e s i gn i f icant i n t e r a c t ion be twe en
s t ra in o f Me r ino ewe and s e ason of j o in i n g for p e rcen t age of ewe l amb ing
( exp r e s s ed a s a p e r c e n t age of ewe s j o ined ) and twin b i r t h s ( as
p e r c e n t a g e o f lamb i n g ewe s ) in
a
a
compari s on o f autumn and s p ring j o i n i n g
o f Young Pepp in and South Au s t ral i an Me r i no ewes ma t ed t o Border
Le i c e s t e r rams .
The i n f e rt i l i t y o f sheep re s ul t in g f rom G E l wa s i nve s t i ga t e d by
Hil lham ( 1 9 7 3 ) .
Two breed s o f ewe s , i . e . , He lsh Mo un t ai n (WM) and
Border L e i c e s ter ( BL ) were compared for reprodu c t ive a t t r ib u t e s
such
as
t ime o f o n s e t o f the breed ing s e a s on , ma t i n g percen t a g e , l amb ing
p ercentage and pa t t erns of cy c l i c a c t ivity under two d i f f e re n t pho t o ­
p eriod s .
Under the local amb i e n t photope riod a t 5 1
°
4 3 ' N th e b r e e d s
d i d n o t d i f f e r s i gn i f i c an t ly b u t u n d e r a s imu l a t ed e q ua t o r i a l pho t o p e r iod , 1 0 0% o f WM ewes showed o e s t rus vs 3 7 . 5 % o f BL ewe s .
The WM
ewe s had 3 t o 1 0 cy c l e s and a h i gh i n c idence of s i l ent he a t s compared
with 2 to 7 cycle s an d no s i l en t hea t s i n the BL ewe s ;
1 0 WM ewe s ma t ed
and 9 l amb e d , but only 2 BL ewe s ma t e d and 1 lambed .
O t hers
C r e s swe l l ( 1 9 58 ) comp ared t h e d i s t an c e t r ave l led by New Z e a l and
Romney and Cheviot sheep g r a z i n g on hill an d lowland p a s t u re s .
d i f ference b e tween t h e breed me a n s was s t a t i s t i c al ly s i g n i f i c an t .
Th e
In
genera l , Ch evio t s covered mo re d i 3 t an c e on t he hill and th1� f l at l an d
46.
t han t h e New Zeal and Romney .
The e f f e c t o f sw i t ch ing t wo b re e d s f rom
h i l l t o f l a t land and f rom f la t l and to h i l l land we re a l s o s t ud i e d .
Romney s r a i s e d their mi leage when t ran s ferred f rom h i l l t o f l at land and
t rans f erence back f rom f l a t to h i l l a c t ually raised t h e i r l eve l o f
a c t iv i t y .
GENET I C PARAMETERS
H e r i t ab i l i ty
He r i t ab i l it y is arguab ly the mo s t imp o r t an t single c o n c e p t in the
app l i c a t ion of gene t i cs t o animal b r e e d ing ( H i l l , 1 9 7 4 ) .
T o t h i s p o in t ,
t he p r ime c on c ern in reviewing the l i t erature for the e f f e c t s o f GEl has
b e en l im i t ed t o two main q ue s t ions :
1.
I s t he he r i t ab i l i t y d i f f erent in d i f f erent env i r o nmen t s , and
2.
I s the ranking o f an imal s on the b a s i s o f gene t i c mer i t
t h e same in d i f f e rent env i r o nment s ?
Ap a r t f rom the above e f f e c t s o f G E I on the rankin g and corre l a t e d
re spons e , t he r e is a spec i f i c e f f e c t o f interact ion o n the e s t ima t e s o f
her i t ab il i t y .
Es t imat e s o f t he he r i t ab i l i t y o f a char ac t e r are norma l l y
mad e w i t h in a s ingle macroenvironme n t ;
i t i s as sumed t h a t t h e micro
f lu c t ua t i o n s opera t e independent ly o f t he gen e t i c vari a t ions , and that
t he two comb ine t he i r e f f e c t s add i t iv e l y .
I t i s u sual , however , in
e s t imat in g he r i t ab i l i ty to analyse r e c o rd s f rom s evera l year s , age group s ,
s ea s ons , e t c . , p ar t i cu l arly in f a rm anima l s where the n umb e r o f anima l s
p e r genera t i o n i s sma l l .
Wh i l e comp u t ing t he e s t imat e s , the d a t a may
b e corre c t e d f o r known env ironmen t a l sources o f var iat i o n ( and
i n t e r a c t ions ) wh i ch wou l d o t herw i s e inf l a t e the error t erm and b ia s t he
e s t imat e o f h er i t ab i l i t y downwar d s .
47 .
I f GEl are importan t , the ave r a ge gene t i c d i f f erence s wou ld be
overe s t ima ted and the he r i t ab i l i t y e s t ima t e s are i n f l a t e d i n t h e
f o l lowing way ( D i ckerson ,
1963 ) :
Per f o rman c e
Te s t
One envi ronme n t
of
He r i t ab i l i t y
Proge ny
2 + 02
0A
GEI
S ame e nvi ronment
a2
A
One environment
+
2
0GEI
+
a2
E
a2
O t h e r envi ronmen t s
a2
A
A
+
2
2
0G E I + a E
Ve ry l i t t l e work has b e e n undert aken for the purpose o f ob t a i n i n g
informa t ion wh i c h might be u s e d to produce val i d and e f f i c i e n t e s t ima t e s
o f gene t i c parame t e r s in vary i n g envi ronmen t s i n s h e e p , e sp e c i a l l y
wool t r a i t s .
Mo s t of the pub l i shed e s t ima t e s o f
h e r i t ab i l i t y
for
ob ta i n e d
by p a te rnal h a l f - s i b me thod are based on analys i s o f the s i r e e f f e c t s
ne s t e d w i thin years wh i�h would i n c lude s i re
x
y e ar e f f ec t s .
Th i s
wou l d i n f l a t e the h e r i t ab i l i t y e s t ima t e s i n the presence o f G E l .
Turner and Young ( 1 9 6 9 ) c l a s s i f ied the vari ous t r a i t s o f e conom] c
imp o r t ance i n sheep based on
a s f o l l ows : her i tab i l i ty ;
a rb i t rary
l imi t s o f her i t ab i l i t y e s t ima t e s
v a lues o f 0 . 3 o r more were regarded a s h i gh leve l s o f
th o s e b e t ween 0 . 1 and 0 . 3 a s i n t e rmed i a t e and th o s e b e l ow
0 . 1 a s l ow .
H e r i t ab i l i ty e s t ima t e s o f some t r a i t s relevant t o t h i s work
ob t a ined by various workers on d i f ferent breeds of sheep are p r e s en t e d
i n Tab l e 1 .
Mo s t o f the he r i t ab i l i t i e s f o r the t ra i t s in sheep are
e s t i ma t e d f rom p a t ernal hal f - s ib correlat ion or daugh t e r-dam regre s s ion .
No i n f o rma t i on was avai l ab le on c l ean wool we ight / un i t s k in area , to t a l ·
c r imp numb e r , t ip p ines s grade , d i s co l oured area grade , co t t in g grade ,
48 .
Some pub l i shed e s t ima t e s of h e r i t ab i l ity o f l ive-we igh t ,
wo o l quan t ity and qua l i ty t r a i t s in sheep
TABLE 1 :
Es t ima te
Age and
1
r emarks
Me thod o f
2 Breed
e s t ima t ion
Re f e rence
L ive-we ight
0 . 64
16 m . o . F
DDR
Me r i no
Young e t a l .
( 1960)
0 . 58
16 m. o . M
DDR
Me r ino
Young e t a l .
( 1960)
0 . 53
1 y.o. M
DDR
Mer ino
Young e t a l .
( 1960)
POR
Mer ino
Mo rley ( 1 9 5 0 )
0 . 36
POR
Me r i no
Mo rley ( 1 9 5 5 a )
0 . 09
PHS
Me r ino
Mo r ley ( 1 9 5 5 a )
0 . 36
10 m . o .
0 . 32
10 m. o .
PHS
N . Z . Romney
Baker e t a l .
( 19 74 )
0 . 38
1 0 m. o .
PHS
N . Z . Romney
Bake r e t a l .
( 1974)
0 . 22
15 m. o .
PHS
N . Z . Romney
Baker e t a l .
( 19 7 4 )
0 . 22
15 m . o .
PHS
N . Z . Romney
Baker ( 1 9 7 7 )
0 . 39
1 0 m. o .
PHS
N . Z . Romney
Ch ' ang and Rae ( 1 9 7 0 )
0 . 42
10 m. o .
DDR
N . Z . Romney
Ch ' ang and Rae ( 1 9 7 0 )
0.51
1 4 m. o .
PHS
N . Z . Romney
Ch ' ang and Rae ( 1 9 7 0 )
0 . 46
14 m. o .
DDR
N . Z . Romney
Ch ' ang and Rae ( 1 9 7 0 )
0 . 45
1 8 m. o .
PHS
Ramb o u i l l e t
Bur fen ing e t a l .
0 . 36
1 y.o.
DDR
Navaj o
Hall e t a l .
DDR
Me r ino
Be a t t ie ( 1 9 6 2 )
16 m.o.
DDR
Mer ino
Brown and Turner ( 1 9 6 8 )
0 . 82
1 4 m. o .
( ad j u s t e d )
PHS
Ramb o uil l e t
Bas s e t t e t a l .
0. 85
14 m. o .
( unadj us t e d )
PHS
Ramb o u i l l e t
Bas s e t t e t a l . ( 1 9 6 7 )
0 . 54
0 . 65
( 197 1)
( 1 964 )
( 1967 )
0 . 02
10 m . o .
PHS
Romney Marsh
Radomska a n d Tys z ka ( 1 9 7 2 )
0 . 14
1 y.o.
PHS
Romney Mar s h
Radomska and T y s z ka ( 1 9 7 2 )
Romney Mar s h
Radomska and Klew i e c ( 1 9 7 5 )
0. 11
0 . 00
1 8 m. o .
PHS
P o l i sh Moun t a i n Nawara and D un i e c ( 1 9 7 2 )
0 . 43
10 m. o .
PHS
P o l i s h Mer ino
1
m. o.
=
mon t h s o ld ,
T
Twin s
y.o.
=
y e a r s o ld ,
Nawa ra ( 1 9 7 1 )
F
=
fema l e ,
=
2
DDR
=
M
=
mal e , S
=
Singl e s ,
Daugh t er-dam regress ion ,
PHS
P a t ernal ha l f - s ib ,
POR
P a r ent - o f f spring regre s s io n ,
ISR
I n t r a - s i r e r e gression
ISC
In t r a- s ire corr e l a t ion .
=
=
=
49 .
TABLE
1 :
Es t imate
( cont inue d )
Age and
remarks 1
Hethod o f
e s t ima t ion 2
Breed
Ref erence
Live-we igh t
0.41
ISC
1 y.o.
( b e f o re shea r i n g )
Corriedale
Kat ad a and Takeda ( 1 9 6 2 )
0 . 55
1 y.o.
( a f t er she a r i n g )
ISC
Corr ieda l e
Ka tada and Takeda ( 1 9 6 2 )
0 . 79
1 y.o.
PHS
Fine wo o l s heep Shel t on and Man z i e s ( 1 9 6 8 )
0 . 40
1 y.o.
DDR
Rambou i l l e t
Ter r i l l and Ha z e l ( 1 9 4 3 )
0 . 39
18 m. o .
DDR
We l s h Mount ain
Dal ton ( 1 9 6 2 )
0 . 59
18 m.o.
POR
�Je lsh Moun t a in
Doney ( 1 9 5 8 )
0 . 46
14 m. o .
DDR
N . Z . Romn ey
Tripa t hy ( 1 9 6 6 )
0 . 42
15 m. o .
PHS
S . A . Romney
Bo sman ( 1 9 5 8 )
0. 13
1 y.o.
PHS
Columb ia
Balch ( 1 9 6 5 )
0.31
1 y.o.
PHS
Kiv i r c ik
Oz can ( 1 9 7 1 )
0 . 33
1 y.o.
ISR
Kiv i r c ik
Oz can ( 1 9 7 1 )
0 . 39
1 y.o.
DDR
Kiv i r c i k
Ozcan ( 1 9 7 1 )
0. 19
1 y.o.
PHS
Rahmani
Karam ( 1 9 5 9 )
0 . 27
14 m. o .
PHS
Perendale
E l l io t t ( 1 9 7 5 )
0 . 44
14 m . o .
DDR
Perendale
E l l io t t ( 1 9 7 5 )
1 . 06
PHS
15 m. o .
( Good envi ronmen t )
Tar ghee
Os man and Brad f o r d ( 1 9 6 5 )
0 . 40
PHS
15 m. o .
( Poor env ironmen t )
Tar ghee
Os man and Brad ford ( 1 9 6 5 )
DDR
Romn ey
Builov ( 1 9 7 0 )
0 . 30
14 m. o .
(unadj u s t e d )
PHS
Rambouil l e t
Bas s e t t e t a l .
( 1 967 )
0. 1 1
14 m. o .
( adj us te d )
PHS
Ramb o u i l l e t
Ba s s e t
et al .
( 1967)
0 . 42
16 m. o .
DDR
Me rino
Brown and Turn e r ( 1 9 6 8 )
0 . 35
14 m . o .
DDR
N . Z . Romney
Rae ( 1 9 4 6 )
0. 15
14 m.o.
DDR
N . Z . Romney
Rae ( 1 9 4 8 )
0 . 32
14 m.o.
PHS
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 31
14 m.o.
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
0. 11
14 m. o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 66
14 m. o .
Grea sy f leece we ight
50.
TABLE 1 :
( cont inu e d )
Es t ima t e
Age and
remarks 1
Me thod o f
e s t ima t ion2
Breed
Re f e rence
Gre a sy fleece we igh t
0 . 45
30 m . o .
DDR
Po lwarth
Mu l l aney e t a l .
( 1970)
0 . 34
1 8 m. o .
DDR
Poh.,rarth
Mu l l aney e t a l .
( 19 7 0 )
0 . 46
30 m . o .
DDR
Corriedale
Mu l l aney e t a l .
( 1 970)
0 . 30
1 8 m. o .
DDR
Corriedale
Hu l l aney e t a l .
( 1970)
0 . 49
30 m. o .
DDR
Me r ino
Mu l l aney e t a l .
( 19 7 0 )
0 . 32
1 8 m. o .
DDR
Mer ino
Hu ll aney e t a l .
( 1970)
0. 39
3 0 m. o .
DDR
Polwa r t h
Hu l l aney e t a l .
( 19 70 )
0. 14
1 8 m. o .
DDR
Polwarth
Mul l aney e t a l .
( 1970)
0 . 40
30 m. o .
DDR
Co rriedale
Mul l aney e t a l .
( 1970)
0. 22
1 8 m. o .
DDR
Cor r i e d a l e
Mul l aney e t a l .
( 1970)
0.51
30 m . o .
DDR
Me r i no
Mu l 1 aney e t a l .
( 1970)
0 . 30
1 8 m. o .
DDR
Me r ino
Hullaney e t a l .
( 1970)
0.31
1 y.o.
PHS
Rambo u i l l e t
Vesely e t a l .
( 1970)
0 . 29
1 y. o .
PHS
Romne l e t
Ves ely e t a l .
( 1970)
0 . 34
1 y. o . M
PHS
Rambou i l l e t
Vesely and Ro b i son ( 1 9 7 0 )
0 . 46
1 y. o . F
PHS
Ramb o u i l l e t
Vesely and R o b i son ( 1 9 7 0 )
0 . 28
1 y.o. M
PHS
Romne l e t
Ve sely and Rob i s o n ( 1 9 7 0 )
0. 18
1 y. o . F
PHS
Romnelet
Ve sely and Rob i s on ( 1 9 7 0 )
0 . 45
1 6 m. o . F
DDR
Me r ino
Young e t a l .
( 1 960)
0.43
1 6 m. o . M
DDR
He rino
Young e t a l .
( 1 960)
0 . 33
1 y.o. M
DDR
Me r ino
Young e t a l .
( 1 960)
0 . 35
DDR
Me r ino
Bea t t i e ( 1 9 6 2 )
0 . 58
PHS
Ramb o u i l l e t
She l t on and Men z i e s ( 1 9 6 8 )
0 . 39
1 y.o.
POR
He rino
Mo rley ( 1 9 5 1 )
0 . 67
1 y. o .
PHS
He r ino
Mo rley ( 1 9 5 1 )
0 . 40
POR
He r i no
Morley ( 1 9 5 5 a )
0 . 44
PH S
Merino
Mo rley ( 1 9 5 5 a )
0 . 84
PH S
1 5 m. o .
( Good environme n t )
Targhee
Osman and B r a d f o r d ( 1 9 6 5 )
0 . 50
PHS
1 5 m. o .
(Poor envi ronmen t )
Targhee
Osman an d Brad f o rd ( 1 9 6 5 )
0 . 47
PHS
A\.;ra s s i
Ghone im e t a l .
( 1974)
0. 16
DDR
Awa s s i
Ghone im e t a l .
( 1974)
51 .
TABLE 1 :
( co n t i nued )
Es t ima t e
Age and
remarks 1
Me thod o f
e s t ima t i on 2
Breed
Re f e r ence
Gr easy fleece we igh t
0 . 38
DDR
Dala
Eikj e ( 1 9 7 5 )
0 . 47
DDR
Rygj a
Eikj e ( 1 9 7 5 )
0 . 48
DDR
Chev iot
Ei kj e ( 1 9 7 5 )
0 . 40
DDR
S p a e l s au
Eikj e ( 1 9 7 5 )
0.51
DDR
S t e igar
Eikj e ( 1 9 7 5 )
0 . 34
1 y.o.
DDR
Navaj o
Hall e t a l .
0 . 28
1 y.o.
DDR
Rambo u i l let
Terr i l l and H a z e l ( 1 9 4 3 )
0 . 10
1 y.o.
DDR
N . Z . Romney
McMahon ( 1 9 4 3 )
0. 12
5 m.o.
PHS
Dala
Gj edrem ( 1 9 6 9 )
0 . 10
5 m.o.
DDR
Da l a
Gj edrem ( 1 9 6 9 )
PHS
Texel
Koo i s t ra e t a l .
0 . 59
( 1 964)
( 1966)
0 . 00
1 y.o.
PHS
Romney Marsh
Radomska and Ty s z ka ( 1 9 7 2 )
0 . 32
2 y.o.
PHS
Romney Marsh
Radoms ka and Tys z ka ( 1 9 7 2 )
0 . 37
3 y.o.
PHS
Romn ey Ma rsh
Radoms ka and Tys z ka ( 1 9 7 2 )
Romney Marsh
Radomska and Klewick ( 1 9 7 5)
0 . 07
0 . 47
1 y.o.
PHS
P o l i s h Hount a in Nawar a and Dun iec ( 1 9 7 2 )
0 . 50
2 y.o.
PHS
Po l i sh Moun t a i n Nawara and Dun i e c ( 1 9 7 2 )
0. 37
3 y.o.
PHS
P o l i s h Moun t a in Nawar a and Dun i e c ( 1 9 7 2 )
PHS
Po l i sh Me r ino
Nawa ra ( 1 9 7 1 )
0 . 33
0 . 48
2 y.o.
PHS
P o l i sh Me r ino
Nawar a ( 1 9 7 1 )
0 . 35
1 y.o. F
ISC
Co r r i e d ale
Ka t ad a and Takeda ( 1 9 6 2 )
0.61
2 y.o.
POR
We l s h Moun t a i n
Doney ( 1 9 5 8 )
0 . 43
1 4 m. o .
DDR
N . Z . Romney
Trip a t hy ( 1 9 6 6 )
0 . 23
14 m. o .
PHS
N . Z . Romney
Lundie ( 1 9 7 1 )
0 . 29
1 5 m. o .
PHS
N . Z . Romney
Baker e t a l .
( 1974)
0. 57
15 m. o .
PHS
N . Z . Romney
Baker e t a l .
( 1974)
0 . 29
1 5 m. o .
PHS
N . Z . Romney
Baker ( 1 9 7 7 )
0 . 57
15 m. o .
DDR
N . Z . Romney
Baker
0 . 54
1 y.o.
PHS
Kiv i r c i k
Oz can ( 1 9 7 1 )
0 . 68
1 y.o.
ISR
Kivi r c i k
O z c an ( 1 9 7 1 )
0 . 62
1 y.o.
DDR
Kivi r c ik
Oz c an ( 1 9 7 1 )
0 . 32
14 m . o .
PHS
Perendale
Elliott ( 1 9 7 5 )
0 . 30
14 m. o .
DDR
Peren d a l e
E l l io t t ( 1 9 7 5 )
( 19 7 7 )
52 .
TABLE 1 :
( cont inued )
E s t imate
Age and
1
remarks
Me t h o d o f
e s t ima t ion 2
Breed
Re f erence
Clean s c oured yield
0. 37
30 m . o .
DDR
P o hvar t h
Mu l l aney e t a l .
( 1 970)
0 . 28
1 8 m. o .
DDR
Polwar th
Mu l l aney e t a l .
( 1 970)
0. 5 1
3 0 m. o .
DDR
Corried a l e
Mu l l aney e t a l .
( 1970)
0 . 44
1 8 m. o .
DDR
Corriedale
MuJ laney e t a l .
( 1970)
0 . 59
30 m. o .
DDR
Me r ino
Mul l aney e t a l .
( 1 970)
0 . 56
18
m. o .
DDR
Me r ino
Mul l aney e t a l .
( 1 9 70)
0 . 39
30 m . o .
DDR
Polwarth
Mul l aney e t a l .
( 1 9 70)
0 . 32
18 m.o.
DDR
Po lwar th
Mu l l aney e t a l .
( 19 70)
0 . 52
30 m . o .
DDR
C o r r ie d a l e
Mu l l aney e t a l .
( 1970)
0 . 50
1 8 m. o .
DDR
Corriedale
Mu l l aney e t a l .
( 1970)
0 . 52
30 m . o .
DDR
Mer ino
Mul l aney e t a l .
( 1970)
0 . 52
1 8 m. o .
DDR
Me r ino
Mul l aney e t a l .
( 1970)
0 . 44
1 y.o.
PHS
Rambou i l l e t
Vesely e t a l .
( 1 970)
0 . 39
1 y.o.
PHS
Romn e l e t
Ve sely e t a l .
( 1970
0 . 56
1 y.o. M
PHS
Rambou i l l e t
Ve s e l y and Rob i son ( 1 9 7 0 )
0 . 45
1 y.o. F
PHS
Ramboui l l e t
Vesely and Rob ison ( 1 9 7 0 )
0. 33
1 y.o. M
PHS
Romnelet
Ves e l y and Rob i s o n ( 1 9 7 0 )
0 . 32
1 y.o. F
PHS
Romnelet
Vesely and Robison ( 1 9 7 0 )
0 . 49
16 m . o . F
DDR
Me r i no
Young e t a l .
( 1960)
0 . 44
16 m. o . M
DDR
Me r ino
Young e t a l .
( 1 960)
0 . 50
1 y.o. M
DDR
Mer ino
Young e t a l .
( 1960)
0 . 39
POR
Merino
Mo rley ( 1 9 5 5 a )
0 . 75
PHS
Me r ino
Mo rley ( 1 9 5 5 a )
0 . 75
POR
Mer ino
Mo rley ( 1 9 5 0 )
0 . 40
DDR
Me rino
Beat t i e ( 1 9 6 2 )
0 . 33
2 y.o.
PHS
Po l i sh Me r ino
Nawara ( 1 9 7 1 )
0 . 49
15 m. o .
DDR
Me r ino
Brown and Turner ( 1 9 6 8 )
S t aple length
0 . 46
14 m. o .
DDR
N . Z . Romn ey
Trip a thy ( 1 9 6 6 )
0 . 73
20 m . o .
POR
We l sh Moun t a in
Doney ( 1 9 5 8 )
0 . 38
20 m. o .
DDR
We l sh Moun t a in
D a l t on ( 1 9 6 2 )
0 . 36
1 y.o.
DDR
Rambouil l e t
T e r r i l l and H az e l ( 1 9 4 3 )
53.
TABLE 1 :
( c o n t i nue d )
E s t ima t e
Age and
rema rk s 1
Method o f
e s t ima t ion2
Breed
Re f e r ence
S t ap le l e ngth
0 . 16
14 m. o .
0.21
DDR
N . Z . Romney
Rae ( 1 9 4 6 )
DDR
N . Z . Romney
Rae ( 1 9 4 8 )
0 . 35
14 m . o .
DDR
N . Z . Romney
Rae ( 1 9 5 0 )
0 . 48
1 4 m. o .
PHS
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 35
14 m . o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 50
14 m. o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 73
1 y.o.
PHS
Columb i a
Balch ( 1 9 6 5 )
0 . 29
1 4 m. o .
DDR
N . Z . Romney
Rru<..
0 . 53
30 m. o .
DDR
Polwa r t h
Mul l aney e t a l .
( 1970)
0 . 48
1 8 m. o .
DDR
Polwa r t h
Mul laney e t a l .
( 1970)
0 . 59
30 m . o .
DDR
Cor r i e d a l e
Mu l l aney e t a l .
( 1970)
0 . 50
1 8 m. o .
DDR
Co r r i e d a l e
Mul laney e t a l .
( 1970)
0 . 43
30 m. o .
DDR
He r ino
Mul laney e t a l .
( 1970)
0 . 36
1 8 m. o .
DDR
Me r ino
Mullaney e t a l .
( 1970)
0 . 47
30 m. o .
DDR
P o lwar th
Mul laney et a l .
( 1970)
0. 53
1 8 m. o .
DDR
Polwa r t h
Mu llaney e t a l .
( 1970)
0 . 42
30 m. o .
DDR
Co r r i e d a l e
Mu llaney e t a l .
( 1970)
0 . 44
1 8 m. o .
DDR
Corr i e d a l e
Mullaney e t a l .
( 1970)
0 . 31
30 m . o .
DDR
Me r ino
Mullaney e t a l .
( 1970)
0. 31
1 8 m. o .
DDR
Me r ino
Mullaney et al .
( 1970)
0 . 25
1 y.o.
PHS
Ramb o u i l l e t
Vesely e t al .
( 1970)
0 . 39
1 y.o.
PHS
Romne l e t
Vesely e t a l .
( 1970)
0 . 31
1 y.o. M
PHS
Ramb ou i l l e t
Vesely and Rob i s o n ( 1 9 7 0 )
0. 19
1 y. o. F
PHS
Ramb o u i l l e t
Ve sely a n d Rob i s on ( 1 9 7 0 )
0 . 36
1 y.o. M
PHS
Romne l e t
Vesely and Rob i s o n ( 1 9 7 0 )
0 . 36
1 y.o. F
PHS
Romn e l e t
Vesely and Rob i s o n ( 1 9 7 0 )
0 . 37
16 m. o . F
DDR
Me r ino
Young et a l .
( 1960)
0 . 35
16 m. o . M
DDR
Me r ino
Young et a l .
( 19 60 )
0 . 31
1 y.o. M
DDR
Me r ino
Young et a l .
( 1960)
0 . 44
2 y.o.
PHS
P o l i sh Me r ino
Nawara ( 1 9 7 1 )
0.31
1 y.o.
PHS
P o l ish Moun t a in Nawara and Dun i e c ( 1 9 7 2 )
0 . 45
2 y.o.
PHS
P o l i s h Moun t a in Nawara and Dun i e c ( 1 9 7 2 )
0 . 57
3 y.o.
PHS
P o l i s h Moun t a in Nawara and Dun i e c ( 1 9 7 2 )
( 1 9 5'6 )
54 .
TABLE 1 :
( co n t inued )
Es t ima te
Age and
rema rks 1
Me thod o f
e s t ima t i on 2
Breed
Re f e rence
S t aEle l ength
0 . 75
PHS
2 y.o.
Cho k l a
Bhas i n and D e s a i ( 1 9 6 6 )
0 . 53
PHS
15 m. o .
(Good envi ronme n t )
Tar ghee
Os man and Brad f o rd ( 1 9 6 5 )
0 . 42
PHS
15 m. o .
(Poor envi ronme n t )
Tar ghee
Osman and Brad ford ( 1 9 6 5 )
0 . 23
l.y. o. F
DDR
Navaj o
Bal l e t a l .
0 . 69
1 y.o.
PHS
C o l umb i a
Balch ( 1 9 6 5 )
0 . 36
1 . y.
0 .
DDR
Ramboui l l e t
Te r r i l l and Haze l ( 1 9 4 3 )
0 . 67
1 y.o.
DDR
Ramboui l l e t
Shel t o n e t a l .
0 . 43
5 m.o .
s
PHS
Dala
Gj edrem ( 1 9 6 9 )
0 . 54
5 m. o . T
PHS
Dala
Gj edrem ( 1 9 6 9 )
0 . 37
5 m. o .
DDR
Dala
Gj edrem ( 1 9 6 9 )
0 . 44
5 m. o . M
PHS
Dala
Gj ed rem ( 1 9 6 9 )
0 . 42
5 m. o . M
PHS
Dala
Gj edrem ( 1 9 6 9 )
0 . 46
5 m.o . F
PHS
Dala
Gj edrem ( 1 9 6 9 )
0 . 50
DDR
Me r in o
Bea t t ie ( 1 9 6 2 )
0 . 43
DDR
Me r i no
Brown and Turner ( 1 9 6 8 )
0 . 49
1 y.o.
( unadj u s t e cl. )
PHS
Rambo u i l le t
Bas s e t t e t a l .
( 1967)
0 . 46
1 y.o.
( a dj u s t e d )
PHS
Rambo u i l l e t
Bas se t t e t a l .
( 1967 )
0 . 37
1 y.o.
ISC
Corr i e d a l e
Ka t ada and Takeda ( 1 9 6 2 )
0 . 69
1 y.o.
PHS
Kivi r c i k
Oz can ( 1 9 7 1 )
0 . 59
1 y.o.
ISR
Kiv i r c i k
O z can ( 1 9 7 1 )
0 . 67
1 y.o.
DDR
Kivir c i k
Oz can ( 1 9 7 1 )
( 1 9 64 )
0 . 49
14
o.
PHS
Perendale
E l l io t t
0 . 35
14 m. o .
DDR
P e r end a l e
E l l io t t ( 1 9 7 5 )
0 . 22
POR
Mer i no
Mo rley ( 1 9 5 0 )
0.21
POR
Me r ino
Mo rley ( 1 9 5 1 )
PHS
Mer ino
Mo rley ( 1 9 5 1 )
0 . 56
POR
Me r ino
Mo rley ( 1 9 5 5 a )
0 . 52
PHS
Me r ino
Mo rley ( 1 9 5 5 a )
0 . 24
m.
1 y.o.
( 19 7 5 )
( 1954)
55 .
TABLE 1 :
( c o n t inued )
E s t imate
Age and
remarks 1
Me thod of
e s t imat ion 2
Breed
Re f e rence
Mean f ib r e d i ame t er
0 . 47
1 6 m. o .
DDR
Me r ino
Brown and Turner ( 1 9 6 8 )
0 . 70
30 m. o .
DDR
Pohvarth
Mul l aney e t a l .
( 1970)
0 . 46
1 8 m. o .
DDR
Polwarth
Mu l l aney e t al .
( 1970)
0 . 59
3 0 m. o .
DDR
Corriedale
Mu l l aney e t al .
( 1970)
0. 49
18 m.o.
DDR
Cor r i edal e
Mu l l aney e t a l .
( 1 970)
0 . 64
30 m . o .
DDR
Me r ino
Mu l l aney e t a l .
( 1970)
0 . 46
1 8 m. o .
DDR
Me r ino
Mu l l aney e t a l .
( 1 9 70)
0 . 44
30 m . o .
DDR
Pohva r t h
Mullaney e t a l .
( 1 970)
0 . 30
18 m. o .
DDR
Polwa r t h
Mullaney e t a l .
( 1970)
0 . 56
3 0 m. o .
DDR
Corriedal e
Mul l aney e t a l .
( 1970)
0 . 44
18 m . o .
DDR
Cor rie dale
Mu l laney e t a l .
( 1970)
0 . 62
30 m . o .
DDR
Me r ino
Mu llaney e t a l .
( 1970)
0 . 1-+ 9
1 8 m. o .
DDR
He r i no
Mu l l aney e t a l .
(1 970)
0 . 45
1 6 m. o . F
DDR
Merino
Young e t a l .
( 1 960)
0. 12
16 m . o . M
DDR
Me r i no
Young e t a l .
( 1 960)
0 . 34
1 y.o. M
DDR
Merino
Young e t a l .
( 1 9 60 )
0 . 35
1 y.o. F
DDR
Navaj o
Hall e t a l .
DDR
N . Z . Romney
McMah on ( 1 9 4 3 )
0 . 35
( 1964)
0 . 34
5 m. o . S
PHS
Dala
Gj edrem ( 1 9 6 9 )
0 . 47
5 m. o . T
PHS
Da la
Gj edrem ( 1 9 6 9 )
0 . 53
5 m. o .
DDR
Dala
Gj edrem ( 1 9 6 9 )
0 . 39
5 m. o .
PHS
Dala
Gj edrem ( 1 9 6 9 )
0 . 45
5 m. o . M
PHS
Dala
Gj edrem ( 1 9 6 9 )
0 . 38
5 m. o . F
PHS
Da la
Gj e d rem ( 1 9 6 9 )
DDR
Me r ino
Bea t t i e ( 1 9 6 2 )
PHS
Po l i sh Mer ino
Nawara ( 1 9 7 1 )
0 . 52
DDR
Me r ino
S ch incke l ( 1 9 5 8 )
0 . 23
DDR
Me r ino
S e i t anova ( 1 9 6 6 )
0 . 57
0 . 48
2 y.o.
0 . 33
2 y.o.
PHS
Chokla
Bha s in and D e s a i ( 1 9 6 6 )
0. 17
14 m. o .
DDR
N . Z . Romney
Tripathy ( 1 9 6 6 )
PHS
S . A . Romney
Bo sman ( 1 9 5 8 )
0 . 29
0 . 52
1 y.o.
PHS
Kiv i r c i k
Oz can ( 1 9 7 1 )
0.61
1 y.o.
ISR
Kiv i r c i k
O z c an ( 1 9 7 1 )
56 .
TABLE 1 :
( con t inued )
Es t ima t e
Age a nd
remarks
l
Me thod o f
e s t imat ion 2
Breed
Re f e r e n c e
Mean f ibre d iame t e r
0 . 65
y.
o.
DDR
Kiv i r c ik
Ozcan ( 1 9 7 1 )
0 . 54
14 m . o .
PHS
Perendale
E l l io t t ( 1 9 7 5 )
0 . 47
14 m . o .
DDR
Perendale
Ellio t t ( 1 9 7 5 )
1
S tandard devia t i on o f t he f ibre d iame t e r
0.41
5 m. o .
DDR
Dala
Gj ed rem ( 1 9 6 9 )
0 . 42
5 m. o .
PHS
Dala
Gj edrem ( 1 9 6 9 )
0 . 54
5 m. o . M
PHS
Dala
Gj edrem ( 1 9 6 9 )
0. 31
5 m. o . F
PHS
Dala
Gj edrem ( 1 9 6 9 )
0. 61
5 m.o. S
PHS
Dal a
Gj ed rem ( 1 9 6 9 )
0 . 48
5 m. o . T
PHS
Dala
Gj edrem ( 1 9 6 9 )
Qua l i ty number
0 . 60
30 m . o .
DDR
P o lwarth
Mullaney e t a l .
( 19 70)
0 . 36
18 m . o .
DDR
P o lwarth
Mul laney e t a l .
( 1970)
0.51
30 m . o .
DDR
Cor r i e d a l e
Mullaney e t a l .
( 19 70 )
0 . 38
18 m . o .
DDR
Corriedale
Mu l laney e t a l .
( 1970)
0 . 43
30 m . o .
DDR
Merino
Mullaney e t a l .
( 1970)
0 . 35
18 m.o.
DDR
Me r ino
Mu llaney e t a l .
( 1970)
0 . 54
30 m . o .
DDR
P o lwar t h
Mu llaney e t a l .
( 19 70 )
0 . 36
18 m.o.
DDR
P o lwa r t h
Mul l aney e t a l .
( 1970)
0 . 39
30 m . o .
DDR
Corriedale
Mu llaney e t a l .
( 19 70)
0 . 37
1 8 m. o .
DDR
Corriedale
Mul laney e t a l .
( 1970)
0 . 33
30 m . o .
DDR
Me r ino
Mullaney e t a l .
( 1970)
0 . 32
18 m. o .
DDR
Me rino
Mullaney e t a l .
( 19 70 )
PHS
Texel
Koo i s t ra e t a l .
( 1966)
0 . 44
0 . 26
14 m.o.
PHS
P e r endale
E l l io t t ( 1 9 7 5 )
0.31
14 m . o .
DDR
P e r end a l e
E l l io t t ( 1 9 7 5 )
0 . 37
1 4 m. o .
DDR
N . Z . Romn e y
Rae ( 1 9 4 6 )
0.41
1 4 m. o .
DDR
N . Z . Romney
Rae ( 1 9 4 8 )
0 . 27
1 4 m. o .
DDR
N . Z . Romney
Rae ( 1 9 5 0 )
0 . 47
14 m. o .
PHS
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 27
14 m. o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 34
1 4 m. o .
DDR
N . Z . Romn e y
Rae ( 1 9 5 8 )
57 .
TABLE 1 :
( co n t i nued )
Es t ima t e
Age an d
r emarks 1
Method o f
es t imat ion 2
B r e ed
Re f e r ence
Crimps per inch / cent ime t e r
0 . 40
30 m . o .
DDR
P o lwar t h
Hul l aney e t a l .
( 1970)
0 . 16
1 8 m. o .
DDR
P o lwar t h
Mul laney e t a l .
( 1970)
0. 27
30 m.o.
DDR
C o r r i edale
Hul l aney e t a l .
( 1970)
0 . 34
18 m.o.
DDR
C o r r i edale
Mul l aney e t a l .
( 1 970)
0 . 35
30 m.o.
DDR
Me r i no
Mu l l aney e t a l .
( 1 970)
0. 13
18 m.o.
DDR
M e r ino
Nul laney e t a l .
( 1970)
0 . 24
30 m.o.
DDR
P o lwa r t h
Mul laney e t a l .
( 1970)
0 . 22
18 m . o .
DDR
P o hvar t h
Mul laney e t a l .
( 1 970)
0.21
30 m.o.
DDR
C o r r i edale
Mul laney e t a l .
( 1970)
0 . 25
18 m.o.
DDR
C o r r iedale
Mull aney e t a l .
( 1970)
0 . 22
30 m.o.
DDR
Me r ino
Mu l l aney e t a l .
( 1970)
0 . 09
18 m . o .
DDR
Mer ino
Mul laney e t a l .
( 1970)
0 . 36
16 m.o. F
DDR
Me r i no
Young e t a l .
( 1 960)
0.51
16 m . o . M
DDR
Her i no
Young e t a l .
( 1960)
0 . 43
1 y.o. M
DDR
M e r ino
Young e t a l .
( 1 960)
0 . 40
POR
Me r ino
Morley ( 1 9 5 0 )
0 . 28
PHS
Mer i no
Mo rley ( 1 9 5 5 a )
0 . 47
POR
Me r i no
Mo rley ( 1 9 5 5 a )
0 . 57
DDR
Mer ino
Beat t i e ( 1 9 6 2 )
0 . 16
PHS
Po l i sh Mer ino
Nawa r a ( 1 9 7 1 )
DDR
Mer ino
Brown and Turner ( 1 9 6 8 )
DDR
Merino
S chinckel ( 1 9 5 8 )
0 . 45
16 m. o.
0 . 40
0 . 24
2 y.o.
PHS
Chokla
Bh asin and D e s a i ( 1 9 6 6 )
0 . 72
14 m. o .
DDR
N . Z . Romn ey
Tr ipa t hy ( 1 9 6 6 )
PHS
S . A . Mer ino
Bo sman ( 1 9 5 8 )
0. 31
Charac t e r gr ade
0 . 49
30 m . o .
DDR
P o lwa r th
Mu l l aney e t a l .
( 1970)
0 . 78
18 m. o .
DDR
P o lwa r t h
Mul l aney e t a l .
( 1970)
0 . 45
3 0 m. o .
DDR
Corriedale
Mu l l aney e t a l .
( 1970)
0.41
18 m. o .
DDR
Co r r i e d a l e
Mul laney e t a l .
( 1970)
0 . 54
30 m . o .
DDR
Mer i no
Mul l aney e t a l .
( 1970)
0 . 43
18 m. o .
DDR
Me r i n o
Mul l aney e t a l .
( 1970)
58 .
TABLE 1 :
( co n t inue d )
Es t ima t e
Age and
remarks 1
Me thod o f
e s t ima t io n 2
B reed
Re f e rence
Cha r a c t e r grade
0 . 39
30 m . o .
DDR
Polwarth
Mul laney e t a l .
( 1970)
0. 39
18 m. o .
DDR
Polwar t h
Mul l aney e t a l .
( 1970)
0 . 44
3 0 m. o .
DDR
Cor r i e dale
Mu l l aney et a l .
( 1970)
0 . 37
18 m. o .
DDR
Cor r i edale
Mul l aney et a l .
( 1970)
0 . 42
30 m . o .
DDR
Mer ino
Mul l aney e t a l .
( 1970)
0 . 32
18 m . o .
DDR
Me r ino
Mul l aney e t a l .
( 1970)
PHS
Me r ino
Mor l e y ( 1 9 5 5b )
0 . 38
0 . 66
1 y.o.
PHS
Columb ia
Balch ( 1 9 6 5 )
0 . 23
14 m. o .
PHS
Perendale
E l l io t t ( 1 9 7 5 )
0 . 23
14 m. o .
DDR
Pe rend ale
E l l io t t ( 1 9 7 5 )
0. 16
14 m. o .
DDR
N . Z . Romney
Rae ( 1 9 4 6 )
0 . 1:5
14 m. o .
DDR
N . Z . Romney
Rae ( 1 9 4 6 )
0 . 27
14 m . o .
( s ide )
DDR
N . Z . Romney
Rae ( 1 9 4 8 )
0 . 20
14 m . o .
( f ore quar t e r )
DDR
N . Z . Romney
Rae ( 1 9 4 8 )
0. 38
14 m. o .
(h ind quar t e r )
DDR
N . Z . Romney
Rae ( 1 9 4 8 )
0. 12
14 m. o .
PHS
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 22
14 m. o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
0. 16
14 m: o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 25
14 m. o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
Han d l e gr ade
0 . 10
18 m. o .
DDR
Mer ino
Mul laney e t a l .
( 1970)
0 . 27
30 m . o .
DDR
Mer ino
Mul laney e t a l .
( 1970)
0 . 25
18 m. o .
DDR
C o r r iedale
Mul l aney et a l .
( 1970)
0 . 10
30 m . o .
DDR
C o r r iedale
Mul laney et a l .
( 1970)
0 . 14
18 m. o .
DDR
P o lwar th
Mul l aney et a l .
( 19 7 0 )
0 . 37
30 m . o .
DDR
P o lwar t h
Mul l aney et a l .
( 1970)
0 . 35
30 m. o .
DDR
Her ino
Mul laney e t a Z .
( 1970)
0 . 25
1 8 m. o .
DDR
Me r ino
Mul l aney e t a l .
( 1970)
0 . 28
1 8 m. o .
DDR
Corriedale
Mul l aney e t a l .
( 1970)
0 . 08
30 m. o .
DDR
C o r r i edale
Mul l aney e t a l .
( 1970)
59.
TABLE 1 :
( con t inue d )
Es t ima t e
Age and
remarks 1
Me thod o f
e s t imat ion 2
Breed
Re f e r e n c e
Hand l e gr ade
0 . 28
18 m. o .
DDR
P o lwa r t h
Mul l aney e t a l .
( 1970)
0 . 56
30 m . o .
DDR
P o lwa r t h
Mu l laney et a l .
( 1 970)
0 . 44
14 m. o .
DDR
N . z . Romney
Rae ( 1 9 4 8 )
PHS
Me r i n o
Mo rley ( 1 9 5 5b )
DDR
N . Z . Romney
Rae ( 1 9 4 8 )
0 . 30
Lus t re grade
0. 27
14 m . o .
Greas� c o l our gr ade
0 . 38
30 m . o .
DDR
P o lw a r t h
Mul l aney e t a l .
( 1970)
0 . 36
18 m . o .
DDR
P o bva r th
Mu l l aney e t a l .
( 1970)
0 . 37
30 m . o .
DDR
C o r r iedale
Mul l aney et a l .
( 1970)
0.41
18 m. o .
DDR
C o r r i e d a le
Mu l l aney et a l .
( 1 970)
0 . 40
30 m . o .
DDR
M e r i no
Mul l aney et a l .
( 19 70)
0. 28
18 m. o .
DDR
Me r i n o
Mul l aney et a l .
( 1970)
0 . 24
30 m . o .
DDR
P o lwa r t h
Mul laney e t a l .
( 1970)
0. 27
18 m. o .
DDR
P o lwarth
Mul l aney et a l .
( 1 970)
0 . 29
30 m . o .
DDR
Corr i e d a l e
Mu l l aney et a l .
( 1 970)
0 . 34
18 m. o .
DDR
C o r r i e d a le
Mul laney et a l .
( 1 9 70)
0 . 32
30 m . o .
DDR
Me r i n o
Mu l laney et a l .
( 1970)
0 . 29
18 m . o .
DDR
He r ino
Mu l laney e t a l .
( 1970)
0 . 00
14 m. o .
DDR
N . Z . Romney
Rae ( 1 9 4 8 )
PHS
Me r i n o
Mo r ley ( 1 9 5 5 b )
Me r i n o
Jacks o n ( 1 9 7 3 )
0 . 63
S co ured co lour grade
0. 20
16 m. o .
60 .
c o t ted a r e a g rade and soundne s s grade in wo o l .
Only one re f erence e ach
on lus t r e grade and s c oured co lour gr ade of woo l by Rae ( 1 9 4 8 ) and
Jackson ( 1 9 7 3 ) resp e c t ively were ava i l ab l e .
I t appears t h a t a l l
quant i t a t ive and qual i t a t ive woo l t r a i t s reported i n Tab l e 1 have
modera t e l y h i gh he r i t ab i l i t y and e s t ima t e s range b e twe en 0 . 2 and 0 . 6 in
mo s t cas e s .
He r i t ab i l ity , b e ing a func t ion o f gene t i c varianc e , c o u l d change
it s value w i t h any change in gene f r e q uency as a con s e quen c e of s e l e c t ion .
Period i c re- e s t ima t io n of heri t ab i l i t y for t r a i t s of e conom i c imp o r t ance
part icul a r ly for f lo c k s und er a r t i f i c i a l s e l e c t ion i s thus u s e ful .
However , H i l l ( 1 9 7 4 ) remarked that gene e f f e c t s have to b e very large
in rel a t i o n to the phenotypic s t ru1dard deviat ion b e f o r e gene t i c varianc e s
are l ikely t o change marke dly i n the f i r s t few genera t ions .
