Title:Breeding Gilt Evaluation

Livestock Judging: Breeding Gilt Evaluation
Supplement for CEV #473
Livestock Judging: Breeding Gilt Selection
Supplement for CEV #473
Goal:
To introduce the desired phenotypic traits, performance records, and
purpose of breeding gilt evaluations.
Objectives:
1. to define the major factors necessary to select replacement
gilts in a commercial operation
2. to be able to analyze and interpret a set of performance
records with specific reference to positive and negative
numbers
3. to evaluate and defend the placing of a breeding gilt class
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Livestock Judging: Breeding Gilt Selection
Quiz I
Short Answer
1. Why is structural soundness of major importance in breeding gilt evaluation?
2. When watching a gilt travel, what are the indicators of a functional rear leg?
3. What management problem would be represented if the dewclaw were touching the
surface when the gilt traveled?
True or False
___4. A sow is expected to produce 4-5 litters in confinement situations.
___5. Small toe size is desirable in replacement gilts.
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Livestock Judging: Breeding Gilt Selection
Quiz II
True or False
___1. An up-turned vulva is desired when selecting replacement gilts.
___2. A short, thick, coarse head is an indicator of a feminine gilt.
___3. An inverted nipple is a non-heritable trait.
Short Answer
4. Name the three factors that indicate a gilt is feminine.
5. Define the following terms or describe how it effects gilt evaluation.
a. Pin nippleb. Small vulvac. Ideal nipple shape-
Discussion
6. Is the old quote, “you’re as useless as the teats on a boar hog,” true in livestock
evaluation? Why?
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Livestock Judging: Breeding Gilt Selection
Quiz III
Discussion
1. Why is bone diameter and length important in breeding gilt selection?
True or False
____2. Bolder ribbed, wider skeletoned gilts are usually heavier muscled.
____3. Arch, spring, and curvature of the ribs are qualities of an ideal breeding gilt.
____4. Gilts should not be excessively deep bodied.
____5. Breeding gilts should exhibit an extremely refined bone structure.
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Livestock Judging: Breeding Gilt Selection
Quiz IV
Short Answer
1. Define composition.
2. Where is fat depth measured?
3. What is the shape of an ideal breeding gilt?
True or False
____4. Blade action is a direct indicator of both muscling and leanness.
____5. A groove down the top is desirable in replacement breeding gilts.
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Livestock Judging: Breeding Gilt Selection
Quiz V
True or False
____1. A gilt with a backfat EPD of -.10 would be expected to produce offspring
with .10 inch less backfat than the average gilt.
____2. Positive EPD’s are more desirable for 21-day litter weights and days to 230.
Short Answer
3. Define EPD.
4. Label the following EPD factors by indicating which are positive (+) and negative (-)
traits.
____ * Days to 230
____ * 21-day Litter Weight
____ * Number Born Alive
____ * Backfat
Discussion
5. How are EPD’s used as a tool to make sound management decisions?
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Livestock Judging: Breeding Gilt Selection
Quiz VI
Scenario: These Yorkshire gilts will be bred to Landrace boars to produce Landrace x
Yorkshire crossbred gilts. These Landrace x Yorkshire gilts will be the sow line to be mated to
terminal line boars in a terminal crossbreeding system with all offspring marketed. Structural
soundness and maternal traits are emphasized. Consider all underlines to be sound.
No.
1
2
3
4
Number
Born Alive
- .3
+ .4
+ .5
+ .6
21-Day
Litter Weight
- 1.0
+ 5.1
+ 7.4
+ 2.3
Backfat
+ .01
- .02
- .03
+ .02
Day/230
+ 2.5
- 7.0
+ 1.0
- 4.0
Short Answer
Write the number for the gilt you choose.
1. Which gilt was the most structurally sound?
2. Which gilt ranked first in sex character?
3. Which gilt ranked first in size and scale?
4. Which gilt was superior in composition?
5. Between 1 and 4, which gilt had the most desirable performance data?
6. To what breed of boars will these gilts be bred?
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7. Which gilt is the most structurally unsound?
8. Between 3 and 1, which gilt had the most desirable performance data?
9. Between 2 and 4, which gilt had the most extension of skeleton?
10. Between 3 and 4, which gilt was the most feminine?
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Livestock Judging: Breeding Gilt Selection
Final Quiz
Short Answer:
1. List the major factors in breeding gilt evaluation.
2. In terms of structural soundness, describe the ideal breeding gilt.
3. In relation to production and longevity, why is structural soundness important?
4. What problems may arise from a fat uddered gilt?
5. List the common defects/flaws that arise in underlines.
6. With the wide use of artificial insemination in modern pork production, why is it
important to discriminate against vulva defects?
7. Why are performance records an integral element in the swine industry?
8. What factors are considered when discussing size and volume?
9. Why is breeding gilt evaluation important?
10. How did you place the Yorkshire gilt class? Defend your placing.
(use back of this page or another sheet for defense)
11. Why is it imperative for EPD’s to be negative in backfat and days to 230?
12. With both performance and phenotypic traits considered, why did 1 place over 4 in
the Yorkshire gilt class?
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Livestock Judging: Breeding Gilt Selection
Terminology
Phenotype: The appearance and function of an animal as a result of its genotype and
environment.
Genotype: Genetic constitution of an individual.
Number Born Alive: The number of pigs born; a maternal trait.
21-Day Litter Weight: An indication of the dam’s milking and mothering ability. This is the
weaning weight. Positive EPD numbers are desired.
Days to 230: A measurement of growth. The number of days required to reach specified
weight. Fewer days are more desirable.
Backfat: The EPD for backfat predicts the backfat for each individual progeny relative to the
average pig. This measurement is taken at the last rib. Negative EPD numbers are desired.
Expected Progeny Difference (EPD): The predicted difference in performance of future
offspring of a sire or dam. This predicted difference is compared to the performance of offspring
from parents of average genetic value with an EPD of zero.
Positive EPD’s: are more desired for number born alive and for 21-Day litter weights.
Negative EPD’s: are more desired for days to 230 and for backfat.
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Livestock Judging: Breeding Gilt Selection
Answer Key for CEV #473
Discussion
1. Why is structural soundness of major importance in breeding gilt evaluation?
Breeding gilts must be able to produce 4 to 5 litters. In today’s
confinement situations, sows are expected to be durable and remain
sound on concrete.
2. When watching a gilt travel, what are the indicators of a functional rear leg?