He s t a t e d
that the gene r a l imp r e s s ion i s t h a t p r ed i c t ions b as ed on p r e s en t e s t ima t e s
are u s e f u l f o r , s ay , f ive gener a t ions .
A reas onable degree o f l ine a r i t y
o f respons e i s thus a s sumed in t h e f ir s t f ew gene rat i o n s .
No
appre c iab l e change in he r i t ab i l i ty of clean wool weight in Me rinos was
ob s erved by Brown and Turner ( 1 9 6 8 ) in the f l o cks wh i c h has b een und e r
s e l e c t ion f o r t h i s t r a i t for 1 2 years .
Con t rary to t h i s , P a t t i e and
Barlow ( 19 7 4 ) rep o r t e d real i z e d h e r i t ab i l i t y of 0 . 5 3 and 0 . 1 1 f o r ewe s
in the f ir s t two , and sub s equent three gene rat ions re s p e c t ive ly in a
f lock a t T r an g i e Agr i cul tural R e s e a r c h S t a t ion , s e lec t ed f o r h igh c l e an
f leece we i gh t .
The correspond ing f i gure s f o r rams we r e 0 . 6 5 and 0 . 0 2 .
Gene t ic c o r r e l a t ions
Intra- t ra i t gene t i c corre la t ions
S in c e Fal coner ( 1 9 5 2 , 1 9 6 0 ) e x t ended the conc e p t of gene t ic
corre l a t i o n b e tween two t ra i t s (Haz e l ,
1 9 4 3 ) , to the gene t i c c o r r e l a t ion
61 .
b e tween phenotypes f o r the same t r a i t exp r e s s e d in two environmen t s , t he
i d e a has b e e n widely r e cogn i z e d by q u an t i t a t ive gen e t i c i s t s .
D i ckerson
( 1 9 6 2 ) p o i n t e d out t h a t the prob l ems p o sed by cons i d e r a t ion o f mo re than
one ch ar a c t e r and mo r e than one env i r o nmen t in sel e c t i o n p ro gr ammes are
quite s imi l a r .
He e quated , in f ac t , the numb e r of charac t e r s t o the
numb e r of envi r onmen t s and the c o r r e l a t i on b e tween cha r a c t e r s wi t h in
ind ividuals t o corre l a t ion b e tween the pheno t y p i c exp r e s s i on o f the s ame
t r a i t in d i f f e r e n t env i ronment s .
On th e b a s i s o f Falcon e r ' s ( 1 9 5 2 ) the s i s , Rob e r t s o n ( 1 9 5 9 )
p r e s ented fo rmu l ae in t e rms o f me an s qu ares f o r e s t ima t ing the gene t i c
c o r r e l a t ion o f t he p e r f o rman c e o f the s ame gen o t ype i n t wo o r mor e
e nvi ronment s and Dicke r s on ( 1 9 6 2 ) p r e s e n t e d a s imi lar me thod f o r
e s t ima t ing gene t i c co r r e l a t ion
in
t e rms o f gene t i c and geno t y p e ­
e nvi ronmen t i n t e ract ion variance compon e n t s o b t a ined f rom the an a l y s i s
o f va r ianc e .
The approp r i a t e p roduct momen t e s t ima t e s o f gene t i c corre l a t ion
b e obt ained f rom gene t i c comp onen t s o f variance and cova r i an c e f o r
pair o f env i r onmen ts .
can
any
However , when l a r ge numbers o f envi r onmen t s a r e
invo lve d , i t would b e mo r e conven i e n t t o es t ima t e the ave r a g e d e gr e e o f
gene t i c corre l a t ion from t h e ord inary componen t s o f var i an c e f o r
geno t y p e s ( o
�
�
a c ro s s env i r onme n t s ) and f o r int e r a c t ion ( o E I )
i n t r a c l as s me t ho d .
b y the
I t was , howeve r , o b s e rved that GE l i s l ike l y t o be
s omewhat ove re s t imated and the gene t i c repea tab i l i t y or c o r r e l a t ion
b e tween env ir onme n t s is und e re s t ima t e d , i n any analy s i s o f a c t ua l
p e r f o rman c e d a t a , becau s e any gene t i c o r env i ronmental e f f e c t s t h a t a r e
no t s t r ic t ly a dd i t ive ( i . e . , mul t ip l i c a t ive o r p roport i o n a l devi a t ions
f rom a dd i t ive e f fe c t s ) w i l l con t r i b u t e to the e s t ima t e s of i n t e r a c t ion
62.
var i anc e .
D i cker s on ( 1 9 6 2 ) and Yamada ( 1 9 6 2 ) wo rked o u t the n e c e s sary
a l gebra f o r adj u s t ing the in t e ra c t ion comp one n t s of var i anc e in r andom
and mi �e d s t a t i s t i c a l mo d els r e s p e c t ive ly so that the u s e o f adj u s t e d
va lue in the intrac l a s s c o r r e l a t ion makes t h i s c o rre lat ion iden t i c a l
w i t h t h e average p roduce moment co e f f ic ient b e tween t h e same geno t y p e
in each o f t h e mac roenv i r o nmen t s .
The ad j u s tmen t i s made f o r any
impor t an t var i a t ion be twe e n env ironment s in t h e s cale o f gene t i c e f f e c t s .
Th ere are no t many r e p o r t s o f magn i t ud e s o f gene t i c correlat ions
b e twe en envi ronme n t s f o r charac t er s o f e conom i c impo r t ance in sheep and
t hese have been d i s c u s s ed ind iv idually in t he p revious s e c t ion .
c o r re l at ions rep o r t e d d id not devia t e marke d l y f r om uni t y .
The
Rob e r t s on
( 1 9 5 9 ) exp l a ined th at t h e e s t ima t e of t he gene t i c cor r e l a t ion b e tween
p e r f ormanc e in two o r mo r e envi ronme n t s as a quan t itat ive exp r e s s ion o f
GEl i s o f value in giving a me asure o f p r ac t i c a l r a ther than s t a t i s t i c a l
s i gn i f i canc e .
He sugge s t ed that an e s t ima t e o f r e around 0 . 8 wo uld b e
o f b io l o g i c a l o r agr i c u l t u r a l imp o r t an c e and no r e su l t s would b e wo r t h
cons ide r in g unl es s a gene t i c c o r r e l a t ion o f 0 . 6 o r l e s s wh ich i s
s igni f i cant ly d i f f e r ent f r om un i t y , is d e t e c t ed .
In t e r- t r a i t gen e t i � c o r r e l a t ions
To th i s po int , in the review of l i t e ra t ur e the conc e p t of gene t i c
c o r relat ion has been l imi t e d t o the p e r f o rman c e o f the same geno t y p e s
f o r a t r a i t in sheep i n two d i f f e rent env i ronmen t s a s a quan t i t a t ive
e x p r e s s ion of GE l .
Howeve r , gene t i c a s s o c iat ion among d i f f e r e n t char a c t e r s are
i mp o r t an t i n fo rmula t in g s e l e c t ion p lans .
The s e are an o u t come o f
p le i o t rop i c e f f e c t s o f gene s and t o a minor d e g r e e o f l inkage o r s e l e c t ion
w i th varying emphas i s on t h e d i f f e r ent charac t e r s i n many i n t e r b r e e d i n g
63.
group s o f a p o p u l a t ion .
Turner ( 1 9 7 7 ) s t a t e d t hat gen e t i c c o rrelat ions
are used in deve lopme n t o f b re e d ing p l ans t o ind icat e wha t o th e r
charac t e r i s t i c s a re l ike ly t o change in f u t u r e genera t i ons b e s i d e s those
und e r s e le c t io n , to d e c ide wha t coun t e r s e l e c t ion migh t b e needed to
p revent such changes and to d e c i d e whe th e r an eas ily-measured charac t e r
can b e used a s a sel e c t i on c r i t e r i a t o ob t a in gene t i c gains in s t ead o f
o n e mo re d i f f i cu l t (or mo re expens ive ) t o me a s ure .
The gene t i c corre l a t ions as repo r t ed by var ious wo rkers among t he
t r a i t s re levan t t o this wo rk f o r d i f f e re n t b r eeds of sh eep are p r e s e n t e d
i n Tab le 2 .
cova r i anc e s .
They are mo s t ly e s t ima t e d f rom daughte r-dam o r hal f - s i b
Gen e t i c correla t i ons among t ra i t s of in t e r e s t in t h i s
wo r k have no t b ee n a s t hor oughly inve s t i g a t ed as have he r i t ab i l i t i e s .
Tab l e 2 g ive s the informat ion for the t ra i t s t h a t have b e e n s t ud i e d
ext ens ive ly .
No informa t ion was ava i l a b l e on gene t i c c o r r e l a t ions for
c l ean wool \ve i gh t / un i t skin area , t o t a l c r imp number , t ip p in e s s grade ,
lus t r e grade , s coured co lour grade , d i s co loured area grad e , c o t t i n g gra d e ,
co t t ed area grade and soundne s s grade in wo ol .
Gene t i c corre l a t i ons , as in t he c a s e of her i t abi l i t y , may ch3nge
und e r s e l ec t i on .
Not only the degree b u t the d i rect ion may chan g e .
Turner and Young ( 1 9 6 9 ) emph a s i s e d that in any s e le c t i o n p r o g r amme
re- e s t ima t e s shou l d be mad e at int erva l s o f a few year s .
Chan g e s in
s ome gene t i c c o rr e l a t ions in groups of Au s t ral ian Merino s und e r s e le c t ion
for h i gh c l ean woo l we i gh t for 12 years were obs e rved b y B rown and Turner
( 1968) .
The gene t i c co r r e l a t ion b e t ween c l ean woo l we i gh t and f i b re
numb e r de creas e d f rom +0 . 4 t o 0 wh i l e r
weigh t increased f rom 0 . 2 t o U . 5 .
also increased in magni t ud e ;
G
f o r c l ean woo l we i gh t and body
Two negat ive gene t i c c o r r e l a t i on s
f ibre numb e r x f ib r e d iame t er f rom - 0 . 6 t o
- 0 . 8 and f ib r e numb e r x f ibre vo lume f rom - 0 . 5 t o - 0 . 9 .
64 .
TABLE 2 :
S ome pub l i shed e s t ima t e s of gen e t i c cor r e l a t i o n s be twe en
various char ac t e r i s t i c s for l ive-we igh t , wo o l quan t i t y
and qua l i ty in sheep
Tra i t s 1
Es t ima t e
LW
GFW
x
A ge
2
Me thod o f
B ree d
e s t imat ion 3
-0 . 0 3
PHS
Mer ino
Mor l e y ( 1 9 5 5 a )
-0 . 1 1
POR
Mer ino
Mo r l e y ( 1 9 5 5 a )
PHS
Rambo u i l l e t
Bas s e t t et a l .
PHS
Ramb o u i l l e t
Bur f e n i n g e t a l .
DDR
Navaj o
Ha l l et a l .
DDR
Me rino
Be a t t i e ( 1 9 6 2 )
0 . 77
14 m . o .
0 . 45
- 0 . 07
1 y.o.
- 0 . 20
Ul
1
Y
x
LW
SL
S FD
CV
QN
CPI
CHG
GCG
SL
DDR
POR
( 1 964 )
DDR
Me r ino
Brown and Turner ( 1 9 6 8 )
-0 . 07
1 4 m. o .
PHS
Perend a l e
Ell io t t ( 1 9 7 5 )
0 . 18
14 m . o .
DDR
Perend a l e
Ell io t t ( 1 9 7 5 )
0.41
5 m. o .
PHS
Dala
Gj edrem ( 1 9 6 9 )
PHS
Mer ino
Nawara ( 1 9 7 1 )
DDR
N . Z . Romney
Tripa thy ( 1 9 6 6 )
-0 . 08
POR
Me r i no
Mo rley ( 1 9 5 5 a )
0 . 44
PHS
Mer ino
Mo r ley ( 1 9 5 5 a )
0. 11
DDR
Me r ino
Beat t i e ( 1 9 6 2 )
14 m . o .
0 . 09
16 m . o .
DDR
Me r i no
Brown and Turner ( 1 9 6 8 )
0 . 65
1 8 m. o .
DDR
P o lwa r t h
Mul l aney e t a Z. ( 1 9 7 0 )
0 . 28
30 m . o .
DDR
Po lwarth
Mul l aney_ e t a l. ( 1 9 7 0 )
0. 11
18 m. o .
DDR
Me r ino
Mul l aney e t a L ( 1 9 7 0 )
0 . 16
30 m . o .
DDR
Me r ino
Mullaney e t a L ( 1 9 7 0 )
Live-we i gh t , GFW = Greasy f l e e c e we i gh t , Y
C l e an s coured y i e l d ,
S t a p l e length , MFD = Mean f ib r e d iame t e r ,
S tandard dev i a t ion o f the f ib r e d i ame t er ,
Coe f f i c ient o f var i a t ion o f f ib r e d iame t e r ,
CPC
C r imp s p e r cen t ime t e r ,
Qua l i t y numb e r ,
Cr imp s p e r inch ,
TCN
To t al c r imp number ,
Chara c t e r grade ,
HG
Han d l e grade ,
Greasy c o lour grade ,
S CG
S coured co l our grad e
2 m . o . = mon t h s o l d ,
3
( 1 9 71 )
16 m. o .
0 . 54
x
( 1967)
0 . 26
0 . 44
LW
Re f e r ence
y . o . = years o ld
Daugh t e r-dam r e g re s s ion ,
PHS
P a r e nt - o f f s p r in g r e g r e s s ion
Pat e rn a l ha l f- s ib ,
65 .
TABLE 2 :
( co n t i nued )
Tr a i t s 1
Es t ima t e
LW
x
x
2
Me thod o f
B ree d
e s t ima t ion 3
Re f erence
-0 . 1 5
30 m . o .
DDR
Co r r i edale
Mu l l aney et a l .
( 1970)
0 . 07
18 m. o .
DDR
C o r r i edale
Mul l aney e t a l .
( 1970)
-1. 11
POR
Me r i no
Mor l e y ( 1 9 5 0 )
-0 . 2 5
PHS
Me r ino
Mor l e y ( 1 9 5 5 a )
-0 . 2 6
POR
Me r in o
Mor l e y ( 1 9 5 5 a )
1 6 m. o .
DDR
Me r i n o
Brown and Turne r ( 1 9 6 8 )
1 4 m. o .
0. 52
( unadj us t e d )
PHS
Rambou i l l e t
Bas s e t e t a l .
( 196 7 )
0 . 47
( adj u s t ed )
1 4 m. o .
PHS
Rambouil l e t
Bas s e t e t al .
( 1 96 7 )
-0 . 0 6
14 m. o .
PHS
P e rendale
El l i o t t ( 1 9 7 5 )
0 . 22
14 m. o .
DDR
Perendale
Ell i o t t ( 1 9 7 5 )
0 . 09
5 m. o .
PHS
Dala
Gj ed r em ( 1 9 6 9 )
0.21
1 4 m. o .
DDR
N . Z . Romn e y
T r ip a thy ( 1 9 6 6 )
-0 . 1 6
1 y.o.
DDR
Navaj o
Hal l e t a l .
-0 . 0 1
5 m.o.
PHS
Dala
Gj ed r em ( 1 9 6 9 )
DDR
Me r i no
Beat t i e ( 1 9 6 2 )
SL
-0 . 0 6
LW
A ge
MFD
0 . 00
( 1964)
0. 12
16 m. o .
DDR
Me r ino
B rown and Turn er ( 1 9 6 8 )
-0 . 0 2
14 m. o .
PHS
P e rendale
Elliot t ( 1 9 7 5 )
0 . 00
14 m . o .
DDR
P e rendale
El l i o t t ( 1 9 7 5 )
0 . 16
14 m . o .
DDR
N . Z . Romney
Tr ipa t h y ( 1 9 6 6 )
5 m. o .
PHS
Dala
Gj edrem ( 1 9 6 9 )
DDR
Me r i no
Beat t ie ( 1 9 6 2 )
LW
x
S FD
0 . 27
LW
x
CV
0 . 18
LW
X
QN
0 . 37
14 m. o .
PHS
Perend ale
E l l io t t ( 1 9 7 5 )
-0 . 1 0
14 m . o .
DDR
Perendale
El l io t t ( 1 9 7 5 )
0. 12
POR
Me r ino
Mo r ley ( 1 9 5 0 )
-0 . 0 2
PHS
Her ino
Ho r ley ( 1 9 5 5 a )
0 . 05
POR
Her in o
Hor l ey ( 1 9 5 5 a )
0. 15
DDR
He r i n o
Bea t t ie ( 1 9 6 2 )
Ul X
CPC/
CP I
0 . 07
1 6 m. o .
DDR
Her ino
Brown and Turner ( 1 9 6 8 )
- 0 . 05
1 4 m. o .
DDR
N . Z . Romney
T r i p athy ( 1 9 6 6 )
66.
TABLE 2 :
( cont inued )
Traits 1
Es t ima t e
x
0 . 21
LW
CHG
LW
x
HG
LW
x
GCG
GFW
GFW
x
x
Y
He thod o f
Breed
e s t ima t i on 3
Re f erence
PHS
Herino
Mo r le y ( 1 9 5 5b )
-0 . 4 7
14 m. o .
PHS
Perendale
El l i o t t ( 1 9 7 5 )
-0 . 3 1
14 m. o .
DDR
Perendale
Ell i o t t ( 1 9 7 5 )
-0 . 09
PHS
He r ino
Ho r l e y ( 1 9 5 5 b )
0. 11
PHS
He r i n o
Ho r ley ( l 9 5 5 b )
DDR
Me r i no
S ch in ck e l ( 1 9 5 8 )
0 . 06
DDR
He r ino
Beat t i e ( 1 9 6 2 )
- 0 . 22
PHS
He r ino
Mor l e y ( 1 9 5 5 a )
- 0 . 05
POR
Me r i no
Mo r l ey ( l 9 5 5 a )
-0 . 09
SL
Age2
16 m . o .
0 . 03
18 m. o .
DDR
Corriedale
Mu 1 lane y e t a l .
( 1970)
0 . 75
18 m. o .
DDR
P o lwa r t h
Mul l aney e t a l .
( 1970)
0 . 40
30 m . o .
DDR
P o lwar t h
Mul laney e t a l .
( 1970)
-0 . 1 8
18 m. o .
DDR
Mer ino
Mu l l aney e t a l .
( 1970)
-0 . 27
30 m. o .
DDR
Mer ino
Hul l aney e t a l .
( 1 970)
- 0 . 25
30 m . o .
DDR
Corriedale
Mul l aney e t a l .
( 1970)
-0 . 49
1 y. o .
PHS
Rambou i l l e t
Vesely e t a l. .
( 1970)
0 . 30
1 y.o.
PHS
Romn e l e t
Vesely e t a l .
( 1970)
0 . 40
14 m. o .
DDR
N . Z . Romney
T r i p a t hy ( 1 9 6 6 )
0 . 45
5 m.o .
DDR
Dala
Gj edrem ( 1 9 6 9 )
0 . 08
1 y.o.
DDR
Navaj o
Hall e t a l .
0 . 40
15 m. o .
PHS
Tar ghe e
O sman and B r a d f o r d ( 1 9 6 5 )
0 . 17
PHS
Mer ino
Mo r ley ( 1 9 5 5 a )
- 0 . 02
POR
Mer ino
Mo r l ey ( 1 9 5 5 a )
PHS
Ramboui l l e t
Basse t t e t a l .
( 1967 )
1 y.o.
PHS
Ramb o u i l l e t
B as s e t t e t a l .
( 1967)
0 . 20
1 8 m. o .
DDR
Corriedale
Mul l aney e t a l .
( 1970)
0 . 47
18 m . o .
DDR
P o lwa r th
Mul laney e t a l .
( 1970)
0 . 29
30 m . o .
DDR
P o lwar th
Mul l aney e t a l .
( 1970)
0. 13
18 m. o .
DDR
Me r ino
Mul l aney e t a l .
( 1970)
0 . 56
1 y.o.
( unadj u s t e d )
0 . 75
(adj u s t e d )
( 1 964)
67 .
TABLE 2 :
( cont inue d )
Tra i t s 1
Es t imat e
A ge
2
Method o f
B r e ed
e s t ima t io n 3
0 . 17
30 m. o .
DDR
Mer ino
Mul laney e t a l .
( 1970)
0 . 18
30 m. o .
DDR
Corr iedale
Mu llaney et a l .
( 1 970)
0 . 25
1 4 m. o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 60
14 m.o.
PHS
N . Z . Romn e y
Rae ( 1 9 5 8 )
0. 2 1
1 4 m. o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
0.26
1 4 m. o .
DDR
N . Z . Romney
Ra e ( 1 9 5 8 )
- 0 . 38
1 y.o.
PHS
Ramb o u i l l e t
Ve s e l y e t a l .
( 1970)
0 . 70
1 y.o.
PH S
Romn e l e t
Ve s e l y e t a l .
( 1 970)
DDR
Me r ino
Bea t t i e ( 1 9 6 2 )
0 . 70
GFW
x
MFD
Re ference
0 . 29
16 m. o .
DDR
Me r ino
Brown and Turner ( 1 9 6 R )
0 . 76
14 m. o .
PHS
Perendale
E l l io t t ( 1 9 7 5 )
0 . 44
14 m. o .
DDR
Perendale
E l l io t t ( 1 9 7 5 )
0 . 14
18 m . o .
DDR
Co r r i e d a l e
Mull aney e t a l .
( 1970)
0. 19
30 m . o .
DDR
Co r r i e d a l e
Mull aney e t al .
( 1 9 70 )
0 . 08
18 m. o .
DDR
Polwa r t h
Mul l aney e t a l .
( 19 70)
'0 . 4 0
30 m . o .
DDR
Polwa r t h
Mull aney e t a l .
( 1970)
0 . 47
18 m.o.
DDR
Me r in o
Mu l l aney et a l .
( 1970)
0 . 43
30 m. o .
DDR
Me r in o
Mul l aney et a l .
( 1970)
PHS
Chokla
Bhasin et a l .
0. 19
( 1 964)
-0 . 1 0
1 y.o.
PHS
Navaj o
Ha ll e t a l .
0 . 23
5 m. o .
PHS
Da l a
Gj edrem ( 1 9 6 9 )
DDR
Me r ino
Beat t i e ( 1 9 6 2 )
0. 19
( 1968)
0. 13
16 m. o .
DDR
Merino
Brown and Turner ( 1 9 6 8 )
0 . 43
14 m. o .
PHS
Perendale
E l l io t t ( 1 9 7 5 )
0 . 44
14 m. o .
DDR
Peren d a l e
Elliott ( 1975)
0 58
14 m . o .
DDR
N . Z . Romney
T r i pathy ( 1 9 6 6 )
5 m. o .
PHS
Dala
Gj e d rem ( 1 9 6 9 )
DDR
Mer ino
Beattie ( 1 9 6 2 )
.
GFW
x
SFD
0 . 35
GFW
x
CV
0 . 15
68 .
TABLE 2 :
( cont inued )
Es t ima t e
GFW
x
QN
A ge
2
Method o f
B ree d
e s t imat i o n 3
-0 . 49
18 m . o .
DDR
C o r r iedale
Mu l laney et a l .
( 1970)
-0 . 55
18 m . o .
DDR
P o lwar th
Mul l aney et a l .
( 1970)
-0 . 66
30 m. o .
DDR
P o lwarth
Mu l laney et a l .
( 1970)
-0 . 75
18 m. o .
DDR
M e r ino
Mu llaney e t a l .
( 1 970)
-0 . 5 3
30 m . o .
DDR
Me r ino
Mu l l aney et a l .
( 1970)
-0 . 48
30 m . o .
DDR
C o r r iedale
Mul laney e t a l .
( 1970)
-0 . 47
14 m . o .
DDR
N . Z . Romn e y
Rae ( 1 9 5 8 )
-0 . 62
14 m . o .
PHS
N . Z . Romney
Rae ( 1 9 5 8 )
-0 . 47
14 m . o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
-0 . 49
14 m . o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
-0 . 48
14 m . o .
PHS
P e r endale
Ell io t t ( 1 9 7 5 )
0 . 09
14 m. o .
PHS
P e rendale
E l l io t t ( 1 9 7 5 )
PHS
Texe l
Ko o i s t ra e t a l .
( 1966)
-0 . 42
GFW
GFW
x
x
Re f e rence
CPC/ - 0 . 6 1
CPI
-0 . 6 7
18 m . o .
DDR
Corr i edale
Mul l aney e t a l .
( 1970)
18 m . o .
DDR
P o lwarth
Mull aney et a l .
( 1 970)
-0 . 7 9
30 m. o .
DDR
P o lwarth
Mu l l aney e t a l .
( 1 970)
-0 . 99
18 m . o .
DDR
Me r in o
Mul laney e t a l .
( 1970)
-0 . 7 7
30 m . o .
DDR
Me r in o
Mu l l aney e t a l .
( 1970)
-0 . 3 5
30 m . o .
DDR
Cor r i edale
Mu l l aney e t a l .
( 1970)
-0 . 5 6
POR
Me r in o
Mo rley ( 1 9 5 5 a )
-0 . 06
PHS
Me r i no
Mo r l ey ( 1 9 5 5 a )
-0 . 38
PHS
Cho k l a
Bhas i n e t a l .
-0 . 87
DDR
Me r ino
Beat t ie ( 1 9 6 2 )
CHG
( 1 968)
-0. 20
16 m . o .
DDR
Mer ino
Brown an d Turner ( 1 96 8 )
-0. 13
14 m . o .
DDR
N . Z . Romney
Tr ipathy ( 1 9 6 6 )
0 . 09
30 m . o .
DDR
Corriedale
Mull aney e t a l .
( 1970)
0 . 32
18 m. 0 .
DDR
C o r r i e dale
Mu l laney e t a l .
( 1 9 7 0)
0 . 43
18 m . o .
DDR
P o lwar th
Mullan ey e t a l .
( 1 97 0)
0 . 29
30 m . o .
DDR
P o lwar t h
Mullaney e t a l .
( 1970)
-0 . 54
18 m. o .
DDR
Mer in o
Mullaney e t a l .
( 1970)
-0 . 27
30 m. o .
DDR
Mer i n o
Mul l aney e t a l .
( 1970)
-0 . 16
14 m . o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 09
14 m . o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
69 .
TABLE 2 :
( c o n t inued)
Tra i t s 1
Es t ima t e
GFW
x
CHG
A ge
2
Me t ho d o f
B ree d
e s t ima t i on 3
0 . 08
14 m. o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
0. 27
14 m. o .
DDR
N . Z . Romney
Ra e ( 1 9 5 8 )
PHS
Me r ino
Mor l e y ( 1 9 5 5 b )
-0 . 0 6
GFW
x
HG
0 . 52
14 m. o .
PHS
P e r endal e
El l io t t ( 1 9 7 5 )
0 . 32
14 m. o .
DDR
Pe r endale
El l io t t ( 1 9 7 5 )
0 . 08
1 8 m. o .
DDR
C o r r iedale
Mul l aney et a l .
( 1970)
-0 . 8 7
18 m. o .
DDR
Po lwarth
Mul l aney et a l .
( 1 970
0 . 08
30 m . o .
DDR
Po lwar th
Mu l l an e y e t a l .
( 1970)
-0 . 7 0
1 8 m. o .
DDR
Me r ino
Mu l laney e t a l .
( 1970)
-0 . 4 7
30 m. o .
DDR
Me r ino
Mul laney e t a l .
( 1 970)
-0 . 5 3
30 m. o .
DDR
Co r r i ed a l e
Mu l laney et al .
( 1970)
PHS
Mer ino
Mo r l e y ( 1 9 5 5 b )
0 . 15
GFW
x
GCG
-0 . 3 0
1 8 rn . o .
DDR
C o r r i edal e
Mu l l aney e t a l .
( 1 970)
0 . 70
18 m. o .
DDR
Po lwarth
Mu l l aney et a l .
( 1970)
0. 10
30 m . o .
DDR
P o lwarth
Mul l aney et a l .
( 1970)
-0 . 4 2
18 m. o .
DDR
Me r ino
Mul lane y e t a l .
( 1970)
-0 . 35
30 m. o .
DDR
Mer ino
Mu l l aney e t a l .
(1 970)
-0 . 45
30 m . o .
DDR
C o r r i edale
Mu l l aney e t a l .
( 1970)
PHS
Mer ino
M o rl ey ( 1 9 5 5 b )
DDR
Me r i no
Brown and Turner ( 1 9 6 8 )
0 . 54
DDR
Me r ino
Beat t ie ( 1 9 6 2 )
0 . 66
PHS
Ramb o ui l l e t
Vesely e t a l .
( 1970)
0 . 32
PHS
Romn e l e t
Vesely e t al .
( 1970)
-0 . 2 8
Y
x
SL
R e f e r en c e
0 . 36
16 m . o .
0 . 57
18 m. o .
DDR
Po lwar t h
Mul l aney et a l .
( 1970)
0 . 27
30 m . o .
DDR
P o lwar t h
Mul l an e y e t a l .
( 1 970)
0 . 42
1 8 m. o .
DDR
Me r ino
Mul laney et a l .
( 1 970)
0 . 36
30 m. o .
DDR
Mer ino
Mul l aney e t a l .
( 1970)
0 . 23
3 0 rn . o .
DDR
C o r r i edale
Mul laney e t a l .
( 1970)
0.41
1 8 m. o .
DDR
Corr i edale
Mul l aney et a l .
( 1970)
0 . 63
POR
Mer ino
Mo r ley ( 1 9 5 5 a )
0 . 27
PHS
Mer ino
Morley ( 1 9 5 5 a )
70 .
TABLE 2 :
( cont i n ue d )
E s t ima t e
Y
x
MFD
A ge
2
Method o f
Br e ed
e s t ima t i o n 3
Re f e r e n c e
0. 15
18 m . o .
DDR
Polwa r t h
Mullaney e t a Z .
( 1 970)
0.01
30 m . o .
DDR
Po lwarth
Mu llaney e t a Z .
( 1970)
-0 . 0 3
18 m.o.
DDR
Me r i n o
Mu llaney e t a Z .
( 1970)
- 0 . 24
30 m.o.
DDR
Me r ino
Mul laney e t a Z .
( 1970)
0 . 23
30 m. o .
DDR
Co r r i e d a l e
Mu l laney e t aZ .
( 1970)
0 . 27
1 8 m. o .
DDR
Corriedale
Mu l l aney e t a Z .
( 1 970)
DDR
Me r i n o
Beat t i e ( 1 9 6 2 )
DDR
Me r i no
Brown and Turner ( 1 9 6 8 )
DDR
Me r i no
Bea t t i e ( 1 9 6 2 )
0 . 03
0. 12
1 6 m. o .
Y
x
CV
0 . 09
Y
x
QN
-0 . 4 6
1 8 m. o .
DDR
Po lwa r th
Mu l laney e t a L
( 1970)
-0 . 6 6
30 m . o .
DDR
Polwa r t h
Mu l l aney e t a L
( 1970)
-0 . 3 7
18 m. o .
DDR
Me r i no
Mul l aney e t a Z .
( 1 970)
-0 . 2 4
30 m . o .
DDR
Me r ino
Mu l laney e t a L
( 1970)
-0 . 3 2
30 m . o .
DDR
Corr i e d a l e
Mu l l aney e t a L
( 1970)
-0 . 5 3
1 8 m. o .
DDR
Co r r i e d a l e
Mul l aney e t a Z .
( 1970)
-0 . 5 4
1 6 m. o .
DDR
Mer ino
Brown and Turner ( 1 9 6 8 )
-0 . 1 5
1 8 m. o .
DDR
Polwa r t h
Mu l l aney e t a Z .
( 1970)
-0. 58
30 m . o .
DDR
Polwarth
Mul l aney e t a Z .
( 1 970)
-0 . 6 9
18 m . o .
DDR
Mer i no
Mul laney et a Z .
( 1 970)
-0 . 14
30 m . o .
DDR
Me r i no
Mul l aney e t a Z .
( 1970)
-0 . 20
30 m . o .
DDR
Co r r i e d a l e
Mul l aney e t a Z .
( 1970)
-0 . 53
18 m.o.
DDR
Corriedale
Mul l aney e t a Z .
( 1970)
-0 . 49
POR
Mer in o
Morley ( 1 9 5 5 a )
-0 . 37
PH S
Mer ino
Mo r l ey ( 1 9 5 5 a )
-0. 47
DDR
Mer ino
Bea t t ie ( 1 9 6 2 )
0 . 30
PHS
Mer ino
Mo r l ey ( 1 9 5 5b )
Y
Y
x
x
CPC /
CPI
CHG
0 . 26
18 m. o.
DDR
P o lwa r t h
Mul l aney e t a Z .
( 1970)
0 . 49
30 m.o.
DDR
Polwa r t h
Mul l aney e t a Z .
( 1970)
0 . 09
1 8 m. o .
DDR
Me r ino
Mul l aney e t a Z .
( 1970)
0 . 26
30 m.o.
DDR
Me r ino
Mul l aney e t a L
( 1970)
0 . 06
30 m . o .
DDR
Corriedale
Mul laney e t a Z .
( 1970)
0 . 28
1 8 m. o .
DDR
Corriedale
Mul laney e t a L
( 1970)
7] .
TABLE 2 :
( cont inue d )
Tr a i t s 1
Es t ima t e
Y
Y
x
HG
x GCG
SL x MFD
Age 2
Me thod o f
e s t ima t ion 3
0 . 14
CV
Re feren c e
PHS
Me r ino
Mor l ey ( 1 9 5 5 b )
18 m.o.
DDR
Polwarth
Mu l l aney e t a l .
( 1970)
0 . 30
30 m. o .
DDR
P o lwar t h
Mu l laney e t a l .
( 1970)
-0 . 0 8
18 m. o.
DDR
Me r i n o
Mu l l aney e t a l .
( 1 970)
-0 . 1 6
30 m . o .
DDR
Me r i no
Mul laney et a l .
( 1970)
-0 . 5 1
30 m. o .
DDR
Corriedale
Mu l l aney e t a l .
( 1 970)
0 . 18
1 8 m. o .
DDR
Cor r i ed a l e
Mul laney e t a l .
( 1970)
PHS
Merino
Mo r ley ( 1 9 5 5 b )
0.31
0 . 57
1 8 m. o .
DDR
Polwarth
Mu l l aney e t a l .
( 1 970)
0 . 76
30 m. o .
DDR
P o lwar t h
Mu l l aney e t a l .
( 1970)
0 . 82
1 8 m. o .
DDR
Mer ino
Mu l l aney et a l .
( 1 970)
0 . 67
30 m. o .
DDR
Me r ino
Mu l l aney et a l .
( 1970)
0 . 65
30 m. o .
DDR
Corriedale
Mul laney e t a l .
( 1970)
0 . 59
18 m. o .
DDR
Corriedale
Mul l aney et a l .
( 1970)
PHS
Chokla
Bhas in e t a l .
- 0 . 35
( 1 968)
0. 15
1 y.o.
DDR
Navaj o
Hal l e t a l .
0 . 53
14 m . o .
PHS
Perendale
Ellio t t ( 1 9 7 5 )
0. 31
14 m. o .
DDR
Peren d a l e
Elliott ( 197 5)
DDR
Mer ino
S ch inckel ( 1 9 5 8 )
( 1964)
-0 . 1 9
18 m. o .
DDR
Po lwar t h
Mull aney e t a l .
( 1 970)
-0 . 63
30 m. o .
DDR
Polwa r t h
Mul l aney e t a l .
( 1970)
0.01
18 m. o .
DDR
Mer ino
Mull aney et a l .
( 1970)
0 . 09
30 m . o .
DDR
Mer ino
Mull aney et a l .
( 1970)
0 . 26
30 m . o .
DDR
Corriedale
Mull aney et a l .
( 1 970)
0 . 29
18 m . o .
DDR
Corriedale
Mul laney e t a l .
( 1 970)
0 . 01
5 m.o.
PHS
Dala
Gj edrem ( 1 9 6 9 )
DDR
Mer ino
Beat t ie ( 1 9 6 2 )
-0 . 1 1
x
ree d
-0 . 1 6
0 . 44
SL
B
0 . 03
16 m.o.
DDR
Merino
B rown and Turn e r ( 1 9 6 8 )
0 . 68
14 m. o .
DDR
N . Z . Romney
T r ipa thy ( 1 9 6 6 )
DDR
Mer ino
Beat t i e ( 1 9 6 2 )
0 . 04
72 .
TABLE 2 :
( c ont i nued )
Tra i t s 1
Es t ima t e
SL x S FD
S L x QN
SL x C P C /
CPI
SL x CHG
Age
2
Hethod o f
Breed
e s t ima t i on 3
Re f erence
0. 19
5 m.o.
PHS
Dala
Gj edrem ( 1 9 6 9 )
-0 . 4 3
18 m. o .
DDR
Po l\varth
Mul laney e t a l .
( 1 970)
-0 . 4 7
30 m. o .
DDR
P o lwarth
Mul l aney et a l .
( 1970)
-0 . 6 6
30 m . o .
DDR
Me r ino
Mul l aney e t a l .
( 1970)
-0 . 57
18 m . o .
DDR
Her ino
Mu l l aney e t a l .
( 1970)
-0 . 6 1
30 m . o .
DDR
Corr i e d a l e
Mullaney et a l .
( 1 9 70)
- 0 . 65
18 m . o .
DDR
Cor r i edale
Mu l l aney et a l .
( 1970)
-0 . 7 3
14 m . o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
-0 . 7 6
14 m. o .
PHS
N . Z . Romney
Rae ( 1 9 5 8 )
-0 . 6 3
14 m. o .
PHS
Perendale
El l io t t ( 1 9 7 5 )
-0 . 4 1
1 4 m. o .
DDR
Pe rendale
Ell iott ( 1 9 7 5 )
-0 . 7 5
DDR
He r ino
Beat t ie ( 1 9 6 2 )
-0 . 1 8
POR
He r i no
Hor l e y ( 1 9 5 0 )
- 0 . 34
POR
Me r ino
Ho r l e y ( l 9 5 5 a )
-0 . 6 6
PHS
Me r ino
Mor l e y ( 1 9 5 5 a )
0 . 25
PHS
Chokla
Bhas i n e t a l .
( 1968)
-0 . 5 7
18 m. o .
DDR
Po lwar th
Mul l aney et a l .
( 1970)
-0 . 2 7
30 m. o .
DDR
Polwarth
Mu l l aney et a l .
( 1 970)
-0 . 60
18 m.o.
DDR
Me r i no
Hul l aney e t a l .
( 1970)
-0 . 5 9
30 m . o .
DDR
He r ino
Mul l aney e t a l .
( 1970)
-0 . 5 5
30 m. o .
DDR
Co r r i edale
Hul l aney e t a l .
( 1970)
-0 . 5 3
18 m.o.
DDR
Co rr i edale
Mul l aney et a l .
( 1970)
-0 . 7 6
14 m. o .
DDR
N . Z . Romney
Tr ipa thy ( 1 9 6 6 )
PHS
He r ino
Ho rley ( 1 9 5 5 b )
0. 31
0. 13
1 4 m. o .
DDR
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 74
14 m. o .
PHS
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 44
18 m. o .
DDR
Pohva r t h
Hul l aney e t a l .
( 1970)
0 . 40
30 m . o .
DDR
Polwa r t h
Hul l aney et a l .
( 1970)
-0. 16
18 m. o .
DDR
Her ino
Mul l aney e t a l .
( 1970)
0 . 20
30 m . o .
DDR
Her ino
Mul l aney e t a l .
( 1970)
0 . 23
30 m. o .
DDR
Corr i ed a l e
Mul l aney e t a l .
( 1970)
73 .
TABLE 2 :
( co n t inue d )
Tra i t s 1
E s t ima t e
SL x CHG
S L x HG
S L x GCG
MFD x S FD
MFD x QN
2
Ag e -
Met hod o f
Br e ed
e s t imat i on 3
Re f e r e n c e
0 . 23
18 m. o .
DDR
Co r r i e d a l e
Mullaney e t a ! .
0 . 47
14 m . o .
PHS
Pe rendale
Ell io t t ( 1 9 7 5 )
0 . 03
14 m. o .
DDR
P e r endal e
E l l io t t ( 1 9 7 5 )
PHS
Me r i no
Mo rley ( 1 9 5 5 b )
0 . 40
( 1970)
0 . 65
18 m. o .
DDR
Po lwa r t h
Mul l an e y e t a l .
( 1970)
0 . 2 8·
30 m. o .
DDR
Po lwa r t h
Mu llaney et a l .
( 1 970)
0. 11
18 m. o .
DDR
Me r ino
Mul laney et a l .
( 1970)
0. 16
30 m . o .
DDR
Mer ino
Mul l aney e t a l .
( 1 9 70 )
-0 . 1 5
30 m . o .
DDR
Co r r i ed a l e
Mullaney et a l .
( 1 970)
0 . 07
18 m . o .
DDR
Co r r i ed a l e
Mullaney e t a l .
( 1970)
0 . 40
18 m. o .
DDR
Me r i no
Mu llaney e t a l .
( 1 970)
0 . 86
18 m . o .
DDR
P o lwarth
Mul laney et a l .
( 1970)
0 . 22
30 m . o .
DDR
Polwar t h
Mul laney et a l .
( 1970)
0 . 23
30 m . o .
DDR
Me r ino
Mul laney e t a l .
( 1970)
0 . 52
30 m . o .
DDR
Co r r i ed a l e
Mullaney et a l .
( 1970)
0 . 30
1 8 m . o . DDR
Cor r i e d a l e
Mullaney et a l .
( 1 970)
-0 . 43
PHS
Me r i n o
Mo rley ( 1 9 5 5 b )
0. 1 1
DDR
M e r ino
Beat t i e ( 1 9 6 2 )
0 . 69
5 m.o.
PHS
Dala
Gj edrem ( 1 9 6 9 )
-0 . 46
14 m . o .
PHS
P e r endale
E l l io t t ( 1 9 7 5 )
-0 . 27
14 m . o .
DDR
P e r en d a l e
El l io t t ( 1 9 7 5 )
-0 . 30
18 m . o .
DDR
P o hmrth
Mul lan e y e t a l .
( 1970)
-0 . 47
30 m . o .
DDR
P o lwarth
Mullaney e t a l .
( 1970)
-0 . 30
18 m . o .
DDR
M e r ino
Mullaney et a l .
( 1970)
-0 . 50
30 m . o .
DDR
M e r ino
Mullaney e t a l .
( 1970)
-0 . 69
30 m . o .
DDR
Cor r i e d a l e
Mullaney e t a l .
( 1970)
-0. 75
18 m. o .
DDR
Cor r i e d a l e
Mullaney e t a l .
( 1970)
74 .
TABLE 2 :
( cont inued )
Tra i t s 1
Es t ima t e
MFD
x
A ge
2
Met ho d o f
Breed
e s t ima t ion 3
CPC / - 0 . 1 1
CP I
-0. 82
18 m. o .
DDR
Polwa r t h
Mul l aney et a l .
( 1970)
30 m . o .
DDR
Polwa r t h
Mu l laney e t a Z. .
( 1970)
-0. 4 1
18 m . o .
DDR
Mer ino
Mull aney e t a l .
( 1970)
-0 . 52
30 m . o .
DDR
Mer ino
Mu l l aney
al .
( 1970)
-0 . 7 3
30 m . o .
DDR
Co r r i e d a l e
Mu llaney e t a l .
( 1 970)
-0. 82
18 m. o .
DDR
Corriedale
Mul laney e t a l .
( 1970)
DDR
Me r ino
Beat t ie ( 1 9 6 2 )
DDR
Mer ino
Brown and Turner ( 1 9 6 8 )
-0 . 1 7
DDR
Me r ino
S chinckel ( 1 9 5 8 )
-0 . 36
PHS
Chokla
Bhas in e t a l .
-0 . 1 7
-0 . 1 0
MFD x CHG
MFD
MFD
x
x
Re f er en c e
HG
GCG
16 m . o .
et
( 1 968)
-0. 63
14 m . o .
DDR
N . Z . Romney
Tripathy ( 1 9 6 6 )
0 . 09
14 m . o .
PHS
Pe rendale
El l io t t ( 1 9 7 5 )
0 . 10
14 m . o .
DDR
Perendale
Ell i o t t ( 1 9 7 5 )
-0 . 33
18 m . o .
DDR
P o lwar t h
Mu l laney e t a l .
( 1970)
-0 . 13
30 m. o .
DDR
Po lwarth
Mul l aney e t a l .
( 1970)
-0 . 46
18 m . o .
DDR
Me r ino
Mul laney e t a l .
( 1970)
-0 . 63
30 m . o .
DDR
Me r ino
Mul l aney e t a l .
( 1 970)
- 0 . 06
30 m . o .
DDR
C o r r i e d a le
Mul l aney e t a l .
( 1970)
-0 . 1 7
18 m . o .
DDR
C o r r iedale
Mu l l aney e t a l .
( 1970)
-0. 70
18 m . o .
DDR
Me r ino
Mul l aney e t a l .
( 1970)
- 0 . 85
30 m . o .
DDR
Mer i no
Mu l laney e t a l .
( 1970)
-0 . 59
18 m . o .
DDR
Corriedale
Mul l aney e t a l .
( 1970)
-0 . 85
30 m. o .
DDR
C o r r ie d a l e
Mul l aney e t a l .
( 1970)
0. 19
1 8 m. o .
DDR
P o lwar t h
Mul l aney e t a l .
( 1970)
-0 . 5 0
30 m . o .
DDR
P o lwar th
Mul l aney et a l .
( 1970)
-0 . 32
1 8 m. o .
DDR
Mer ino
Mul laney et a l .
( 19 7 0 )
-0 . 3 2
30 m . o .
DDR
Mer ino
Mul l aney et a l .
( 1970)
- 0 . 08
18 m. o .
DDR
Corriedale
Mul l aney e t a l .
( 1 97 0 )
-0 . 14
30 m . o .
DDR
Co r r i e d a l e
Mul l aney e t a l .
( 1 97 0 )
-0 . 1 1
18 m. o .
DDR
P o lwar th
Mul l aney e t a l .
( 1970)
0 . 26
30 m . o .
DDR
Po lwa r t h
Mu l l aney e t a l .
( 1970)
750
TABLE 2 :
( cont inue d )
E s t ima t e
A
- ge
2
Met hod o f
Br e ed
e s t imat ion 3
SFD x CPC / - 0 . 4 2
CPI
QN
x
CPC/
CPI
QN x CHG
QN
QN
x
x
HG
GCG
Re f e rence
DDR
Me r ino
Be a t t i e ( 1 9 6 2 )
1 . 00
18 m. o .
DDR
P o lwa r t h
Mu llaney e t a l .
( 1970 )
0 . 96
30 m . o .
DDR
P o hvar t h
Mul laney e t a l .
( 1 970)
1 . 39
1 8 m. o .
DDR
Me r ino
Mul l aney e t a l .
( 1970)
1.11
30 m . o .
DDR
Her ino
Mu l l aney e t a l .
( 1 970)
1 . 05
30 m . o .
DDR
Co r r i ed a l e
Mu l l aney e t a l .
( 1 970)
0 . 94
1 8 m. o .
DDR
Cor r i ed a l e
Mu l l aney e t a l .
( 1970)
-0 . 1 3
1 4 m. o .
PHS
P e r end a l e
Elliott ( 19 7 5 )
0 . 44
1 4 m. o .
DDR
P e re nd a l e
El l io t t ( 1 9 7 5 )
0. 21
1 4 m. o .
DDR
N . Z . Romn ey
Rae ( 1 9 5 8 )
-0 . 4 1
1 4 m. o .
PHS
N . Z . Romney
Rae ( 1 9 5 8 )
0 . 08
1 8 m. o .
DDR
P o lwar th
Mul l aney et a l .
( 1 970)
-0 . 2 1
30 m . o .
DDR
Po lwarth
Mul l aney e t a l .
( 1 970)
0 . 26
18 m.o.
DDR
Me r i no
Mu l l aney et a l .
( 1 970)
0 . 55
30 m . o .
DDR
He r ino
Mu l l aney et a l .
( 1 970)
0.01
30 m . o .
DDR
Corr i e d a l e
Mul l aney e t a l .
( 1 970)
-0 . 27
1 8 m. o .
DDR
Cor r i edale
Mu l l aney e t a l .
( 1970)
0 . 20
18 m. o .
DDR
P o lwar t h
Mu llaney e t a l .
( 1970)
0 . 34
30 m. o .
DDR
P o lwa r t h
Mul l aney e t a l .
( 1 970)
0 . 53
1 8 m. o .
DDR
Merino
Mul laney e t a l .
( 1970)
0 . 80
30 m . o .
DDR
Her in o
Mu l l aney e t a l .
( 1 970)
0 . 56
30 m . o .
DDR
Corriedale
Mul laney e t a l .
( 1970)
0. 10
18 m . o .
DDR
Corriedale
Mu llaney e t a l .
( 1970)
-0 62
•
18 m . o .
DDR
P o lwar t h
Mul laney e t a l .
( 1970)
-0 . 33
30 m . o .
DDR
P o lwar t h
Mu l l aney e t a l .
( 1970)
-0. 03
18 m. o .
DDR
Her ino
Mu l l aney et a l .
( 1970)
0 . 08
30 m. o .
DDR
Me r ino
Mul l aney et a l .
( 1970)
0 . 05
30 m . o .
DDR
C o r r i ed a l e
Hul l aney e t a l .
( 1970)
-0 . 27
18 m . o .
DDR
C o r r i ed a l e
Mul laney e t a l .
( 1970)
76 .
TABLE 2 :
( co n t inue d )
Tra i t s 1
Es t ima t e
CP C / CP I
x CHG
CPC / C P I
x HG
CPC / CP I
x GCG
CHG x HG
CHG x GCG
Age 2
Method o f
e s t ima t ion 3
-0 . 28
B ree d
Re f e rence
PHS
Me r ino
Morley ( l 9 5 5 b )
0 . 33
18 m. o .
DDR
Polwa r t h
Mu llaney et a t .
( 1970)
-0 . 20
30 m. o .
DDR
Pol\\'arth
Mullaney et a l .
( 1970)
0 . 37
18 m. o .
DDR
Mer ino
Mul laney e t a l .
( 1970)
0 . 30
30 m . o .
DDR
Mer ino
Mul l aney e t a l .
( 1970)
0. 15
30 m. o .
DDR
Corr i e d a l e
Mul laney et a l .
( 1 970)
- 0 . 08
18 m. o .
DDR
Co r r i e d a l e
Mu llaney e t al .
( 1 970)
PHS
Me r ino
No r 1ey ( 1 9 5 5 b )
-0 . 32
-0 . 05
18 m.o.
DDR
P o 1war t h
Nu llaney e t a l .
( 1 970)
0 . 33
30 m. o .
DDR
Po l wa r t h
Hul laney e t a l .
( 1970)
0 . 67
18 m . o .
DDR
Me r i no
Hu llaney e t a l .
( 1 970)
0 . 66
30 m . o .
DDR
Me r i n o
Hull aney e t a l .
( 1 97 0 )
0 . 57
30 m. o .
DDR
Co r r iedale
Hul l an e y e t a l .
( 1970)
0.41
18 m. o .
DDR
Corr i e d a l e
Hu 1 1 aney e t a l .
( 1970)
PHS
He r i no
Ho r l e y ( 1 9 5 5b )
0 . 29
- 0 . 08
18 m. o .
DDR
P o lwarth
Hul l aney et a l .
( 1970)
-0 . 4 2
30 m . o .
DDR
Pohvar th
Mu l l aney et a l .
( 1970)
0 . 09
18 m.o.
DDR
Me r ino
Hul laney e t a l .
( 1970)
0 . 27
30 m. o .
DDR
Me r in o
Mu 1 l aney e t a l .
( 1970)
0. 16
30 m.o.
DDR
Co r r i ed a l e
Mul laney e t a l .
( 1970)
-0 . 1 0
18 m. o .
DDR
Corriedale
Hu l laney e t a l .
( 1 97 0 )
1 . 08
1 8 m. o .
DDR
P o lwa r t h
Mul l aney et a l .
( 1970)
0.91
30 m. o .
DDR
P o lwa r t h
Hu l l aney e t a l .
( 1 970)
0 . 65
1 8 rn . o .
DDR
Ner in o
Hul l aney e t a l .
( 1970)
0 . 95
3 0 rn . o .
DDR
Mer in o
Hul l aney et a l .
( 1970)
0. 73
3 0 rn . o .
DDR
Cor r i e d a l e
Hul l aney et a l .
( 1970)
0 . 84
1 8 rn . o .
DDR
Cor r ie d a l e
Mul l aney e t a l .
( 1970)
0 . 86
PHS
Me r ino
Hor l ey ( 1 9 5 5 b )
0. 18
PHS
Me r in o
Hor l e y ( l 9 5 5b )
77.
TABLE 2 :
( continue d )
Traits 1
Es t imate
x
0 . 31
HG
GCG
Age 2
Me thod o f
B ree d
e s t imat ion 3
R e f erence
PHS
Mer i no
Morley ( 1 9 5 5 b )
0 . 09
18 m.o.
DDR
Polwarth
Mu l l aney et a l .
( 1970)
0 . 48
30 m . o .
DDR
Po lwar th
Mul laney et a l .
( 1970)
0 . 43
18 m. o .
DDR
Me r ino
Mul laney e t a l .
( 1970)
0 . 34
30 m . o .
DDR
Mer ino
Mul laney et a l .
( 1970)
0 . 09
30 m. o .
DDR
Corriedale
Mu ll aney et a t .
( 1970)
0 . 36
18 m. o .
DDR
Co r r i edale
Mul l aney e t a l .
( 1 970)
78 .
GENERAL C ONCLUS IONS
From t he above review , it is evident tha t t h e maj o r i t y o f f ac t o r i a l
e xp e r imen t s t o s t udy G E l i n she e p have b e e n e i th e r o f t h e breed x
e nv ir onmen t ( loc a t i on ) or th e s i r e x env i ronme n t (nu t r i t ional l eve l )
type .
Both of the s e int e r a c t ions have s i gn i f i c ance in re l a t i on t o
s e le c t i o n , t h e f i r s t i n c onne c t i o n w i t h the cho i c e o f b r e e d o r s t r ain
and the s e cond in re l a t ion t o w i thin f l o c k s e l e c t ion .
The gene r a l
conc lus i on i s t h a t a l t hough s i gn i f i c ant T y p e 3 a n d Typ e 4 int e r a c t ions
( Dun lop ' s c l a s s i f i c a t i o n ) are some t imes found wi th sh e e p , they are
un impo r t an t i n r e l a t i o n t o sheep b r e e d ing p l an s in reducing the exp e c t e d
g a in s e xc e p t when v e r y wide d i f f e r e n c e s i n e nv i r onment ( ra i n f a l l ,
t emp e r a t u r e , pho t o p e r i o d s , nut r i t ion ) e x i s t .
The r e p o r t s o f i n t r a- t r n i t
gene t i c cor r e la t ions b e tween envi ronmen t s f o r charac t e r s o f e c o nom i c
impo r t an c e i n she ep a l s o rev e a l that the cor r e l a t i ons d o n o t i n gen e r a l ,
devia t e ma rkedly f r om un i t y and the env i ronme n t s h ave t o d i f fe r
cons i d e r ab ly for r ank order changes t o b e impo r t ant .
79 .
CHAPTER THREE
SOURCE OF DATA
A long- t e rm expe r imen t wa s d e s i gned at Mas s ey Un iv e r s i t y in 1 9 6 6
t o i nv e s t iga t e p o s s ib l e i n t e ra c t ion b e tween the geno type o f s i re w i t h in
t he New Zeal and Romney b r e e d o f sheep and d i f f e r e n t leve l s o f s t o c ki n g .
The d a t a used in this s t udy , c ove r ing a p e r iod o f 8 y e a r s f rom 1 9 6 7 t o
1 9 7 4 i n c l u s ive , we re o b t a ined f r om t h e two sub f l o cks o f a randomly-bred
f lo ck ma i n t a ined a t Ma s s ey Un ive r s i t y .
Th i s f l o ck has b e en u s e d f o r
many y ears a s a source o f d a t a f o r c a l c ul a t ion o f gene t i c p arame t e r s .
The o r i g in and the e a r l i e r mana gement o f t h e f lo c k has been
d e s c r ibed e l s ewhe r e (Rae ,
1958;
Ch ' ang ,
1 967) .
Th i s f l o c k s i nce i t s
e s t a b l ishment i n 1 9 4 4 ha s b e en ma in t a ined b y a s y s t em o f random
and r andom s e l e c t ion of f ema l e r e p l a c emen t s .
ha s b e en prac t i s ed wit hin t h e f l o ck .
h rced ing
No ar t i f i c i a l s e l e c t i o n
Young rams we re ob t a ined f rom
v a r i ous Romne y ram-b r e ed i n g f l o cks a s we l l as f rom
a
s e l e c t ion f l o c k
wh i ch ha s subgroups wh i ch a r e s e l e c t e d f o r h i gh e r g r e a s y f l e e c e He i ght
and for open fac e s .
The r e was l i t t l e l ike l ihood o f inbre e d i ng o c cu r r i n g
i n the f l o c k .
The randomly- bred f lo c k w a s s p l i t i n t o two s ub f lo c k s in Ma rc h ,
1 966 .
Each age group o f the f l o c k wa s d iv i ded a t random i n t o two p a r t s , one
p a r t a l lo c a t e d t o each sub f lock .
The s e sub f l o c ks a r e s ub s equen t l y
r e f e rred t o as the h i gh s t o cking r a t e f l ock (HSR) and con t ro l s to c k i ng
r a t e f lo c k ( C S R ) .
The graz ing uni t s and the ir management has been d e s c r ib e d by Sumne r
( 1969) .
Howev e r , i t i s n e c e s sary to o u t l i n e c e r t a i n a s pe c t s o f t he
s t ru c t ur e o f the exp e r iment and d a t a c o l l e c t i o n r e l evan t t o t h i s s t udy .
80 .
H SR : -
Approxima t e l y 2 2 0 mixed-age Romney ewe s and their rep l a c emen t
hoggets were grazed on 1 0 . 1 2 hec t a res area o f land d iv ided i n t o e i ght
app roxima t e ly e qual - s i z ed paddocks .
the who l e area .
t h e area .
In 1 9 6 6 the ewes were grazed over
Subse quent ly f ema l e rep l a c emen t s wer e a l so graz ed on
The young ewe s to en t e r t h e breed ing f l ock were s e l e c t e d a t
The s t o c k ing r a t e o f
random f r om t h e s t o ck born and bred o n the un i t .
the uni t f o r the years repo r t ed i n t h i s s t udy wa s kep t a t approxima t e l y
2 6 ewe e qu ival en t s per he c t are ( a s suming 1 hogget
=
0 . 6 ewe e q u ivalent s ) .
No c a t t l e were run on the un i t and hay was c u t and saved dur ing the
s ummer f o r win t e r feed ing .
C SR : -
The mixed-aged ewe s and t h e i r replacemen t ho g g e t s were grazed on
the adj o in ing 1 7 . 4 0 hectares area of land at a norma l s t o c k ing r a t e o f
1 6 ewe e qu iva l ent s per hec tare .
s imilar a g e s t ruc ture t o HSR .
suppo r t ing excep t f o r rams .
Th i s f l o c k wa s s l i gh t ly larger and o f
Like the HSR un i t t h i s un i t wa s s e l f
Wether lamb s were removed f rom the
exper iment a l area at wean ing or soon a f t e r .
Occas ional ly c a t t l e were
used t o contro l exc e s s pasture growth .
P a s tures on both un i t s were predominan t ly a ryegra s s -wh i t e-c lover
a s s o c i a t ion .
All ro u t ine f arm operat ions such as drenching again s t
p aras i t e s , d i p p in g , care o f f e e t , c r u t ching and shear ing were c a r r i e d
o u t a s n e a r l y al ike a s p o s s ib l e o n b o t h u n i t s .
The s ame rams were used f o r b o t h the u n i t s .
Each group o f rams
were u s ed f o r two years thus a l l owing the records u s e d in t h i s s t udy t o
i nve s t i g a t e t h e p o s s ib l e o c currence o f s ir e x y ear int era c t ion a l s o .
Each r am was hand ma t ed to approxima t e ly 2 2 ewe s in the H S R and t o 2 5
ewe s i n t he CSR uni t .
sire g r o up .
In a l l years the ewes were random i s e d t o e a ch
The ma t in g season s t a r t e d b e tween 1 5 and 2 5 Ma rch in each
81 .
year and the durat ion o f ma t ing p e r io d va r ied only a l i t t l e f rom year
year , b e ing no t l e s s than 5 1 days o r mo re than 5 8 days .
to
Dur i ng ma t i ng ,
va s e c t omised r ams , equipped wi th harne s s e s carry ing t up p ing c r ayons , we r e
As ewes c ame i n t o t h e ir hea t p e r i o d they were marked
r u n w i t h the ewes .
Ewe s r e c o g n i s e d as b e ing in o e s t ru s we r e put into
by the teaser rams .
pen w i th the app ropr ia t e ram .
The breed ing ewe s r ema ined f o r f o ur
l amb ing seasons i n the f lock un t i l c a s t f o r age as f ive and a hal f year
The l amb s we re b o rn in Aug u s t and S ep t embe r and wean ing t o o k
o ld s .
p l a c e towa r d s t he end o f November o r ear l y i n Decemb e r .
Al l we ther
lamb s were s o l d a f t e r weaning but ewe lambs we r e r e t a ined in t h e i r
r e s p e c t ive un i t s .
llo gget shear ing o c c u rred in Oc tob e r , ewe shearing
o c curred one mon t h l a t e r wh i l e lamb s we r e shorn
in
January .
THE DATA
The d a t a used in t h i s s t udy r e p r e s ented the f ema l e p r o geny o f 34
New Zealand Romney s ir e s .
As men t ioned , s i r e s used in the p revious
year were r e t a i ned f o r f u r t her ma t i ng in a s e c ond year .
Two groups o f
1 0 s i res each were u s ed in y ears 1 9 6 8 / 6 9 and 1 9 7 0 / 7 1 but i n 1 9 6 6 / 6 7 and
1 9 7 2 / 7 3 the l o s s of s ome rams meant tha t the data f rom the p r o geny o f
only 7 s i r e s we re sat i s f ac t o ry f o r ana lys i s .
The d a t a ava i lable f o r
the p r e s en t ana lys is were t he r e f o re b a s ed on t h o s e c o l l e c t e d o v e r f o u r
consec ut ive two-year s i re per iod s .
These s i re group s a r e subse q uen t l y
r e f erred t o a s fol low i n the s t udy .
S ir e s
Year o f D a t a
S ir e group 1
7
1 9 6 7 / 68
S ir e group 2
10
1 969 / 7 0
S ir e group 3
10
1971/72
S i re group 4
7
1 9 7 3 / 74
Group
a
82 .
The da t a f r om daugh t e r s o f tho s e s ir e s wh ich we re no t u s ed in the
s e c o nd year have been exc lud e d .
For the purpose of the i nves t ig a t ion d a t a on hogge t l ive -we ight
( HLW ) , greasy f leece we ight ( G8�) , c l ean woo l weight per un i t area (WA ) ,
c le an s c oured y i e l d ( Y ) , s t ap l e l e ng th ( S L ) , mean f ibre d i ame t e r (MFD ) ,
s tandard d ev i a t ion of the f ib r e d iame t e r ( S FD ) , qu a l i t y numb er ( QN) ,
c r imp s p e r c e n t imeter ( CPC ) , t o t a l c r imp numb e r ( TCN ) , char a c t e r ( CHG) ,
t ip p iness (TG) , hand l e ( HG ) , lus t re (LG) , greasy c o l our ( GC G ) , s coured
c o lour ( S CG) , d i s co loured area ( DAG ) , co t t ing ( CG ) , c o t t e d area ( CAG )
and s oundne s s ( SG ) of wo o l were ana lysed .
The HLW used in t h i s s t udy i s the p o s t - s hear ing we ight of hogge t s
a t 1 4 - 1 5 mon ths o f age .
The measurement wa s mad e ini t i a l ly to t he
n e a r e s t p ound b u t l a t e r measuremen t s we r e recorded to the neare s t 0 . 5 kg .
The e ar l ie r r e c o r d s we re c o nve r t e d to k i logramme s .
Wool we igh t p e r u n i t a r e a wa s meas ured f rom the mid - s ide p o s i t i on
p r i o r t9 she a r i ng .
The s amp l e s were s c oured and the c l ean wo o l we igh t
p er square c en t ime t r e was c a l c u la t ed .
The d e t a i l s o f s amp l ing and
s c our ing me thods have b e en d e s c r ibed e l s ewh e r e by Sumn e r ( 1 9 6 9 ) .
The
s amp l e s we r e s coured by a f our bowl d e t ergent and scour ing metho d .
The
d a t a for th i s t r a i t r e c o rd e d in S i r e g r oup 3 p e r iod were incomp l e t e and
w e r e not analysed .
GFW wa s r e co rded imme d i a t e ly af t e r shear ing and wa s mea s ur e d t o t h e
nea r e s t 0 . 05 kg .
The b e l ly-wo o l we i gh t wa s inc luded in t h i s we i gh t .
The meas u r ement o f GFW r e p r e s e n t ed only the g rowt h o f abo u t 9- 1 0 mon t h s
b e tween l amb shear ing a n d ho gge t she a r ing in O c t o b e r o f e a c h y ea r .
I
83.
For c a l c u la t ion o f Y , the mid - s i d e s amp l e s we re we ighed g r e a sy a f t e r
°
b e ing cond i t ioned to 68 F and 6 5 % r e l a t ive humid i t y f o r 4 8 hour s .
S amp l ing and s c our ing me thods have b e e n d e s c r ibed by S umne r ( 1 9 6 9 ) .
The
s c oured samp l e s were aga in allowed to cond i t ion for 4 8 hours b e f o r e
r ewe ighing .
Y wa s c a l cula t ed a s p e r c ent c l ean f l e ece we i gh t o f the
greasy wo o l we ight o f the samp le .
The S L o f the greasy samp le f rom the mid-side reg ion wa s measured t o
t h e near e s t 0 . 5 cm .
S ince the t ip o f the s t aple in Romneys tapers t owa rd s
a p o in t , the meas uremen t was made f rom the base o f the s t a p l e
to a
p o s i t ion midway b e tween the p o i n t whe r e the s t ap l e s ta r t s t o t a p e r and
t h e t ip , t ak i ng care n o t to s t r e t ch the s t ap l e unduly .
MFD wa s measured on the s c oure d mid - s id e sample .
One hun d r e d and
f i f ty f ib r e s f rom each sample were measured by proj e c t ion m i c ro s c op e .
The mean and s tandard d eviat ion ( in m i c rome t ers ) was c a l c ul a t e d from
these ob s e rva t ions .
The data f o r MFD a nd S FD in S i r e group 2 and S ir e
group 4 p e r i o d s wer e n o t analy sed a s i t wa s incompl e t e .
QN i s a visual app raisal o f the sp innab i l i t y and hen c e f inene s s o f
woo l .
I t i s based ma inly on s t ap l e c r imp frequency and l u s t r e
( Hende r s o n , 1 9 6 5 ;
W i c kham and B i gham ,
a f f e c t ed by observer var ia t ion .
1973) .
Th i s a s s e s smen t can be
The s t and ards gen e r a l l y in u s e in New
Z ea land ( which are s imilar t o tho s e in wo r l d t rade) were u s ed .
The number o f c r imp s we r e coun t ed over the who l e l e n g t h o f a s t ap l e
f rom the greasy mid- s id e samp l e o f woo l .
i n a s ta p l e and SL .
CPC were c a l c ul a ted f rom TCN
S ince the d a t a for bo th t he s e t r a i t s we r e i nc omp l e t e
i n S ir e group 3 p e r io d , i t wa s no t analys ed f o r tha t group .
84 .
CHG , TG , HG , LG , GCG , CG and SG of wo o l were subj e c t ively graded on
greasy mid-s ide samp le s .
These we r e graded on a one t o n i ne s c a l e .
In a l l c a s e s nine g r a d e s we re used , the s c o r e o f 9 be ing a l l o t t e d t o
the exp r e s s ion cons i d e r e d mo s t d e s i r ab l e ,
1
t o the l e a s t d e s i rab l e .
Th e sy s t em o f the grad ing was d e s i gned so tha t the d i s t r ib u t io n t ended
to f o l l ow a no rma l curve .
Sumner ( 1 9 6 9 ) has d e s c r ib ed t h i s grad ing
sys t em .
CHG r e f l e c t s c l a r i t y and evenne s s o f s t a p l e c r imp , ab s ence o f
t ap e r i n g t ip and medu l l a t ion .
Wher e c r imps were we l l d e f ined throughout
the s ta p l e a high s co r e wa s g iven .
Lower grades ref l e c t e d poorly
de f ined c r imp ing .
TG ranged from absolutely f la t and blo c ky ( 9 ) to extreme ly
taper ing t ip ( 1 ) .
HG wa s a s s e s s ed wi thout rega r d t o QN w i t h the samp le s c r e ened f rom
the v i ew o f the a s s e s s o r .
S o f t wo o l wa s g iven high grad e s .
LG wa s graded w i thout r e f e rence to f i nene s s .
H i gh grades we r e l ike
Lin c o l n woo l .
The l owe s t GCG were g iven t o samp l e s wh i c h were mo s t d i s c o l oured .
CG r e f l e c t ed t h e degree o f f ibre en t an g l emen t on the mid - s ide
p o s i t ion with h igh grades b e in g free o f entanglement .
S G was bas ed on f reedom o f woo l f rom t en d e rness or b reak .
Samples were
eva lua t ed by p l a c ing ' s tanda r d s i z e d ' s t ap l e s und er hand t en s ion w i t h
sound s taples b e ing g iven h igh grad e s .
The d a t a f o r SG in t h e S i r e
group 1 p e r io d were not ana l y s ed a s i t w a s incomp le t e .
85 .
F o l l owing s couring a l l s amp l e s we re a s s e s s ed for t h e SCG us ing the
s ame s tandards a s f o r GCG o f woo l .
CAG and DAG o f the f l e e c e were a s s e s sed on t he who l e f l e e c e a t the
t ime of s hearing .
The s e who l e- f l eece charac t e r i s t i c s were a l s o
subj e c t ively graded o n a s c a l e o f
1
( in f er io r ) t o 9 ( s uperio r ) .
CAG o f
the who l e f l e e c e was dependent o n the d e gree and ext e n t o f ent anglemen t
over t h e whole f l e e c e wh i l e DAG was e s t ima t ed ma inly on the b a s i s o f how
f a r t he d i scolou r a t ion extend s o ver the f le e c e w i t h the accoun t t aken o f
seve r i ty o f d i s c o loura t ion .
The d a t a f o r DAG i n the S ir e group 1 and
S i r e g r oup 2 p e r iods were no t analysed as t hey wer e incomp le t e .
Inac curac i e s o f grad ing in a l l t h e above subj e c t ively graded t ra i t s
could r e su l t f rom ob server var i a t ion , a s we l l a s o t her unc o n t r o l led
env i r o nment a l f a c t or s .
86 .
CHAPTER FOUR
STAT I STICAL METHODS
PRES ENCE OF INTERACT I ON
The d e t e c t i o n and evaluat ion o f GEl by d i f f e rent t e chn i q ue s :
ranking o f geno t yp e s in each env ironmen t (Hal dane ,
194 6 ) ;
d i f f e ren c e s
i n r e sponse o f e ach o f t h e geno t y p e s in two environmen t s ( Osborn e ,
195 1) ;
regre s s ion o f mea s u r ement s o f a t ra i t on env ironmen tal leve l s f o r e ach
genotype (Ya t e s and Cochran , 1 9 3 8 ) ;
(Ma t h e r and Jone s ,
Fede r e r , 1 9 5 1 ) ;
1 958) ;
o r t ho gonal compar i s on o f sub c l as s e s
f a c t o r ial ana ly s i s o f variance ( Sp r ague and
g en e t i c correlat ion o f the same t rait in two
env i ronmen t s e s t i ma t ed f r om var iance and covariance analy s i s ( Fa l c o ne r ,
1952 ) ;
s e l e c t i o n in two environmen t s (Falcone r ,
1952) ;
d i f f e r e n c e s in
t he magni tudes of he r i t ab i l i t y and exp e r ime n t s wit h iden t i ca l twin s , have
b ee n repor t e d by var ious wo rker s .
S t a t i s t i c a l me thods ava i l a b l e f o r
anal y s i s o f int e r a c t ions in general a n d GEl i n p a r t icular w e r e reviewed
by Freeman ( 1 9 7 3 ) .
I f the GEl i s s ign i f i c ant , the next s t ep i s f requen t ly t o t ry t o
d e s c r ib e t h i s i n t e r a c t ion in t e rms o f b io l o g i ca l l y mean i n g f u l p a r ame t e r s .
To f ind whe th e r i n t e ra c t ions are p r e s e n t and then to con s id e r t h e i r
imp o r t an c e , i t i s some t imes n o t enough t o e s t imat e the componen t s o f
var i a t ion a t t r ib u t ab le t o the main e f f e c t s and t o look f o r t h e s t r u c t u r e
und e r ly ing the o b s e rved non-ad d i t ivi t y .
Fol l owing Falconer ' s ( 1 9 5 2 )
ext e n s ion o f t h e concept o f gene t i c corre l a t ion t o the s t udy o f G E l , t h e
u s e o f f a c t or i a l ana ly s i s o f v a r i a n c e t echniques in e s t ima t in g t h e
imp o r t ance a n d t e s t in g f o r s ign i f i can c e o f GE l has r e c e ived much
a t t ent ion i n an imal b reed ing .
On the b a s i s o f Falcone r ' s ( 1 9 5 2 ) conc ep t ,
Robe r t s on ( 1 9 5 9 ) p r e s en t e d f o rmulae in t e rms o f mean squares wi t h the i r
87 .
app r op r ia t e var iances for e s t imat ing the gene t i c correlat ion o f the
p er f o rmance in two or mo re envi ronment s .
He showed the comp o s i t ion
of the component of var iance for GEl to b e :
whe r e cr
Gl
and a
G2
refer to the gene t i c s t andard deviat ions in envi ronment
1 and 2 respe c t ively and r g is the gene t i c correlat ion b e tween the
p e r f o rmance in the two envi ronment s .
D i ckerson ( 1 9 6 2 ) d i s c u s s e d the s ubj e c t o f quant i t a t ive e s t imat ion
o f GEl in terms of var i ance componen t s and sugge sted that , in general ,
the s t andard analy s i s o f vari ance i s a s a t i s f a c t o ry me thod o f es t ima t ing
GEl and intra- c lass genet i c c o rrela t i on p rovided
( 1)
adj us tment is made for any imp o r t ant var iat ion be tween
env i ronmen t s in the s cale of gene t i c e f f e c t s ( i . e . , for
int e r - environmental var i ance in the int ra-environmental
(2)
the variance component for aver age gene t ic ranking acro s s
a l l environment s i s in terpreted as t h e aver age covariance
for t he same genotype in d i f ferent environment s
(i . e . , a2
G
=
o
) , to inc lude the real pos s ib il i t y o f
Gij
negat ive gene t ic co rrelat ion .
Yamada ( 1 9 6 2 ) presented f ormulae f o r both random and mixed mod e l s
to e s t imate gen e t i c corre l a t i ons be tween performance in two o r more
environments a f ter adj u s t ing the int eract ion c omponent of varianc e so
that the use of t he adj u s t ed value in t he int ra-clas s correlat ion mak e s
t h i s correlat i on ident ical with the ave rage product-moment coef f i c i en t
b e tween t he _same geno type i n each o f the macro environme nt s .
88.
In t h e f r amework o f t h i s exp e r imen t conc erned wi t h comp a r i s on o f
p a t ernal h a l f- s ib group s , the analy s i s o f var i ance t e c hn i q ue i s
emp loyed i n d e t ec t ing and eva luat ing GEI and the ro l e p l ayed b y GEI w i t h
regard t o t he s t ruct ure o f he r i t ab i l i t y e s t imat es .
ANALY S I S OF VARIANCE
Least squares and compu t i ng me thod s
The e s t imat e s o f gene t i c p ar ame t e r s are mad e mo r e a c c u r a t e i f the
ident i f i ab le e nvironme n t a l sour c e s of varia t io n ( and i n t e r a c t ions ) in
t h e data are adequa t e l y removed .
S ince t h e inclusion o f the f a c t o r s
in the mod e l u s e d for s t udying gene t i c var i a t ion and cova r i a t ion depend
upon whe ther o r not t h e t e rms inc luded in t h e model are s t a t i s t i c al l y
s i gn i f i c an t , p r e l iminary ana ly s e s o f variance were c a r r i ed o u t .
The
p r e l iminary analy s e s f o rmed the b a s i s o f the d e c i s i o n for the approp r i a t e
mo dels t o b e f i t t ed i n t h e s ub s e q uent ana l y s e s t o c a l c ul a t e p roport i o n
o f the o b s e rved variance cont ro l l ed by t h e var ious f a c t o r s ( and
i n t era c t ion s ) i n the mo de l .
For t h e p r e l iminary analys i s o f var ian c e , a sub s e t o f the d a t a i n
wh i ch each r e c ord h a d ob s e rva t ions on a l l measured a n d s ub j e c t ively
a s s e s s ed t r a i t s inc luded i n t h e s t udy was s e l e c t ed and analysed .
The
d i s t r ib u t ion o f numb e r s of observa t ions in the sub c l a s s e s was
non- o rtho gona l .
Henc e the me t ho d o f least squares p r o c e d u r e s was u s e d .
The p r in c i p l e s of l e a s t squares anal y s e s and the d e t a i l e d s t ep s u s e d i n
t h e e s t ima t i o n pro c e s s have been d is c u ssed b y Kemp thorne ( 1 9 5 2 ) and
Harvey ( 1 9 6 0 ) .
89.
S o lut ions to the le a s t square s equa t ions
A general mathema t i c al mod e l can be wr i t t en in the mat r ix no t a t ion
as :
Y
+
Xb
e
where
Y i s a known Nx1 ve c t or o f ob s e rvat ions
(N is the total numb e r of observat ions )
X is an Nxp incidence ma t r ix o f known value s
(p i s the numb er of f a c t o r s in the mod e l )
b i s a p x 1 v e c t o r o f unknown p arame t e r values t o b e e s t ima t e d
e i s an N x 1 vector o f random e r r o r e f fe c t s
E (e)
=
0
where I i s NxN ident i t y mat r ix
Derivat i on of leas t s q uare s e s t ima tor of b f o l l ows minimi z a t ion of the
sum of s quares of t he observat ions from t h e i r expected value s .
S ince E ( e )
0 and hence E (y )
Xb
t hen
e1 e
[y
E (y ) j
I
[y
- E (y)]
(y - Xb ) I ( y - Xb )
y 1 y - 2b 1 X 1 y
+
b 1 X 1 Xb
" *
Cho o s ing a s the e s t imat o r b
that value o f b which minimi z e s e 1 e
invo lve s d i f feren t i a t ing e 1 e with respect t o elemen t s o f b and equat ing
p ar t i a l der ivat ive s to z e ro .
X1 X b
Provided ( X 1 X) -
=
1
The resul t ing normal equat i ons are
X1y
e x is t s , the normal equat ions have the unique s o l u t ion
"
for b
*
"
"
b
(X 1 X )
-1
X1 y
i s used to ind i c a t e an e s t imat e
90 .
The s o lut ion o f normal equat ions requires that the mat r ix X ' X i s o f f u l l
r ank .
I f X ' X is no t o f f u l l rank , i t has no inve rse and no un ique
s o l u t ion .
I f (X ' X)
-1
d o e s not exi s t , a solut ion can b e o b t ained by
u s ing a general i s ed inve r s e of X ' X ( S ear le , 1 9 7 1 ) .
Al t e rnat ively , Harvey ( 1 9 6 0 ) d i s cus sed the t ypes o f r e s t r i ct ions
wh ich may b e imposed on the e s t imat e s of parame t e r s to o b t a in a solut ion .
The two t yp e s of res t r i c t i ons used for reduc ing normal equat ions to f u l l
r an k in the p r e l iminary anal y s i s and t h e analy s e s f o r e s t imat ing the
gene t i c parameters in t h i s work respect ively are :
(1)
That for each f a c t o r in a mo d e l , one o f the e f f e c t s
equa l s zero .
and
(2)
That for each f a c t or in a mod e l , the sum o f the
con s t ant e s t ima t e s equa l s z e r o .
Corresponding t o the above re s t r ic t ions app l ied in the analy s e s , the
o rd inary least squares and the use o f gener a l i s e d inverse me thods g ive
i d ent ical solut ions for the e s t imab le funct ions of the unknown parame t ers .
A c omputer subrou t ine was available for inve r t in g s quare mat r i c e s
o f order l e s s t han 3 5
x
35 .
Larger inverse mat r i c e s we r e o b t a ined
through the use of ma t r i x par t i t ion ing procedures as d e s c r ibed by
Searle ( 1 9 6 6 ) .
F i t t ing mod e l s t o the d a t a
A general model f i t t e d in t e s t ing for the s igni f i cance o f t h e main
e f f e c t s and intera c t ions for HLW and woo l t ra i t s in the S ir e group 2
and S ire group 3 periods was :
91.
y
lJ
.
.
klmn
� +
si
+
(rt) j k
rj
+
+
tk
( rb ) j l
+
+
b1
+
�
+
( s r t ) ij k
( s r ) ij
+
+
( s t ) ik
+
e ij klmn
where
�
mean o f a l l records o f a character when equal
f r e quencies exi s t in each sub c l as s .
si
rj
=
the e f f e c t of the i th s ire .
i
1 t o 1 0 ( S ire group 2 r e cord s )
i
1 to 7
the e f f e c t of the j th s t o ck ing ra t e .
j = 1 , 2 (j
tk
( S ire group 3 record s )
=
1 imp l ie s HSR, j
=
2 imp l ies CSR)
the e f f e c t o f the kth year .
k
1' 2
The ' year ' e f f e c t i s a meas ure o f the var iat ion
in t he data caused by environmental cond i t i ons
p e cul iar to e a ch year s u ch as d i f ferences in the
amount and d i s t r ib u t ion of the rainf a l l , mean
monthly temperatur e , feed supp ly , and o t h e r l e s s
t angib le fac t o r s which make u p the yearly
envi ronment .
The year e f f e c t s wi l l a l s o be
p a r t ly due t o year to year incons i s t ency o f grad ing
o f sub j e c t ive t r a i t s .
D i f f e rent graders were
a s s es s ing the t r a i t s in d i f f erent years .
b1
the e f f e c t o f the l t h b ir t h rank .
1 = 1 or 2 , s p e c i fy ing ewe hogge t s b o rn as a s ingle
o r ewe ho gge t s b o rn as a twin respect ive l y .
The very
f ew born as t r ip l e t s we re inc luded with the twins .
� = the e f fect o f t he rnth age o f darn .
m
=
1 or 2 , s p e c i fy ing age o f dam as 2 year o l d o r o ld e r
r e s p e c t ive ly .
92 .
(sr)
.
.
l]
( s t ) ik
the e f f e c t s o f int eract ion b e tween s i re and s t o cking r a te .
t he e f f e c t s o f int eract ion be tween s ire and ye ar .
t he e f f e c t s o f interac t ion b e tween s t ocking rate and year .
t he e f fe c t s o f int e rac t ion b e tween s t ocking rate an d b irth
rank .
( s rt)ij k
t he e f f e c t s o f int eract ion b e t ween s ire , s t o cking rat e
and year .
y ij klmn
the ob s ervat ion on the nth ind ividual born in the l t h
b i r th r ank , ma inta ined o n j t h s t o cking r a t e in t h e kth
year , d aughter o f a ewe in the mth age group and the
ith sire .
is the random error peculiar t o the ij klmn th ob s e rvat ion
and f o l lows NID ( O ; a 2 ) .
All e f f e c t s in t he mod e l we r e regarded as f ixed except S i ,
( s r ) ij •
( s t ) ik and ( s r t ) i j k which are random set s o f e f f e ct s ( o ther than e ij klmn ) .
Ot her interac t ions not included in the mo d e l we re not cons idered
imp o r t ant .
S ir e group 2 and 3 periods dat a we re analysed separ at ely .
Fo rmal F- t e s t s o f s i gni f i c ance were carried out on the f a c t o r s included
in the model .
The term used as denominat o r was the error excep t whe re
two- o r three- t e rm interact ions were s i gni f ic an t .
Where a thre e - t e rm
in teract ion was s ignif icant , the r e l evant two- t erm int e r a c t ions were
t e s t ed again s t i t .
The ma in e f f e c t s wer e t e s t e d again s t relevant
two - t e rm int er a c t ions in case of random int eract ions b e in g s ign i f ic an t .
Fo l lowing the exclus ion o f e f f e c t s o f age o f d am , in t e ract ion
b etween s t o cking rate and b irth r ank , int e ract ion b e tween s i r e , s t o cking
r a t e and year whi ch were found to have no s i gni f ican t e f f e c t (P<O . OS )
o n t he t rait concerned , pro cedur e s were appl ied t o d e r ive s ui t ab l e mod�l s
f o r e s t imat ing populat ion p arame t e r s and evaluat ion o f GEl .
93.
A general model d e s c r i b in g a da tum for wh i ch every s igni f i c ant
e f f e c t was f i t t ed in the c omb ined s t o cking rat e analysis i s :
where t he terms are as d e s c ribed previously exc ept the f o l l owing
si
the e f f e c t o f t he i t h s ire .
i
1 to 7 ( S ir e group 1 record s )
i
1 to 10 ( S ire group 2 record s )
i
1 to 1 0 ( S ire group 3 record s )
i
1 to 7 ( S ir e group 4 record s )
the obs erva t io n on t he mth ind ividual born under l t h
b irth rank , ma int a ined o n j th s t o cking r a t e in the
kth year , d aughter of the ith s i re .
i s the random error p e cul iar t o the ij klm th ob servat ion
and fol lows NID ( O ; cr 2 ) .
A l l e f f e c t s in t he mode l were regarded as f ixed exc ept s i ,
( s t ) ik whi ch are random s e t s o f e f f ec t s .
( s r ) ij •
I f the geno types are regarded
a s r andom and environmen t s a s f i xed , the int e r a c t ions e f f e c t s are a l s o
r an d om (Harvey , 1 9 6 0 ) .
w e r e analy s ed s ep arat e l y .
The data in al l the four S ir e group p e r i o d s
Formal F- t e s t s were carr ied out in
accordance with the proc edure exp l ained ear l ie r .
The e xpectat ions o f
mean s quares f o r the above model a r e shown i n Tab l e 3 .
The mod e l used t o represen t a datum for wi thin s t o ck ing rate
(HSR and CSR) analys e s c an be wr i t ten a s :
94 .
TABLE 3 :
Comb ined S t ock ing Ra t e Ana lys i s
Calcula t i on o f Red u c t ions * in Sums o f Sguare s ( S . Sgs )
and Expe c t a t ions of He an Sguares ( EMS )
EMS
Re duct ion
Source
R ( s I u , r , t ' b , s r , s t , rt )
(} 2 +
e
S t ockin g r a t e
R (r l u , s ' t ' b , st , r t )
(} 2 + k 7 0" 2 + k s q 2
r
e
sr
Year
R (t l u , s ' r , b , sr , rt)
(} 2
e
B i r th- rank
R <b I u , s , r , t ' s r , s t ' rt )
(} 2 + k4 q
e
S i re x s t o ck ing rate
R ( s r l u , s , r , t ' b , s t , rt )
(} 2
e
S ir e x y e a r
R ( s t l u , s ' r , t ' b , s r , rt )
0 2 + k cr 2
e
2 st
R (rt l u , s , r , t , b , s r , s t )
cr 2
e
S i re
S t o cking r a t e
X
year
+
+
+
kg (J;
ksG2 + k q2
st
Ei t
�
k 3 cr2
sr
�
k q
l
t
y ' y - R ( u , s ' r , t ' b , s r , s t , r t ) cr 2
e
Error
q2
*
quadra t i c term ( f ixed e f f e c t )
The t e rmino l o gy for reduct ions in s ums o f squares given by
S e arle ( 1 9 7 1 ) will be used throughout the text in t h i s wo rk .
R ( . ) imp l i e s redu c t ion , and the l e t ters within the parent heses
refer to the mod el b e in g f i t t e d .
f a c t o r is f i t t ed a f t e r ano t he r .
a l s o impl i e d .
R
(. 1 . )
me ans that one
The p l ural d e f i n i t ion i s
95 .
TABLE 4 :
Source
Within S to ck ing Ra t e Analys i s
Calcu l a t ion o f Re duc t ions in Sums of Sguare s ( S . Sgs )
and Expe c t a t ions of Mean Sguares ( EMS )
Reduc t i on
EMS
S ir e
R (s I u , t ' b , s t )
o2
e
+
k so2
s
Year
R et I u, s, b)
o2
e
+
k 3o2 + k4q2
st
t
B i r th-rank
R Cb I u , s ' t ' s t )
+
k2 q 2
b
S i re x year
R (st l u , s , t ' b )
o2
e
02
e
+
kl o2
st
y ' y - R (y ' s ' t , b , s t )
Error
q2
quad r a t i c t e rm ( f ixed e f f e c t )
o2
e
96 .
.
whe r e the terms are as d e s c r ib e d previously excep t the f o l lowing :
t h e observat ion on mth individual in the k t h year ,
d aught e r o f i t h s i re and born unde r lth b i r th r ank .
i s the random error p e cul iar to the iklm th o b s e rvat ion
and f o l lows NID ( O ; a 2 ) .
A l l e f f e c t s in the model we r e regarded as f ixed exce p t s i and ( s t ) ik
whi ch are rand om s e t s of e f f e c t s .
The d a t a in all the four S ir e group
p e r i o d s we re analysed s epara t e l y .
Formal F- t e s t s wer e c a r r i e d out in
a c c o r dance wi t h the procedure exp l a ined earl i e r .
The exp e c t a t ions o f
mean s q uares f o r above mo d e l a r e shown i n Tab l e 4 .
Es t ima t i on of me an square s , variance
and covar i ance componen t s
The d ir e c t me thod o f Harvey ( 1 9 6 0 ) was used i n comp u t ing sums o f
squares from wh i c h mean squar e s were cal culat ed .
An abb r ev i a t ed f o rm
o f the direct me thod of comp u t ing s ums o f squares is :
whe r e
B'
a row ve c t o r o f leas t squares e s t ima t e s f o r a g iven
s e t of equat i on s .
Z
-1
the inverse o f square s e gmen t o f the inver s e o f t h e
var i ance cova r i ance mat r ix correspond i n g , b y row and
c o l umn to t h i s set o f e s t ima t e s .
and
B
a co lumn ve c t o r o f the l e a s t s quares e s t ima t e s for the
g iven set of e qua t ions .
97 .
The above s imp l i f ied pro c edure o f calculat ing sums o f s quar e s o f
t h e various e f f e c t s in the r e s p e c t ive mod e l s used i s equ iva lent t o f i t t in g
s ubmo d e l s (Harvey , 1 9 6 0 ;
S e a r le , 1 9 6 6 ;
Cunn ingham , 1 9 7 0 ) .
The
exp e c t at ions of mean s quares for b o t h the mod e l s used in the
inve s t igat ion wer e ob t a ined unde r as sump t ions of mixed mod e l s in
acco r d ance with the procedur e s d e s c r ibed by Hend erson ( 1 9 5 4 ) and Harvey
( 1960) .
The gene ral theory involved in the use o f l e a s t squar e s pro cedure s
w i t h unequal sub c l as s f r equen c i e s for the e s t ima t ion o f var iance and
cova r i ance component s wi th t h e mixed mod e l s has b een d i s cus s ed by
Thr ee
Hend e r s on ( 1 9 5 3 ) , Searle and Hender s on ( 1 9 6 1 ) and Searle ( 1 9 6 8 ) .
me thods of e s t imat in g variance componen t s are d e s cribed in Hende rson
( 1953 ) .
S ince Method 1 i s approp r i a t e for random mod e l s only , it was
not used in this s tudy .
Me thod 2 was also found inapp rop r ia t e in t h i s
s t udy b e cause o f t h e n e ce s s i t y t o analy s e int e r a c t ions be tween random
and f ixed e f f e c t s .
Me thod 3 was app lied for this inve s t i ga t i o n as i t
w a s n o t subj e c t t o any o f t h e l imi t a t ions o f t h e other two me thod s .
Var iance comp onent s were r e q u i red f rom mixed mod e l s and random
i n t e r a c t ions of s ire x s t o ck ing r a t e and s ir e x year we re a l s o included
in t h e mo del s .
Me thod 3 i s based on the me thod o f f i t t in g con s t an t s .
I t u s e s reduc t ions in s ums o f s quares due t o f i t t ing d i f f erent sub groups
of f ac t o r s in th e mod e l .
The e s t imat ion o f var i ance component s i s done
b y equa t ing each comp u t e d r e du c t ion to i t s e xp e c t ed value .
Comp ared
to Me thod 1 and Method 2 , t h i s method i s f ar mo r e app r op r i a t e f o r t h e
m i xe d mod el , s ince i t y i e l d s var i ance component e s t ima t o r s t h a t are
r e l a t ively una f fe c t ed and uncomp l i c ated b y the f ixed e f f e c t s .
Its
d i sadvan t age i s that i n mod e ls cont a ining a large numbe r o f e f f e c t s , i t
may b e d i f f i cult t o ob t a in the co e f f i c i e n t s i n the exp e c t a t ions , a s t h e
inve r s e o f full mat r ix l e s s t h e e f f e c t o f int e r e s t is required .
98 .
Computer p r o grammes were �r i t ten f o l lowing Harvey ( 1 960 , 1 9 7 0 ) to comp u t e
t h e var i anc e and covar i ance comp onents by Me thod 3 .
The k c o e f f i ci en t s
i n T ab l e s 3 and 4 were c omputed b y the d i r e c t and ind i r e c t procedures
d e s c r ib e d by Harvey ( 1 9 6 0 ) .
LEAST SQUARES EST IMATE S
The l e a s t square s e s t ima t e s o f t h e ma in e f f e c t s re garded as f ixed
and various int era c t ions included in the model f o r the c omb ined s t o cking
r a t e ana l y s i s were comp u t e d for a l l the Sire group periods separately
by solving the least s quares equat ions (Harvey ,
1 9 6 0) .
The s t andard
e r rors of t he least s q ua r e s e s t imat e s were calculated for a l l the four
S ir e g roup p e r iods s ep a r a t e l y ac cording to the f o l lowing formu la as
sugge s t ed by Harvey ( 1 9 6 0 ) .
whe r e c i i is the corres ponding d iagonal inve r s e e l ement for that con s t an t
and o e 2 i s t he error me an square .
A
POOLING O F THE S IRE GROUP PERIODS ANALY S E S
In o r d e r to p o o l t h e resul t s o f t h e analy s e s over all the S ire
g r oup p e r iods , the me thod sugge s t ed b y Cunningham ( 1 9 7 0 ) was used .
In
this method , the sums o f s quare s and degrees o f f reedom are added f o r
a l l t h e s o ur c e s o f var i a t ion .
The variance component s co e f f i c i en t s are
o b t ained by averaging , we i ght ing each by its corresponding numbe r of
degrees o f f r eedom .
99 .
PARTITIONING THE VARIATION
The propo r t ion of var iance a c c ount ed f o r each f a c t o r in the poo led
analys e s for t he comb ined dat a was c a l cul a t ed from the p o s i t ive
variance component s ( includ ing f ixed e f f e c t q uad r a t i c c omponent s ) and
For examp le , variance due t o s t o ck ing
t h en c onve r t ed to a p ercentage .
r a t e ( % Vr ) f o r a t r a i t might be
X
100
VARIANCE COMPONENT E S T IMATES
The var i ance component s es t ima t e s o f s i r e , s ire x s t o cking rate
and s ir e x y e ar inter a c t i ons der ived from the least s quares analy s i s of
data in t h e c omb ined s t o cking rate and wi thin s t o cking rate analyses for
a l l the four S ire group periods ind iv idual l y and the p o o l e d anal y s e s
were u sed i n determining t h e imp o r t ance o f G E l f o r the t r a i t s under
inve s t igat i on .
Us ing the notat ion sp e c i f i e d e ar l ier for the e f f e c t s in the model ,
the f o l l owing intra- c l a s s relat ionsh ips wer e obt ained :
1.
The r e l a t ive magni tudes o f the in t e r a c t ion var i ance componen t s
( individual l y or comb ined) t o t h e t o t a l var iance wer e c a l c u l a t e d a s
fol lows :
(a)
comb ined s t o cking r a t e analys i s
(i)
02
o2 + o 2
s
sr
sr
+ o2
+ o2
+ o2
+ o2
st
e
o2
( ii )
o2 + o2
s
st
sr
st
e
1 00 .
+ a2
st
(iii)
(b )
Within s t o cking rate ana l y s i s
2.
The proport ions which the sire
s i re
x
x
s t o c king rate intera c t ion and
year interac t i on var iance componen t s ( i ndividually o r comb ined )
con t ribute to the t o t a l gene t i c varian c e s we re calculated as f o l l ows :
(a)
Comb in e d s t o cking rate analy s i s
a
(i)
sr
2 +
2
a
a
sr
s
(ii)
2
a
a
2
st
2
2 +
a
s
+ a2
st
sr
+ a2
st
(iii)
(b)
Within s t o cking r a t e analys i s
a2
st
(i)
3.
A comp a r i s o n o f the r e l a t ive magn i t ud e o f the two p a r t s o f the
gene t ic var ianc e ( i . e . , the in t e r a c t ion and the be tween- s ir e componen t s )
was made a s f o l l ows :
(a)
Comb ined s to cking r a t e analys i s
(b)
Within s t ocking r a t e analy s i s
a
2
st
-;;z
s
101 .
I f the r a t io i s large , the p e r f o rmance o f a geno type wou ld b e l e s s
r ep e a t ab l e over a l l environmen t s and vice versa.
GENE T I C PARAMETERS
He r i t ab i l ity
E s t ima t e s o f herit ab i l i t y we r e o b t ained f rom pat e rnal half- s i b
c o r re l a t ions .
The e s t ima t e s o f he r i t ab i l i t y der ived from p a t ernal
h a l f- s ib corre l a t ions using the s i re component does no t contain var i an c e
d u e t o dominanc e , t o ep i s t a s i s invo lving dominance dev i a t ion or t o
mat e rnal e f f e c t s (Turner a n d Y oun g ,
S ince the betwe en- s ire
1969) .
c omp onent i s the varian c e b e tween the means of half-sib f ami l i e s , i t
e s t imates t h e pheno typ i c covar iance o f half-s i b s , Cov (HS ) , wh i ch i s
� VA ( Falcone r , 1 9 60a) whe r e VA i s a n abb r evi a t ion f o r add i t ive gene t i c
var iance .
Thus in a populat ion ma t ing at random 4
gene t i c var iance o f the p op u l at i on .
i n t e r a c t ions ( i . e . , s ir e
x
cr�
e s t ima t e s the
But in t h i s s t udy a s the r andom
s t o ck ing rate and s i r e
x
y e a r ) were found t o
b e s i gn i f icant , the s i z e o f t he variance f o r r andom i n t e r a c t ions we re
e s t ima t ed t o make allowance for it s pre sence .
In the p r e s en t s tudy , h e r i t ab i l i ty e s t ima t e s were pooled over a l l
t he S ir e group periods analy sed b o t h i n t h e comb ined s t o cking r a t e and
w i t h in s t o cking rate ana ly s e s by the me t hod s u g g e s t e d b y Cunningham
( 1 9 7 0 ) , i . e . , by adding t he sums of s q uares and degrees of fre edom f o r
b e tween and wi thin s ir e s .
Gregory et a l .
( 1 9 7 8 ) showed that the u s e o f
t h i s procedure was mo r e accurate t han comb ining hal f - s ib e s t imat e s b y
we i gh t ing e a ch e s t imat e by t h e r e ciprocal o f i t s var i an c e , a me thod
which may b ia s the p o o l e d e s t ima t e downwards t oward s z e r o .
1 02 .
With the not a t ion used earlier in t h e analy s e s o f varianc e , the
her i t ab i l i t y for each t rait was e s t ima ted as f o l l ows :
(a)
Comb ined s t o cking r a t e ana l y s i s
h2
(b )
a2
s
+
2
4 as
a 2 + a2
st
sr
+
a2
e
Within s t o cking rate analy s i s
h2
2
4 as
a2 + a2
s
st
+
a2
e
Mo s t o f the pub l i shed e s t imat e s o b t a ined by the paternal h a l f - s i b me thod
are based on analy s e s of the s ire e f f e c t s ne s t ed within years and hence
would include s ir e x y e ar int eract ions as p a r t of the s i re e f f e c t .
Al s o mo s t e s t ima t e s are for sh eep at the s ame s t o cking rat e .
To s tudy
the e f f e c t s o f these f ace t s of the norma l me thods of o b t aining gen e t i c
p arame t er s , t h e he r i t ab i l i ty e s t imat e s were a l s o o b t a ined by the f o l l owing
f o rmulae :
(c)
Comb ined s to cking r a t e ana ly s i s
h2
(d)
2
2
2
4 (a s + a s r + a s t )
a2 + a2 + a2 + a 2
e
st
sr
s
Within s t o cking r a t e anal y s i s
h2
4 (a 2 + a 2 )
st
s
a2 + a2 + a2
s
e
st
Prec i s ion o f Her i t ab i l i ty
A large s amp l e variance o f h er i t ab i l i t y u s ing mean squares r a th e r
t han var i ance comp onen t s as d e s c r ib ed by Kemp thorne ( 1 9 5 7 ) w a s adap t e d
in t h i s s tudy t o calculate the app r oxima t e s t andard e r r o r s o f t h e
e s t imat e d heri t ab i l i t i e s .
103.
U s in g large s amp le theory f o r a b a l anced s i t ua t i on , if
X
y
e
where u i and v i are cons t an t s and A , B , C . . . . . e t c . are mean s quares ,
then l arge s amp le va r iance o f 6 i s :
V (6 )
where
V (X )
V (Y )
Cov ( XY )
V ( X)
y2
f
vf V (A)
2 X Cov ( XY )
.:..._.::_:_:.___:'-"-'---..!y3
_
u V (A ) + u � V ( B )
+
u r v1 V (A)
�
v V(B)
+
+
+
+
x2
-
y
�
v� V ( C )
u V (C )
u2 v 2 V ( B )
+
V (Y)
4
+
+
u3v3V (C ) +
S ince the denomina tors o f the her itab i l i t y e s t imat es in this s t udy
con t a in the inte ract ion var iance componen t s , the l arge- s amp l e var i an c e
o f her i t ab i l i t y d e r ived b y Swi ger e t a Z .
( 1 9 6 4 ) w a s found inap p ro p r i a t e .
Gene t i c corr e l a t ions
Int er- t r a i t gene t i c correlat ions
Harvey ( 1 9 7 0 ) showed that varianc e and covar iance componen t s c an be
e s t imat ed s imul t aneou s ly .
Coe f f ic i en t s for covarian c e comp one n t s
in
t he exp e c t a t ion of mean produc t s are the s ame as for c o rre sponding
variance component s when all depend ent var iables are ava ilable for a l l
o b s e rvat ions .
Variance and covariance comp onen t s wer e e s t imat ed by
Henderso n ' s Method 3 for all the t r a i t s und er inve s t igat ion in t h e
p o o l e d ana ly s i s f o r the combined s t o cking r a t e analy s i s .
In
a
populat i on mat ing a t random , the covar iance component s betwe en s ir e s
equals one fourth o f t h e covar iance b e tween the add i t ive deviat ions
c aus e d b y genes in the two charac t e r s .
1 04 .
The genet ic co r r e l a t ion b e tween the t ra i t s x and y wer e e s t ima t e d
f rom t h e s i re var i an c e and covariance comp onen t s as :
4 Cov s x s y
where
a i s an abbrevi a t ion for ad d i t ive g ene t i c , and
s r e f e r s to the s i r e comp onent .
The f o rmu la o f T a l l i s ( 1 9 5 9 ) was adap t e d to e s t ima t e approxima t e
s amp l ing errors o f t h e gene t i c co r r e l a t ion s .
Th i s formu l a i s a
mod i f i ca t ion o f t h a t g iven by Rob e r t son ( 1 9 5 9 ) wh ich is app l i c ab l e only
to t he cases wher e the her i t ab i l i t i e s for the two trai t s are the s ame .
Int r a- t r a i t gene t i c c o rrelat ions
Formul a p r e s en t e d by Yamada ( 1 9 6 2 ) for mixed model s and two
env i ronmen t s was adap t ed for e s t ima t ing the gene t i c corr e l a t ions b e tween
p e r f o rmanc e in two s t o cking r a t e s as a q uant i t a t ive exp r e s s ion of s i res t o c k ing rate in t e r a c t ion .
whe r e s r e f e r s t o t h e s i r e comp onent and a s
1
and a s r e f e r t o gene t i c
2
s t andard deviat ions in s t o cking r a t e H S R and CSR respe c t ive l y .
The
ab ove f o rmula of r g is no t subj e c t to any o f the l imi t at ions su f f e r e d
b y D i ckerson ' s ( 1 9 6 2 ) formula which wa s der ived under the a s sump t ion
o f t h e s ame gene t i c variance in each of the env i ronment s .
The
app r oxima t e s t andard errors of the intra - t ra i t gene t i c c o r r e l a t ion
c oe f f i c ient s we r e e s t ima t e d by Robe r t son ' s ( 1 9 5 9 ) formu l a .
105 .
CHAPTER F IVE
RESULTS AND D I SCUSS I ON
E S T IMATES OF NON- GENET IC FACTORS , I NTERACTIONS
AND
VARIANCE COMPONENTS
The records of the var ious p r odu c t ive t ra i t s such as l ive-we i gh t
and t h e woo l t r a i t s o f hogge t s are a f f e c t ed b y a var i e t y o f envi ronmen t a l
f a c t o r s such a s a ge o f dam , t y p e o f b i r th , s e x , nut r i t ion and year o f
re c o r d .
Some o f these f a c t o r s are easily iden t i f iab l e and recorded .
The i r e f f e c t s can be removed s t a t i s t i c ally f rom the p e r f o rman ce r e c o r d s
s o t h a t t h e a c curacy o f s e l e c t ion i s imp roved .
In the p re s ent s t u dy , as indi c a t ed in Chap t e r 4 , the known
env i r onme n t a l f a c t o r s c ons ide red l i kel y to be o f imp o r t an c e in the d a t a
a n d i n c luded i n the s t a t i s t i c a l mo d e l we re :
s t o ck i n g r a t e ( C SR or H S R ) ,
a g e o f dam ( 2 year old or o ld e r ) , type o f b i r th ( s ingle or twin ) , e f f e c t
o f t h e y ear i n which t h e r e c o rd was made and t h e re levant i n t e ra c t i o n s
b e tween the main e f f e c t s .
The prel iminary an alyses o f va r i an c e o f the
e f f e c t s o f age of dam , s t o ck ing r a t e
x
b i r th r ank and s i re
x
s t o c king
rate x y ear in t era c t i ons ind i c a t e d tha t in a l l ins t an c e s , these three
e f fe c t s were s t a t i s t i c a l l y non- s i gn i f i c ant ( P < O . O S ) .
Analy ses o f var i a n c e f o r o t her ma in e f f e c t s and in t e ra c t ions we re
c omp le t ed in each Sire group p e r i o d separat e ly and poo led a c c o r d i n g to
the p ro c e dure exp l ained in t he earl ier chap t er .
The s t a t i s t i cal
mod e l s to d e s c r ibe the comp u t a t ion procedures invo lved in these an a l y s e s
h av e b e e n d e s c r ibed p r ev i o us ly .
The p rop o r t i o n o f the t o t al va r i a t i on
a t t r ibu t ab le t o each f ac t or for each va r iab l e in t h e comb ined s t o cking
r a t e ana ly s i s pooled f r om t h e d i f f e rent S i re group p e r iods i s shown i n
T ab l e 5 t ogether with the s t a t i s t i cal s ign i f i cance o f e ac h f a c t o r .
TABLE 5 :
•'
Percentage o f to tal var iance a t t r i b u t a b l e to each f a c t o r for each var iable from
the comb ined s to cking rate ana lys is po o l e d f rom t h e d i f f e rent S i re group p e r io d s
Factor
HLW
GFW
HA
Sire
1 . 9 >'< 1<
3 . 3 i< i<
7 . 5 >'< >'<
4 . 5 * >'<
1 0 . 9 >'d<
6 3 . 8 >'o'<
3 7 . 3 >'<>'<
1 0 . 3 >'< >'<
2 . 6 >'< 1<
1 8 . 2 >'< >'<
Year
6 . 9 >'<*
2 4 . 9 .,., ,.,
9 . O i<>'<
14 . 4 **
3 . 7 i< i<
B i r th- rank
0 . 8 >'< >'<
S tocking r a t e
-
0.3
-
S i re
x
S t o cking rate
1 . 3 >'< *
0.4
S i re
x
year
1 . 2 -1< *
1 . 3 >'< >'<
2.2
1 . 5 >b'<
4 . 5 **
4 . 1 **
S t ocking r a t e
Error
x
Year
28 . 3
22 . 6
66 . 6
y
-
SL
0.2
1.6
0.5
1 9 . 6 * >''
56 . 8
1.0
2 . 1 >'<
63 . 9
S t a t i s t i c a l s i gn i f i cance o f mean s quares
*
**
P<0 . 05
P<0 . 0 1
......
0
0\
TABLE 5 :
( cont inue d )
Fac tor
MFD
V
1 0 . 2 -lc *
S ire
S t o cking rate
2.4
Year
l . 6 '� *
-
B i r t h- rank
SFD
6 . 1 ,. .�
1.7
1 1 . 6 >'d<
3 . 4* *
3 . 6 >'< >'<
1 2 . 0 * '�
44 . 2**
0. 6
0.2
-
-
2 . 7'�
3 . 9**
S i re
x
Year
0.7
1.5
Error
8 . 3 '< *
0.5
S to cking rate
Year
1 0 . 2**
0.5
x
x
CPC
1 . 4 >� *
S i re
S t o cking rate
QN
1 3 . 2 1d<
1 5 . 4 >'< *
69 . 2
58 . 4
6 . 7 * >'<
66 . 6
TCN
1 0 . 9 * '''
3 8 . 2 * -1'
l . 8 >'<
0.2
0.3
42 . 9
48 . 9
,_.
0
--.)
TABLE 5 :
( cont inue d )
Fac t o r
CHG
TG
HG
LG
GCG
S i re
4 . ] id<
5 . 4 -ln�
4 . 5 >'< >'<
5 . 8 >' d<
3 . 3 '� '''
S tocking rate
3 . 7**
1 . 4*
0. 1
0 . 8 i<
1 2 . 4 i<>'<
1 9 . l >'d<
2 1 . 3 >'< 1<
28 . 2 io�
2 . P*
1.0
0.6
1.4
2 8 . 9 1< >'<
Year
1 . 3 * 1<
B i r t h - rank
S i re
x
S t o cki ng rate
0.2
S i re
x
Year
0.3
S to cking rate
Error
x
Year
1.3
59. 6
4 . 0 * '�
-
-
-
-
89 . 2
2 . 9 1<
1.2
69 . 5
-
3 . 2 "' *
66 . 5
1 . 4 >�
1.3
1. 1
52 . 3
,__.
0
00
TABLE 5 :
( co n t inued )
Fac t o r
SCG
DAG
S i re
2.0
2.
S to cking rate
Year
CG
CAG
SG
l
5 . o ,., ,.,
3 . 4 ''' *
l . 8 in'<
5 . 6 >'n'<
5 . 6 **
3 . 7 >'< >'<
4 . 9 >'< >'<
2 5 . 4 >� >'<
8 . l ,� ,·,
0. 5
8 . 0 >'< *
3 9 . 0 >'< >'<
1 2 . 8 >'"�
-
B i rth- rank
S i re
x
S t ocking r a t e
1.3
S i re
x
Year
2 . 7*
S tocking rate
Error
x
Ye ar
6 . 1 >'< *
74 . 2
-
0. 5
-
-
7 . 4 -ld<
84 . 4
2 . 5 **
80 . 3
0.7
0.7
51.3
1 7 . 5 >'d<
42 . 5
......
0
'-0
1 10 .
The e s t ima t e s o f the ma in envi ronmen t a l e f fects in the d i f ferent
S ire group p e r iods analysed , e xp r e s s ed as dev i at ions f rom the overall
mean , t o g e ther w i th the ir s t andard d ev i a t ions der ived f rom the error
mean square are presen ted in Tab l e s 6- 1 5 .
The analy t i cal r e su l t s for each t r ai t s t ud ied are p r e s en t e d as
f o l lows :
Hogge t l ive-we igh t
HLW i n th i s s t udy rep re s e n t s t h e p o s t - shearing l ive-we i ght at
1 4 - 1 5 months of age .
Th e ove r a l l ave r ages o f HLW f o r e ach S i r e group p e r i od and
the leas t s quares e f f e c t s for d i f f erent sub c l as s e s o b t a ined b y the me thod
of f i t t ing con s t an t s are l i s t ed in Tab l e 6 .
In a l l t h e four S i re group p e r i o d s , the leas t s q uare s e f f e c t s show
that the r e was a pr onounced s t o cking l evel e f f ec t on HLW at shearing
with the HLW b e ing depressed in t h e H S R gr oup .
in clo s e agre emen t w i t h Sumner ( 1 9 6 9 ) .
The above r e s u l t s are
The nut r i t i on o f the HSR
anima l s was s everely res t r i c t ed i n the early part o f the s p r ing as a
r e sult o f c on f ining the anima l s t o a l imit ed are a .
Th i s p r a c t i c e ,
though enab l ing the l ambing ewe s t o h ave an access t o mor e p a s t ur e ,
r e t arded the b ody growth o f the hogge t s .
Live-we i ght gain is p ropo r t ional t o int ake in e xc e s s o f the
main t e nanc e r e qu iremen t s .
When s t o cking r a t e s are inc r e a s e d , int ake
p e r sheep f a l l s but intake in e xc e s s of ma i n tenance shows a g r e a t e r
propo r t ionat e change .
As a r e s u l t l ive-we i ght gain p e r h e c t ar e i s
more s ens i t ive t o increas ing t h e s t o cking r a t e than is woo l produ c t i on
TABLE 6 :
Leas t squares e s t ima tes and s t andard errors o f environmen tal e f f e c t s for HLW and GFW
Tra i t
Fac t o r
HLW
(kg)
S i re group 1
1967 / 1968
S ir e group 2
1 9 69 / 1 9 7 0
S i re group 3
197 1 / 1972
S ire group 4
1973/ 1974
S tocking r a t e
CSR
HSR
5 . 1 1 ± 0 . 23
-5 . 1 1 ± 0 . 23
5 . 34 ± 0 . 24
- 5 . 34 ± 0 . 2 4
3 . 1 2 ± 0 . 26
- 3 . 12 ± 0 . 26
3 . 5 1 ± 0 . 30
- 3 . 5 1 ± 0 . 30
1
2
2 . 12 ± 0 . 23
-2 . 1 2 ± 0 . 2 3
1 . 73 ± 0 . 23
- 1 . 73 ± 0 . 23
-0 . 38 ± 0 . 24
0 . 38 ± 0 . 24
0 . 76 ± 0 . 28
-0 . 7 6 ± 0 . 28
S ingle
Twin
0 . 38 ± 0 . 2 2
-0 . 3 8 ± 0 . 2 2
0 . 69 ± 0 . 2 6
-0 . 6 9 ± 0 . 2 6
0 . 77 ± 0 . 33
-0 . 7 7 ± 0 . 3 3
0 . 55 ± 0 . 4 1
-0. 55 ± 0 . 4 1
32 . 9 3 ± 0 . 2 3
3 . 94
35 . 1 2 ± 0 . 24
4 . 03
30 . 1 4 ± 0 . 2 9
3 . 67
34 . 1 8 ± 0 . 39
3 . 64
CSR
HSR
0 . 3 2 ± 0 . 03
-0 . 3 2 ± 0 . 0 3
0 . 60 ± 0 . 0 4
-0 . 60 ± 0 . 04
0 . 1 7 ± 0 . 03
-0 . 1 7 ± 0 . 03
0 . 3 8 ± 0 . 04
-0 . 3 8 ± 0 . 0 4
1
2
0 . 55 ± 0 . 03
-0 . 5 5 ± 0 . 0 3
0 . 25 ± 0 . 03
-0 . 2 5 ± 0 . 0 3
0 . 0 7 ± 0 . 03
-0 . 07 ± 0 . 03
0 . 1 3 ± 0 . 04
-0 . 1 3 ± 0 . 04
S ingle
Twin
0 . 03 ± 0 . 0 3
-0 . 0 3 ± 0 . 0 3
0 . 0 3 ± 0 . 04
-0 . 0 3 ± 0 . 0 4
0 . 0 6 ± 0 . 04
-0 . 0 6 ± 0 . 04
-0 . 0 1 ± 0 . 0 6
0 . 0 1 ± 0 . 06
3 . 56 ± 0 . 03
0 . 48
3 . 28 ± 0 . 03
0 . 59
3 . 00 ± 0 . 03
0 . 43
3 . 1 7 ± 0 . 05
0 . 49
Year
B i r th- rank
General mean
S t andard dev i a t ion
GFW
(kg)
S t o cking rate
Year
B i r th-rank
Gene ral mean
S t andard devi a t i on
>--'
>--'
>--'
112.
(Langlands and Benne t t ,
1973) .
D i f f e renc es in t he p lane o f nu t r i t ion
due t o s t o cking leve l may have variab l e int e r a c t i ons w i t h the incidence
o r seve r i ty of the d i s eas e .
Wh i l e increas ing the s t o cking rat e may
increase the incidence o f d i s e a s e a s s o c iated w i t h i nc r e a s ing phy s i c a l
c o n t a c t b e tween anima l s ( S pedd ing , 1 9 6 5 ) , the r e i s only l im i t ed
inf ormat ion on the e f f e c t of s t o cking rate on n ematode i n f e c t ion .
Under Au s t r a l i an cond i t ions it appears there i s l i t t l e e f f e c t w i t h the
ma ture sheep (McManus and Arno ld ,
1965 ;
Southco t t et a l . , 1 9 6 7 ) a l t hough
s ub s t an t ia l worm burdens may b u i ld up in young sh eep at h i gh e r leve l s
o f s t o ck ing p o s s ib ly d u e t o the i r p o o r immun i t y s t atus o r nu t r i t i o n
(McManus and Arno ld , 1 9 6 5 ) .
Th e animals b o rn as s ingles are sup e r i o r in the i r growth r a t e to
animals b o rn as twins , a t t aining a heavier body we ight at ho gge t s t age
in this s t udy .
S imilar obs erva t ions were mad e by Rae ( 1 9 5 0 ) , Ch ' ang
( 1 9 6 7 ) , T r i p a thy ( 1 9 6 6 ) and Bake r et a l .
( 1 9 7 4 ) in New Zealand Romne y s .
Rae ( 1 9 5 0 ) ob s e rved tha t the s ingle born New Z e a l and Romney hogge t s we r e
3 . 0 2 k g heav i e r than twins .
The magni tude o f b i r th r ank e f f e c t was
h oweve r , lower in t h i s s t udy on HLW t han r e p o r t e d by the se worke r s .
Terrill e t a l .
( 19 4 7 ) noted tha t the type o f b i r t h had an imp o r t a n t
e f fe c t o n b ody we i gh t a c c oun t ing for 7 and 1 3 % o f t h e t o t a l var i a t ion
i n Columb i a and Targh e e ewes r e s p e c t ively .
Be tween-year e f f e c t s are caused by f a c t o r s such a s nu t r i t i o n ,
c l imat e and managemen t p e culiar t o e a ch year .
The t rend in t h i s s t udy
sugge s t s that the HLW is eas i ly a f f e c t ed by envi r onment al cond i t ions
p ecul i ar t o e ach year such as d i f f erences in t h e amount and d i s t r ibut ion
of t he rainf a l l .
113.
The main sour c e o f environmen t a l var ia t io n in HLW , as ident i f i e d
by the analy sis o f var iance and quant i f ie d b y p roport ioning the varian c e ,
was s t o ck ing rat e .
T ab le 5 shows that t h i s a c c ount s for 6 3 . 8 % in the
pooled var iance analy s i s and it ranges from 5 1 . 1 % to 6 6 . 8 % in the
ind ividual S ire group p eriods .
The ' year ' e f f e ct con t r ib ut ed 6 . 9 %
( P < 0 . 0 1 ) t o the t o t al observed var ianc e .
B i r t h-rank though s i gni f i cant
( P < 0 . 0 1 ) accounted for only 0 . 8 % of the var i an c e in the p o o l ed analy s i s
whi l e i t cont ribu t e d 2 . 6 % in the S ire group 3 p e r iod .
The importance o f t he s i gn i f i c ant int e r a c t ions was evalua t e d by
var i an c e componen� an alysis from the pooled analys is of variance and the
ind ividual S ire group analys es o f var iance .
x year and s t o ck ing rate
x
S i re x s tocking r a t e , s i re
year int eract ions were sign i f i c an t ( P < O . O D in
the pooled analy s i s o f variance for HLW .
HLW is imp o r t an t from a
s e l e c t i on s t andp o in t , and the presence o f r andom in terac t i on s wou l d
hamp e r the gene t i c p r o g r e s s unle s s properly a c c ounted for .
In t eractions o f s i re x s t o cking r a t e are o f pr ime int e r e s t in t h i s
inve s t i g a t ion .
S ir e
x
s t o ck ing rate in t e r a c t ion cont rib u t e d 1 . 3 % o f the
t o t a l o b s erved var i an c e in the pooled variance analy s i s wh i l e i t
cont r ib u t ed 2 . 3 % o f t h e t o t al var iab i l ity i n S ire group 3 p e r io d .
Mor le y ( 1 9 5 6 ) repor t e d highly s igni f i cant s i re x nut r i t ion int e r a c t ions
at 1 2 and 1 7 mont h s b o dy we igh t .
were large and h i gh l y s igni f i c ant .
In thes e , t he int erac t i o n componen t s
The d i f f e rence b e twee n the p lanes o f
nut r i t ion i n h i s e xp e r iment w a s mo re ext reme than commonly encoun t e r e d in
prac t i ce .
Osman and Brad ford ( 1 9 6 5 ) a l s o f o und highly s i gn i f i cant s i re
x nut r i t ion int e r a c t i ons ( from poo led mean s quare s ) for 450 d ay we i gh t
in sheep .
Cart er e t a l . ( 1 9 7 1b ) ob s erved s ignif i cant int e r a c t ions f o r
1 20 d a y b ody we i gh t .
S igni f i cant g eno t y p e x nut r i t ion i n t e r a c t ions
1 14 .
were r ep o r t ed for growth and s l augh t e r we i gh t by Budans t ev ( 1 9 7 3 ) .
Howeve r , in Dunlop ' s ( 1 9 6 3 ) s t udy s t r a in x l o c a t ion interact ions for
adul t weights in sheep were non- s i gn i f i c an t .
S i r e x year int e r a c t ions con t r ib u t ed 1 . 2 % t o the t o t a l va r i ab i l i t y
f o r HLW
in
the p o o l e d var ian c e an a l y s i s .
Al t hough the s i z e o f in t e r-
a c t ions var iance component was abou t 2% in t he S ir e group 2 p e r iod , no
s ire x y ear in t e r a c t ions we re observed in S i r e group 4 p e r iod .
Pos s ib l e
c auses o f s i r e x y ear in t erac t ions have been d i s cussed b y Rae ( 1 9 5 8 ) .
The f a c t that the s i r e x year intera c t ions are s i gni f i cant t hough sma l l
in the p o o led ana l y s i s has cons iderable s e l e c t ion imp l i cat ions .
Ch ' ang ( 1 9 6 7 ) s t ud ied the s i re x year inte ract ion in HLW and f ound
i t to be a negl igib l e s o urce o f var i a t ion .
Dunlop ( 1 9 6 3 ) o b s e rved non-
s i gni f i c an t s t r a in x y e a r int e r a c t ions for adu l t we igh t .
King and Young
( 1 9 5 5 ) r e po r t ed non- s i gn i f i cant breed x envi ronmen t interac t i ons in
y ea r l ing weight .
Rae ( 1 9 5 8 ) found the s i re x year interact ions f o r
body t y p e t o b e not s i gn i f i can t .
A f u r ther s t ep t aken to a s s e s s the p r ac t i c al imp l i cat ions o f the
observed s ign i f i can t r andom interact ions and t h e ro l e p layed by these
in t e r a c t ions with r e gard to the s t ructure of h e r i t ab i l i ty e s t imat e s
sha l l b e d i s cu s s ed i n the next s e c t i on .
S t o cking r a t e
X
y e a r int eract ions wer e s i gn i f i c an t ( P < 0 . 0 1 ) an d
con t r ib u t e d 1 . 5 % o f the t o t a l observed varian c e i n HLW f rom t h e p o o l e d
analys i s wh i l e i n S ir e group 3 per iod i t cont r ibuted about 8 % o f t h e t o t al
var i a t ion .
Such i n t e r a c t ion s were a l s o repor t ed as s ign i f i c ant b y
Dunlo p ( 1 9 6 3 ) f o r adul t we igh t s .
1 15 .
Greasy f l e e c e we igh t
The ove r a l l averages and l e a s t squares cons tants f o r GFW f o r 9 - 1 0
mon ths wo o l growth b e tween l amb and hogget shear ing for e ach o f the S ir e
gr oup p e r i o d s analysed a r e p r e s en t ed i n Tab l e 6 .
In a l l the four S ir e group p e r iods , CSR anima l s had h i gher GFW than
t he HSR an imals .
The magn i t ude o f s t o cking r a t e e f f e c t s in S i r e group
2 p e r iod was mo re pronounced than in the o ther S ir e group periods
p r ob ably b e cause of s umme r d rought cond i t ions p r evail ing d u r ing t h o s e
t w o y ear s .
HLW showed s imilar t r ends during t h i s per iod .
The re i s
cons id e rable ev idence that t he f l e e c e weight is inve r s e l y related t o t h e
s t o cking r a t e and is approxima t e ly proport ional t o he rbage int ake .
Bub l a t h ( 1 9 6 9 ) r ep o r t e d that the Romney we thers a t l ow s t o c k ing
r a t e s grew s i gni f i c an t l y ( P < 0 . 0 1 ) more \voo l as compared wi th tho s e
graz ing at h i gh s t o c king r a t e s .
Joyce et a l .
( 1 9 7 6 ) ob s e rved that the
sheep s t ocked at highe s t r a t e s produced 1 1 % l e s s wool than tho s e at t h e
lowe s t r a t e s .
McManus ( 1 9 6 1 ) r e f e rred to s ome wo r k carr ied out in
V i c t o r i a , Aus t ralia with s t o cking rates o f two , f o ur and s ix sheep p e r
acre .
The average f l e e c e weigh t s per sheep d e c r eased s u c c e s s ively as
f o l lows : 1 3 . 8 , 1 2 . 3 and 1 1 . 3 lb .
Resu l t s s imilar to tho s e repor t ed in
t he present s t udy were o b t ained by Sumner ( 1 9 6 9 ) in the s ame f lock u s e d
in this s tudy .
The r esponse to nut r i t ional l evel i s also r e f l e c t ed by chan g e s in
both t he d i amet e r of f ib r e s and the ir length growth r at e .
A reduc t ion
in t he f e e d ing l evel will r educe the f ib r e length growth e f f ec t ively
and wi l l also reduce the d i ame t e r of f ib res .
As a p r o l onged p e r iod o f
s evere under-nut r i t ion i s required t o reduce t h e t o t a l f ib r e popul a t ion
1 16.
(Allden ,
1 9 6 8 ) , the r e sp onse i n f le e c e we ight t o a change i n s t o cking
rate w i l l almost alway s b e due t o a change in f ib r e-vo lume .
Ke l l y
( 1 9 4 9 ) i n a n exp e r iment i n wh ich s t rong woo l and f ine woo l Mer ino gave
respec t iv e l y 8 . 0 and 7 . 3 lb on a ' Low P l ane ' of nu t r i t ion and 1 8 . 4 and
1 3 . 3 lb on a ' Hi gh P l ane ' of nut r i t ion , a t t r ib u t e d the i n c r e ased
d i f f erenc e of GFW b e tween the s t r a ins ma inly to the chan g e s in the c r o s s ­
s e c t ional a r e a o f the f ibres , s i n c e t h e d i f f erence i n mean d iame t e r
increased f rom 3 . 6
�
on the ' Low P l ane ' t o 8
�
on the ' Hi gh P l ane ' .
The s i gns o f the b i rth rank e f f e c t s on GFW in t h i s s t udy are
con s is t en t with tho s e f o r Romney data repo r t ed by Tripathy ( 1 9 6 6 ) and
Baker et a l .
( 1 9 7 4 ) but the ma gn i t ude was l ower than r ep or t ed by t h e s e
worke r s .
B etween ' year ' e f f e c t s could t ake into ac count a wide array o f
comb in a t ions o f a t l e a s t t emp era t u r e s , r a i n f al l , pho t op e r i o d s and
sys t em o f managemen t .
Adver s e environme n t a l cond i t ions d u r ing t h e
y e a r c o u l d depre s s the GFW ind i r e c t ly through the r a t e o f growth i n HLW
and the deve lopme n t of se condary f o l l i c le s .
The resul t s o f the pooled analys i s o f var iance f o r GFW are
present e d in Tab l e 5 .
S t o cking r a t e and year e f f e c t s wer e s ig n i f i cant
( P < 0 . 0 1 ) and account f o r 3 7 . 3 % and 24 . 9 % of the t o t a l v a r i an ce .
S ir e
x
s to cking r a t e int e r a c t ions c on t r ib u t ed only 0 . 4 % ( N S ) t o
the t o t al observed variance i n t h e p o o l e d analys is o f var i anc e .
It
cont r ib u t e d 1 . 1 % ( P < O . O S ) only t o the t o t a l o b s e rved var i a t ion i n t h e
S ir e g r o up 1 per iod wh ile i n o th e r S ir e group p e r io d s i t w a s nons igni f i cant .
The p r a c t i c a l imp o r t an c e o f i t s b e ing s ign i f i cant i n
S i r e g r o u p 1 p e r io d would b e neg l i g i b l e in v iew o f t h e sma l l numb e r o f
117.
degrees o f f reedom ava i l ab l e for the analys i s .
S imi l a r r e s u l t s were
o b t a ined by Mo r l ey ( 1 9 5 6 ) who repor t ed non- s i gn i f i cant geno t y p e x
nu t r i t ion i n t e r a c t ions f o r GFW .
- Ne i t h e r int e r a c t ions o f b reed c r o s s x
p l ane of nut r i t io n nor the twin p a i r s within a cross x p l ane o f nu t r i t ion
were s igni f i c an t f or GFW in a s tudy condu c t ed by King e t a l .
( 1 959) .
The e f f e c t s o f these int erac t ions on GFW we re also found non- s i gn i f i can t
by O sman and Brad ford ( 1 9 6 5 ) .
S t rain x s t at ions int e r a c t ions f o r GFW ,
though s i gni f icant , in a s tudy by Dun l o p ( 1 9 6 2 ) were gene r a l l y sma l l and
a c counted f o r only a minor f ra c t ion o f the var i ance .
S i r e x year int e r a c t ions we r e s i gn i f icant ( P < 0 . 0 1 ) in t h i s s t udy
and con t r ib u t ed 1 . 3 % of the t o t a l var iance in the pooled analys is o f
var iance .
No s i gn i f i cant s ir e x y e a r i n t e r a c t ions f o r GFW were
o b s e rved b y Rae ( 1 9 5 8 ) .
Dunlop ( 1 9 6 2 ) also r epor t ed s t ra i n x year
i n t e r a c t ions f o r the t r a i t we r e non- s i g n i f i c an t .
The sma l l s i z e o f
variance component account b y t ho s e int eract ions ind i c a t e t h a t s e l e c t ion
of rams in o ne y e ar for use in an o t he r is un l ikely to h ind e r gene t i c
p rogress i n GFW .
S to ck ing r a t e x y ear in t er a c t ions were f ound s i gn i f i c an t ( P< 0 . 0 1 )
and con t r ib u t e d 4 . 5 % t o the t o t al var i ab i l i t y in the p o o l e d ana l y s i s o f
var i ance as aga ins t 2 1 . 6 % in t he S ir e g roup 4 p eriod i n wh i c h i t was
ob s e rved as h i gh ly s i gn i f i c an t .
Dun l o p ( 1 9 6 2 ) repor t ed s t at ion x y e a r s
i n t eract ions wer e highly s ign i f i c an t
( P < 0 . 0 1 ) for GFW .
H i gh s i gni f i cance
of s t o cking r a t e x year in this s t udy sugge s t s that t o s ome e x t e n t t h e
lack o f imp o r t ance o f s i r e x s t o cking r a t e intera c t ions r e s u l t s f rom t he
y e a r t o y ear variab i l i t y o f c l imat e and hen c e var iat ion in quan t i t y and
qual i t y of f o d d e r ava i l a b l e w i t h in ind ividu a l s t o cking r a t e s .
1 18.
Clean wool we ight per unit area
Ra t e of wo o l growth i s mea s ured as t h e we ight of c l ean ( d r y ) wo o l
in grams p e r square cent ime t e r
o f skin over a s p e c i f ied p e r iod o f t ime .
The overall ave r a g e s o f WA for three S i r e g roup periods analysed are
p r e s ented in Tab l e 7 toge ther with the l ea s t squares e s t ima t e s of the
main e f f e c t s in the mod e l .
D i f feren c e s b e tween s t ocking r a t e s u g ge s t that the WA i s d e p r e s s e d
in the H S R .
The s t ocking rate e f f ec t c o n t ributed 1 0 . 3 % t o t h e t o t a l
var i ab i l i t y and was s i gni f i cant ( P< 0 . 0 1 ) i n t h e p ooled ana l y s i s o f
var i anc e .
The s t o ck ing rate e f f e c t was more pronounced in the S ire
group 2 period p r o b ably b e caus e of t he s ummer d rought cond i t ions
p r ev a i l ing dur i n g t ho s e two years and r educed feed int ake .
re s ul t s are in a g r e ement with Bub lath ( 1 9 6 9) .
The above
He r ep o r t e d t ha t the
New Zealand Romney sheep grew more woo l p e r un i t area at a l ow s t ocking
r a t e as comp ar e d t o the sheep i n the h i gh s t o cking r at e .
Between�year e f f e c t s were a l s o h i gh l y s i gn i f ic ant and c o n t r ibuted
9 % o f var iab i l i t y in the p o o l e d analys i s of vari ance .
V a r i a t ion in
woo l produ c t ion b e tween years was probably a s s o c iated wi t h r e d u c e d
p a s ture growth a n d hence feed i n t ake .
S ire
x
s t o ck i ng rate int e r a c t ions were non- s igni f i cant f o r t h i s
t r a i t i n t he p o o l e d analys i s o f var i an c e and the ind ividual S ir e group
p e r io d s .
Thu s the s i r e s ranked cons i s t en t ly in the s ame o r d e r .
King and Y oung ( 1 9 5 5 ) h oweve r , r ep o r t ed s i gni f i cant b r e ed x p l ane
of nut r it ion i n t e r ac t io n s for c lean we i gh t of woo l f ib r e s o n a t at to o e d
area and c l e an we i gh t o f a l l f ib r e s o n t he t a t t ooed area .
TABLE 7 :
Lea s t square s e s t ima t e s and s t andard e r r o r s o f envir onmental e f f e c t s f o r WA and Y
Tra i t
Fac t o r
S i r e group 1
1 9 6 7 / 1 9 68
WA
S t ocking r a t e
CSR
( gms / cm2 )
HSR
Year
1
2
B i r th-rank
S ingle
Twin
General mean
S t andard devia t ion
y
S t ocking r a t e
CSR
HSR
( p e r c en t )
±
0 . 00 3
0 . 00 3
0 . 017
-0 . 0 1 7
±
0 . 00 2 ± 0 . 00 3
- 0 . 00 2 ± 0 . 00 3
-0 . 004
0 . 004
±
± 0 . 00 3
0 . 05
0 . 308
-0 . 009 ± 0 . 00 3
0 . 009 + 0 . 0 0 3
0 . 022
- 0 . 022
-0 . 0 1 5 ± 0 . 00 3
0 . 0 1 5 ± 0 . 003
0 . 366
-0 . 2 4 ± 0 . 2 3
0 . 24 ± 0 . 23
Gene ral mean
S t andard devi a t i on
S i r e group 4
1973/ 1974
-
-
0 .012
-0 . 0 1 2
±
0 . 00 6
0 . 00 6
0 . 003
0 . 003
-
0 . 003
-0 . 003
±
0 . 00 5
0 . 005
0 . 003
0 . 00 3
-
-0 . 0 1 1
0.011
±
0 . 008
0 . 008
± 0 . 003
0 . 05
-
0 . 365
±
±
±
±
±
±
± 0 . 00 7
0 . 07
-0 . 0 7 ± 0 . 3 1
0 . 07 ± 0 . 3 1
0 . 24
0 . 24
1 . 29 ± 0 . 22
- 1 . 29 ± 0 . 22
-2 . 15
2 . 15
±
0 . 30
0 . 30
2 . 0 2 ± 0 . 35
-2 . 0 2 ± 0 . 3 5
0 . 2 1 ± 0 . 23
-0 . 2 1 ± 0 . 2 3
-0 . 23 ± 0 . 25
0 . 23 ± 0 . 25
-0 . 45
0 . 45
±
0.41
0.41
-0 . 1 3 ± 0 . 5 1
0 . 13 ± 0 . 5 1
± 0 . 22
4 . 07
7 6 . 39 ± 0 . 2 2
3 . 83
7 8 . 37 ± 0 . 35
4 . 49
7 6 . 8 1 ± 0 . 48
4 . 53
0 . 40
- 0 . 40
±
±
B i r t h- rank
S ingle
Twin
S ir e group 3
197 1 / 1972
-0. 9 1 ± 0 . 23
0 . 9 1 ± 0 . 23
Year
1
2
S i re group 2
1969/ 1970
7 7 . 14
±
±
1 . 24
- 1 . 24
±
±
0 . 38
0 . 38
,......
,......
\0
120.
S i re
x
year i n t e rac t i ons though non- s ign i f i c ant in t h e pooled
ana l y s i s cont rib u t ed s l igh t ly mo r e than 2 % of t h e var i an c e .
in s amp l in g may have con t r ib u t ed t o the s i r e
x
Var iat ions
year in t e r a c t ion s in the
S i r e g ro up 2 per iod where i t ( P < O . OS ) a c coun t ed for 4 . 4 % of t he t o t al
var i ab i l i t y .
S t o c king r a t e
x
year int e ra c t ions were s i gn i f icant in the p o o l e d
analy s i s o f var ianc e .
C l ean s coured yield
The l eas t s quares e f f e c t s f o r each of the f our S ir e group p e r i o d s
f o r y i e l d a r e l i s t ed i n Tab l e 7 .
t h e v a r i o u s S ir e g roup p e r iod s .
Th e s t o cking r a t e e f f e c t s d i f f e r f o r
Th i s could be a t t r i b u t ed to the
samp l in g variat ion .
Sumner ( 1 9 6 9 ) rep o r t ed h i gh e r means for Y i n t h e
CSR an ima l s group .
Mor l ey ( 1 9 56 ) a l s o observed higher Y i n the ' Hi gh
Plane ' animals as compared to ' Low P l ane ' an ima l s though the d i f f e rence
Between s t ocking r a t e e f f e c t s on Y in th e poo led
was not s i gnif icant .
analys i s of var iance though s i gn i f i c ant , con t r ib u t ed only 2 . 6 % to the
t o t al var iab i l i t y wh i l e the b e tween years e f f e c t a ccoun t ed for 1 4 . 4 % and
Between years e f f e c t s could be due t o the
was h i gh l y s i gn i f i c an t .
d i f f er e n c e in r a in f a l l and o ther cl imat i c f a c t or s .
D i f f e r in g d e g r e e s
o f c o n t amina t ion with mud a n d dus t could be imp o r t an t .
S i r e x s t o cking rate int e r a c t ions con t r i b u t e d l e s s t han 2 % t o the
t o t a l ob s e rved var iance and was non- s i gn i f i cant in t h e p o o l e d va r i an c e
component analy s i s .
I t was s i gnif i can t ( P < 0 . 05 ) and a c c ount ed f o r 4 . 5 %
t o t h e t o t a l var i ab i l i t y in t h e S ir e group 3 p e r i o d .
The r e s u l t
ob t ained from t h e pooled analy s is o f var ian c e agrees wi t h Mo r l ey ( 1 9 5 6 )
who r e p o r t e d that s i re
x
nut r i t ion in t e r a c t ions were non- s i gn i f i c an t .
121 .
Dunlop ( 1 9 6 2 ) however , obs erved s i gni f i c an t s t r a i n x s t a t io n i n t e ra c t i on s
t hough the s i z e o f the int erac t ions t e rm was not large .
In t h e p o o l e d var iance component analys i s s ir e x y e ar i n t e r a c t ions
were f ound non- s i gn i f i c ant and r e l a t iv e l y of l e s s imp or t an c e .
S i gn i f icant in t er a c t ion ( P < 0 . 0 5 ) b e tween s i r e and year was , however ,
ob s erved in the S i re group 3 p e r i o d and i t con t r ibuted s l i gh t l y over
4 % to the t o t al variat ion .
Dun lop ( 1 9 6 2 ) also observed s i gn i f i c an t
s t rain x y e a r int eract ions i n the t r a i t t hough i t accoun t e d f o r j us t
over 1 % o f t he t o t al variab i l i t y .
S t o cking r a t e x year int e r a c t ions
cont r ibut ed maj o r p o r t ion o f var i a t ion due t o interac t ions .
S t aple length
S t ap l e lengt h in t h i s s tudy reduced wi t h h i gh s t o cking r a t e t hough
t h e extent o f r e s pons e d i f f e r ed in d i f f e rent S ir e group p e r i od s .
S t ap le
length has b e en o b s erved by various wo rkers t o l ower wi t h increased
s t ocking rate ( Sharkey e t a l . , 1 9 6 2 ;
L ip s on and Bacon-Ha l l ,
1 974 ;
S umne r ,
1 969 ;
Canon ,
Wh i t e and McConch i e , 1 9 7 6 ) .
1972 ;
B e tween
s t o cking r a t e s SL d i f f e red mor e markedly during the S ir e group 2 p e r i o d
a s 1 9 6 9 a n d 1 9 7 0 h a d s umme r d r o ugh t s wh i ch c o u l d dep r e s s woo l growth
t hrough nut r i t ional d e p r iva t i on .
In t h e p o o l e d analys i s o f v a r iance
1 8 . 2% o f the var i at ion was b e tween s t o cking r a t e s whi l e t h i s component
increased to 3 4 . 8% in t he S ir e group 2 p e r iod .
In th i s s tudy s ingles have s l ig h t l y short er SL than t h e twins in
a l l t he f our S i r e group p e r i od s .
Th i s is in agreemen t wi t h Lax and
B rown ( 1 9 6 7 ) and E l l io t t ( 1 9 7 5 ) .
Lowe red t o t a l f o l l i c l e numbe r o f twins
could p erhaps explain these r e s ul t s .
Longer f ib res may b e p roduced b y
s h e e p wit h lower f o l l i c l e p o p u l a t ion (Fras e r , 1 95 2 ;
S chinckel and S ho r t ,
TABLE 8 :
Leas t squares e s t ima t e s and s t andard errors of environmen t al e f f e c t s for SL and MFD
Tra i t
Fac t o r
SL
( cm)
S ire group 1
1967/68
S i re group 2
1969/ 1970
S i re group 3
197 1 / 1972
S i r e group 4
1 97 3 / 1 974
S t o cking rate
CSR
HSR
0 . 27 ± 0 . 09
- 0 . 2 7 ± 0 . 09
1 . 02 ± 0 . 09
- 1 . 02 ± 0 . 09
0 . 36 ± 0 . 1 3
-0 . 3 6 ± 0 . 1 3
0 . 48 ± 0 . 1 2
- 0 . 48 ± 0 . 1 2
1
2
-0 . 12 ± 0 . 10
0 . 12 ± 0 . 10
0 . 68 ± 0 . 09
- 0 . 6 8 ± 0 . 09
-0 . 25 ± 0 . 1 2
0 . 25 ± 0 . 12
0 . 59 ± 0 . 1 1
-0 . 59 ± 0 . 1 1
S ingle
Twin
- 0 . 1 3 ± 0 . 09
0 . 1 3 ± 0 . 09
-0 . 1 3 ± 0 . 1 0
0 . 13 ± 0 . 10
-0 . 02 ± 0 . 16
0 . 02 ± 0 . 1 6
-0 . 2 6 ± 0 . 1 6
0 . 26 ± 0 . 16
14 . 6 3 ± 0 . 10
1 . 66
1 3 . 90 ± 0 . 09
1 . 57
13 . 58 ± 0 . 14
1 . 82
1 3 . 25 ± 0 . 15
1 . 45
CSR
HSR
0 . 53 ± 0 . 15
-0 . 5 3 ± 0 . 1 5
-
0 . 1 1 ± 0. 19
-0. 1 1 ± 0 . 19
1
2
0 . 37 ± 0 . 16
-0 . 37 ± 0 . 16
-
0 . 30 ± 0 . 18
-0 . 30 ± 0 . 18
S ingle
Twin
0 . 09 ± 0 . 1 5
- 0 . 09 ± 0 . 1 5
Year
Bir th- rank
Gene ral mean
S t andard deviat ion
MFD
( \lm)
S t ocking rate
Year
B i r th- rank
Gene ral mean
S t andard dev i a t ion
35 . 4 6 ± 0 . 1 6
2 . 66
-
-
-
- 0 . 1 7 ± 0 . 24
0 . 17 ± 0 . 24
-
35 . 02 ± 0 . 2 1
2 . 67
.......
N
N
123.
1961) .
Lax and B rown ( 1 9 6 7 ) obs e rved an inc r e as e d (P< 0 . 0 1 ) numb e r o f
f ib r e s per mm2 f o r s in gl e s .
Sumner and Wi c kham ( 1 9 7 0 ) , howeve r ,
obs erved no s i gn i f icant e f f e c t o f b i r t h r ank on t h e S f / P f r a t io a t t h e
h o g g e t shear ing in t h e s ame f lock as und er s t udy .
D i f f erences b e tween year ac coun t ed for 3 . 7 % ( P< 0 . 0 1 ) o f the t o t a l
var ia t ion i n t h e pooled ana l y s i s o f variance t ho ugh i t exp l a ined 1 7 . 7 %
in t h e S i r e group 3 p e r io d .
Varia t ion b e tween years coul d b e due t o t h e
c l imat i c cond i t ions pr eva i l ing or man agement d e c i s ions such as t ime
b e tween shearing s .
A short a l t e r a t ion b e tween the shearing t ime s could
b e i n s t rument al (Wi ckham and Bigham ,
'
1 9 7 3 ) p a r t i c u larly whe n the woo l
g r ow t h i s app roaching i t s maximum , i . e . , dur ing Novemb e r ( Hend e r son , 1 9 6 8 ) .
Sire x s tocking r a t e in t eract ions were non- s i gn i f i c an t b o t h in the
p o o l e d analy s i s of variance and from t h e four Sire group p e r io d s ana l y s e s .
The s e resul t s are in agreement with Mo r l e y ( 1 9 5 6 ) who repo r t e d nons i gni f ic an t s i r e x nut r i t ion in t e r a c t ions for t h i s t r a i t .
S imilar
r e s u l t s we r e reported by King and Young ( 1 9 5 5 ) and King et a l .
f o r average f i b r e leng t h .
S t an s f i e l d e t a l .
( 1959)
( 1 9 6 4 ) a l s o o b s e rved no
s igni f icant g eno t yp e x l o c a t ion i n t e r a c t ions f o r SL .
Dunlop ( 1 9 6 2 )
however , ind i c a t ed smal l s i g n i f icant s t r a in x l o c a t ion i n t erac t ions .
N e ve r thel e s s t h e in t e r a c t ions f o r t h i s t r a i t in h i s exp e r iment a c coun t e d
f o r only a very minor ( l e s s than 1 % ) f r a c t ion o f the var i a t io n .
S ir e x
f lo c k int e r a c t ions were o b s e rved s i gni f i cant f o r SL f rom t h e p o o l e d
e s t imat e s only b y Osman and Brad f o r d ( 1 9 6 5 ) .
S i r e x year int e r a c t ions exp l a ined only 1 % (NS ) in t h e p o o l e d
v a r i ance c omponent analys i s .
S imilar o b s ervat ions f o r s ir e x year
i n t e ra ct ions were repo r t e d for t he t r a i t i n t h e New Z e a l an d Romney s h e e p
(
124 .
Dunl o p ( 1 9 6 2 ) a l s o s t ud ied s t rain x year in t er a c t ions
by Rae ( 1 9 5 8 ) .
and f ound no s uch int erac t ions as s i gni f i cant for t h e t r a i t .
S t ocking r a t e x year i n t e r a c t ions t hough s i gn i f icant ( P < 0 . 0 5 )
account f o r only 2 . 1 % in the pooled ana l y s i s o f var ianc e .
In general , in t er a c t ions were not impo r t ant f o r the t r a i t and
a c co un t e d for only a very minor f r act ion of t h e var iance component s .
S t o cking rates wer e t he mo s t imp o r t an t s o u r c e o f variat ion .
Mean f ib r e d iame t er
Resu l t s reco rded in the s t udy und er inve s t i g a t ion in bo th the S i r e
group periods ana l y s e d sugge s t ed t h a t MFD d e creases wi th increased
The r e is consid erab l e evidence that the MFD d e c r e a s e s
s to ck ing rat e .
w i t h the incre a s e d s t o cking rat e ( Sharkey e t a l . , 1 9 6 2 ;
W i ckham , 1 9 6 9 ;
C an o n , 1 9 7 2 ;
McConch i e , 1 9 7 6 ) .
Sumner and
Lip son and Ba con-Hal l , 1 9 7 4 ;
Wh i t e and
As a p r o longed p e r io d o f d e c re ased l evel o f
nut r i t ion i s requ ired t o r educe the t o t al f ibre populat ion o f non­
b r e e d in g sheep ( A l l den , 1 9 6 8 ) , the l ower f l eece we igh t wi t h increased
s t o c k in g r a t e will norma l l y b e due t o a reduced f ibre-vo lume .
Ryder
( 1 9 5 6 ) and Coop ( 1 9 5 3 ) have sugges t ed that the length and d i ame t e r o f
f ib r e a r e a f f e c t ed equa l l y by p o o r nut r i t i o n .
Between year e f fe c t s though s igni f i c an t ( P < 0 . 0 1 ) con t r ibu t ed only
1 . 6 % of the t o t al var ia t i on i n the p o o l e d variance componen t s an alys i s .
S ire x s t o cking r a t e interac t ions wer e s i gn i f i c an t ( P < 0 . 0 5 ) f o r
MFD and exp lained 2 . 7 % o f t he t o t al v a r i a t ion in t h e p o o l e d v a r i an c e
component ana ly s i s .
Dunlop ( 1 9 6 2 ) a l s o r e p o r t e d s igni f i cant s t rain x
l o c a t ion int e r a c t ions o f mod e r a t e s i z e in MFD .
Flocks x l ev e l o f
nut r it ion int er a c t ions were f ound s i gn i f i can t f o r f ib r e c r o s s-se c t ional
125 .
area by Wi l l i ams ( 1 9 6 6 ) .
King and Young ( 1 9 5 5 ) however , d i d not
observe any s i gn i f i cant breed
x
nut r i t ion interac t ions f o r the ave rage
d iame t er of wool f ibre .
S ir e
x
year i n t e r a c t ions we r e o f no s i gni f i c ance in t h e populat i on
under s t udy and a c coun t e d for l e s s t han 1 % o f the t o t a l var i a t ion in t h e
poo led ana ly s is o f var iance .
The r e su l t s ob t a ined are suppor t ed by
observa t ions on s u ch int era c t ions f o r MFD by Dunlop ( 1 9 6 2 ) .
rate
x
S t o cking
year int er a c t ions were f ound highly s i gn i f icant ( P< 0 . 0 1 ) and we r e
t h e ma i n s ource o f var i a t ion i n t h i s t r a i t .
S t andard dev i a t ion o f the f ibre d i ame t e r
The s to cking r a t e e f f e c t wa s n o t s t a t i s t i cally s i gn i f i c ant and
cont r ib u t e d le s s t han 2% of t he t o t al o b s e rved variat ion .
S FD was
howeve r , h i gher in the HSR t han CSR in b o t h the S i re group period
anal y s e d though the d i f f erence wa s no t s i gn i f i cant .
Year d i f f er en c e s
were h i gh ly s i gn i f i c an t and con t r ib u t ed 1 1 . 6 % t o t h e t o t al obs erved
var i a t ion .
The b i r t h rank e f f e c t was also f ound s i gn i f i c ant ( P < 0 . 0 1 ) .
Var i a t ion in f ib r e d iame t e r could be f rom f ib r e t o f ib r e w i t h i n a s i t e
o r f rom p o int t o p o in t along the f ibre .
S ig n i f icant s i re
x
s t o cking r a t e ( P < 0 . 0 1 ) and s ir e x year ( NS )
int e r a c t i ons exp l a ined about 4 and 1 . 5 % o f the var i a t ion r e sp ec t ive l y .
Var i a t i o n due t o interact ions could be in p a r t due t o nu t r i t ional level
x f ib r e i n t e ra c t ions and a l s o the d i f ferences b e twe en y e a r s in s ea s onal
ava i l a b i l i ty of f e e d .
TABLE 9 :
Lea s t square s e s t ima t e s and s t andard errors o f environmental e f f e c t s for S FD and QN
Trai t
Fac t o r
SFD
( \lm )
S i r e group 1
1 9 6 7 / 1 9 68
S to cking r a t e
CSR
HSR
-0 . 1 8 ± 0 . 06
0 . 18 ± 0 . 06
1
2
-0 . 3 5 ± 0 . 0 5
0 . 35 ± 0 . 05
S ingle
Twin
Year
QN
( un i t )
-
S ir e group 3
197 1 / 1972
S i re group 4
1973/ 1974
-0 . 08 ± 0 . 07
0 . 08 ± 0 . 07
-
-0 . 2 8 ± 0 . 0 7
0 . 28 ± 0 . 07
0 . 03 ± 0 . 05
-0 . 0 3 ± 0 . 05
-
-0 . 24 ± 0 . 0 9
0 . 24 ± 0 . 0 9
8 . 9 1 ± 0 . 06
0 . 96
-
8 . 48 ± 0 . 08
1 . 02
B i r th-rank
Gene r a l mean
S t andard devia t ion
S i re group 2
1969/ 1970
S t ocking r a t e
CSR
HSR
-0 . 1 2 ± 0 . 0 9
0 . 1 2 ± 0 . 09
-0 . 1 8 ± 0 . 1 0
0 . 18 ± 0 . 1 0
-0 . 54 ± 0 . 1 3
0 . 54 ± 0 . 1 3
-0 . 2 1 ± 0 . 1 4
0 . 2 1 ± 0 . 14
1
2
0 . 0 4 ± 0 . 09
- 0 . 04 ± 0 . 0 9
- 0 . 24 ± 0 . 1 0
0 . 24 ± 0 . 10
0. 14 ± 0. 12
-0 . 14 ± 0 . 1 2
- 1 . 19 ± 0 . 1 3
1 . 19 ± 0. 13
S ingle
Twin
0 . 04 ± 0 . 08
- 0 . 04 ± 0 . 0 8
0 . 17 ± 0. 1 1
-0 . 1 7 ± 0 . 1 1
0 . 08 ± 0 . 1 7
-0 . 08 ± 0 . 1 7
0 . 36 ± 0 . 1 8
- 0 . 36 ± 0 . 1 8
4 8 . 2 2 ± 0 . 09
1 . 50
48 . 5 3 ± 0 . 10
1. 71
48 . 60 ± 0 . 1 5
1 . 86
49 . 40 ± 0 . 1 7
1 . 64
Year
B i r th- rank
Gener a l mean
S t andard devia t i on
.......
N
0'
127 .
Qua l i ty number
QN wh ich has been used to ind i c a t e f inene s s and s p inning
chara c t e r i s t i c s , is subj e c t ive ly as s e s s ed ma inly on cr imp f re quency
w i t h lus t r e ano t her imp or t an t f a c t o r (Wickham and B i gham , 1 9 7 3 ) .
Other
factors s uch as leng t h , and handle are cons i d e red t o a f f e c t the a s s e s sment
of QN , though the variat ion in the s e a t t r i b u t e s does no t n e c e s s a r i ly
e q ua t e w i t h t he changes in f ib re d i ame t er .
In a l l t h e four S i re p e r iods an alysed , QN was higher in HSR sheep �
the var i a t ion d ue to s t o cking r a t e agrees with the se chan g e s in CP C .
S imilar r e s u l t s were o b t ained in New Z ealand Romney hogge t s b y Bub l a t h
( 1969) .
The s o f tne s s o f hand le is c l o s e ly r e l a t e d t o t h e f ineness o f
. l
f ibres and longer s t ap l e s to be ma rked down in QN , probably o f the
b e l ie f t h a t they mus t be t he r e f o r e coars e r .
rate on QN has been examined by Joyce e t a l .
The e f f e c t o f s t ocking
( 1976) .
mad e in t h i s s t udy are in agr eement with the s e wo r ke r s .
Wickham ( 1 9 6 9 ) however ,
in
�
The o b s ervat ions
Sumne r and
anal y s e s o f QN r e p o r t e d that t h e f l e e c e s were
j udged to be coar s e r a t the higher s t o cking r a t e in the New Zeal and
Romney ewe s .
Th i s was perhap s due t o the wool grown a t the h i gh s t ocking
r a t e b e in g mor e lus t rous than t h a t grown a t the low s t o cking r a t e .
The e f f e c t o f years accoun t ed f o r the maj or fraction o f the t o tal
ob served var i a t ion in the t ra i t and was h i ghly s i gn i f i can t .
A part of
t h i s var i a t ion could b e due t o var ia t ions i n the s t andards d u e t o
varying emp h a s i s p l a c e d on the component a t t r ibutes b y t h e o b s e rvers
during t h e years unde r s t udy .
S ir e x s tocking r a t e int e ra c t ions wer e found non- s i gn i f i cant f o r
the t r a i t s i n t h e p o o led and t h e ind ividual S ir e group p e r i o d s ana l y s e s
128 .
of var i an c e .
Osman and Brad f o r d ( 1 9 6 5 ) also r e p o r t e d s ir e x f l o ck
int e r a c t ions as non- s i gn i f i c an t in t h i s t rai t .
Dunl op ( 1 9 6 2 ) obs erved t h a t s t rain x l o c a t ion int e r a c t ions f o r the
t ra i t a c c ount s f o r only a n e g l i g ib l e f r a c t ion of the var ian ce and a r e
non- s i gn i f i can t .
S i r e x year int er a c t ions were non- s ign i f i cant f o r t h e t ra i t i n t h i s
inve s t i g a t ion and we re n o t imp o r t an t i n t h e pooled o r t h e individual
S i re g r o up per iod anal y s e s .
Rae ( 1 9 5 8 ) and Dunlop ( 1 9 6 2 ) a l s o rep o r t ed
that geno type x year int e r a c t ions were not s i gn i f i c an t f o r t h e t ra i t .
As a cause o f variab i l i t y o f QN , s t o cking r a t e x year int e r a c t ions
app e a r s to be more impor t an t t h an CPC in this inve s t igat ion .
Cr imps per centime t e r
S t aple c r imp i s u s e d in as s e s s ing woo l q ua l i ty b e c au s e o f the
app r o x ima t e inv e r s e r e l a t i on s h i p be twe en t h e CPC and MFD (Ry d e r and
S t e p he nson , 1 9 6 8 ) , though w i t h some woo l s , a t l e a s t , c r imp is no t a
good indicator o f t he f ibre c r o s s - s e c t ional area (Rob e r t s an d Dun lop ,
1957) .
The e f f e c t of st o ck in g r a t e on the t r a i t exp la ined 3 . 6 % ( P < 0 . 0 1 )
o f t h e t o t al ob s e rved var i a t ion in the poo l ed varian c e componen t s anal y s i s .
A t en d e ncy f o r CPC t o inc r e a s e with increa s e d s t ocking r a t e wa s n o t e d in
a l l the three S ir e group p e r iods analysed .
Re sul t s s imilar t o t h i s
s t udy have b e e n repo r t e d by S umner ( 1 9 6 9 ) .
A n inc r e a s e in f ib r e l en g t h
c au s e d b y nut r i t ion c o u l d r e s u l t in a d e c r e a s e o f CPC , i f c r imp i s a
p er io d ic func t ion o f t ime .
Robards e t a Z .
( 1 9 7 4 ) s t ud i e d t h e d i f f e r e n c e s
i n i n t ake o f f o o d on c r imp f r equency and ob s e rved n o s i gn i f i cant e f f e c t .
TABLE 1 0 :
Lea s t squares e s t imat e s and s t andard errors of environment a l e f f e c t s for CPC and TCN
S i re group 1
1 9 6 7 / 1 9 68
Tra i t
Fac tor
CPC
( un i t )
S tocking rate
S ir e group 2
1969/ 1970
S i r e group 3
197 1 / 1972
CSR
HSR
-0 . 02 ± 0 . 0 1
0 . 02 ± 0 . 0 1
- 0 . 08 ± 0 . 0 1
0 . 08 ± 0 . 0 1
-
-0 . 0 5 ± 0 . 0 3
0 . 05 ± 0 . 03
1
2
0. 17 ± 0 . 01
-0 . 1 7 ± 0 . 0 1
0 . 02 ± 0 . 0 1
-0 . 0 2 ± 0 . 0 1
-
-0 . 0 1 ± 0 . 02
0 . 0 1 ± 0 . 02
S ingle
Tw in
0 . 01 ± 0.01
-0 . 0 1 ± 0 . 0 1
0 . 03 ± 0 . 02
- 0 . 03 ± 0 . 02
-
1 . 06 ± 0 . 0 1
0 . 23
1 . 14 ± 0 . 0 1
0 . 23
-
-
1 . 44 ± 0 . 03
0 . 32
CSR
HSR
0. 1 0 ± 0 . 16
-0 . 1 0 ± 0 . 1 6
0 . 05 ± 0 . 15
-0 . 05 + 0 . 15
-
0 . 05 ± 0 . 23
-0 . 0 5 ± 0 . 2 3
1
2
-2 . 28 ± 0 . 16
2 . 28 ± 0 . 16
1 . 06 ± 0. 15
- 1 . 06 ± 0 . 15
-
-
0 . 68 ± 0 . 2 1
- 0 . 68 ± 0 . 2 1
S ingle
Twin
0 . 12 ± 0. 15
-0 . 1 2 ± 0 . 1 5
0 . 24 ± 0 . 1 6
-0 . 2 4 ± 0 . 1 6
-
0 . 19 ± 0 . 3 1
-0 . 1 9 ± 0 . 3 1
1 5 . 14 ± 0 . 16
2 . 73
15 . 59 ± 0 . 15
2 . 56
-
Year
-
-
Bir th- rank
Gene ral mean
S t andard devia t ion
TCN
( un i t )
S i re group 4
1 9 7 3/ 1974
-
0 . 0 4 ± 0 . 04
-0 . 04 ± 0 . 0 4
S to ckin g rate
Year
B i r t h-rank
Gener a l mean
S t andard devia t ion
-
1 8 . 74
+ 0 . 29
2 . 75
,__..
N
1..0
1 30 .
On the pub l i shed evid en c e ( Rob e r t s and Dun lo p , 1 9 5 7 ) CPC is l i t t l e , i f
at a l l , a f f e c t ed b y nu t r i t ion .
Be tween y e a r d i f f erences we r e the maj o r source o f var i a t ion and
a c coun t e d f or 4 4 . 2 % .
Th i s could r e s u l t f r om the d i f feren c e s in c l ima t i c
con d i t ions such as rain f a l l i n part i cul ar during t h e years , ina c cu r a c i e s
o f measureme n t s a n d t e chnician var i a t ion .
Wickham and B i gham ( 1 9 7 3 )
sugge s t ed that t h e s t ap le crimp can b e a f f e c t ed by d isor ien t a t ion o f
c r imp-waves o f ind ividua l f ib r e s wh i c h r e s u l t s f rom sev eral env ironmen t a l
cond i t ions such a s we athering and b rushing o f t h e f l eece again s t obj e c t s .
None o f t h e i n t e r a c t ions was s i gn i f i c ant s ources o f v a r i a t ion in
the pooled analys i s o f var ianc e .
s ire
x
However , s i r e
x
s t o cking r a t e and
year int e r a c t ions cont r ib u t ed 3 . 2 and 2 . 7 % of the t o t al observed
var iat ion r e s p e c t ively in S i re group 2 p e riod .
Dunlop ( 1 9 6 2 ) f ound t h e
i n t e r a c t ions b e t ween s t r a ins and l o c a t ions though s i gn i f i cant o n
o cc a s ions , a c counted for a ne g l i g ib le f r a c t ion o f the v a r i a t ion .
S t ra in
x
x
y e a r s and l oc a t ion
s i gnif icant .
y e ar i n t e r a c t ions were rep o r t ed a s non-
Non- s ignif i cant geno t yp e
x
p l ane o f nu t r i t ion i n t e r a c t ions
we re repo r t e d for t he t rai t by Mo r l ey ( 1 9 5 6 ) .
T o t a l c r imp numb e r
TCN w a s no t a f f e c t ed by the s t ock ing int ens i t y in a l l t h e t h r e e
S ir e group p e r iods analysed .
Swar t and Ko t z e ( 1 9 3 7 ) sugge s t ed that
t o t al numb e r of c r imp s in the f ib r e s of a lock was no t con s t an t , a l t hough
there was a c o r r e l a t ion o f +0 . 9 b e tween c r imp s i z e and f i b r e length
ind i c a t ing that the t o t a l numb e r of c r imp s i s independent of fibre
lengt h .
)
13 1 .
The maj o r and only impor t ant s o u r c e o f var iat ion in the t r a i t was
I t explained 3 8 . 2%
the year e f f e c t .
of
the t o t a l observed var iat ion
in the p o o l e d var i an c e componen t s ana lys i s .
As in CPC t h i s cou l d have
resul t ed f rom the various environmen t al s ources of var i a t ion wh ich make
up t he y e a r ly environment in add i t ion to t he var i a t ions due t o the
t e chn i c i an and ina c curacies o f measuremen t s .
S i r e x s t ock ing r a t e were t h e only s i gn i f i c an t in t e r a c t ions ( P< O . O S )
and con t r ibu t ed s l i gh t ly l e s s t h a n 2 % t o the t o t a l ob s e rved var i at ion .
Howev e r , i t con t r ib u t ed 5 . 9 % o f t he t o t a l var iat ion , though s t a t i s t i c a l l y
non- s i gni f icant i n the Sire gr oup 4 per iod when t h e d e g r e e s o f f r e edom
we r e l ow .
Th i s could be due to
the change o f r anking o f s i r e s in the
two s to ck ing r a t e s .
Cha ra c t e r gr ade
CHG is an a s s e s smen t based on s t ap le c r imp c l ar i t y and evenn e s s ,
s t a p l e f orma t io n , b l o ckine s s o f the s t aple t i p and f r eedom f rom
med u l l a t ion (Wickham and B i gham , 1 9 7 3 ) .
CHG was l owe r in HSR sheep .
Re sul t s obt a ined f rom t h e s tudy we r e
i n g e n e r a l agr eemen t with Bub l a t h ( 1 9 6 9 ) , Lan gland s and B enne t t ( 1 9 7 3 )
and Joyce e t a l .
( 1976) .
Increased s t o c k ing leve l s w i l l lead t o a
p o o r e r charac t e r , p ar t l y as a resul t o f woo l b e coming mor e t ippy
( Sumn e r , 1 9 6 9 ) .
The b e tween s t ocking r a t e s e f f e c t was h i ghly
s i gn i f i can t and exp lained 3 . 7 % (P < 0 . 0 1 ) of the t o t a l var i a t ion in t h e
p o o l e d var iance compon ent s analy s i s .
p oi n t e d ou t that CHG s e ems t o become
Ryd e r and SHephen s on ( 1 9 6 8 )
wo rse only a f t er p r o longed and
s evere nut r i t ional s t r e s s , a l though CHG i s b ad ly a f f e c t e d by copper
d e f i c i ency .
TABLE 1 1 :
Leas t squares e s t ima t e s and s t andard errors of environmental e f f e c t s for CHG and TG
S i re group 1
1967/ 1968
Tra i t
Fac t o r
CHG
( grade )
S t ocking r a t e
S ir e group 2
1969/ 1970
S i re group 3
197 1/ 1972
S i re group 4
1973/ 1974
CSR
HSR
0 . 02 ± 0 . 06
-0 . 0 2 ± 0 . 0 6
0 . 2 7 ± 0 . 07
-0 . 2 7 ± 0 . 07
- 0 . 0 9 ± 0 . 06
0 . 09 ± 0 . 06
0 . 27 ± 0 . 07
-0 . 27 ± 0 . 07
1
2
0 . 66 ± 0 . 06
-0 . 6 6 ± 0 . 0 6
0 . 59 ± 0 . 06
-0 . 5 9 ± 0 . 06
0 . 05 ± 0 . 0 6
-0 . 0 5 ± 0 . 0 6
-0 . 1 1 ± 0 . 07
0 . 1 1 ± 0 . 07
S ingle
Twin
0 . 05 ± 0 . 06
- 0 . 05 ± 0 . 0 6
0 . 20 ± 0 . 07
-0 . 20 ± 0 . 07
0 . 08 ± 0 . 07
-0 . 08 ± 0 . 07
-0 . 0 8 ± 0 . 1 0
0 . 08 ± 0 . 1 0
4 . 95 ± 0 . 05
1 . 03
5 . 22 ± 0 . 06
1 . 09
5 . 49 ± 0 . 06
0 . 83
5 . 69 ± 0 . 09
0 . 90
CSR
HSR
0 . 03 ± 0 . 07
-0 . 0 3 ± 0 . 0 7
- 0 . 08 ± 0 . 0 5
0 . 08 ± 0 . 05
-0. 2 1 ± 0 . 07
0 . 2 1 ± 0 . 07
-0 . 03 ± 0 . 06
0 . 03 ± 0 . 06
1
2
0. 15 ± 0 . 07
-0 . 15 ± 0 . 07
- 0 . 09 ± 0 . 05
0 . 09 ± 0 . 05
0 . 1 5 ± 0 . 07
-0 . 1 5 ± 0 . 0 7
-0 . 25 ± 0 . 06
0 . 25 ± 0 . 06
S ingle
Twin
0 . 09 ± 0 . 06
-0 . 09 ± 0 . 06
-0 . 0 1 ± 0 . 05
0 . 0 1 ± 0 . 05
0 . 00 3 ± 0 . 0 9 6
-0. 003 ± 0 . 096
0 . 1 2 ± 0 . 08
-0 . 1 2 ± 0 . 0 8
6 . 88 ± 0 . 06
1 . 14
6 . 4 3 ± 0 . 04
0.81
Year
B i r th-rank
Gener a l mean
S tandard dev ia t ion
TG
( grade )
S t ockin g r a t e
Year
B i r th-rank
Gene ral mean
S t andard devia t ion
5 . 38 ± 0 . 0 8
1 . 06
5 . 1 8 ± 0 . 08
0 . 75
,.....
w
N
1 33 .
Be tween years d i f f e r e n c e s were
f o r the maj o r f r a c t ion , i . e . , 2 8 . 9 %
varian c e c omp one n t s
a na l y s i s
h i gh l y
of
s i gn i f i cant an d a c c oun t e d
t h e t o t a l var iat ion in the po o l e d
for t h e t r a i t .
Chapman ( 1 9 6 4 ) a s s o c i a t e d
d o g g i n e s s in woo l with i n c r e a s ing r a i n f a l l .
A s '\vo o l ch ara c t e r " may h ave d i f f e r ent mean i n g to d i f f e rent
ob s e rve r s , va r i a t i ons be tween obse rve rs may c o n t r ibute t o year to
year
var i a t i on in t h i s trai t .
Twi n-b o r n hogge t s in general had lower CHG than the s in g l e - h o r ns .
S im i l a r o b s erva t i ons on CHG due to b i r t h- rank were re c o r d e d by E l l i o t t
( 1 9 7 5 ) in t h e P e r endale h o g ge t s .
None o f the in t e ra c t i o ns analy s e d were s i gn i f i c a n t a n d they
c on t r i bu ted o n l y a ne g l i g i b l e frac t i on of the variat i o n t o t h e t o t a l
var ia t ion in the pooled vari ance c omp onen t s
analys i s .
S i re x s t o c k ing ra t e i n t e r a c t i ons though non- s i gn i f i c a n t con t r i b u t e d
4 % t o t h e t o t al va r iat i o n in t h e
S i re
g roup 3 p e r iod .
Dun l o p ( l % 2 )
re c o rded s i gn i f i c ant s t a t i on x s t ra i n i n t e r ac t i o n s ( P < O . O S ) o f mod 0 r a t e
s i ze for t he t r a i t .
S i r e x year i n t e r a c t ions th ough n o n- s i gn i f i c an t e xp l a i ned 1 . 9 a n d
2 . 2 % i n the S i re group 3 and 4 p e r i o d s re s p e c t ively .
Rae ( 1 9 5 8 )
r e corded s ign i f i c ant s i re x year i n t e r a c t i o n s ( P < O . O l ) f o r CHG i n a
f l o c k o f New Zea land Romney sh e ep .
He
s u g ge s t ed tha t th i s could b e d u e
t o the genu i n e non- l inear i n t e ra c t i o n s be twe e n t h e s i re geno t ype and
envi ronmen t a l cond i t i ons p e c u l i a r to e a ch· year or th e d i f f e r e n c e s
b e tween dams and s i re
x
dam in t e ra c t i ons .
o f t h e subj e c t ive a s s e s sment .
I t could a l s o be an art e f a c t
S t ra i n x years inte rac t ions , howeve r ,
were found non- s igni f i c a n t in a s t udy by Dun lop ( 1 9 6 2 ) .
1 34 .
T ippin e s s gr ade
TG is subj e c t ive ly as s e s s e d w i th wool hav ing a ra t h e r p o i n t e d ' t i p '
p ro t rud ing beyond the bulk o f s t ap l e b e ing graded low and woo l wi th
' s quare t ipped ' s t ap l e s ge t t i n g h i gh grades .
Hende rson ( 1 9 6 8 ) at t r i b u t e d t h i s t ra i t t o two ma in f a c t o r s
(1)
h i gh va r iab i l i ty of f i b r e l e n g t h s and d i ame t e r
(2)
wide d i f ferences
i n f i b r e diame t e r b e tween the t ip a n d bu t t o f the s t ap l e .
A thin and
' w i s p y ' t i p in t he Merino can b e caus ed b y poor n11 t r i t i on a t the
t i me
of
she a r in g , whe r e a s t i p p i n e s s in Bri t i s h breeds i s due t o mo re rap id
growth o f the coarser f ib r e s ( Ryder and S t ephenson ,
1968) .
Wh en i t
is
p re s e n t t h i s f aul t b e come s mo r e e v i d e n t in she ep w i th r e l a t ively l ow
f i b r e numb e r and l i t t l e yo l k .
The l e a s t s q uare s e s t ima t e s pre s e n t e d i n Tab l e 1 1 sugge s t t ha t
i s b e t t e r in the HSR group of sheep .
TG
Howeve r , the b e twe en s t o c k i n g r a t e
e f f e c t though s i gn i f ican t ( P <O . O S ) c o n t r ibu ted on ly a negl i g i b l e f ra c t ion
o f t h e var i a t ion i n the p o o l e d va r i a n c e c omp o n e n t s an alys i s .
The be tween year e f f e c t was found h i ghly s i gn i f i cant ( P < O . O l ) and
con t r ibut e d 4 % t o the va r i a t i on in the pooled var ian c e component s an aly s i s .
' Ye a r ' d i f f e r e n c e s could a r i s e f rom d i f f erences in the c l ima t i c c o n d i t i o n s ,
e s p e c i ally r a in f a l l , as T G may b e a f f e c t ed by we t t in g and d ry ing o f the
s t ap l e .
S in c e this t r a i t i s sub j e c t ively graded , va r i a t ions in s c o r i n g
b y d i f fe rent ob s e rve r s could a l s o cont ribu t e t o t h e var iat ion d u e t o t h i s
s ourc e .
Non e o f the interact ions con t r i buted t o the t o t al ob s e rved va r i a t ion
in the p o o l e d var iance comp on e n t s analys i s .
s ir e
x
S i re x s t o cking r a t e and
year i n t e ract ion s tho ugh found non- s i gn i f i ca n t con t r ibuted ove r
3 % i n t he S ir e group 2 p e r i o d .
S t ocking ra t e
x
year in t e ra c t i o n s were
1 35 .
howeve r , un impor t an t a s a s o u r c e
of
va r i a t i o n
i n a l l the S ire
group
p e r iods analysed .
Ha n d l e gra d e
T h e s t o cking
rate
e f fect s
o n hand l e
There wa s a tend ency fo r
s igni f i c a n t .
g ra d e
were
sma l l a n d non-
H S R woo ls t o be s o f t e r
the
h a nd l ing .
B e tween ye a r
e f fe c t s
we r e h i gh l y s i gn i f i c a n t and e xp l ained 1 9 . 1 %
t h e maj o r cau s e s o f
harshnes s ,
d i f f e r en c e s i n t h e yea r ly envi r onme n t s
b e c a u s e o f c l ima t i c c o n d i t i on s may h a ve c on t r i b u t e d t o t h i s
f a c t o r s such a s va r i a t i o n s i n
o f va r ia t ion .
Other
s c o r i n g and t h e
s u b j e c t i ve
con t r ib u t e d to t h e
' year '
of
S i n c e wea t h e r in g i s o n e
o f t he var i a t i o n in t h e pooled An a l y s i s .
a s s e s sme n t o f t h e
t ra i t
the
m i gh t
source
of
s t an d a r d s
have
a l so
e f fe c t s .
S in g l e-born h o gge t s d i s p l a yed re l a t ive l y h i gh e r HG t h an t h e
twin-b a rns .
Th is e f f e c t
wa s
h i gh ly s i gn i f i c a n t
and
2. 1%
e xp l a i n e d
in
t h e p o o l ed va r i an c e c omp onen t s a n a l y s i s .
S i re
x
s t o ckin g
rate
i n t e ra c t i o n s were
con t r ibu t e d only 0 . 6 % in t he p o o l e d
Dun lop ( 1 9 6 2 ) a l s o
reported
s t ra i n
n o t s ign i f i c a n t a n d
c omponen t s a n a l y s i s .
var i an c e
x
l o c a t i o n s intera c t i on s ( N S )
were
a
n e g l i g i b l e source o f vari a t i on s f o r the t ra i t .
S i re x year in t e r a c t ions we re found s i gn i f i c a n t ( P < O . O S )
exp l a ined 2 . 9 % o f t h e t o t al variat ion i n
a nalys i s .
t h e p ool e d
Highly s i gn i f i can t int era c t i o n s
g roup 3 p e r i o d .
were
I t c o n t ribu t ed 1 1 . 7 % o f t h e
real o r an a r t e f a c t o f the g r a d i n g s y s t em .
and
va rian c e c omp o n e n t s
ob s e rved in t h e S i re
va r i a t i o n .
Th i s c o u l d be
TABLE 1 2 :
Le a s t squares e s t ima t e s and s t andard errors o f environmental e f f e c t s f o r HG and LG
S i r e group 1
1967 / 1968
Tra i t
Fac t o r
HG
( grade )
S t ocking rate
S i re group 2
1 9 69 / 1 9 7 0
S i re group 3
197 1 / 1972
S ir e group 4
1973/ 1974
CSR
HSR
-0 . 1 0 ± 0 . 0 5
0 . 10 ± 0 . 05
-0 . 0 3 ± 0 . 04
0 . 03 ± 0 . 04
0 . 03 ± 0 . 06
-0 . 0 3 ± 0 . 0 6
-0 . 1 1 ± 0 . 06
0 . 1 1 ± 0 . 06
1
2
-0 . 3 7 ± 0 . 0 5
0 . 37 ± 0 . 05
- 0 . 39 ± 0 . 04
0 . 3 9 ± 0 . 04
0 . 1 5 ± 0 . 05
-0 . 1 5 ± 0 . 05
-0 . 08 ± 0 . 05
0 . 08 ± 0 . 05
S ingle
Twin
0 . 07 ± 0 . 05
-0 . 07 ± 0 . 05
0 . 15 ± 0 . 05
-0 . 1 5 ± 0 . 05
0 . 10 ± 0 . 07
-0 . 10 ± 0 . 0 7
0 . 1 5 ± 0 . 07
-0 . 1 5 ± 0 . 0 7
6 . 50 ± 0 . 05
0 . 92
6 . 2 8 ± 0 . 04
0 . 73
5 . 83 ± 0 . 06
0 . 80
6 . 13 ± 0 . 07
0 . 67
CSR
HSR
0 . 08 ± 0 . 06
-0 . 08 ± 0 . 0 6
- 0 . 1 2 ± 0 . 04
0 . 1 2 ± 0 . 04
0 . 04 ± 0 . 04
- 0 . 0 4 ± 0 . 04
-0 . 0 3 ± 0 . 0 6
0 . 03 ± 0 . 06
1
2
-0 . 4 6 ± 0 . 0 5
0 . 46 ± 0 . 05
0 . 29 ± 0 . 04
- 0 . 2 9 ± 0 . 04
0 . 002 ± 0 . 0 4
-0 . 002 ± 0 . 04
0 . 1 0 ± 0 . 06
- 0 . 10 ± 0 . 06
S ingle
Twin
-0 . 0 2 ± 0 . 0 5
0 . 02 ± 0 . 05
0 . 1 1 ± 0 . 04
-0 . 1 1 ± 0 . 04
0 . 06 ± 0 . 06
-0 . 0 6 ± 0 . 0 6
- 0 . 1 6 ± 0 . 08
0 . 1 6 ± 0 . 08
5 . 68 ± 0 . 06
0.91
5 . 93 ± 0 . 03
0 . 62
5 . 5 3 ± 0 . 05
0 . 63
5 . 08 ± 0 . 08
0 . 76
Year
Bir th- rank
General mean
S tandard devia t ion
LG
( grade )
S t oc king ra t e
Year
B i r th- rank
General mean
S t andard dev i a t ion
�
w
(j\
1 37 .
S to ck ing r a t e
I
x
year i n t e r a c t ions we re non- s i gn i f i cant and
con t r i b u t e d very l i t t l e o f the va r iat ion .
Lus t re grade
LG was sub j e c t ively graded w i thout r e f e rence to f inene s s .
H i gh
The ove r a l l ave rages o f LG o f hogget wo o l
grades were very l u s t rous .
f o r e a ch S i re group pe riod ana l y s e d are presented i n Tab l e 1 2 .
The
leas t s quares cons t an t s for d i f f e rent sub c l a s s e s o f the main e f fe c t s are
l i s t e d in Tab l e 1 2 .
The s tocking r a t e e f f e c t t h o u gh s i gn i f i c an t ( P < O . O S ) con t r ibuted
only 0 . 8% , a negl i g ib l e f r a c t ion o f the to t a l var i a t ion i n the pooled
var i anc e c omponen t s analy s i s .
Th e s i gn i f i canc e o f s t o cking r a t e
appears l a rgely a n a r t e f ac t o f t h e me thod o f s t a t i s t i c a l analy s i s s i n c e
t h e r ankin g o f the two s t ocking r a tes w a s non- cons i s t en t .
An analy s i s
o f var iance with a l l years included as a c ro s s - c l as s i f i c a t ion woul d
probab l y r e s u l t i n mo s t of the var iance being a s c r ibed t o the s t o cking
rate
x
year interac t i ons .
The b i rth rank e f f e c t was only 1 % ( NS ) o f
t he t o t a l var ia t i on .
The y ear e f fe c t was the maj o r source of vari a t ion and a c coun t ed for
2 1 . 3 % o f t he total va riat ion in the p o o l e d var iance compone n t s an a ly s i s .
Var iat i on s in the s t andards o f s c o ring by d i f f e rent observers i s p robably
the maj o r cause of this .
S ir e
x
s to ckin g rate an d s i r e
x
year in t e ra c t ions we r e non - s i gni f i ca n t
in the p o o led var iance comp onen t s analy s i s .
Howeve r , in S i r e group 4
period , i t was f ound t o be h i gh ly s igni f i cant and con t r ib u t ed 7 % o f the
observ e d vari a t ion .
Th i s r e s p o n s e could be due t o genuine non- l inear
in t e ra c t ions b e tween the s i re geno type and s t o cking leve l .
S i re
x
year
1 38 .
interac t ions were howeve r , unimp o r t an t in a l l the f our S ire group p e r i o d s
ana ly s e d .
S t o c k in g rate x year intera c t ions exp l a ined 3 . 2 % o f t h e t o t al
variat i o n and was obs erved t o be h i ghly s igni f i c an t in the pooled
var ian c e component s analys i s .
However , t he app arent imp o r tan c e o f
these i nt er a c t ions may b e large ly a n a r t e f a c t o f the grading sys t em
a s so c i at ed wi th the d i f f icul t y o f ma inta ining cons i s t en t s t andard s .
Greasy co lour grade
GCG was bet t er in the HSR wool in all the Sire group p e r i o d s
analy s ed .
The response o f GCG t o s t o cking r a t e was in a c cord wi t h the
f ind ings by Bublath ( 1 9 6 9 ) ,
and Joy c e e t al .
( 1976) .
Sumner ( 1 9 6 9 ) , Lan g l ands and Bennett ( 1 9 7 3 ) ,
Th i s may have been due to f ewer p i gmen t s
s e c r e t e d b y skin glands (Ryder and S t ephenson ,
1968) .
The d i f f e ren ce
be tween s t o cking rates exp la ined about 1 2 . 4 % ( P < 0 . 0 1 ) of the variat ion in
t he p o o led var ian ce c ompone n t s analys is .
The year e f f e c t was h i ghly s i gni f i cant and was the maj o r s ource o f
var i a t i o n a c co un t ing f o r 28 . 2 % o f t he varia t i on i n t h e p o o led v a r i an c e
component s ana ly s i s .
Var iat ions in c l imat i c cond i t ions are imp o r t a n t
in caus i ng year t o y e a r d i f f erenc e s i n woo l co lour .
The causes o f
d i s c o loura t ion are comp lex but i t appears that prolonged wet t in g ,
p ar t ic ul ar ly in the warm condi t ions , t ends to be a s s o c i a t e d w i t h h i gh
leve l s o f d is co l ourat ion .
Problems o f s ubj e c t ive a s s e s sment may a l s o
cont ribute t o t h i s s ource o f v ar i a t i on .
S ire x s t o c king rate i n t e r a c t ions a c coun t ed f o r 1 . 4 % ( P < 0 . 0 5 ) o f
the t o t al var iat ion i n the p o o l e d var iance componen t s ana ly s i s .
TABLE 1 3 :
Leas t squar e s e s t ima t e s and s t andard errors o f environment a l e f f e c t s for GC G and SCG
S ire group 1
1967/ 1968
Tra i t
Fac t o r
GCG
( gr ade )
S tocking rate
S ire group 2
1969/ 1970
S ir e group 3
197 1 / 1972
S ir e group 4
1973/ 1974
CSR
HSR
-0 . 33 ± 0 . 05
0 . 3 3 ± 0 . 05
-0 . 23 ± 0 . 03
0 . 23 ± 0 . 03
-0 . 07 ± 0 . 03
0 . 07 ± 0 . 0 3
- 0 . 0 1 ± 0 . 04
0 . 0 1 ± 0 . 04
1
2
0 . 55 ± 0 . 05
- 0 . 5 5 ± 0 . 05
-0 . 02 ± 0 . 03
0 . 02 ± 0 . 03
-0 . 2 5 ± 0 . 0 3
0 . 25 ± 0 . 03
-0 . 2 2 ± 0 . 05
0 . 22 ± 0 . 05
S ingle
Twin
0 . 05 ± 0 . 05
-0 . 05 ± 0 . 05
0 . 03 ± 0 . 03
-0 . 03 ± 0 . 03
- 0 . 0 1 ± 0 . 04
0 . 0 1 ± 0 . 04
0 . 05 ± 0 . 06
-0 . 0 5 ± 0 . 0 6
6 . 5 6 ± 0 . 05
0 . 88
6 . 35 ± 0 . 03
0 . 53
6 . 15 ± 0 . 03
0 . 46
6 . 37 ± 0 . 06
0 . 53
CSR
HSR
-0 . 1 7 ± 0 . 0 4
0 . 17 ± 0 . 04
-0 . 1 1 ± 0 . 04
0 . 1 1 ± 0 . 04
- 0 . 1 9 ± 0 . 04
0 . 1 9 ± 0 . 04
0 . 02 ± 0 . 08
-0 . 02 ± 0 . 08
1
2
-0 . 2 5 ± 0 . 04
0 . 25 ± 0 . 04
0 . 0 6 ± 0 . 04
- 0 . 0 6 ± 0 . 04
- 0 . 1 1 ± 0 . 04
0 . 1 1 ± 0 . 04
-0 . 2 1 ± 0 . 0 7
0 . 2 1 ± 0 . 07
S ingle
Twin
- 0 . 06 ± 0 . 0 4
0 . 06 ± 0 . 04
- 0 . 0 4 ± 0 . 04
0 . 04 ± 0 . 04
0 . 06 ± 0 . 0 5
-0 . 06 ± 0 . 05
-0 . 01 ± 0 . 10
0 . 01 ± 0 . 10
6 . 2 1 ± 0 . 04
0 . 70
6 . 38 ± 0 . 0 3
0 . 65
6 . 1 3 ± 0 . 04
0 . 56
5 . 62 ± 0 . 10
0 . 94
Year
B i r t h- rank
Gene r a l mean
S t andard deviat ion
SCG
( grade )
S tocking rate
Year
B i rth-rank
General mean
S tandard devi a t i on
,_.
w
\.0
140 .
S ignif i c an t d i f f erences ( P < 0 . 0 1 ) in GCG due to the s e i n t e r a c t ions were
ob s e rved i n S ir e g r oup 1 per iod whe re in i t con t r ib uted 2 . 8% o f the
ob s e rved var i at i o n .
Dun lop ( 1 9 6 2 ) rep o r t ed s ign i f ican t s t rain x
s t a t i on interac t io n s , though the ave rage s i z e o f the i n t e r a c t i o ns t e rm
was sma l l .
S ir e x year inte rac t ions contribu t e d only a l i t t l e ove r 1 % o f the
variat ion and we r e non- s i gn if i c ant .
S imilar resu l t s o f s t r a i n x year
i n t erac t ions in the trait we re repor t ed by Dunlop ( 1 9 6 2 ) .
I t was
howeve r , s i gn i f ic an t in three of the f our S ir e group p e r iods analy sed
and exp lained s l i gh t ly over 2 % of the var i at ion in each analys i s .
S t o cking r a t e x year interact ions we r e unimpo rtan t as a s ou r c e o f
var i a t ion .
S coured co l ou r grade
S CG o f wo o l was subj e c t ively a s s e s s e d f o l l owing s cour in g , u s ing the
s ame s t andards a s for GCG of woo l .
H S R woo l a s c omp ared to CSR woo l .
Sumner ( 1 9 6 9 ) .
L ike GCG o f woo l , S C G wa s h i gher in
The s e resul t s are i n agr eement w i t h
S t o cking rate a c coun t ed for 5 . 6 % (P<0 . 0 1 ) o f the t o t a l
var iat ion in t he pooled analy s i s .
The year e f f ect though h i gh l y
s i gn i f icant a n d a maj or sour c e o f va r i a t i on was comparat ive l y l e s s
imp o r t an t than i n GCG .
Int e r a c t ions in general were imp o r t an t sources o f var i a t ion and
c o n t r ibuted ab out 10% of the t o t a l v a r i a t ion .
S ire x year int e r a c t ions
were observed to b e s ign i f i c an t ( P < O . O S ) an d contr ibuted 2 . 7 % i n the
p o o l ed var i anc e component s analy s i s .
The extent o f the r e s p o n s e c l e a r l y
d i f f ered b e tween S ir e group p er iods , t h e great e s t var i a t i o n d u e t o s i r e
x
14 1 .
year i n t e rac t ions being in S i re group 3 p e r iod when i t con t r ibuted 6 %
o f t he varia t i on .
As a cause o f variab i l i t y S ir e x s t o ck i ng r a t e
i n t e r a c t ions were l e s s imp o r t ant than t h e s i re x year in t er a c t ions and
a c coun ted for a l i t t le ove r 1% of the ob s e rved var i a t ion in the p o o l e d
ana ly s is .
I t was f ound e q ua l ly unimp o r t an t as a source o f va r i ab i l i ty
i n t h e S i re group p e r i o d s analysed ind ividual ly and shows a good
r e s emb lance t o those e s t ima t e d in the GCG .
S t ock ing r a t e x year
i n t e r a c t ions were highly s i gn i f i c an t and exp l a ined 6 . 1 % of the t o t a l
ob s e rved var iat ion i n the pooled an aly s i s .
D i s c o loured area grade
DAG was a s s e s s ed a t the t ime of shearing ma inly on the bas i s of how
f a r the d is co lourat ion ext ended over the wh o l e f l e e ce w i t h ac count t aken
o f the seve r i t y of d i s c o lourat ion .
The ove r a l l averages o f DAG o f
f le e c e for each S i re group p e r i o d anal ysed are pre sent ed i n Tab l e 1 4 .
DAG was b e t t e r in t h e C S R f leec e s , a f i nding s imilar t o that o f Sumner
( 1969) .
W i c kham and B i gh am ( 1 9 7 3 ) sugge s t ed that t he very h i gh s t o c k in g
r a t e appears t o result i n increased d i s c o l ourat ion pe rha p s as a r e s u l t o f
inc reased d i r t con t amina t i on o r s lowe r drying o f more c o t ted woo l .
D i f feren c e s due to s t o ck ing rate in the t r a i t we r e found t o be h i gh ly
s i gn i f i cant and accoun t ed f o r 5 . 6 % o f the t o t al ob served va r i a t ion in the
p o o led var iance componen t s an a lys i s .
The year e f f e c t was f ound t o b e
non-s i gni f i cant and cont r ib u t e d a sma l l f ra c t ion t o t h e t o t a l var i ab i l i t y
i n t h e pooled analy s i s .
Bo th s ire x s t ock ing r a t e and s ir e x year i n t e r a c t ions were f ound t o
b e non- s i gn i f i c ant and d id no t c on t r ib u t e t o the t o t a l var i a t ion
in DAG .
Howeve r , in S i re group 4 p e r i o d , s ir e x s t o c king r a t e and s i r e x year
TABLE 1 4 :
Le a s t squares e s t imat e s and s t andard errors o f environment a l e f f e c t s for DAG and CG
S i re group 1
1967/ 1968
Tra i t
Fac t o r
DAG
( grade)
S tocking rate
S ire group 2
1969/ 1970
S ire group 3
197 1 / 1972
CSR
HSR
-
-
0 . 09 ± 0 . 04
-0 . 09 ± 0 . 04
0 . 1 5 ± 0 . 05
-0. 1 5 ± 0 . 05
1
2
-
-
-0 . 05 ± 0 . 04
0 . 0 5 ± 0 . 04
0 . 06 ± 0 . 05
-0 . 0 6 ± 0 . 0 5
-
-0 . 0 6 ± 0 . 0 5
0 . 06 ± 0 . 05
0 . 04 ± 0 . 0 7
-0 . 04 ± 0 . 0 7
-
6 . 3 1 ± 0 . 04
0 . 57
5 . 28 ± 0 . 07
0. 63
Year
B i rth- rank
S ingle
Twin
Gene ral mean
S t andard deviat ion
CG
( grade)
S ire group 4
1973/ 1974
-
-
-
S t ocking ra t e
CSR
HSR
-0 . 0 6 ± 0 . 0 4
0 . 0 6 ± 0 . 04
0 . 10 ± 0 . 02
- 0 . 10 ± 0 . 02
-0 . 08 ± 0 . 0 3
0 . 08 ± 0 . 03
0 . 1 1 ± 0 . 05
-0 . 1 1 ± 0 . 05
1
2
0 . 1 9 ± 0 . 04
-0 . 1 9 ± 0 . 0 4
-0 . 0 8 ± 0 . 0 2
0 . 08 ± 0 . 02
0 . 004 ± 0 . 0 3
-0 . 004 ± 0 . 0 3
-0. 1 1 ± 0 . 05
0 . 1 1 ± 0 . 05
S ingle
Twin
0 . 06 ± 0 . 03
-0 . 0 6 ± 0 . 0 3
0 . 04 ± 0 . 03
-0 . 04 ± 0 . 03
0 . 0 3 ± 0 . 04
-0 . 0 3 ± 0 . 04
-0 . 04 ± 0 . 0 7
0 . 04 ± 0 . 0 7
6 . 88 ± 0 . 0 3
0. 63
6 . 89 ± 0 . 02
0 . 40
6 . 02 ± 0 . 0 3
0.41
6 . 5 7 ± 0 . 06
0 . 59
Year
B i r t h- rank
Gene ral mean
S t andard deviat ion
.......
.,...
N
143 .
in t e r a c t ions con t r ibuted 3 . 3 % ( N S ) and 1 . 4 % (NS ) o f the t o t a l ob s e rved
var i a t ion re s p e c t ively .
s t oc k i n g rate
x
As a c ause o f var i ab i l i ty in the t ra i t ,
y ear int erac t ions we r e a maj o r f a c t o r .
C o t t ing grade
W i c kham and B i gham ( 1 9 7 3 ) a t t ribu t ed the co t t ing of the f leece ma inly
t o two even t s :
shedd ing of f in e f ib re s ;
the migra t ion of t h e she d f ib r e s
We tne s s and d ry ing o f t he
t o e n t an gle w i t h o ther f ib r e s in the f l eece .
f l e e c e may aid the p roce s s .
C o t t in g is s e ldom s evere in ho gge t f l e e c e s .
D i f ference s in CG b e tween s t o cking r a t e s were h i ghly s i gn i f i c an t
( P <0 . 0 1 , 3 . 7 % o f the var i a t i o n ) b u t incons i s t ent i n rankin g .
Bub l a t h
( 1 9 6 9 ) , Sumner and Wickham , ( 1 9 6 9 ) and Langlan d s and B enne t t ( 1 9 7 3 )
repo r t ed that C G increased w i th the s t ocking ra t e .
Joyce ( 1 9 6 1 ) ob s e rve d
tha t t h e low p l an e nut r i t ion mo re t han doub led the inc i d en c e o f CG .
The ' ye ar ' e f fe c t was h i ghly s i gn i f i cant and was the maj o r s ou r c e o f
var i a t i on i n t he poo led an a lys i s .
The c l ima t i c d i f f e ren c e s b e tween t h e
y e a r s , espec ially the rai n f a l l , c o u l d be a maj o r f a c t o r in t h i s s ource o f
var i a t i on .
Joyce ( 1 9 6 1 ) found that the incidenc e o f CG was a f f e c t e d by
s e a s on , b reed , age , reproduc t ive p e r formanc e and nu t r i t ion .
As in o th e r
sub j ec t ively graded t r a i t s , t h e obse rver var i a t ion could a l s o con t r ib u t e t o
t he ' year ' e f f e c t in t h e t ra i t .
Both s ir e
x
s t ocking r a t e and s i re
x
year interact ions were non­
s ig n i f i can t and d id not c o n t r ibute to the t o t a l var i a t ion in the p o o l e d
analy s is .
Though non- s i g n i f ican t , the s ir e
x
s t ocking r a t e i n t e r a c t i o n s
were respons i b l e for 2 . 7 a n d 1 . 8 % o f var i a t ion in t h e S i r e group 2 and
3 p e r i od s r e s p e c t ively .
imp o r t anc e .
S ire
x
year int e rac t ions were no t o f any
144 .
S t o ckin g r a t e x year interact ions were s i gn i f i c an t in the pooled
an a l y s i s and t h i s was r e i n f o r c e d by the incon s i s t ency of the s t o cking
r a t e e f f e c t s b e tween p e r iod s .
I t was o f part icular imp o r t an c e in S i re
group 4 pe r i od wh ere i t cont ributed ove r 10% t o the t o t a l obs erved
var i a t i on .
Cot t ed area grade
CAG was s ubj e c t i vely a s se s s e d on the d e g r e e and extent o f
ent angleme n t o f the wo o l f ibres over the who le f l eece .
In a l l f l e e c e s
t he re i s s ome evidence o f entanglement o f wo ol f ib res b u t i t i s only when
i t is severe enough to c ause d i f f i c u l t y in d iv i d ing the f l ee c e that a
f l eece i s given the de sc r ip t ion " c o t t e d " o r " ma t t ed " (Henderson , 1 9 6 8 ) .
CAG was ge nerally more s evere in the HSR f l eec e s .
The s e resu l t s are in
a g reeme n t wi th Joy ce ( 1 9 6 1 ) , Sumner ( 1 9 6 9 ) and Langlan d s and Benne t t
( 1973) .
Sumner and Wickham ( 1 9 6 9 ) ob s e rved that inc r e a s e d s t ockin g r a t e
t ends t o r e s u l t in a grea t e r amp l i t ud e o f t h e s e ason a l rhy t hm o f woo l
growth and f ib re d iame t e r with the t rough
i n t h e year .
o f the rhy thm o c c u r r in g l a t e r
Th i s c an r e s u l t in inc reased co t t ing .
I t is b e l ieved
t hat poor f e e d in g or any other s t re s s wh ich i s l ike ly to r e i n f o r c e o r
p rolong the normal win t e r d e p r e s s ion w i l l c au s e she d d i n g o f mo r e f ib r e s
and may r e s u l t in more c o t t in g .
Co t t ing t en d s t o b e mo re severe o n t h e
r e gions having the gre a t e s t var iab i l i t y o f f ib r e d i ame t e r .
S t o c king r a t e wa s observe d to be s ign i f i cant ( P < 0 . 0 1 ) and
con t r ib u t e d 4 . 9 % to the t o t a l variat ion in the poo l e d analy s i s .
The ' year ' e f f e c t was h i gh ly s i gn i f i can t and exp l a ined 3 9 % , a very
h i gh p r op o r t ion of t h e total varia t ion in the pooled variance componen t s
analys i s .
C l ima t i c d i f ferenc e s and grading d i f f i c u l t i e s h ave probab ly
both con t r ibuted t o t h e e f f e c t .
TABLE 1 5 :
Leas t squares e s t ima t e s and s t andard errors of environmen tal e f fects for CAG and S G
S i r e group 1
1967/ 1968
Trai t
Fac t o r
CAG
( grade )
S t o cking r a t e
S ir e group 2
1 9 69 / 1 9 7 0
S ire group 3
197 1 / 1972
CSR
HSR
- 0 . 05 ± 0 . 0 4
0 . 05 ± 0 . 04
0 . 2 7 ± 0 . 04
-0 . 2 7 ± 0 . 0 4
0 . 04 ± 0 . 0 3
- 0 . 04 ± 0 . 0 3
0 . 04 ± 0 . 0 6
-0 . 04 ± 0 . 06
1
2
-0 . 5 0 ± 0 . 0 4
0 . 50 ± 0 . 04
-0 . 1 9 ± 0 . 0 4
0 . 1 9 ± 0 . 04
-0 . 0 9 ± 0 . 0 3
0 . 09 ± 0 . 03
0 . 59 ± 0 . 05
-0 . 5 9 ± 0 . 0 5
S ingle
Tw in
-0 . 0 3 ± 0 . 0 3
0 . 03 ± 0 . 03
-0 . 04 ± 0 . 0 5
0 . 04 ± 0 . 05
0 . 00 ± 0 . 04
0 . 00 ± 0 . 04
-0 . 0 5 ± 0 . 0 8
0 . 0 5 ± 0 . 08
± 0 . 04
0. 71
6 . 85 ± 0 . 03
0 . 44
6 . 11 ± 0 . 07
0 . 68
-
0 . 46 ± 0 . 07
-0 . 46 ± 0 . 07
-0 . 1 1 ± 0 . 0 9
0 . 1 1 ± 0 . 09
1 . 25 ± 0 . 10
-1 . 25 ± 0 . 10
-
0 . 63 ± 0 . 07
-0 . 6 3 ± 0 . 0 7
0 . 4 2 ± 0 . 09
-0 . 4 2 ± 0 . 0 9
-0 . 09 ± 0 . 0 9
0 . 09 ± 0 . 0 9
0 . 10 ± 0 . 08
-0 . 1 0 ± 0 . 0 8
0 . 09 ± 0 . 1 1
-0 . 09 ± 0 . 1 1
-0 . 0 7 ± 0 . 1 3
0 . 07 ± 0 . 1 3
6 . 3 1 ± 0 . 07
1 . 21
5 . 88 ± 0 . 10
1 . 27
5 . 49 ± 0 . 1 3
1 . 15
Year
B i r th- rank
Ge ne ral mean
S t andard devia t ion
SG
( grad e )
S ire group 4
1973/ 1974
6 . 6 2 ± 0 . 04
0. 61
6 . 72
S tocking rate
CSR
HSR
Year
1
2
B i r th- rank
S ingle
Twin
General mean
S t andard d evia t i on
-
-
-
,_.
+:'­
\.J1
146 .
None o f the i n t e r a c t ions was s ign i f i c an t in t h e pooled analys i s .
S ire x s t o cking rat e interac t i ons , though non- s i gn i f i c an t exp l ained 2 . 7 %
in the S ir e group 2 p e r iod .
n e g l i g ib l e impor t an c e .
In o t her p e r io d s i t was found t o b e o f
S t o c king r a t e x year interact ions we r e
s igni f i cant i n t he S i re group 1 p eriod whe r e i t exp lained 2 . 1 % only o f
t h e t o t a l observed var iat ion .
Soundne s s grade
S t o c king rat e wa s high ly s i gn i f icant and cont ribut ed 2 5 . 4 % of t h e
t o t a l variat ion i n the pooled analys i s .
Hender son ( 1 9 6 8 ) at t r ib u t ed the uns oundne s s in woo l t o t h e d e c r ea s e
in c ro s s- s e c t iona l area o f a r e g ion o f t h e f ib re s , shedd in g a n d the
f undament al s t ru c tural weakne s s o f the f ib r e s , - these e f f e c t s a c t ing
s ingly o r in c omb in a t ion .
Wickham ( 1 9 6 8 ) examined the var ious f a c t o r s caus ing t h e lack o f
s t r e n g t h in the f ibres and p o in t ed out that increas ing s t o cking-r a t e s can
r e s u l t i n t he h i gher leve l s o f uns oundne s s .
Other p o s s ib l e c aus e s are
s e a s on a l d i f f e r e n c e s in woo l growth r at e , p r e gnancy , l ac t a t ion , l ambing
and o t h e r s t r es s e s accentuat ing the f undamen t al seasonal e f f e c t .
B r own ( 1 9 7 1 ) sugge s t ed that sudden changes in feed s u ch as sudden
int r o du c t ion o f sheep t o an a l l hay o r a l l crop d i e t o r t h e sheep f rom
d ry f e e d to lush g r een f e e d could a l s o be a f a c t or in t h e b r e ak o f woo l .
Analyses o f SG app r a i s a l s ind i c a t e that SG was gen e r a l l y lower in the
HSR f l eeces .
The s e resul t s are in c o n f o rmi t y with Bub l a t h ( 1 9 6 9 ) and
Lan g l and s and B enne t t ( 1 9 7 3 ) .
r e su lt s ;
Howeve r , Sumn e r ( 1 9 6 9 ) o b t ained var i a b l e
the hogget woo l in 1 9 6 7 was sounder in HSR whi l e in t h e ewe
f l e ec e s in 1 9 6 6 the HSR g roup had s ounde r woo l , the p o s it ion was rever s ed
in 1 9 6 7 .
147.
' Year ' e xp lained 1 2 . 8 % o f the t o t al ob s e rved var iat ion and was
found h i gh l y s ign i f ic an t .
Year t o year d i f ferences could b e due t o the
c l ima t i c cond i t ions such as r a in f a l l , paras i t ic i n f e c t ions , or any o t h e r
s t re s s e s c o n t r ib u t in g t o t h e fund amental s e asonal e f f e c t .
Var i a t ions
in the s t andards o f s c o r ing may a l s o have con t r ibuted to t h i s s ou r c e o f
var ia t i on .
Bo th s ire x s t o c king r a t e and s ire x year in t e rac t ions were non­
s i gni f i c an t , the e s t ima t e s are e x t reme ly sma l l and cause only a sma l l
f r a c t ion o f the var iance i n t h e analy s e s .
Dun lop ( 1 9 6 2 ) also r ep o r t e d
s t r a i n x locat ion and s t r ain x y e a r in t er a c t ions were no t s i gn i f icant
f o r soundne s s .
S t ocking r a t e x year int e r a c t ions cont ributed 1 7 . 5 % to the t o t a l
ob s e rved var i a t ion and were h i ghly s i gn i f i c ant i n t h e p ooled varian c e
compo nen t s analy s i s .
148 .
HERITABILITY E S T IMATES , INTRA-TRAIT GENET I C CORRELAT IONS AND
INTERACTION VARIANCE COMPONENT S
To this po int , the d is cu s s ion o f s i r e x s t o cking r a t e and s i r e x
y e a r int e ract ions has b e en l ar gely conf ined t o t he conc lus ions that
int e r a c t ions have or have no t b een d e t e c t e d .
The imp a c t o f t h e s e
i n t e r a c t i ons , with par t icul ar r e g a r d t o the s t ruc ture o f he r i t ab i l i ty
e s t imat es for various t ra i t s , needs further cons idera t ion .
The he r i t ab i l i ty e s t ima t e s o f the t ra i t s f o r the C S R , HSR and the
c omb ined data analyses f rom the poo led variance c omponent s an alys e s by
two d i f f e ren t me t hods are l i s t ed along w i t h their s t anda r d e rrors in
Tab l e 1 6 .
The two me t ho d s u s ed are NEI ( i n t e r a c t io n var i an c e
component s excluded in the numer a t o r o f the he r i t ab i l i t y exp r e s s ion ) and
N i l ( intera c t ion variance componen t s inc luded in the nume r a t o r o f the
he r i t ab i l i t y e xp r e s s ion ) .
The s i gn i f i c an c e o f d i f f e rences b e tween t h e
var ious he r i t ab i l i t y e s t imat e s w e r e a s s e s s ed by calculat ing the s t an d a r d
e r r o r o f the d i f f erence a n d examining t he change i n the e s t ima t e s i n
t e rms o f t h i s s t andard e r ro r .
Wh en compar ing the e s t imates o f her i t ab i l i t y in the p r e s e n t s t udy
w i t h the e s t ima t e s f r om o t h e r s t u d ies , it mus t b e r ememb e r e d t ha t the
b as i c mod e l a s s umed i s f re quent ly d i f f e r en t .
Mo s t es t imat e s o f
he r i t ab i l i t y a r e based on mo d e l s which l ea d t o e s t imat e s s imilar t o tho s e
o f N i l t y p e o f Tab l e 1 6 .
When int erac t ions are impor t an t sour c e s o f
v a r i anc e , sele c t ion resp onses cal cula t e d f rom thes e types o f e s t ima t e s
may wel l b e h i gher t han t he responses l ikely t o b e ach i eved i n p r ac t i c e .
The g en e t i c corre l a t ions o f e ach t ra i t b etween t he two s t o cking r a t e s
w e r e calculated as a quan t i t a t ive expre s s io n o f t h e s ir e x s t o cking r a t e
TABLE 1 6 :
Her i tab i l i ty e s t imat e s and s t andard errors o f var ious trai t s obtained f rom the
poo led analys e s by d i f fe rent me thod s *
CSR
HSR
COMBINED
NEI
Nil
NEI
h2 ± S . E .
h2 ± S . E .
h2 ± S . E .
0 . 7 2 ± 0 . 24
0.21 ± 0. 11
0 . 47 ± 0 . 22
0 . 2 7 ± 0 . 10
0 . 64 ± 0 . 20
0 . 38 ± 0 . 1 5
0 . 38 ± 0 . 1 5
0.61 ± 0.21
0.61 ± 0.21
0 . 39 ± 0 . 13
0 . 60 ± 0 . 1 7
WA
0 . 4 1 ± 0 . 19
0 . 4 7 ± 0 . 19
0 . 3 1 ± 0 . 16
0 . 3 1 ± 0 . 16
0 . 40 ± 0 . 1 5
0 . 49 ± 0 . 1 7
y
0 . 53 ± 0 . 19
0 . 53 ± 0 . 19
0. 19 ± 0 . 1 1
0 . 19 ± 0 . 1 1
0 . 2 8 ± 0 . 10
0 . 42 ± 0 . 1 2
SL
0 . 54 ± 0 . 19
0 . 5 7 ± 0 . 20
0 . 5 5 ± 0 . 20
0 . 56 ± 0 . 18
0 . 57 ± 0 . 17
0 . 6 3 ± 0 . 18
MFD
0 . 8 1 ± 0 . 34
0 . 87 ± 0 . 33
0 . 34 ± 0 . 2 0
0 . 46 ± 0 . 26
0 . 49 ± 0 . 20
0 . 66 ± 0 . 25
S FD
0 . 5 7 ± 0 . 26
0 . 58 ± 0 . 2 5
0 . 4 7 ± 0 . 24
0 . 58 ± 0 . 2 7
0 . 35 ± 0 . 15
0 . 66 ± 0 . 24
Me thod
NEI
Nil
Trai t
h2 ± S . E .
HLW
0 . 46 ± 0 . 17
GFW
h
2
± S . E.
* For CSR and HSR data
N:�
Nil
2
h
-
=
4
4
*
[
o
o2
s
[
o2
s
0
�
1
1
+
o2 + o2
st
e
2
s
+ 0
+
2
st
2
o2 + o
e
st
Nil
For Comb ined data
N:�
-
4
NII
h2
=
4
[
[
o2
s
o2
s
o
+
o
+
2
s
h
�
o2
sr
+
o2
st
+
+
o2
sr
+
o2
st
o2
sr
+
o2
st
2
± S.E.
]
]
o2
e
o
2
e
.......
The no t a t ion
used in the above exp re s s ion have been des c r ibed earl ier in Chap t e r 3 .
�
TABLE 1 6 :
( cont inued )
HSR
CSR
COMB INED
NEI
Nil
NEI
Nil
NEI
Tra i t
h2 ± S . E.
h2 ± S . E.
h2 ± S . E.
h2 ± S . E.
h2 ± S . E.
h2 ± S . E .
QN
0 . 46 ± 0 . 17
0 . 46 ± 0 . 1 7
0 . 59 ± 0 . 20
0 . 7 2 ± 0 . 25
0 . 52 ± 0 . 16
0 . 56 ± 0 . 1 7
CPC
0 . 48 ± 0 . 20
0 . 56 ± 0 . 2 1
0 . 75 ± 0 . 28
0 . 88 ± 0 . 26
0 . 64 ± 0 . 2 2
0 . 66 ± 0 . 2 2
TCN
0 . 65 ± 0 . 25
0 . 8 1 ± 0 . 27
0 . 86 ± 0 . 3 1
1 . 09 ± 0 . 2 9
0 . 7 0 ± 0 . 24
0 . 83 ± 0 . 26
CHG
0 . 24 ± 0 . 1 2
0 . 28 ± 0 . 1 3
0 . 31 ± 0 . 14
0 . 32 ± 0 . 13
0 . 29 ± 0 . 10
0 . 34 ± 0 . 1 2
TG
0 . 1 3 ± 0 . 09
0 . 26 ± 0 . 17
0 . 27 ± 0 . 1 2
0 . 27 ± 0 . 12
0 . 22 ± 0 . 09
0 . 2 2 ± 0 . 09
HG
0 . 30 ± 0 . 1 3
0 . 66 ± 0 . 2 2
0 . 48 ± 0 . 1 1
0 . 48 ± 0 . 1 1
0 . 23 ± 0 . 09
0 . 42 ± 0 . 15
LG
0 . 42 ± 0 . 16
0 . 42 ± 0. 16
0 . 32 ± 0 . 1 4
0 . 32 ± 0 . 14
0 . 32 ± 0 . 1 1
0 . 39 ± 0 . 1 2
GCG
0 . 3 1 ± 0 . 10
0. 31 ± 0 . 10
0 . 34 ± 0 . 1 4
0 . 44 ± 0 . 1 6
0 . 2 2 ± 0 . 09
0 . 4 1 ± 0. 15
SCG
0. 19 ± 0 . 1 1
0 . 39 ± 0 . 20
0 . 1 2 ± 0 . 09
0 . 36 ± 0 . 15
0 . 10 ± 0 . 06
0 . 30 ± 0 . 1 3
DAG
0 . 04 ± 0 . 0 7
0 . 2 1 ± 0 . 17
0 . 20 ± 0 . 17
0 . 20 ± 0 . 1 7
0 . 10 ± 0 . 08
0 . 10 ± 0 . 0 8
CG
0 . 39 ± 0 . 1 5
0 . 67 ± 0 . 23
0 . 12 ± 0 . 10
0 . 12 ± 0 . 10
0 . 2 3 ± 0 . 09
0 . 2 3 ± 0 . 09
CAG
0. 37 ± 0. 15
0 . 53 ± 0 . 18
0 . 18 ± 0 . 1 1
0 . 27 ± 0 . 1 3
0 . 2 3 ± 0 . 09
0 . 29 ± 0 . 1 1
SG
0 . 22 ± 0 . 13
0 . 22 ± 0 . 13
0 . 00 ± 0 . 00
0 . 00 ± 0 . 00
0 . 1 6 ± 0 . 08
0 . 16 ± 0 . 08
Me thod
Nil
,_.
Ul
0
.
TABLE 1 7 :
Int ra- t r a i t gene t ic co rrelat ions and s t andard errors o f t ra i t s
i n two s t ocking rates
Tr a i t
re
S.E.
Trait
re
S. E.
HLW
0 . 58
0 . 20
CHe
0 . 92
0. 13
eFW
0 . 90
0 . 10
HG
0 . 90
0. 16
y
0 . 74
0 . 17
Le
0 . 80
0 . 15
MFD
0 . 93
0 . 09
GCe
0 . 65
0.21
SFD
0 . 52
0 . 27
see
0 . 57
0 . 37
QN
0 . 95
0 . 07
CAG
0 . 96
0 . 15
CPC
l . 03
0. 18
se
1 . 06
0 . 20
TCN
0 . 87
0 . 09
......
Ul
......
152 .
The s e
i n t e r a c t ions t o e xamine i t s p r a c t i c a l s i gn i f i canc e in s e l e c t ion .
int ra- t ra i t gene t i c corre l a t ions a l o n g w i t h the i r s t and ard e r r o r s a r e
The s i gn i f i can c e o f devi a t ion o f the i n t r a- t rai t
p r e s en t e d i n Tab l e 1 7 .
corre l a t ions f rom unity was t e s ted .
Th e r e l a t ive magn i tudes o f the s i r e x s t o cking r a t e and s i r e x year
var iance componen t s to the t o t a l var iance and t o t a l gene t i c variance
we re comp u t ed t o i l lu s t r a t e the imp o r t an c e of t h e s e random int e r a c t ions
in the t r a i t s unde r inve s t i ga t ion .
Hogge t l ive-we igh t
The her i t ab i l i ty e s t ima t e s o f HL\� comp u t ed by N E I a n d N i l me thods
in the pooled an a l yses were 0 . 4 6 ± 0 . 1 7 and
0 . 2 1 ± 0 . 1 1 and 0 . 4 7
±
0 . 2 2 in the HSR ;
0.
72 ± 0 . 2 4 in the C S R ;
0 . 2 7 ± 0 . 1 0 and 0 . 6 4 ± 0 . 20
in
Th e e s t ima t e s by NEI me thod in gene r a l
the comb ined d a t a resp e c t ively .
are s imilar to the o ther e s t ima t e s o f t h e he r i t ab i l i t y o f HLW i n t h e New
Zeal and Romney ( 0 . 4 6 Tripathy ,
Baker et a l . ,
1974 ) .
1966 ;
0 . 5 1 Ch ' an g and Rae ,
1970 ;
0 . 22
The e s t ima t e s b y N i l me t hod in th i s s t udy though
at the upper l imi t are w e l l within the range o f e s t imat e s f o r the o th e r
b r e e d s repo r t ed in t h e l i t e rature .
A l t hough t he her i t ab i l i t i e s c a l cu l a t e d f rom the C S R d a t a were
h i gher than tho s e for t he HSR , there were no s i gnifi c an t d i f f e r e n c e s
b e tween the s e e s t imat e s .
As a r e s u l t o f large s t and ard error s , there
we r e no s ign i f i c ant d i f f e r ences in all t h e three ana ly s e s b e tween the
e s t imat e s b y NEI and N i l method s .
S i gn i f i c an t sire x year int e r a c t ions ( P < 0 . 0 5 ) con t r ib u t e d 6 . 4 and
6 . 5 % in th e C S R and HSR r e s p e c t ive ly to the t o t a l var i an c e and f o rmed a
153 .
very s ub s t an t i a l prop o r t ion of the t o t al gene t i c varian c e in b o t h the
analys e s .
In HSR , whi l e compar ing t he r e l a t ive magn i tude of s ir e x
year interact ions and b e tween s ir e var ian c e component s , the r a t i o was
exc e e d ingly large indicat ing that the p e r f ormanc e o f the pro geny of a
s ir e would no t b e h i ghly repeatab l e over the year s .
The r anking o f
s i res may b e very d i f f e rent in var ious y e ars .
In the comb ined d a t a analy s i s , s i re x s t o ck ing r a t e and s i r e x year
interact ions were s i gn i f i cant ( P <0 . 0 1 ) , c on t r ibuted 4 . 6 and 4 . 5 %
r e s p e c t ive l y t o t he t o t a l var i ance and f o rmed 2 9 . 1
o f t he t o t a l gene t ic var iance .
and 2 8 % r e s p e c t ive l y
The rat i o o f s i re x s t o cking r a t e and
s ir e x year i n t e r a c t ions to the b e tween- s ire var iance was abou t 1 . 3 ,
ind i c a t in g t h e impor tance o f t h e s e random interac t ions in t h i s t rai t .
The same t rend wa s observed in the ind ividual S i re group p e r iod s .
The
d i f f e rence b e twe e n the e s t ima t e s by two methods appro ached s i gn i f i c an c e
( 0 . 0 5 < P< O . 1 0 ) .
Evidence of gen o t ype x nut r i t i on int e r a c t ions b e ing
important in t h i s trait has been provided by var ious workers (Mo r l e y ,
1956 ;
Osman and Brad f o r d , 1 9 6 5 ;
Car t e r et a l . , 1 9 7 1b ;
Budans t ev , 1 9 7 3 ) .
In Dunlop ' s ( 1 9 6 3 ) wor k , the lack o f l a r g e and cons i s t en t genotype x
l o c a t ion i n t e r a c t ions in HLW were a t t r ibuted to the p r e s e n c e o f year x
lo cat ion in t erac t ions o f some imp o r t anc e .
The in t r a- t ra i t gene t i c c o r r e l a t ion be tween the two s t o ck i n g r a t e s
f o r HLW was e s t imated t o be 0 . 58 ± 0 . 2 0 , s ign i f icant l y ( P< 0 . 0 5 ) d i f fe rent
f r om uni t y .
Rob e r t s on ( 1 9 5 9 ) sugg e s t e d that an e s t imat e o f r e around
0 . 6 would be o f consequence in s e l e c t io n .
Falconer ( 1 9 5 2 ) s t ated that the r a t io o f the ' co r r e l a t e d r e s p ons e '
( � ' G 1 ) in environment 1 t o the ' d i r e c t r e s p on s e '
(�G l ) i s
1 54 .
r
G
.. .. .. . . .. .
(l)
whe re h 2 and h 1 are t h e square roo t s o f t he h e r i t ab i l i t y in envi ronme n t
2 and 1 r e s pe c t ively and rG is t h e intra- t r a i t gene t i c corre l a t ion
be tween the two env i r onmen t s .
Au
a s s ump t i on o f e qua l in t en s i t y o f
s e l e c t ion was made in de riving t h e e q u at ion .
From the above exp r e s s ion
i t f o l lows , that an advantage of s e l e c t i on in t he secondary environmen t
would a c c rue only t h r o u gh an increase o f he r i t ab i l i t y .
The i n c r e a s e in
her i t ab i l i ty wou l d have t o be great enou gh to o f f s e t the l o s s o f
e f f i c iency th rough s e l e c t i on b e i ng mad e i n o n e envi ronment t h a t h a s n o t
exa c t ly t h e same gene t i c bas is a s t h e o t h e r environmen t , i . e . , h 2 r G mu s t
be grea t er t han h 1 .
The observed h e r i t abi l i t i e s in t h i s inve s t iga t ion were 0 . 4 6 and
0 . 7 2 in the CSR ;
resp e c t ive ly .
0 . 2 1 and 0 . 4 7 in the H S R by NEI and N i l me t h o d s
W i t h t h e va l ue of r G be ing 0 . 5 8 , t he above r a t i o s
( e q ua t i on 1 ) worked o u t t o be abo u t 0 . 8 7 and 0 . 7 2 wi t h N E I and N i l
respe c t ive ly .
Thu s no advan t age would be o b t ained by s e l e c t in g sheep
in t h e C S R for u s e in t he H S R .
The d i r e c t s e lec t ion i n the ind ividual
s t ocking rates w i l l y i e ld b e t t e r r e s u l t s s in c e the inc r e a s e o f
I
h e r i t ab i l i t y in the C S R was n o t great enough t o o f f s e t the l o s s c a u s e d
b y r G b e tween t h e t wo s tock ing rat e s .
Th e p r e s ence o f s i re x year i n t e ra c t ions may have some imp l i c a t ions
in comme r c i a l b r e e d ing pra c t i c e as the rams s e l e c t ed for b r e e d ing are
normal ly used ove r s everal years and their progeny a r e exp o s e d t o year
t o year var iat ions in environmen t .
155.
Gre a sy f l eece we igh t
Value s calcu l a t ed for h e r i t ab i l i ty o f GFW by NEI and N i l me t h o d s i n
t h e p oo led an alyses were 0 . 3 8
±
0 . 1 5 and 0 . 3 8 ± 0 . 1 5 in the C S R ;
0 . 39
0 . 6 1 ± 0 . 2 1 and 0 . 6 1 ± 0 . 2 1 in t h e HSR ;
the comb in ed data r e s p e c t ive l y .
±
0 . 1 3 and 0 . 60 ± 0 . 1 7 in
The e s t ima t e s though somewha t h i gher
comp a re we ll with other e s t imates o f the he r i t ab i l i ty o f GFW in New
Zealand Romney hogge t s ( 0 . 3 5 Rae ,
1966 ;
1946 ;
0 . 2 9 and 0 . 5 7 B aker e t a l . �
0 . 3 2 Rae ,
1974) .
1958 ;
0 . 4 3 T r i p a t hy ,
The her i t ab i l i t ie s o b t a ined
in this s t udy are also we l l w i thin the range of e s t ima t e s reported f o r
t h e o t her breeds in t h e l i t e ra t ure .
N o s igni f i cant d i f f eren c e s b e tween the h e r i t ab i l i ty e s t ima t e s
ob t a ined in the C S R an d in t h e H S R were ob s e rved .
The e s t imat e s we re
iden t i c al by two me thods in the C S R and in t h e H S R , as s i re
x
year
in t e r a c t ions (NS ) d id not cont r ibu t e to the t o t al var i a t ion in the t ra i t .
S imilar observa t ions were re corded in the ind ividual S ire group p e r i o ds .
In t he comb ined d a t a an alys i s , s ire
x
s t o cking r a t e in t e r a c t ions
(NS ) con t r ibuted only 1 % to t h e t o t al varian c e and f o rmed about 7 % o f
the t o t a l gene t i c v a r i anc e .
Geno type
x
nut r i t ion intera c t ions in GFW
have a l s o been ob s e rved as non- s i gn i f i c an t and of l i t t l e impor t an c e b y
o ther workers (Mor l e y , 1 9 5 6 ;
1965 ;
Car t er et a l . �
197 1a) .
King e t a l . �
1959 ;
Osman and Brad f o r d ,
The d i f f e ren c e in the her i t ab i l i t y
es t imat e s (NS ) b e tween the values ob t a ined b y two met hod s , could l ar g e l y
b e a t t r i bu t ed t o t h e s i gn i f i cant (P<0 . 0 1 ) s ir e
x
y e a r int erac t ions ( 4 %
o f the t o t al var i an c e and 2 7 . 5 % o f t h e t o t a l gene t ic var i anc e ) .
S in c e the h e r i t ab i l i t ie s o f GFW d i d no t d if f er s i gn i f i c an t l y b e t we en
t he two s t o cking ra t e s and s in c e no s ign i f i c an t s ire
x
s t o cking r a t e
156 .
i n t e r a c t ions were d e t e c t ed in the comb ined data analy s i s , i t s e ems t hat
no meaningful d i f f e rences in the ranking of sires exi s t ed .
No par t i cul a r advan tage would a c c Y� by s e l e c t ing sheep in 'the HSR
( h i gher he r i t ab i l i t y ) for use in CSR ( l ower her i t abil i t y ) d e s p i t e r e
b e in g 0 . 90 .
Cl ean wo ol we igh t pe r u n i t area
E s t ima t e s for WA h e r i t ab i l i t y comp u t e d in t he poo l ed analy s e s by
NEI and Ni l meth o d s we re 0 . 4 1 ± 0 . 1 9 and 0 . 4 7 ± 0 . 1 9 in the C S R ;
0 . 3 1 ± 0 . 1 6 and 0 . 3 1 ± 0 . 1 6 i n t h e HSR ;
0 . 4 0 ± 0 . 1 5 and 0 . 4 9 ± 0 . 1 7 in
the comb ined d a t a respe c t ively .
Al t hough t h e h e r i t ab i l ity e s t imat es were h i gher in t he C S R t han in
the HSR , the d i f f er enc es were n o t s i gn i f i cant .
The two e s t ima t e s o f the
The d i f f erence in the two
h e r i t ab i l i t y we r e i dent i c a l in the H S R .
her i t ab il i t y e s t ima t e s in the CSR were non- s i gn i f i can t .
S ire x year
i n t e r a c t ions con t r ibuted 1 . 5 % t o the t o t a l var i an c e and f o rmed 1 2 . 7 %
The s e int e r a c t ions wer e
o f t he t o t al gene t i c variance in the C S R .
imp o r t an t only i n t h e S ire group 2 p e r i o d whe re i t ac coun t ed f o r over 1 0 %
o f t h e t o t a l var iance b u t i t d id n o t c on t r ibut e t o the t o t a l var i a t ion
i n the S ir e group 3 per iod .
In the comb in e d data analy s i s , s ir e
x
s t o cking r a t e int er a c t ions
(NS ) d id not con t r ibute t o t he t o t a l var i a t ion .
Iden t i c a l r e su l t s were
r e c o rded i n the ind ividual S ir e g roup p e r i o d analy ses .
breed
x
S ign i f i can t
p l ane o f n ut r i t ion int e ra c t ions f o r c l e an we ight o f woo l f ib r e s
a n d c lean we i gh t o f all f ib re s on the t a t t o ed area wer e repo r t ed b y
K i n g a n d Young ( 1 9 5 5 ) f rom s t u d i e s on a small s amp le o f b r e e d s and
e nvironmen t s .
157.
S ir e
x
year interact ions (NS ) cont r ib u t e d s l i gh t ly mo r e t han 2 % o f
the t o tal var i ance and f o rmed about 1 9 . 1 % o f the t o t a l genet ic var ianc e
The d i f f erence (NS ) b e tween the two
i n t he comb ined dat a analy s i s .
e s t ima t e s by NEI and Ni l were due t o the p r e s ence of s ir e
x
year
in t e r action s .
The ab s ence o f s i gn i f i c an t s ir e
x
s t o ckin g
ra t e , s ir e
x
year
int e ract ions and t he non- s ign i f i c an t d i f f erence in the her i t ab i l it y
e s t ima t e s b e twe en t h e two s t o cking r a t e s sugge s t t hat i n t e r a c t ions are
n o t l ikely t o b e imp o r t an t f o r WA i n the f lo cks under s t udy .
The high e s t imat e s f o r h e r i t ab i l i ty in WA ind icate that s e l e c t ion
i s l ikely t o b e e f f e c t ive if t here was s u f f i c ient j us t i f i ca t ion t o
i n c l u d e t h i s as a s e l e c t io n c r i t er ion .
C l e an s coured yie ld
The her i t ab i l i ty e s t imat e s for Y ob t a ined by two me thods in the
p o o l e d analy s e s we r e 0 . 5 3 ± 0 . 1 9 and 0 . 5 3 ± 0 . 1 9 in the CSR ;
0 . 1 1 and 0 . 1 9
±
0 . 1 1 in the HSR ;
comb ined data r e s p e c t ively .
New Z ealand Romney .
0. 19
±
0 . 2 8 ± 0 . 1 0 and 0 . 4 2 ± 0 . 1 2 in the
There are no comparable r ep o r t s for the
Howeve r , these e s t imat e s compare we l l w i t h those
in t h e l i terature a t 1-2 years o f age in o th e r bre eds (Morley , 1 9 5 5a ;
Young et a � . �
1 9 60 ;
Ve s e ly and Rob i s on ,
1970;
Mullaney e t a � . �
1970) .
The her i t ab i l i ty e s t imat e was lower w i t h large s t andard e r r o r s i n
the H S R when compared t o the e s t imat e i n the C S R but no s igni f i c an t
d i f f e rence was observed b e tween t he two e s t imat es .
The her i t ab i l i t y
e s t ima t e s wer e ident ical by N E I and N i l methods b o t h in t h e CSR a n d HSR .
S ir e
x
year i n t e ract ions ( N S ) d i d not con t r ib u t e t o the t o t a l variance
158.
Howeve r i t con t r ibut ed 4 . 0 and 1 6 . 0% in t h e
in b o th t h e analy s e s .
S i re group 1 p e riod in t h e CSR (NS ) and H S R ( P < 0 . 0 1 ) r e s p e c t ively .
In t h e comb ined d a t a analy s i s s ir e
x
s t ocking r a t e (NS ) a c c ounted
f o r 2 . 6 % of the total var i ance and formed a s ub s t ant ial f r a c t ion ( 2 4 . 6 % )
The above r e su l t s agree with Mo r l ey
o f the t o t al gene t i c var iance .
( 1 9 5 6 ) , who reported that s i r e
s i gn i f icant in this t r a i t .
s t rain
x
x
nu t r i t ion int e r a c t ions were non-
Dun lop ( 1 9 6 2 ) however , o b s e rved s i gn i f i cant
s t a t ion int er a c t ions though the s i z e of t he int erac t ions t e rm
wa s no t l arge .
Sire
x
y e ar i n t e r a c t ions (NS ) in this analy s i s were
r e l a t ive ly l e s s imp o r t an t and con t r ibut ed a n e g l i gib l e f r a c t ion t o t he
t o t al var i ance .
The d i f f erence (NS ) in the e s t imates by NEI and N i l
x
w a s thus l argely at t r ib u t able t o t h e s i r e
s t o ck ing r a t e in t e rac t ions .
The int ra- t r a i t gene t ic correlat ion c a l cu l a t ed was 0 . 7 4 ± 0 . 1 7
( devi a t ion f rom uni t y , 0 . 0 5 <P< 0 . 1 ) .
The ob s erved her i t ab i l i t i e s were
The rat i o o f t h e
0 . 5 3 and 0 . 1 9 in the CSR and H S R resp e c t ive ly .
' c orrela t e d ' t o t h e ' d i r e c t ' r e sponse e s t ima t ed w a s 1 . 2 4 sugge s t in g
t h a t n o d i s t in c t advant ag e would b e a ch i eved by s e l e c t ing sheep i n the
CSR for use in the H S R .
S t apl e l engt h
The h e r i t ab i l i ty e s t imat e s o f SL comp u t ed by NEI and N i l were
0 . 54
±
0 . 1 9 and 0 . 5 7 ± 0 . 2 0 in t h e C S R ;
t he HSR ;
0 . 5 7 ± 0 . 1 7 and 0 . 6 3
±
0 . 55
±
0 . 20 and 0 . 5 6
±
0 . 1 8 in
0 . 1 8 i n t h e comb ined d a t a r e s pe c t ively .
The s e e s t imat e s in g en er a l comp a r e we l l w i t h the est imat e s o f t h e
h e r i t ab i l i t y o f S L i n N e w Zealand Romney hogge t s ( 0 . 50 , 0 . 3 5 , 0 . 4 8
Rae , 1 9 5 8 ;
0 . 4 6 Tripat h y ,
1 9 6 6 ) and o ther b r eeds lis t ed in Tabl e 1 .
159 .
The h e r i t ab i l i ty est ima t e s o f SL in the C SR and i n the HSR wer e
almo s t s imilar .
Osman and Brad f o rd ( 1 9 6 5 ) wh i l e examining genotype x
loca t io n interac t i ons in SL al s o did not ob s e rve any s i gnif i c an t
d i f f e rence o f the her i t ab i l i ty e s t ima t e s in two locat ions .
The
e s t ima t e s of h e r i t ab i l i ty by two me thod s were al ike b o t h in the CSR and
S i r e x year interac t ions ( N S ) were small and f o rmed l e s s than 1 %
HSR .
I t however , contributed
o f the t o t al variance both in the CSR and HSR .
ove r 4 . 1 % in the S ire group 1 p e r i od in the HSR and 4 . 8% in the S ir e
group 3 p e r iod in t h e C S R resp e c t ively t o t h e t o t a l var i a t ion .
S i re x s t o cking rate int e r a c t ions (NS ) d id n o t cont r ibute to the
to tal var i ance in the comb i ned d a t a analy s is .
S imi lar resul t s we re
ob t a in e d in the indiv idual S ir e g roup p e r iods analys e s .
Evi d ence o f
geno type x nu t r i t ion interac t i ons b e ing unimportan t i n S L has b e e n
provided b y o t h e r wo rke rs (Mo r ley , 1 9 5 6 ;
Brad fo r d ,
1965 ) .
Dun lop , 1 9 6 2 ;
King and Young ( 1 9 5 5 ) and King e t a Z .
rep o r t e d s imilar r e sul t s for ave r a ge f ib r e length .
O sman and
( 1 9 5 9 ) al s o
S ir e x year
interact ions ( N S ) too , as in the CSR and HSR analy s e s were extreme ly
sma l l ( 1 . 3 % o f the t o t al varianc e ) in the comb ined data analy s i s .
Rae ' s ( 1 9 5 8 ) and Dunlop ' s ( 1 9 6 2 ) observat ions for such interac t ions in
SL suppo r t the r e s u l t s ob t a ined f o r s ir e x year in t e r a c t ions in the
s t udy .
Mean f ib r e d i ame t e r
T h e h e r i t ab i l i ty e s t imat e s o f MFD in t h e poo led analys e s b y NEI
and Nil me t hods we r e 0 . 8 1 ± 0 . 3 4 and 0 . 8 7 ± 0 . 3 3 i n the C S R ;
and 0 . 4 6 ± 0 . 2 6 in the HSR ;
data r e s p e c t ive ly .
0 . 4 9 ± 0 . 2 0 and 0 . 66
±
0 . 34
±
0 . 20
0 . 2 5 in the comb ined
The only o th e r e s t imat e , 0 . 1 7 ± 0 . 1 0 (DDR) f o r MFD
1 60 .
in New Zealand Romney hogget s , wa s rep o r t ed by Tripa t hy ( 1 9 6 6 ) .
It
was l ow when comp ar e d t o the values reported i n the o ther bre e d s .
The
values d e r ive d from t h i s s t udy are q u i t e comp a r able t o E l l i o t t ' s ( 1 9 7 5 )
PHS ( 0 . 5 4
±
0 . 0 1 ) and DDR ( 0 . 4 7
±
0 . 0 2 ) in P er endal e s .
The s amp l ing
errors were large in the p re s en t inve s t igat ion becau s e o f the sma l l
numb e r o f observat ions ava i l ab l e .
Al th ough the h e r i t ab i l i t ie s we r e comparably h i gher i n the CSR t han
in the H S R , d i f f e ren c e s b e twe en the e s t ima t e s were n o t s i gn i f i cant .
The gene t i c var iance was reduced by the h i gher s t ocking r a t e r e s u l t ing
in the l ower e s t ima t e s of her i t ab i l i ty in t he H S R .
I t sugge s t s that
CSR i s more favourab l e for the expr ess ion of gene t ic d i f ferences in
this t r a i t .
The h e r i t ab i l i t y e s t imat e s were somewha t h i gher by N i l me thod a s
c ompared t o b y NEI .
However , there were no s i gn i f i cant d i f f e rences in
all the t hree ana l y s e s b etwe en the two e s t imat e s .
S ir e x year
intera c t i on s (NS ) con t r ibuted about 1 . 4 and 2 . 9 % t o t he t o t a l var iance
i n the CSR and HSR r e s p e c t ivel y .
In t he comb ined d a t a ana l y s i s s i gn i f icant s ire x s t o cking r a t e
intera c t i on s ( P < 0 . 0 5 ) ac coun t e d for 3 . 2 % o f the t o t a l variance and
f ormed 1 9 . 7 % of the t o t a l gene t i c variance conf i rming the imp o r t an c e o f
t hese i n t e r a c t i on s .
Such o b s e rvat ions we r e a l s o mad e by W i l l i ams
( 1 9 6 6 ) and Dunlop ( 1 9 6 2 ) for MFD in exp e r ime n t s o f s imilar n a t ur e .
The d i f f er ence (NS ) b e tween the her i t ab i l i t y e s t imat e s by two me thods
i n the p r e sent s t udy was largely due t o the p r e s ence of s ign i f i c an t
s i re x s to cking r a t e i n t e r a c t ions .
S i r e x year int e r a c t ions ( N S )
contrib ut e d l e s s t han 1 % o f t h e t o t a l var iance a n d wer e unimp o r t an t ,
a s imilar f in ding to t h a t o f Dunlop ( 1 9 6 2 ) .
16 1 .
The he r i t ab i l i t ies in t h i s s t udy by NEI and N i l me thods r e s p e c t ivel y
we r e 0 . 8 1 and 0 . 8 7 i n t h e CSR ;
0 . 3 4 and 0 . 4 6 in the HSR .
W i t h the
va lue of intra- t r a i t gene t i c c o r r e l a t ion b e ing 0 . 9 3 ± 0 . 0 9 , the r a t i o
o f t he ' co r re l at ed ' to the ' d ir e c t ' response in the HSR wo r ked out t o
b e 1 . 4 4 and 1 . 2 8 b y N E I and N i l r e s p e c t iv e ly .
The h i gh h e r i t ab i l i t y e s t ima t e s f o r MFD ind icate that there is an
advantage in s e l e c t ion f o r MFD as c omp ared to t he s e l e c t ion f o r the
r e l a t ive ly l e s s-he r i t ab l e subj e c t ive l y- a s s e s s e d qual i t y numb e r s as a
c r i t e r ion o f f in ene s s .
I f s e l e c t ion f o r f iner wool was j us t i f ied
mea s ur ing d i ame t e r to use in the f inal s t ages of ram s e l e c t ion
p a r t icularly in nuc leus f locks could b e worthwh i l e .
S t andard devia t ion o f the f i bre d iame t e r
The he r i t ab i l i t y est ima t e s o f S FD we r e 0 . 5 7 ± 0 . 2 6 and 0 . 5 8
in t he CSR ;
0 . 4 7 ± 0 . 2 4 and 0 . 5 8 ± 0 . 2 7 in the HSR ;
0 . 6 6 ± 0 . 2 4 in the comb ined d a t a r e s p e c t ive ly .
r ep o r t s for SFD i n the New Zeal and Romney .
±
0 . 25
0 . 3 5 ± 0 . 1 5 and
Ther e are no comparab l e
However , the e s t ima t e s o f
t h e s ame magn i t u d e s f o r SFD a r e g iven by Kyl e and Ter r i l l ( 1 9 5 3 ) ,
Bea t t ie ( 1 9 6 2 ) and Gj edrem ( 1 9 6 9 ) .
Kyl e and T e r r i l l ( 1 9 5 3 ) r e p o r t e d
a her i t ab i l i t y o f int erme d i a t e magn i tude f o r d i ame ter var i ab i l i t y and
Be a t t i e ( 1 9 6 2 ) f ound a h e r i t ab i l i ty o f 0 . 4 3 for C . V . o f f ib r e d i ame t e r .
Her itab i l i t y e s t ima t e s for SFD r epo r t e d by Gj edrem ( 1 9 6 9 ) range b e tween
0. 31 - 0.61.
No s i gni f i can t d i f f erenc e s were ob s e rved b e tween the e s t imat e s o f
her i t ab i l i t y i n the CSR and HSR owing t o t he large s t andard error s .
162 .
x
S ir e
year int e r a c t ions (NS ) accoun t e d f o r 2 . 7 % o f the t o t a l
variance in t he HSR wh i l e it was negligib l e ( 0 . 2 2 %) in the CSR .
However , the d i f f erence ( 0 . 1 1 ) b e tween the e s t ima t e s by NEI and N i l
methods in t h e HSR w a s non- s i gn i f i can t .
In t he combined d a t a analy s i s , s ire
x
s t o c k ing r a t e int erac t ions
( P< 0 . 0 1 ) accoun t ed f o r 5 . 5 % o f the total va r i a t ion and 3 3 . 4 % o f the
t o t al gene t i c variat i o n .
S ir e
x
year intera c t i ons ( N S ) though
r e lat ive ly l e s s imp o r t ant , ac count ed for 2 . 4 % o f the t o t al var iance
and were s l i gh t ly over 14% of t he t o t al gene t i c var i an c e .
In t he comb ined d a t a analy s i s , t he r a t io o f sire
and s i re
x
x
s to cking rat e
year int e r a c t ions to the b e tween- s ir e var iance was 0 . 9 1
indicat ing t he impor t ance o f t h e s e r andom int e r a c t ions .
The l arge
d i f f erence o f the he r i t a b i l i t y e s t imat e s in the comb ined data analys i s
( 0 . 3 5 v s 0 . 6 6 ) was howeve r , non- s i gn i f icant .
The intra- t r a i t gene t i c correlat ion b e tween the two s t o cking r a t e s
was 0 . 52
±
0 . 2 7 ( d ev i a t io n f rom un it y , 0 . 0 5 < P < 0 . 1 ) .
By s e l e c t ing i n
C S R (her i t ab i l i t y b e in g 0 . 5 7 ) f o r u s e in t he HSR (he r i t ab i l i t y b e in g
0 . 4 7 ) , t h e gen e t i c p r o gre s s f o r f ibre var i ab i l i t y would b e at a lmo s t
h a l f o f t he r a t e o f improvement ob t a ined b y d i r e c t s e l e ct ion .
Qua l i ty number
E s t ima t e s for QN her i t ab i l i t y computed in t h e p o o l e d ana ly s e s wer e
0 . 46
±
0 . 1 7 and 0 . 4 6
t h e HSR ;
0 . 52
±
±
0 . 1 7 in t h e C S R ;
0 . 1 6 and 0 . 5 6
±
0 . 59
±
0 . 20 and 0 . 7 2
±
0 . 25 in
0 . 1 7 in t h e c omb ined d a t a r e s p e c t ive l y .
These e s t imat e s are somewhat h i gher t han t h e o th e r e s t imat e s o f QN i n
New Zealand Romney h o g ge t s ( 0 . 2 5 , 0 . 34 , 0 . 3 5 , 0 . 4 7 Rae ,
1 95 8 ;
0 . 35 -
0 . 40 McMahon , 1 9 4 3 ) b u t are well with in t he range of e s t imat e s f o r o th e r
breed s repo r t ed i n the l i t erature .
163.
The he r i t ab i l i t i e s ob t ained were h i gh e r in the HSR than in the C S R
b u t t h e d i f f erences b e tween t h e e s t ima t e s wer e non- s i gn i f i c an t .
S ir e
x
year int e r a c t ions (NS ) did not con t r ib u t e t o the t o t al
var i ance in the CSR wh i l e i t formed s l i ght ly over 3 % o f the t o t a l varian c e
in t he HS R .
The d i f f e ren c e ( 0 . 1 3 ) b e tween t he es t imat e s b y NEI and N i l
me thods in t he H S R w a s however , non- s igni f i c an t .
In the comb ined data analys i s , s i r e
x
s t o c king r a t e interac t io n s (NS )
In the ind ividual S i r e
c o n t r ibut ed l e s s than 1 % o f the t o t al varian c e .
g r ou p p e r i o d s as we l l , s u c h interact ions w e r e unimp o r t an t .
d emons t rated that s t ra in
x
Dunlop ( 1 9 6 2 )
locat ion interact ions in QN ac counted f o r only
a n e g l ig ib l e f r a c t i on o f the variance .
S ir e
x
year interact ions ( N S )
were not o f any importan c e b o th in the pooled and ind ividual S ir e group
p e r iods .
Evidence o f genotype
x
year interact i ons b e in g unimp o r t an t in
t h i s t rait was p rovided by Rae ( 1 9 5 8 ) and Dun l o p ( 1 9 6 2 ) .
The
h e r i t ab il i t i e s by two me thods were q u i t e s imilar .
The ab sence of s i gni f i c ant int erac t ion s , the s imi lar ity o f
h e r i t ab i l i t ies i n the t wo s t o cking rat e s and the very h i gh ( 0 . 9 5 ± 0 . 0 7 )
i n t r a- t ra i t gene t i c c o r r e l a t ion ind icat e that s ir e
s ir e
x
x
s t o cking rate and
year interact ions a r e not imp o r t an t f o r QN in t h e s e group s o f sheep .
C r imps pe r cent ime t e r
Values c a l culat e d f o r h er i t ab i l i t y o f C P C were 0 . 4 8
0 . 56
±
0 . 2 1 in the C S R ;
±
0 . 20 and
0 . 7 5 ± 0 . 2 8 and 0 . 8 8 ± 0 . 2 6 i n t h e HSR ;
0 . 64 ± 0 . 2 2 and 0 . 6 6 ± 0 . 2 2 in the comb ined d a t a r e s p e c t ively .
The
values derived f rom the p r e s en t analyses comp a r e wel l with the
h e r i t ab i l i t y e s t imate of 0 . 7 2 in New Zealand Romney hogget s by T r i p athy
( 1 9 6 6 ) and t h e e s t imat e s for other breeds .
1 64 .
E s t imates o b t a i ned in the HSR were h i ghe r than the e s t imat e s i n
t h e CSR s ugge s t in g that HSR w a s mo re f avourab l e for t h e exp re s s ion o f
t he gene t i c d i f f e rences .
Howeve r , the d i f f erenc e s b e twe en t h e e s t ima t e s
The int r a- t r a i t gene t ic correlat ion c a l cu l a t ed
were non- s i gn i f i cant .
b e tween the two s t o cking rates was 1 . 0 3 ± 0 . 1 8 .
S ire x year i n t e r a c t ions (NS ) accoun t e d for 2 . 0 and 3 . 0 % o f t h e t o t a l
vari a t i on i n the CSR and H S R r e sp e c t ively .
The two e s t ima t e s o f her i t ab i l i ty d e r ived in the comb ined d a t a
ana ly s e s we re s im i l a r .
S i re x s t o cking r a t e interact ions ( N S )
cont r ib u t e d l i t t l e ( 0 . 3%) t o t h e t o t a l varian c e .
Mo r ley ( 1 9 5 6 ) and
Dunlop ( 1 9 6 2 ) a l s o reported such intera c t i on s to be of no consequence
in the t ra i t .
S ire x year interac t ions ( N S ) d id not con t r ib u t e to the
t o t al var i ance , a f ind ing s imilar t o that of Dunlop ( 1 9 6 2 ) .
To t a l c r imp numb er
E s t ima tes of t he he ri t ab i l i t y we r e 0 . 6 5 ± 0 . 2 5 and 0 . 8 1 ± 0 . 2 7 in
the C S R ;
0 . 8 6 ± 0 . 3 1 and 1 . 09 ± 0 . 2 9 in t he HSR ;
0 . 8 3 ± 0 . 2 6 in the c omb ined d a t a r e s p e c t ively .
0 . 70
±
0 . 2 4 and
No p ub l ished e s t ima t e s
are ava i l ab le on t he New Zealand Romney and o t her breeds w i t h wh ich t o
comp a r e t h e es t ima t e s obt ained i n this s t udy .
A l though the h e r i t ab i l i t ies o b t a ined
were h i gher in the HSR than in
the C S R , the d i f f er en c es b etween the e s t imat e s were n o t s i gn i f i can t .
The int ra- t rait gene t i c correlat ion b e tween t he two s to cking r a t e s was
close to uni ty ( 0 . 8 7
±
0 . 09 ) .
165 .
S ire
x
year interac t i ons (P< 0 . 0 5 ) cont r ibut ed 4 . 0 and 5 . 7 % t o the
However , no s i gn i f i c ant
t o t a l var i an c e in the CSR and HSR r e s p e c t ively .
d i f f erences were ob s e rved b e tween the e s t ima tes both in the CSR and HSR
analys e s .
In the c omb ined data analys i s s i gn i f i c an t s i re
x
s t o cking r a t e
inter a c t ions (P< 0 . 0 5 ) acc oun t e d f o r 2 . 9 % o f the t o t a l var i an c e and
formed 1 3 . 8 % of the gene t i c varian c e .
Sire
x
year i n t e r a c t ions ( N S )
cont ribu t e d l i t t l e ( 0 . 3 % ) t o the t o t a l variat ion .
The d i f f erence
b e tween t h e t wo e s t ima t e s in the c omb ined data was largely due t o the
p r e sence of s i gn i f i cant s i re
x
s t o ck ing rate int erac t ions .
However ,
this d i f f e rence was obs e rved to be non- s igni f i c ant .
The p r e s ent s t udy reveal e d that TCN i s a h i ghly heri t ab l e t ra i t
and c o u l d b e cons idered as a p o s s ib l e s e l e c t ion c r i t e r ion f o r gene t i c
improvemen t in s ome t r ai t s .
Charac t e r grade
Th e heri t ab i l i t y e s t ima t e s of CHG comput ed by NEI and N i l me thods
were 0 . 2 4 ± 0 . 1 2 and 0 . 2 8 ± 0 . 1 3 in t he CSR ;
in the H S R ;
respect ively .
0 . 3 1 ± 0 . 1 4 and 0 . 3 2
±
0. 13
0 . 2 9 ± 0 . 1 0 and 0 . 3 4 ± 0 . 1 2 in the comb ined d a t a analys e s
The s e e s t imat e s in general compare well w i th Rae ' s
( 1 9 5 8 ) t ab u l a t ed values (DDR) 0 . 2 5 ± 0 . 1 0 , 0 . 1 6 ± 0 . 1 2 , 0 . 2 2
(PHS) 0 . 1 2 in New Zealand Romney h o g ge t s .
±
0 . 0 7 and
The he r i t ab i l i t y ( 0 . 2 5 )
calculated f r om the regress i on o f h o g get measurement o f daugh t e r o n
ma t ure measur ement o f dam in h i s work d i f fered non- s i gn i f i cant ly f rom
the heri t ab i l i ty ( 0 . 1 6 ) calculated f r om the hogget measuremen t o f
daugh t e r o n ho gge t measuremen t o f dam.
The her i tab i l i ty e s t ima t e o f
0 . 1 2 c omp u t ed f rom PHS corre l a t ion i n Rae ' s ( 1 9 5 8 ) wor k we r e b ased o n
166 .
The e s t ima t e s d e r ived f rom the p r e s e n t
f ew s ir e degrees o f f reedom .
s tudy are we l l w i t h in t h e range o f e s t ima t e s f o r othe r b r e e d s r ep o r t ed
in t h e l i t erature .
There were no s i gn i f ican t d i f f e r e n c e s b e tween t h e h e r i t ab i l i t y
The int ra- t r a i t gene t i c
e s t imat e s ob t a ined i n t h e CSR a n d HSR .
corre l a t i on calculated b e tween the two s t o c k ing rates was c l o s e to unity
( 0 . 92 ± 0 . 13) .
S ir e
x
year in t e r a c t ions (NS ) c o n t rib u t e d l i t t le ( 1 . 2 and 0 . 2 %
the CSR and HSR resp e c t ively ) t o the t o t al var i a t ion .
in
Howeve r , t hey
contributed s l i gh t l y ov e r 7 and 4 % i n the C S R an d HSR r e s p e c t ively to
t h e to t a l var i a t i on in t h e S i re group 3 period .
No s i gn i f i can t
d i f ferences were ob s e rved i n the e s t ima t e s b y two me thod s both i n t h e
C S R and HSR anal y s e s .
In the combined d a t a an alys e s s i re
( N S ) con t r ib u t ed l e s s t h an 1 %
to
x
s t o ck i n g-r a t e i n t e r a c t ions
the t o t a l varia t ion .
i n t e rac t ions ( N S ) al so a c coun t e d for
a
S ir e
x
year
n e g l i g i b l e percen t a ge ( l e s s than
one) o f t he to tal var i a t i o n , a r e s u l t s imi lar t o that of Dun lop ( 1 9 6 2 ) .
Cont rary t o the above r e s u l t s , Ra e ( 1 9 5 8 ) r e p o r t e d s i gn i f icant s i re
year interac t ions in t h e t rait .
x
In the p r e s e n t inve s t i gat ion t h e r e
w e r e no s ign i f i cant d i f f e r en c e s between t h e h e r i t abil i t y e s t ima t e s
ob t a in ed b y two me thod s .
I t h a s been a s s umed t ha t s e l e c t i on f o r CHG i n New Z e aland Romney
is an ine f f ic i e nt way o f u s ing s e l e c t ion p o t en t i a l s in c e the her i t ab i l i ty
e s t imat e s rep o r t e d so f a r are o f low magn i t ud e (Wi ckham , 1 9 7 3 ) .
Howeve r ,
t h e h i gh e r e s t ima t e s o f i n termed i a t e ma gn i t ude in this s t udy sugge s t t h a t
t h ere i s a pos s ib i l i t y o f a c h i ev i n g s ome gene t i c improvemen t i n C H G b y
s e le c t ion .
167 .
Tippiness grade
Values c a l cu l a t ed f o r he r i t ab i l i t y o f TG we re 0 . 1 3
0 . 2 6 ± 0 . 1 7 in t h e C SR ;
0 . 22
±
0 . 0 9 and 0 . 2 2
±
±
0 . 09 and
0 . 2 7 ± 0 . 1 2 and 0 . 2 7 ± 0 . 1 2 i n the HSR ;
0 . 0 9 in the comb ined d a t a analy s e s r e s p e c t ivel y .
No p ub l i shed e s t imat e s are ava i lable f o r compar i son .
There we r e no s i gn i f i cant d i f f erences b e tween the e s t ima t e s in the
CSR and HSR.
S ir e x year int e r a c t ions ( NS ) exp lained 3 . 2 % of t h e t o t a l
var i a t ion in the C S R .
The s e int e r a c t ions were ab sent in t h e HSR .
The
di f f e rence ( 0 . 1 3 ) b e tween the e s t ima t e s o b t a ined by NEI and N i l me t h o d s
in t h e CSR was non- s i gn i f i cant .
None o f the i n t e r ac t i ons ( s i re x s t o cking r a t e and s i r e x y e a r
i n t e r a c t ions ) cont r ib u ted to the to t a l var i a t ion i n the c omb ined analy s i s ,
al tho ugh in the S ir e group 3 per iod , s i re x s t o ck ing r a t e and s i r e x year
int e r a c t i ons exp l a ined ove r 3% each o f the t o t al varian c e .
The
he r i t ab il ity e s t ima t e s ob t a i ned f rom the pooled d a t a we r e s imilar b y the
NEI and N i l me t ho d s .
In the p a s t t ip p ine s s has generally b e en a s sumed to b e l argely
d e t e rmined by gen e t i c f a c t o r s a l t hough proof o f t h i s wa s lacking
( Hende r s on , 1 9 6 8 ) .
Con t r ary t o the above , the e s t ima t e s o f h e r i t ab i l i t y
obt ained in t h i s s t udy sugge s t s that i t i s a lowly heritable f a u l t and
there i s n o t much s cope f o r improvement o f TG through s e l e c t i o n .
s eems t h a t t ipp ine s s in t he s e f locks o f sheep was mor e a r e s u l t o f
weathering and no t b e c ause o f inhe r i t e d var iab i l i t y o f f ib r e grow t h
rat e .
It
1 68 .
Hand le grade
The heri t ab i l i t y e s t ima t e s of HG computed in the pooled an alyses
we r e 0 . 3 0
±
0 . 1 3 and 0 . 6 6 ± 0 . 2 2 in the CSR ;
in t he H S R ;
resp e c t ively .
0 . 4 8 ± 0 . 1 1 and 0 . 4 8 ± 0 . 1 1
0 . 2 3 ± 0 . 09 and 0 . 4 2 ± 0 . 1 5 in the comb ined d a t a analys e s
Th e values d e r ived from the p r e s ent analyses comp a re we l l
with t h e heri t ab i l ity e s t ima t e o f 0 . 4 4 in the New Zeal and Romney by Rae
( 1 9 4 8 ) and are we l l wi thin the range of the est ima t e s f o r o t h e r b r eeds
repo r t ed in the l i t e r a t ure .
The r e we re no s i gn i f i cant d i f ferences b e tween t h e e s t ima t e s
ob t a i ne d i n the C S R and H S R .
The int r a- t r a i t gene t i c c or r e l a t ion be tween
the two s t ocking r a t e s was 0 . 9 0 ± 0 . 1 6 .
Th e d i f f er e n c e ( 0 . 3 0 vs 0 . 6 6 )
b e tween t he es t ima t e s by NEI and N i l me thod s in the C S R app ro a ched
s i gn i f i c ance ( O . O S < P< 0 . 1 ) .
S i gn i f i cant s ir e x year in t er a c t ions
( P < O . OS ) explained ove r 9 % o f t h e t o t al var i a t ion in the C S R .
Such
int e r a c t ions we re not app aren t i n the HSR d a t a .
I n t h e comb ined data ana ly s i s s ir e x s t ockin g r a t e int e r a c t ions (NS )
formed a n e g l i g lb l e fract ion ( 0 . 8 % ) of the t o t a l var i a t i o n , a f inding
s im i l a r to tha t of Dun lop ( 1 9 6 2 ) .
Such in t e ra c t i ons were e qual ly
unimp o r t an t in the ind ividual S i r e group p e r i o d an a ly s e s .
S igni f icant s ire x year i n t e r a c t ions ( P < O . OS ) accounted f o r 3 . 8% o f
t he t o t a l varia t io n i n the p o o l e d ana l y s i s f o r the comb i ned da t a .
The
d i f f er e n c e ( 0 . 2 3 vs 0 . 4 2 ) of t he her i t ab i l ity by two d i f f erent me thods
was l ar g e l y a t t r ib u t ab l e to t h e p r e s ence of s i gni f i cant s ir e x year
in t e r a c t ions in t h e comb ined data analy s i s .
However , t here was no
s ig n i f i c a n t d i f fe rence b e tween the two e s t ima t es .
HG d epends great ly
on subj e c t ive grading and t h i s is probab ly a maj o r f a c t o r l imi t ing t h e
169 .
h e r i t ab i l i t y .
To some extent the subj ec t iv i t y of t h e s e grades may b e
a f ac t or in t h e s i re x year i n t e r a c t ions s ince t h e gr aders chan ged be tween
years and d i f fe re n t graders may have emph a s ised sligh t ly d i f f e r en t f ace t s
o f h andle .
Lus t re gr ade
The corre s p onding e s t ima t e s of her i t ab i l i t y for LG in the p o o l ed
analys e s were 0 . 4 2 ± 0 . 1 6 and 0 . 4 2 ± 0 . 1 6 in the CS R ;
0 . 32
±
0 . 1 4 in the HSR ;
d a t a r e s pec t ive ly .
0 . 32
±
0 . 32
±
0 . 1 4 and
0 . 1 1 and 0 . 39 ± 0 . 1 2 in the comb ined
The s e e s t ima t e s are s l i gh t ly high e r than t h e value
of 0 . 2 7 repor t ed b y Rae ( 1 9 4 8 ) in New Zeal and Romney .
The re are no
o t her p ubl ished e s t ima t e s .
There were no s i gn i f icant d i f f e rences be tween the e s t ima t e s o f
h e r i t ab i l i t y ob t a ined in the C S R and H S R .
The intra- t ra i t gene t i c
c o r r e la t ion c a l c u l a ted b e tween the two s t o cking rates was 0 . 80 ± 0 . 1 5 .
S ir e x year i n t e r a c t ions were abs ent b o t h in the C S R and HSR
analy s e s .
Such i n t e r a c t ions were unimpo r t an t in the ind iv idual S ir e
g r o u p p e r iods exce p t in S i r e group 3 p e r iod whe r e in i t e xp l a ined 6 . 7 % o f
t h e t o t a l var i a t ion .
However , s i re x year interact ions could n o t
inf luence t he h e r i t ab i l i t y e s t ima t e s b o t h i n C S R and H S R p o o l e d analy s e s .
In the c omb ined d a t a analy s is s i re x s t o cking r a t e i n t e r a c t i o ns ( N S )
ac coun t ed for 1 . 9 % o f t he t o t al var i a t ion ;
exp l a ined 7 . 3 % o f the t o t a l vari a t ion .
unimp o r t an t .
in S ir e group 4 p e r i od i t
S i r e x year i n t e rac t io n s were
The sma l l d i f ference in t he two her i t ab i l i ty e s t i ma t e s
f r om the comb ined d a t a analy s i s was due t o t he e f f e c t o f s i r e x s t o ck in g
r a t e i n t e rac t ion s , which w a s n o t s i gn i f i c an t however .
170.
The her i t ab i l i t y e s t ima t e s o f int erme d i a t e magnitude in LG p o in t
t o t h e pos s ib i l i t y o f improv ing L G by s e l e c t ion ( i f the l us t re i s
s u f f i c i ent t o j us t ify cons ide rat ion i n s e l e c t i o n p l an� ) .
Greasy co lour grade
Her i t ab i l i t ies of GCG in the poo led ana l y s e s were 0 . 3 1 ± 0 . 1 0 and
0. 3 1
±
0 . 1 0 in the C S R ;
0. 22
±
0 . 0 9 and 0 . 4 1
±
±
0 . 34
0 . 1 4 and 0 . 4 4
±
0 . 1 6 i n t h e HSR ;
0 . 1 5 in the combined d a t a ana ly s e s r e sp e c t ively .
Th e only o ther New Zealand s t udy in Romney sheep ind i c a t e d that GCG wa s
no t h e r i t able ( Rae , 1 9 4 8 ) .
Rae ' s s t udy .
A sma l l numb er o f sheep wer e invo lved i n
Mul l aney e t a l .
( 1 9 7 0 ) found GCG to have me d i um
h e r i t ab i l i t y (Me r ino 0 . 2 9 - 0 . 40 , C o r r ie dale 0 . 2 9 - 0 . 4 1 , P o lwar th
0 . 24 - 0 . 38) .
Mo r ley ( 1 9 5 5 b ) repo r t ed an e s t ima t e o f 0 . 6 3 for GCG
in the Aus t r a l ian Me rino .
The he r i t ab i l i ty e s t ima t e s o f GCG in the C S R and HSR by NEI me thod
were almo s t iden t ical .
Th e d i f f e rence o f the e s t ima t e s ( 0 . 3 1 vs 0 . 4 4 )
b y N i l me thod i n the C S R and H S R was non- s i gni f i c ant .
The intra- t r a i t
gen e t i c correlat ion c a l c u l a t e d b e tween t h e two s t o cking r a t e s was
0 . 6 5 ± 0 . 2 1 ( deviat ion f rom un i ty , 0 . 0 5 < P < 0 . 1 ) .
P ro gr e s s f r om GCG
in C S R ( lower h e r i t ab i l i t y ) by sel e c t ing in HSR ( h i gh e r h e r i t ab i l i t y )
w i th N i l me thod would b e only three quar t e r s t h e r a t e o f improvement
o b t a in e d by d i r e c t s e l e c t ion .
S ir e x year intera c t ions were un impor t ant in the C S R .
h e r i t ab il i ty e s t ima t e s in t h e C S R we r e iden t i c a l .
The two
In the HSR analy s i s ,
s i r e x y ea r in t er a c t ions ( N S ) e xp l ained 2 . 5 % o f t he t o t a l var iat ion and
2 3% of t he t o t a l gene t i c var ian c e .
The d i f f erence b e t ween t he two
h e r i t ab il i ty e s t imat e s howeve r , was non - s i gn i f i c an t .
171 .
In the c omb ined data analy s i s , s i re x s t o ck ing r a t e interact ions
'
( P < O . O S ) exp l ained 2 . 4 % o f t he t o t al var i an c e and f o rmed 2 3 . 7 % o f the
t o t al gene t i c var i an c e .
S i re x year in t e r a c t ions (NS ) a l s o a c c o un t e d
f o r 2 . 2 % o f the t o t a l variance a n d 2 1 . 7 % o f t h e t o t al gene t i c variance .
The s e f indings a r e s imilar t o those o f Dunlop ( 1 9 6 2 ) .
The d i f f erence
of the her i t ab i l i t ie s ( 0 . 2 2 vs 0 . 4 1 ) b y two d i f ferent me thods was
non- s igni f i c an t .
Med ium he r i t ab i l ity e s t ima t e s o f GCG in this s t udy ind i c a t e t h e
pos s ib i l i ty o f ach i ev ing mo re wh i t ene s s i n Romney woo l b y s e l e c t i o n o f
GCG .
The ind i re c t s el e c t ion f o r GCG in woo l would not y i e ld wo r t hwhi l e
resul t s b ecause o f i t s weak gene t i c a s s o c i a t ions wi t h other w o o l t ra i t s
cons i dered t o b e o f importance i n s e l e c t io n p lans .
Scoured colo ur gr ade
The he r i t ab i l ity est ima t e s of SCG were 0 . 1 9 ± 0 . 1 1 and 0 . 3 9
in the C S R ;
0 . 30
±
0 . 1 2 ± 0 . 0 9 and 0 . 3 6 ± 0 . 1 5 in the HSR;
0 . 1 3 in the combined d a t a anly s e s r e s p e c t ively .
comp arable e s t ima t e s in the New Zeal and Romney .
±
0 . 20
0 . 1 0 ± 0 . 0 6 and
The re are no
Jackson ( 1 9 7 3 ) has
rep o r t e d an e s t ima t e of 0 . 2 0 in Aus t ra l ian Me r inos ( the only o t her s t udy
rep o r t e d i n the l i t e r a ture ) .
The e s t imat e s obt ained f o r SCG are l ower
than t he h e r i t ab i l i ty e s t ima t e s for GCG , p r e s umably b ec au s e o f a
gene t i cally inf luenced coloured contaminan t b e ing washed out during
scouring o r b ecause o f gre a t e r d i f f i c u l t y i n maintain ing s t andards
dur ing the visual g r ad ing of s coured woo l .
A l tho ugh t he h e r i tab i l i ty e s t ima t e s were h igher in the C S R than i n
the H S R , the d i f f e re n c e b e tween t h e e s t ima t e s w e r e non- s igni f i can t .
The gen e t i c var iance was reduced by the h i gher s t o cking r a t e e f f e c t
re sul t ing in the l ower est ima t e s o f h e r i t ab i l i t y in t h e HSR .
The
172 .
intra- t r a i t gene t i c cor relat ion b e twe en the t wo s t ocking r a t e s was
0 . 57
±
0 . 3 7 (deviat ion f rom un i t�, O . O S < P< O . l ) .
Th e ob s e rved
her i t ab i l i t ies by NEI methods w e re 0 . 1 9 and 0 . 1 2 in the C S R and HSR
resp e c t ive ly .
The ratio o f the ' c orre lated '
to the ' d i r e c t ' r e s ponse
e s t imat e d was 0 . 7 2 sugge s t in g that ind i r e c t s e l e c t ion wou ld b e l e s s
e f f i c ie n t t han t h e d i r e c t s e l e c t i o n i n H S R .
S ir e x year i n t e r a c t ions ( P < O . O S ) in t he H S R e xp l a ined 6 . 1 % o f the
total v a r i a t ion and 6 7 % of the t o t a l gene t i c varian c e .
The c o r r e s ponding
f i gur e s for s ire x year int e r a c t ions ( P < O . O S ) in the CSR were 5 and 5 1 %
r e sp e c t ive ly .
The ranking o f s ir e s may be very d i f f erent in various
y ears ind i c a t ing that the p e r fo rman c e of the progeny of a s i re wo uld not
b e h i gh ly r e p e a t ab l e .
In the c omb ined data ana ly s i s , sire x s t ockin g r a t e i n t e r a c t i ons (NS )
accoun t e d f o r 1 . 6 % o f the t o t a l var iat ion and 2 0 . 9% o f t h e t o t a l gene t i c
varian c e .
The corresponding f i gu r e s for s i gn i f icant ( P < O . O S ) s i r e x
y ear i n t e rac t ions we r e 3 . 4 and 4 5 . 7 % respe c t ively .
The h e r i t ab i l i t y
e s t ima t e s by NEI and N i l me tho ds were not s i gn i f i c an t ly d i f ferent .
The r e s u l t s in t h i s s t udy r eve a led that re sponse to s e l e c t ion f o r
S C G i s l ikely t o b e s low .
Discoloured area grade
Val u e s c alculated for h e r i t ab i l i ty of DAG by NEI and N i l me thods
were 0 . 04
±
i n the H S R ;
0 . 0 7 and 0 . 2 1
0 . 10
±
±
0 . 1 7 in t he CSR;
0 . 0 8 and 0 . 1 0
±
0 . 20
±
0 . 1 7 and 0 . 2 0
0. 17
0 . 08 in the comb ined d a t a r e s p e c t ively .
The s amp l in g e rrors were large b e c au s e o f the sma l l numb e r o f
observa t ions ava i lab l e .
±
There a r e no o th e r publ i shed e s t imat e s .
173.
There were no s i gn i f i c ant d i f ferenc e s b e twe �n the e s t imat e s ob t a ined
i n the two s t ocking r a t e s .
S i re x year in t e r a c t ions (NS ) c on t r ib u t ed
s l i gh t ly ove r 4% to the t o t al var iat ion in the CSR wh e r e as they were
ab s ent in the HSR .
As a cons equence , t h e two e s t ima t e s o f h e r i t ab i l i t y
w e r e d i f ferent ( N S ) i n C S R .
Wid e ly d i f f e r ing he r i t ab i l i t y es t imat e s were evident f rom t h e d a t a
i n t h e two individual S i r e group p e r iods analysed .
The e s t imat e s t hough
p o s i t ive had large s t andard errors in t h e S i r e group 3 p e r iod b o t h in
the CSR ( 0 . 0 9 ± 0 . 1 7 ) and HSR ( 0 . 4 2 ± 0 . 3 2 ) .
The corresponding
e s t imates in t he S i re group 4 p e r iod wer e -0 . 3 2 ± 0 . 3 5 and -0 . 09 ± 0 . 1 2 .
A s imilar t rend was ob s e rved in the ind ividual S i re group periods f o r the
comb ined da t a .
Th e values o f h e r i t ab i l i t y computed f rom the ind ividual
S i r e group p e r iods are of l im i t e d r e l iab i l i t y s ince sma ll d e gr e e s of
f r e ed om ( 9 and 6 in the S i re group 3 and 4 periods r e s p e c t ive l y ) were
ava i l ab le on wh ich t o b a s e a n e s t ima t e of var i an c e among gene t i c values
of t h e s i re s .
I t i s o f t en though t that scourab 1 e d i f fuse y e l l ow d i s c o l our a t ions
in wool are i nh e r i t e d (Hen d e r son ,
1 9 6 8 ) and this fault could be
c o nt r o l led b y b reed ing me thod s .
No wo r t hwh i l e e xamina t i o n o f the
gene t i cs o f the trait has b e en made so f a r .
Low he r i t ab i l i ty e s t ima t e s
f o r DAG in th i s s t udy su gge s t that l i t t l e gene t i c imp rovement can be
made by s e l e c t ion on th i s c r i t er i on .
Co t t ing grade
The es t ima t es o f h e r i t ab i l i t y for CG were 0 . 3 9 ± 0 . 1 5 and
0. 67
±
0 , 2 3 in the C S R ;
0 . 1 2 ± 0 . 1 0 and 0 . 1 2 ± 0 . 1 0 in the HSR ;
0 . 2 3 ± 0 . 09 and 0 . 2 3 ± 0 . 09 in the
comb ined d at a .
c omp ar ab l e e s t ima t e s i n t h e l i t e r a t ur e .
The r e are n o
1 74 .
The e s t ima t e s o f he r i t ab i l i ty d i f f ered w id e ly .
The re were
s i gni f i cant d i f f e rences ( P< 0 . 0 5 ) b e twe en the e s t ima t e s by N I I me thod in
the CSR and HSR b u t such d i f f e rences wer e non - s i gn i f i c an t b e tween the
e s t ima tes by NEI me thod .
S i g n i f i can t s ire x year i n t e r a c t ions ( P < 0 . 0 5 ) accoun t ed f o r 6 . 9 % o f
the t o tal var i a t ion and 4 1 . 5 % o f the t o t a l gene t i c var i a t ion i n t h e C S R .
Th i s resulted i n t h e d i f f e rence ( 0 . 2 8 ) o f t he h e r i t ab i l i t y e s t ima t e s by
two metho ds .
This d i f f e rence was howeve r , non- s ign i f i c ant b ec a u s e o f
th e large s t and ard error s .
S i r e x year interact ions were ab s e n t in the
HSR da t a .
In t he comb ined dat a , s ir e x s t o cking rate and s i r e
were ab sent .
x
year in t e r a c t ions
In t he ind ividual S i r e group analyses , the interact ions were
equally unimp o r t an t excep t in g S i re group 3 and 4 periods whe re they were
smal l in magn i t ude .
Co t t ing i s a s s umed t o b e a fault a s s o c iated wi th hered i t y , f ib r e
va r i ab i l i t y b e ing a he r i t ab l e t r a i t o f the sheep and with the env i ronment
through poor nut r i t ion and the p r e s ence o f mo i s ture ( Hend e r s on ,
1955) .
The l ow to med ium s i z e of h e r i t ab i l ity e s t ima t e s o f CG in t h i s s tudy
sugge s t that ve ry l imi ted gene t i c improvement is l ike ly to be a c h i eved
by s e le c t ion to c on t rol c o t t ing .
C o t t e d area grade
The he r i t ab i l i t y e s t ima t e s of CAG computed i n the pooled analys e s
wer e 0 . 3 7
±
in the HSR ;
0 . 1 5 and 0 . 5 3
0 . 23
±
±
0 . 1 8 i n the C S R ;
0 . 0 9 and 0 . 2 9
±
0. 18
±
0 . 1 1 and 0 . 2 7
0 . 1 1 in the comb ined d at a .
±
0. 13
No
p ub l i s hed e s t ima t e s are ava i l ab l e f o r CAG in the New Zealand Romney and
o th e r b reeds w i th wh i ch to c ompare the r e s u l t s ob t ained i n t h i s s t udy .
175.
Al th ough the h e r i t ab i l i t y e s t ima t e s we r e h i gher in the C S R than in
the H S R , no s igni f i c an t d i f f e r en c e s b e tween the e s t ima t e s were observed .
The gene t i c var iance was lowe r a t the h i gher s t ocking r a t e and t h i s
re s ul t ed i n t h e lower e s t ima t e s o f h e r i t ab i l i t y in t he HSR.
S ire
x
year int e r a c t ions ( N S ) con t r ibuted 4 . 6% t o the t o t al
varia t i on and f o rmed 3 4 � 3% o f the t o t a l gene t i c var iance in the CSR .
The c o r r e sponding f i gures in the HSR for such intera c t ions wer e 2 . 3 and
3 3 . 5 % r e s p e c t ively .
The her i t ab i l i t y e s t ima t e s in the C S R and HSR b y
NEI a n d N i l me thods d i f f e red non- s i gn i f i c an t l y .
The i n t r a- t r a i t
gene t i c co rrelation was c l o s e t o unit y .
I n t h e comb ined data an a ly s i s , s i re
x
s t ocking r a t e inter a c t ions
( N S ) c on t r ibuted 1 . 2 % to the t o t a l var iat ion and 1 6 . 3 % t o the t o t a l
gene t i c var ian ce .
S i re
x
year interact ions were ab sent b o t h in the
pooled a s well as the ind ividual S i re group perio ds .
The d i f f e renc e o f
the h e r i tab i l i t y e s t imat es ( 0 . 2 3 vs 0 . 2 9 ) by two me thods was
non- s i gn i f i c ant .
I t i s ob s erved that the h e r i t ab i l i ty e s t ima t es f o r C G and CAG are
comp arab l y lower in the HSR .
Th e gene t i c variance was r e duced by the
h i gh e r s t ocking r a t e e f f e c t r e s u l t ing in the lower e s t ima t e s o f
he r i t ab i l i t y .
S in c e CG and CAG do not re s pond gre a t ly , i t s e ems that
direct s e l e c t i on for the s e t r a i t s i s an ine f f ic ient way of us ing
s e le c t io n p o t en t i a l .
1 76 ·
S oundne s s grade
A l l e s t imat e s of the h e r i t ab i l i t y of SG were l ow , the e s t ima t e s
b e in g 0 . 2 2
0 . 16
±
±
0 . 1 3 and 0 . 2 2 ± 0 . 1 3 i n the C S R ;
0 . 0 8 in the combined data .
0 . 16
±
0 . 0 8 and
The e qu ivalent r e s u l t s in the H S R
data ind icated that S G was not he r i t ab le .
There a r e no o t h e r comparable
e s t ima t e s .
Env ironmen t a l variat ions we r e o f cons iderab l e impo r t an c e in the
pooled HSR analy s is ( reducing the gene t i c d i f f erences to a lmo s t z e ro ) .
The r a t i o o f the g e ne t i c to t o tal var i ance was much h ighe r in the C S R ,
sugg e s t ing t hat C S R was mo re f avou rab le f o r t h e exp r e s s i o n o f t h e gene t i c
differences .
S imilar trends we re r e co rded in the individual S ire group
perio d s analys e s .
The intra- t r a i t gene t i c correlat ion cal culated b e tween the two
s t o cking r a t e s was 1 . 0 6 ± 0 . 2 0 .
With the obs e rved h e r i t ab i l i t i e s o f
0 . 2 2 i n t he CSR and 0 . 0 0 in t h e H S R , the s e l e c t ion r e spons e o f S G could
only b e obt ained when s e l e c t ing the sheep in the C S R .
S i r e x year i n t e r a c t i ons we re absent in a l l t h e t h r e e p o o l ed
ana ly s e s .
S imilar t rend was
periods analy ses .
o b s e rved in t h e individual S ir e group
S ir e x s t o ckin g r a t e int e r a c t ions were o f no
consequence in the comb ined da t a .
Howeve r , t h ey con t r ibuted s l i gh t ly
ove r 4 % t o the to t al variation in the S i re group 4 p e r iod wh i l e i t wa s
ab s en t in the o th e r two period s .
Low e s t imat e s o f h e r i t ab i l i ty in SG reveal that there i s a l i t t l e
l ikelihood o f a l l evi a t i ng the maj o r f a c t o r s inducing unsoundn e s s in wo o l
by s e l e c t in g for S G .
177 .
INTER-TRAIT GENET I C CORRELAT IONS
The e s t ima t e s of the
gene t i c c o rrelat ions ob t a in e d in t h e pooled
analy s i s for the comb ined d a t a are p re s en t e d in Tab l e 1 8 .
The
l i t er a ture con t a in s l i t t le i n f o rmat ion on the gene t i c b a s i s o f
covar i a t ion among the var ious t r a i t s inve s t i ga t ed i n t h i s s t udy .
S in c e no o ther p ub l i shed e s t ima t e s are available for comp a r i s o n with
the p r e s e nt value s of gene t i c c o r r e l a t ions for c lean woo l we i gh t per
un i t a re a , t o t a l c r imp numb e r , t ippine s s grade , lus t r e grade , s coured
colour grade , d i s co l oured area grade , c o t t ing grade , c o t t ed area grade
and s o undne s s grade of wo ol , the f o l l owing d i s cu s s ion is ma inly con f ined
t o t he resul t s in this s t udy .
S ome o f the gene t i c corre lat ions ob t ained
in t h i s s t udy exceeded the the o r e t ic a l l imi t ing value of unity ;
errors n o doubt have cont ribut e d t o these result s .
s ampl ing
Al though t he
unc e r t a in t y ab out the real value ( large s t andard errors b e cause o f small
numb er of observa t i ons ) do not a l l ow d e f i n i t e conclus ions to be drawn
from the p resent e s t ima tes , an o u t l ine o f the gene ral p a t t ern o f d i r e c t
and c o r r e l a ted r e s p o n s e to s e l e c t i on w i th refe rence t o gene t i c
imp rovemen t o f hogget l ive-we i gh t , f l e e c e we i gh t , f inene s s , wh i t ene s s ,
c o t t ing and soundn e s s o f woo l can b e sket ched .
The her i t ab i l i t y r e s u l t s
used f o r th i s purp o s e are tho s e ob t a ined f rom the p o o l e d analy s is f o r
t h e c omb ined d a t a by N E I me thod p r e sented in Tab l e 1 6 .
The in f orma t ion avai lab le on the gene t ic corre lat i o n s among HLW
and wool t r a i t s in sheep , though o f cons iderab l e s i gn i f i cance ( e x t en t
a n d d ir e c t ion o f the correlated r e s ponses e xp e c t e d with HLW s e le c t ion ) ,
is s can t y i n the l i t er a ture .
As HLW is one o f the imp o r t an t t r a i t s in
s e l e c t i o n p l ans f o r the Romney s h e e p , it i s wor thwh i l e to d i s cus s wha t
wool t r a i t s may change i n the Romney f l o cks as a resul t o f s e l e c t ion f o r
HLW .
178.
TABLE 1 8 :
Gene t i c c o r r e l a t ions 1 and s t andard errors 2 among various t r a i t s
f r om t h e po o l e d analys i s o f variance and cova r i ance
Tra i t s
HLW
HLW
y
SL
TCN
CHG
TG
HG
LG
0 . 53
0 . 44
0 . 07
0 . 02
o . 2s
0 . 69
0 . 24
0 . 03
-0 . 02
0 . 04
0 . 43
0 . 18
-0 . 62
-0 . 4 3
- 0 . 32
- 0. 36
0 . 29
-0 . 5 3
- 0 . 44
0 . 53
-0 . 09
MFD
S FD
QN
0 . 50
0 . 02
0 . 55
0 . 37
0 . 14
0 . 58
0 .81
0.21
0 . 02
0 . 89
0 . 66
0 . 88
-0 . 2 3
0 . 03
0 . 33
0.41
GFW
WA
0. 11
0 . 22
0 . 06
0 . 98
GCG
SCG
DAG
CG
CAG
SG
0 . 29
0 . 30
0 . 26
-0 . 26
0 . 15
0 . 14
0 . 20
-0 . 84
- 0 . 20
-0. 19
-0 . 1 1
-0 . 7 9
0 . 50
0 . 53
0 . 74
0. 19
- 0 . 86
0 . 01
0. 13
-0 . 2 2
- 0 . 02
0 . 66
0 . 58
>1
0 . 15
-0 . 18
0 . 02
0 . 50
0 . 67
0 . 44
<- 1
0 . 10
0 . 22
0 . 36
0 . 07
-0 . 28
-0 . 6 1
-0 . 48
0 . 21
-0 . 06
-0 . 2 3
0 . 22
-0 . 10
0 . 02
0 . 46
0 . 40
0 . 93
0 . 54
0 . 36
<- 1
- 0 . 09
0 . 43
0 . 30
- 0 . 88
0 . 77
0 . 75
0 . 46
>1
>1
0 . 34
0 . 45
-0 . 7 3
-0 . 77
- 0 . 07
0. 13
<- 1
0 . 08
0 . 40
-0 . 4 7
>1
>1
0.61
0 . 97
-0 . 1 6
-0 . 84
0 . 02
0 . 27
0 . 50
0 . 58
0 . 57
-0 . 35
0 . 86
0 . 33
0. 88
-0 . 3 1
-0 . 87
0. 12
0 . 40
0.31
0. 71
0 . 68
0 . 14
0 . 54
0. 7 2
-0 . 6 6
<- 1
0 . 08
0 . 25
0 . 32
0 . 77
0 . 78
0 . 32
0 . 74
0. 13
0 . 25
0 . 57
0 . 20
0 . 36
0 . 63
0 . 60
0.01
<- 1
0. 21
0 . 26
0 . 89
0 . 77
0 . 78
<- 1
0 . 54
0 . 02
0 . 08
-0 . 06
-0. 50
>1
-0 . 57
-0 . 0 2
-0 . 4 3
-0 . 4 7
-0 . 44
-0 . 7 1
0 . 08
>1
0 . 37
0 . 65
-0 . 4 7
0 . 34
0 . 35
0 . 67
-0 . 44
0 . 17
0 . 44
-0. 19
0 . 99
0. 21
CPG
GFW
0 . 25
WA
0 . 25
0.01
y
0 . 26
0 . 24
0 . 05
SL
0 . 23
0 . 15
0 . 13
0 . 23
MFD
0 . 48
0 . 09
0 . 12
0 . 23
0.21
S FD
0 . 36
0 . 23
0 . 44
0 . 17
0 . 23
0.21
QN
0 . 12
0 . 23
0 . 24
0 . 19
0. 15
0 . 25
CPC
0.21
0 . 22
0 . 25
0 . 22
0 . 18
0 . 22
a
a
TCN
0 . 18
0. 12
0.21
0 . 22
0 . 22
0. 18
a
a
CHG
0 . 20
0 . 16
0 . 06
0 . 24
0.21
0 . 19
0 . 24
0 . 14
0 . 22
0 . 17
TG
0 . 27
0 . 26
0 . 27
0 . 26
0 . 16
0 . 25
0 . 24
0 . 02
0 . 06
0. 13
0. 12
HG
0 . 27
0 . 07
0 . 06
0 . 26
0 . 19
0 . 13
0 . 24
0 . 23
0 . 14
0 . 26
LG
0 . 24
0 . 23
0 . 25
0. 18
0 . 22
0 . 26
0. 11
0 . 07
0 . 06
a
0 . 23
GCG
0 . 25
0 . 25
0 . 27
0. 15
0 . 25
0 . 23
0 . 29
0 . 25
0 . 26
0 . 26
0. 18
0 . 28
0 . 28
0 . 27
SCG
0.31
0.31
0 . 32
0 . 26
0 . 28
0. 11
0 . 13
0 . 28
0 . 27
0 . 30
0 . 31
0 . 33
0 . 34
0 . 26
DAG
0 . 36
0. 13
0 . 38
0 . 32
0 . 09
0 . 26
0 . 25
0. 33
0 . 32
0 . 08
0 . 39
0 . 29
CG
0. 26
0 . 19
0 . 15
0 . 26
0 . 24
0. 11
0 . 29
0 . 16
0 . 13
0 . 10
0 . 16
0. 12
0.21
0.21
0 . 24
0 . 30
0 . 38
CAG
0 . 26
0 . 18
0. 18
0 . 25
0 . 24
0. 12
0 . 24
0 . 17
0 . 14
0 . 10
0. 17
0. 12
0 . 13
0. 16
0. 19
0 . 40
0.01
SG
0 . 29
0. 13
0 . 26
0 . 22
0 . 25
0 . 25
0 . 24
0 . 29
0 . 26
0 . 29
0 . 29
0 . 25
0 . 33
0 . 43
0 . 30
1
. 2
a
a
a
a
Gene t i c corre l a t ions a bove d iagonal
S t andard e r r o r s b e low d iagonal
Great e r than t h eo r e t i c al l imi t ing value o f un i ty
0 . 26
0 . 24
a
0 . 06
-0 . 2 9
0 . 26
a
a
0. 18
a
0.21
•
0 . 85
0 . 10
a
0.43
-0 . 99
0 . 01
179.
S l i gh t pos i t ive c o r r e l a t e d r e s p.on s e s wou l d be exp e c t e d in GFH w i th
HLW s e le c t ion b e caus e o f the low ( 0 . 1 1 ) gene t i c co rre l a t i o n s among t h e s e
The only o ther Romney e s t ima t e is much h i gher a t 0 . 5 4 ( T r i p at hy ,
traits .
1966) .
The r ange repo r t ed in the r evi ew for Me r inos i s - 0 . 0 3 to +0 . 2 6
which is mo r e i n agre emen t .
Sma l l po s i t ive r e sponses in body-we i gh t
dur ing s e l e c t io n f o r f l e e c e we i ght h ave been repor t ed b y Dun ( 1 9 58 ) and
Brown and Turn e r ( 1 9 6 8 ) con f i rming a s mal l p o s i t ive gene t i c c o r r e l a t ion
b e tween HLW and GFW .
E l l iot t ( 1 9 7 5 ) r ep o r t e d e s t ima t e s a t 0 . 1 8 in
Pe renda l e s .
A med i um- s i z e d p o s i t ive gene t i c c o r relat ion (0 . 5 0 ) wa s f ound f o r
HLW � i th SL and i s i n gene ral agreemen t w i th Mul l aney e t a l .
Po h..:r a rth a n d Bass e t t e t a l .
( 1 9 6 7 ) in Rambo u i l l e t .
ava ilable i n Romney was 0 . 2 1 ( T r i p a t hy , 1 9 6 6 ) .
( 1970) in
The o n ly es t ima t e
Mo s t o f the o ther
e s t imat e s in the l i t e rature were e i t h e r l ow p o s i t ive or negat ive .
If
the cor r e l a t i o n ob t a ined i n t h i s s t udy i s re a l , then i t wou l d b e u s e fu l
t o rely on HLW s e le c t ion for l o n g e r s t ap l e s .
S e l e c t ion f o r HLW is a
common way o f us ing s e l e c t ion p o t en t i a l and returns c an b e made in t e rms
o f both HLW and SL .
Conve r s e l y s e l e c t i on f o r inc reased s t ap le length
wo uld imp rove HLW at about two- th irds the r a t e ach ieved b y d i r e c t
s e l e c t ion .
Thi s s t udy p rovi des eviden ce t ha t s e l e c t i on for inc r e a s e d hogge t
l i ve-we i gh t wo uld r e s u l t in b e t t e r f l e e c e ch arac ter .
Mo r l e y ( 1 9 5 5 b )
a l s o ob t a ined p o s i t ive gene t i c cor r e l a t i ons o f intermed i a t e magn i tude
b e tween HLW and CHG .
Other e f f e c t s o f HLW s e l e c t io n s u g ge s t ed by the
e s t imat e s in this s t udy are inc r e a s e d var iat ion in f ib r e d i ame t e r ,
incre a s e d qua l i ty numb er and c r imp ing and mo r e lust r e .
180 .
C lean woo l we i gh t is the commercial c r i t e r ion of quan t i ty o f w o o l
and s e l e c t ion should h ave improvement o f c le an f le e ce we i gh t as a n
ob j e c t ive .
But the e s t imat ion o f c l e an woo l we ight ent a i l s e x t r a c o s t
and e f f o r t s in col l e c t ing and measuring a s amp le f o r percentage c l e an
yield .
Greasy f l e e c e we i gh t is a mo re e as i ly me asured c r i t e r io n and
i t s gen e t i c and phen o t y p i c c o r r e l a t ions with c l e an woo l we i gh t a r e b o t h
p o s i t ive ( 0 . 8 t o 0 . 9 ) as reviewed b y Turn e r ( 1 9 7 7 ) .
H i gh po s i t ive gen e t i c c o r r e l a t ions b e tween GFW x SL ( 0 . 5 8 ) and
WA x SL ( 0 . 6 6 ) were f o und .
S e l e c t ion f o r h i gher GFW wou ld resu l t i n
l onge r s t aples wh i l e s e l e c t ion for s t ap l e length would improve f l e e c e
weigh t at two-thirds t he r a t e ach ieved b y d i r e c t s e le c t io n .
The
e s t ima t e s for GFW x SL gene t i c co rrelat ions for New Zealand Romney are
w i thin the range ( 0 . 2 1 - 0 . 6 0 ) of the p revious e s t ima t e s r ep o r t e d b y Rae
( 1 9 5 8 ) and Tripathy ( 1 9 6 6 ) .
Es t ima t e s o f 0 . 70 and 0 . 7 6 have b e en
repo r t e d re � pe c t ively by Be a t t ie ( 1 9 6 2 ) in Me r inos and E l l i o t t ( 1 9 7 5 )
in P e r endales .
V e ry h i gh ne g a t i ve gene t i c correlat ions for GFW x HG ( - 0 . 8 4 ) and
WA x H G ( -0 . 8 6 ) s ugge s t that s e l e c t ion for h i gher f l eece we i gh t wou l d
r e s u l t i n harsh h and l e o f woo l .
E s t imat e s o f s imi lar magn i tude f o r
GFW x H G were a l s o reported b y Mu llaney e t a l .
( 1 9 7 0 ) i n Po lwa r t h ( - 0 . 8 7 ) ,
Me rinos ( -0 . 4 7 , - 0 . 7 0 ) and Corri edale ( - 0 . 5 3 ) .
Other co r r e l a t e d responses to be exp e c t ed in the woo l w i t h f l e e c e
we i gh t s e l e c t ion are le s s c o t t in g and l e s s e r suscep t i.b i l i t y t o b re ak .
S e l e c t ion for GFW c ould r e s u l t i n h i gh e r d e gree o f y e l l ownes s i n w o o l
b e c a u s e o f i t s ne gat ive gene t i c a s s o c i a t ions w i th GCG , SCG and DAG .
Negat ive gene t i c c o r relat i on s o f int e rme d i a t e magn itude f o r GFW x GCG
have also b een r e p o r t ed b y Mor l ey ( 1 9 5 5b ) and Mul laney et a l .
( 1970) .
181.
S el e c t ion for SL may r e sul t in mo r e t ipp i ne s s in woo l .
Th i s i s
e v i dent f r om t h e h i gh negat ive gene t i c correlat ions ( - 0 . 6 1 ) b e tween
SL x TG.
Other imp o r t an t corre l a t ed r e spons e s e xp e c t e d with SL
s e l e c t i on are decrease in QN and harsher hand l e of woo l .
The negat ive
gene t i c c o r r e l a t ions of i n t ermediate ma gn i t ude exist for SL x QN
( - 0 . 5 3 ) and SL x HG ( -0 . 4 8 ) .
Rae ( 1 9 5 8 ) r e p o r t e d the e s t imat e s f o r
SL x QN a t -0 . 7 3 ( DDR) and -0 . 7 6 (PHS ) i n t h e New Zealand Romney .
I f s e l e c t i on f o r f ineness in woo l was to b e cons idered , the very
h i gh p o s i t ive gene t i c c o r r e l a t ions for MFD x G�� ( 0 . 8 1 ) and MFD x WA
( 0 . 8 8 ) woul d h inder p r o g re s s .
The s e are in cont rast t o very sma l l
gene t i c c o r r e l a t ions o f QN with GFW ( 0 . 0 2 ) and WA (- 0 . 0 2 ) .
Trip a thy
( 1 9 6 6 ) and E l l i o t t ( 1 9 7 5 ) rep o r t e d values of MFD x GFW a t 0 . 5 8 i n New
Z e a land Romney and 0 . 4 4 in Perendales r e� � e c t ivel y .
The negat ive
gene t i c correlat ions b e tween QN and MFD was surpr i s ingly sma l l ( - 0 . 09 ) .
A med i um- s i z ed p o s i t ive gene t i c c o r r e l a t ion ( 0 . 4 1 ) was f ound f o r
HFD x SL .
Gene t i c corre l at ions o f s imilar magn i tude were r epor t ed by
o th e r worke rs ( S chincke l ,
19 5 8 ;
Tripathy , 1 9 6 6 ;
Ellio t t , 1 9 7 5 ) .
A
n e gat ive gene t ic correlat i on o f interme d i a t e magn itude ( - 0 . 5 3 ) b e tween
QN and SL suppo r t s the e s t ima t e ob t a ined for MFD x SL .
The gene t ic c o r r e l a t ions reported here s how the ant agon i sm f o r
a t t a inme n t o f a comb ina t ion o f heavier f l e e c e we i ght and longer s t ap l e s
w i th f in e r wo o l .
MFD has a very h i gh negat ive gene t i c c o r r e la t io n with HG , a f inding
s imilar to that o f Mul l aney et a Z .
( 1970) .
Th i s ind i c a t es the p o s s ib i l i ty
o f imp roving f inene s s by sele c t in g f o r s o f t e r handle .
The p ro g r e s s ·
would howeve r , b e 1 . 5 t imes as r a p i d i f s e l e c t i o n i s b a s ed o n me asured
f ibre d i ame t e r .
182 .
O t her adver s e cor r e l a t ed responses exp e c t ed with reduced MFD selec t io n
includ e s higher de gree o f f ib r e entanglement and l e s s sound woo l .
QN is p o s i t ively co r r e l a t ed ( 0 . 3 7 ) with HLW sugge s t ing the possib i l i t y
o f p o s i t ive correlated r e s p o n s e s with HLW s e l e c t ion .
Elliott ( 1 975)
ob t a ined s imilar gene t i c c o r r e l a t ions in Peren d a l e s b y the PHS met ho d .
B u t t h e ind i r e c t response t hr ough HLW wou ld be a lmo s t one-quart e r as
e f f i c ient as d i r e c t s e l e c t ion for QN .
As exp e c t e d a very h i gh pos it ive gene t i c c o r r e l a t ion was f ound
b e t w e en QN and TCN .
S FD is p o s i t ively c o r r e l a t ed ( 0 . 5 3 ) wi t h MFD .
Gj e d r em ( 1 9 6 9 ) a l s o
ob t a ined a very high ( 0 . 6 9 ) g ene t i c corre l a t ion b etween S FD and MFD thus
s up p o r t ing t h e e s t imat e o b t a ined in this s tudy .
S FD has b e en ob s e rved t o be very highly c o r re l a t ed w i t h TCN , indi c a t ing
the p o s s ibi l i t y of imp roving SFD through ind i r e c t se l e c t io n f o r reduced
TCN .
SFD i s also negat ive l y corr e l a t ed with HG ( - 0 . 7 3 ) and LG ( -0 . 7 7 ) .
The o t he r corre l a t e d r e s p onses expe c t ed wi t h s e l e c t ion f o r reduced
v a r i a b i l i ty are h i gher y i e l d , mo re sound and l e s s d i s co loured woo l .
Po s t - s couring colour ( d e gree o f whi t enes s ) i s s t a t ed by manu f a c t u r e r s
t o b e imp o r t an t s ince p u r e wh i t e woo l can b e d y e d t o any o ther c o lou r .
S C G i s very h i ghly p o s i t ively corre l a t ed ( 0 . 8 5 ) w i t h GCG , t hu s ind i ca t in g
t h e p o s s ib i l i ty o f improving SCG by s e l e c t ing f o r GCG .
I f t h e gene t i c
c o r r e lat ion b e tween t h e SCG and GCG is real ( t he her i t ab i l it i e s f o r SCG
and GCG being 0 . 1 0 and 0 . 2 2 respe c t ively ) , t h e ' co r r e l at e d ' r e s p o n s e
wou l d be s l ight ly mo re , i . e . , 1 . 3 t imes the d ir e c t r e spons e .
The c o r r e l a t ions o f S CG , excep t ing w i t h Y ( 0 . 4 4 ) , CPC ( 0 . 4 0 )
CAG ( 0 . 6 7 ) , S G ( - 0 . 4 4 ) and L G (- 0 . 4 3 ) a r e l ow w i t h o th e r t ra i t s .
183 .
x
Mo r l e y ( 1 9 5 5b ) r ep o r t ed e s t imat e s at 0 . 3 1 and 0 . 2 9 f o r GCG
GC G
x
CP I resp e c t ive ly .
Mu l l aney e t a l .
Y and
( 1 9 7 0 ) ob served h i gh gen e t i c
c o rr e l a t ions ( 0 . 5 9 - 0 . 8 2 ) f o r GCG x Y .
A very h igh pos i t ive gene t i c corre lat ion was found f o r GCG x DAG .
S in c e t h e h e r i t ab i l i t y f o r DAG is low ( 0 . 1 0 ) ,
it c an b e changed mo re
read i ly through ind i r e c t s e l e c t i on for GCG .
De s p i t e p o s i t ive gene t i c c o r r e l a t ion o f int erme d i a t e ma gnitudes
b e tween GCG
x
CH G ( 0 . 5 7 ) , no wo r thwhi le gene t i c improvement would be
p o s s ib l e in GCG through ind i r e c t s e l e c t i on for CHG ( t h e heri tab i l i t y o f
CHG b e ing 0 . 2 9 ) .
Mo rley ( 1 9 5 5b ) howeve r , ob s e rved a low gene t i c
c o r r e l at ion at 0 . 1 8 between GCG x CHG .
Lack o f t en s i l e s t rength i n f ib r e s a nd entanglement o f f i bres a r e
f a c t o r s cont r ib u t ing to f i b r e breakage during p r o c e s s ing ;
t h e reduced
f ib re l en g t h c an be o f con s i d e rable proces s i ng s i gn i f i cance (Wi ckham ,
1973) .
CG , CAG , S G , have a h igh p o s i t ive gene t i c c o r r e l a t ion with
GFW ( 0 . 5 0 - 0 . 7 4 ) and WA ( 0 . 5 8 - 1 . 0 ) .
S e l e c t ion f o r GFW o r WA ,,.;o u l d
r e s u l t i n l e s s cot t ing and mo re sound woo l by ind i r e c t s e l e c t ion .
S in c e the h e r i t ab i l i t ie s o f C G ( 0 . 2 3 ) , CAG ( 0 . 2 3 ) an d SG ( 0 . 1 6 ) are
c omp a r a t ive ly lowe r than G FW or WA , not much advan t a ge wou l d b e ob t a ined
b y d i re c t s e le c t ion f o r t h e t ra i t s .
S e l e c t ion for f l e e c e we i ght cou l d
b e r e l i e d on t o imp rove t h e t ra i t s i nd i r e c t ly .
H i gh p o s i t ive gene t i c c o r re l a t i ons exist b e twe en CG
x
and CAG x CHG ( 0 . 6 0 ) b u t t h e r e i s no correlat ion b e tween S G
CHG ( 0 . 6 3 )
x
CHG .
S e l e c t ion f o r CHG wou l d no doub t r e s u l t in a sma l l p o s i t ive c o r r e l a t e d
r e s p onse f o r l e s s cot t in g b u t i t would b e about th r e e- quar t e r s as
e f f i c ient as d i re c t s e l e c t ion .
1 84 .
CG and CAG are nega t ively c o r r e l a t e d gene t ic al ly ( - 0 . 44 and -0 . 7 1 )
with LG , and there are ind i c a t ions o f improving co t t ing ind i re c t ly by
s e l e c t in g for lowe r LG .
The r e are ind i c a t ions that f r eedom f rom c o t t ing can b e imp roved
ind i r e c t ly by s e le c t ing for CPC or TCN a s the gene t ic c o r r e l a t ions f o r
C G and CAG wi t h CPC and TCN b o t h a r e h i gh ( th e her i t ab i l i t i e s f o r CPC
and TCN b e ing 0 . 64 and 0 . 7 0 r e s p e c t ively ) .
I f the c o r r e l a t ions
b e tween the t ra i t s are real , the r a t io of t he ' correla t ed ' response
through T CN s e l e c t ion t o t h e d i r e c t r e sponse i s about 1 . 3 6 .
From the
gene t i c c o rr e l a t i on s i t app e a r s t h a t s e l e c t ion f o r TCN would a l s o r e s u l t
in f avourable changes i n HLW , GFW , WA , TG , co lour and s oundne s s but
y i e ld , l u s t re and s o f t ne s s would d e c l ine .
Surp r i s ingly b o t h the me an
and var i a t ion in f ib r e d i ame t e r wo uld increase wh i l e t h e qu a l i t y number ,
CPC and LG would sugge s t t h a t t h e woo l was g e t t ing f ine r .
S i n c e CG , CAG and SG are a l l p o s i t ive l y corre l a t e d ( 0 . 4 6 - 0 . 7 7 )
w i t h MFD , s e le c t io n for f iner mean d i amet e r would adve r s e ly a f f e c t the s e
t ra i t s b u t s e l e c t i on f o r reduced SFD would imp rove s oundne s s ( t he
gene t i c corr e l a t ion b e in g - 0 . 4 7 b e tween SFD and SG) .
CG and CAG are
p o s i t ive ly correlated ( 0 . 5 8 and 0 . 5 7 ) with QN whereas a negat ive
c o r r e l a t ion of med ium s i z e ( - 0 . 3 5 ) exis t s with SG .
185 .
CHAPTER S IX
CONCLUDING D I SCUS S ION ON PRACTI CAL IMPLICAT IONS
Gene t i c gains from s e l e c t ion within a f l o ck or wi t h in a b r e ed
depend mainly on the he r i t ab i l i t y o f t he char a c t e r i s t i c s unde r s el e c t ion ,
on t he numb er of t hem con s i d e r e d in the s e l e c t ion obj e c t ive ( the g r e a t e r
t h e numb e r o f charac t e r i s t i c s cons idered , the l e s s t h e p r o g r e s s i n any
one o f t hem ) and t he gene t i c co r r e lat ions b e tween t hem .
E s t ima t e s o f
he r i t ab i l ity o f a cha r a c t e r a r e norma l l y mad e within a s ingle macro­
env i ronmen t ;
i t i s usually a s s umed t ha t the micro- f luc t uat ions o p e r a t e
independen t ly o f t he gene t i c va r i a t ions , and t hat t he t w o comb ine t h e i r
e f f e c t s add i t ively .
In New Zealan d , i t is common prac t i c e t o breed and s e l e c t rams o n
s tud f arms wh ich provide relat ive ly g o o d env i ronmental cond i t ions , above
average husb andry and managemen t and op e r a t e at low s t o cking r a t e s to
ensure adequate l ev e l s o f f ee d in g .
The progeny o f t h e s e r ams a r e
exp e c t e d t o produce s a t i s f a c t o r i l y over a w i d e range o f env i ro nme n t s and
s t o cking r a t e s but usually at l ower leve l s of f e eding and poorer
husb andry .
Rams s e le c ted f o r b r eed ing are normally u s e d over several
years and the ir p ro geny are expo s ed to y e ar- t o-year variat ions i n
environment .
The p r e s en c e o f s i re x s t o cking r a t e and s i r e x year
i n t e r a c t ions thus h ave imp l i c a t i ons in comme r c ial b r e ed ing .
The u sual
her i t ab i l ity e s t imat e s based on t he ana ly s e s o f s i r e- e f f e c t s ne s t e d
within y ears and a t one p ar t i cu l a r s t o cking l evel a r e t hu s n o t ent i r e l y
approp r i a t e f o r use in t h e f o rmul at ion o f s e l e c t ion p l ans ;
t he average
gene t i c d i f f erenc e s c an b e ove r e s t imat ed thus reduc ing t he e f f e c t iven e s s
o f s e l ec t ion .
Thi s may l imit t he rat e o f gene t i c imp rovement .
186.
Th e r e fore t he he r i t ab i l i t y e s t ima t e s app l i c ab l e under t he comme r c i al
cond i t ions may we l l requ ire cons idera t i o n o f t h e s e random int er a c t ions
to i ncreas e the e f fec t ivene s s o f s e l e c t i o n .
The concep t o f p r e d i c t in g
b r e e d in g values a c cura t e ly when s i r e x s t o cking rate or s i r e x year
in t er a c t i on s are presen t thus needs cons iderat ion before d i s c us s ing the
ap p l i c a t i on of the resu l t s in the s t udy .
Supp o s e the ma t hema t ical mo de l und e r ly ing the analy s i s o f the d a t a
is :
y l. ]. k
]..1
+ a l· + 8 J· + ( a B ) l· J· + e l· J· k
wher e , as s uming f o r s imp l i c i t y equal s ub c lass numbers
. . . . . a
j
. 1 , 2 , . . . . . b and k
i
1, 2,
]..1
mean o f a l l r e c o r d s o f a charac ter
1, 2,
..... n
the e f f e c t of i t h s i r e
the e f f e c t o f j t h s t o ck ing r a t e o r j th year
the e f f e c t s o f i n t e r a c t ion be tween s i r e and s t o cking
r a t e or s i re an d y e ar
y l. J. k
the obs erva t ion on the kth individual maint a ined on
j t h s t ocking r a t e or j th year and daugh t e r of
the i t h s ir e
is t h e random error p e culiar t o ij k t h ob s e r v a t ion
and f o l l ows NID ( 0 ; 0 2 )
I t w i l l b e a s s umed that b j are f ixed e f f e c t s whereas a i and ( a B ) ij and
r an dom e f f e c t s w i th var i ances 0 2 and 0 2
a
aS
The p r e d i c t i on o f breed ing val u e s b y b e s t linear unb ia s e d pred i c t ion
a s s uming the var iance componen t s are known , i s worked out o n the f o l lowing
bas is :
187 .
1.
When o 2
=
aB
0 , the regress ion coe f f ic ient in the pred i c t ion o f
g iven the s amp le is as f o l lows
nbo 2
o2
a
et
o2
e
2
o +
a
bn
2.
When o
�B
o 2 + nb o 2
e
a
I 0 and i t is r e q u i red to r ank the sires a c c o r d ing t o
I f , for
knowledge o f the i r l ike ly u s e over t h e s t ocking rat e s .
examp l e , t h e s i r e s a re t o b e u s e d equally over all s t ocking ra t e s ,
1
one wo uld r ank on the bas is o f pred i c t ion o f a . + b
l
t represen t s
L
j
( a B ) . . , where
lJ
the f r a c t i o n o f the f u t ure pro geny in t h e j t h s t o cking
In the case o f d a t a w i t h une qual sub c l a s s numb e r s , the
rate .
a. +
on
ranking of s ires is based
l
L
A .
(a B ) . . , whe r e
lJ
J
j
A .
J
r e p r e s en t s
the f r a c t ion o f fut ure progeny in t h e j th env i ronment a l s i t ua t ion .
The r e g r e s s ion coe f f i c ie n t in the p r e d ict ion o f a . +
l
1
b
-
given the s amp le is as f o l l ows
o2 +
a
a2
aB
b
o2
a2
2
�
0 + � +
b
bn
et
nbo 2
a
+
o 2 + no 2
aB
e
L
.
J
(aB) . . ,
lJ
no 2
aB
+
bno 2
a
The u s e o f the above regre s s ion co e f f i c i ent a s s umes t h a t t h e
env ironmen t a l e f f e c t s ( i . e . , s t o cking r a t e s ) wh ich o c curred in the
samp l e were the same as tho s e f o r which the s i r e s are t o be s e l e c t ed .
3.
When o
�B
I 0 and in co n t r a s t t o the 2 . above i f t h e Bj r e p r e s e n t the
' year ' e f f e c t s and the s e l e c t e d s i res are to b e u s ed i n ano t h e r set
of ' ye a r s ' .
As the ' ye ar s ' and s ire x y ear e f f e c t s wh i c h w i l l
o c c u r in t h e f u t u r e a r e unp r e d i c t ab l e , t h e s ir e s can only b e r anked
on the i r general comb ining
ab i l i t y (a . ) .
l
In mo s t r am b reeding
f locks , i t is very d i f f i c u l t t o p r e d i c t the s t o cking r a t e s at wh i ch
1 88 .
t h e p ro geny o f rams s o l d from the f l ock wou l d be e xp e c t e d t o p e r f o rm ,
t h i s procedu re would apply t o s t o ck ing r a t e s a s we l l as years .
The regre s s ion coe f f i c ient in the pred i c t ion o f a , given the
i
s amp le is a s fo l lows
a2
a
a2
nbo 2
a
a2
a2 + � + �
b
a
bn
a 2 + no 2 + bno 2
e
aB
a
Th e above regre s s ion co e f f i c i e n t s in 2 . and 3 . above may b e
wr i t t en in t e rms o f h e r i t ab i l i t i e s .
The he r i t ab i l i t i e s by two
me thods (NEI and H l l ) given e a r l i e r in chap t e r 5 are in t h e present
s i tua t ion a s f o l lows
and
Now the regre s s ion c o e f f i c ient for 2 . above is as f o l lows
b n h 2 + n (h 22 - h 2 )
1
1
1 + ( n - 1 ) h 22 + (b n - n ) h
t
The s e cond term in the nume r a t o r o f t h e regr e s s ion co e f f i c i ent
g iven above e x i s t s bec ause o f the a s s ump t ion that B . s t o ck i n g r a t e
J
e f f e c t s are f i xe d and thes e s ame e f f e c t s are p r e s e n t f o r wh i ch the
s ires are to be s e l e c ted .
But whe n the B . rep r e s en t s ' year ' e f f e c t s
J
and s ir e s a r e t o be s e l e c t e d for u s e in another s e t o f y e a r s , the
s e cond t e rm in the nume r a t o r should be d e l e ted in comp u t i n g
regr e s s i o n c oe f f i c i ent s .
The p r e s e n t s t udy was unde r t aken w i t h the maj o r obj e c t ives o f
d e t e c t ing a n d evaluat ing the r o l e p l ayed b y s i re x s t ocking r a t e and
s i re x year i n t e r a c t ions on various e s t ima t e s of her i t ab i l i t y o f
c haracters o f e c onomic impo r t ance ( i . e . , HLW , wool quan t i t y and qual i t y
t ra i t s ) in N ew Zealand Romney hogget s .
Howeve r , i n the app l i c a t ion o f
t he s e resul t s t o f i e l d cond i t ions , i t i s above all , n e c e s sary t o assume
1 89 .
that gene t i c and environment a l r e l a t ionships in o t her Romney f l o cks are
s imi l ar t o tho s e in t he present f l o ck .
B e f o r e d i s cu s s in g the p r a c t ical app l i c a t ions o f t h e s e f indings on
the s heep and woo l improvemen t in the New Zea land Romney , i t is n e c e s s a ry
t o d e f ine t he pr e s en t obj e c t ives and t he r e l evan t s e l e c t ion c r i t e r i a
invo l ve d .
The s e l e c t ion obj e c t ive s
in
a p a r t icular s e l e c t ion g r o up o f
sheep depend on t he end use o f t he produc t .
In t he New Zealand Romney ,
a d u a l p urp o s e sheep , HLW and f l e ece weight are imp o r t an t s e l e c t ion
obj e c t ive s .
The
Good c o lour i s des i red in t he general purp o s e wo o l s .
o t h e r s e le c t ion c r i t e r i a cons idered impor t an t for the imp rovemen t o f wo o l
q ua l i t y include s o undne ss and f r eedom f rom c o t t ing .
a t t a ched t o chan g ing f ibre d i ame t e r (NZ SAP ,
No value i s
1974) .
The evi dence pre sent ed i n t h i s s t ud y sugge s t s s t rongly t ha t s i re x
s t o c king rate i n t e r a c t ions are rea l f o r HLW .
Such interac t ions
howev e r , are of n o import ance in t r a i t s concerned with woo l p r o duc t i on .
S i g n i f i c ant s i re x s t o cking ra t e in t e r a c t ions we r e f ound b o t h f o r mean
and var i a t ion in f i b re di ame t e r , TCN and GCG o f wool .
S i r e x s t o c k ing
rate in t e r a c t ions we re however , unimp o r t an t in o t her woo l q ua l i t y t r a i t s .
S i re x year in t e ract ions we re h i ghly s i gn i f i can t b o t h f o r HLW and
G� .
Su ch int e r a c t ions were a l so o b s e rved s i gn i f icant in SCG .
The
only o ther woo l q u a l i t y t ra i t (measured or subj e c t ively a s s e s sed )
a f f e c t ed by t h i s r andom source o f var i a t ion was HG .
The presen c e o f s i re x s t o cking r a t e and s i re x year in t e rac t ions
in HLW has clear imp l i c a t ions in comme r c i a l b r e ed ing pra c t i c e .
The
r e s u l t s f r om t h e s t udy s ugge s t ed that the low ( C SR) s t o cking r a t e is
mo r e f avo urab l e f o r the e xp r e s s ion of t he gene t i c d i f f e r e n c e s in HLW .
1 90 .
The gene t i c var i an c e wa s re duc ed by the h i gh s t ocking r a t e thus r e s u l t ing
i n the lowe r e s t ima t e s of her i t ab i l i t y .
The impor t an c e o f t h i s
i n t e r a c t i on w a s f u r t her demonst r a t e d b y t h e low int ra- t ra i t gene t i c
correlat ion b e tween the two s t o c king rat e s .
The s t udy f ur ther
s ub s t an t i a t e d t h a t d irect s e l e c t ion in the ind ividual s t o ck in g r a t e
wo uld yield b e t t er gene t i c gains ( 1 3 % by NEI and 2 8 % by N i l me t h o d s
r e sp e c t ively i n H S R ) than ind ir e c t s e l e c t ion i n othe r s t o cking r a t e .
This means that t he cur rent pol i cy o f s e le c t in g breeding r ams a t t h e
s t ud breeder ' s f arm at low s t ocking r a t e a n d in above-ave rage husbandry
and manageme n t f o r use over a wide r ange o f high s t ockin g r a t e s wou l d
s ever l y reduce the ef f e c t iven e s s o f s e l e c t ion .
No doub t , the only
s a f e course i s to s e le c t the rams a t the ' c ommerc ial ' s t ocking r a t e but
t h i s has prac t i c a l prob l ems and l imi t a t ions .
I t is thus sugge s t ed that
wh i l e e s t imat in g he r i t ab i l i ty for us e in the f ormulat ion o f s e l e c t ion
p l ans , it i s e s s en t i a l to t ake into accoun t the imp a c t of the s ir e x
s t o cking rat e i n t e r a c t ions in HLW .
The average redu c t ion in e xp e c t e d
g a ins would b e o f much consequence in s e l e c t ion because o f the d e c rease
i n he r i t ab i l i t y .
S ire x s to cking r a t e int e r a c t ions a r e of very sma l l magn i t ud e f o r
GFW .
The s e r e s ul t s are suppor t e d by the absence o f such int e r a c t ions
i n characters c l o s e ly rela t ed to f l ee c e we i ght .
Fur ther evidence o f
t h i s observat io n was provided b y a very l arge intra- t r a i t gene t ic
c o rr e la t ion b e t ween the two s t o cking r a t e s .
The much sma l l e r s i r e x
s t o ck in g rat e in t e r act ions in GFW ind i c a t e that s e l e c t ion o f r ams in one
s t o cking r a t e f o r use in the o t he r is un l i kely to hinder gen e t i c p rogre s s
a n d the decrease i n he r i t ab i l i t y as a r e s u l t o f i t w i l l b e o f n o
c on s e quence .
191 .
S ir e x year i n t e r a c t ions cont r o l led over 4 % o f t h e t o t a l var i a t ions
in HLW and GFW .
Und e r the condi t ions , as t h e s i res s e l e c t ed are u s e d
ove r a number o f y e a r s , i t i s n o t f e a s i b l e t o nar row down t h e
envi ronmental f l u c t u a t ions that make u p the y e arly e nvironment .
The
only p r a c t i cal me asure sugge s t ed by the f inding o f s ignif i c an t s ir e x
year in t er a c t ions i s c ons ide r a t io n o f i t s e f f e c t on the h e r i t ab i l i t y
e s t imat e s and pred i c t i o n o f b reed ing values wh i l e f o rmul a t ing s e l e c t ion
p l an s for HLW and GFW .
S ir e x s t o cking r a t e interac t ions o f mod e r a t e ma gn i t ud e have b e e n
f ound s i gn i f i c an t f o r MFD , S F D and TCN .
In t he New Zealand Romn e y a s
s e l e c t ion for f ib re f i nene s s is s e ldom p r a c t i c ed (be cause o f v i r t u a l l y
n o p r ic e d i f feren t i a l for f inene s s i n wo o l c o a r ser t han 3 3��) such
int er a c t ions are of no economic impor t anc e .
The low s t o cking r a t e ( C SR)
was mo r e f avourable for the e xp re s s ion of t h e genet i c d i f f erence s .
S ir e x year int e r a c t ions were r e l a t ively l e s s impo r t an t in t h e s e t r a i t s .
S i re x year i n t e r a c t ions of interme d i a t e magn i t ud e in s ubj e c t ively
a s s e s s e d t ra i t s of woo l in SCG , GCG and HG could result f rom t h e p r o b l ems
o f s ubj e c t ive a s s e s sment .
D i f f i culty in main t a ining s t andards o f v i sual
grading f r om year to y ear and t e chnic i an var i a t ion are t h e l ikely c a u s e s
o f such interac t io n s .
Graders c hanged b e tween years and d i f f e r e n t
g r ad e r s may have p u t emphas i s o n s l ightly d i f f er ent f a c e t s o f co lour and
hand l e .
S ire x s t o c k ing r a t e i n t e r a c t ions were r e l a t ively unimp o r t an t
f o r t h e s ubj e c t ively a s s e s s e d t r a i t s ( excep t ing GCG ) i n woo l .
Such
int e r a c t ions in GCG , n o doub t r e a l , cont r ib u t e very l i t t le t o t h e t o t al
var i a t i o n .
The d e c r ease in her i t ab i l i t y w i l l be sma l l .
A mor e comp l e t e a s s e s smen t o f the app l i c ab il i t y o f the r e su l t s
r e q u i r e s consider a t i o n o f the he r i t ab i l i t y e s t imat e s and t h e gene t ic
1 92 .
correlat ions among the t r a i t s s t ud ied .
I t may b e no t ed that mo s t o f
the s ubj e c t ive ly a s s e s s ed tra i t s in wool are o f l ow t o mo dera t e
h e r i t ab i l i t y .
Al tho ugh the he r i t ab i l i t y e s t ima t e s in t h i s s t udy f o r SCG we re o f
i n t e rme d i a t e magn i tude b y N i l me thod , the pre sence o f s i gn i f i can t s i r e
x y e a r int era c t ions ( over 5 % o f t h e t o t a l v a r i a t ion) reduced t h e average
gene t i c d i f f e renc e s t o a great exten t .
The evid ence p r e s e n t ed in the
s t udy sugge s t s that there is s ome p o s s ib i l i t y of achieving mo re wh i t en e s s
i n the New Zealand Romney wo ol b y s e l e c t ing f o r GCG whe reas t h e respons e
·
to s e l e c t ion for SCG i s r elat ively very low .
As SCG i s very h i ghly
correlated with GCG , the ' c orrelated ' response to s e l e c t ion for SCG would
b e s l i gh t ly mo re , i . e . ,
1 . 3 t ime s the d i rect response .
It i s , as we l l ,
e a s i e r t o u s e GCG as s e l ect ion c r i t e r i a f o r wo o l colour .
C G , CAG and SG do not res pond much to d i r e c t s e l e c t ion .
Thus t h e
maj or f a c t o r s induc in g c o t t ing and lack o f s t rength in wool canno t b e
a l leviated e a s i l y by d i rect s e l e c t ion .
S e l e c t ion f o r f l e e c e weight
could b e rel ied on t o improve these t r ai t s ind i rect ly .
The se t ra i t s
a r e b e s t dealt w i t h changes i n mana gement ch i e f ly b y t ime o f shearing in
New Zealand Romney .
Fleece char a c t e r i s f r equen t l y cons idered in s e l e c t ion by she e p
farme r s , many o f whom b e l i eve i t t o b e h i ghly h e r i t ab le .
The p r e s en t
e s t ima t e s r e in f o r c e s e a r l i e r ob s e rva t ions t h a t i t i s only o f l ow t o
mod e r a t e h e r i t ab i l i ty .
S imilarly t i ppine s s , one o f the component s o f
f l e e ce charac t e r , has h e r i t ab i l i t y e s t ima t e s o f s imilar magn i t ude .
The h i gh her i t ab i l i ty e s t ima t e s o b t a ined for TCN d e s e rve s men t i o n .
The evidence p r e s e n t e d in t h i s s t udy has sugge s t ed that s e l e c t ion f o r
1 93 .
TCN would resu l t in f avou rable changes in HLW , f l e e c e we i gh t , colour ,
c o t t in g and soundne ss - a d e s i rab le combinat ion in the New Zealand
Romney hogge t s .
194 .
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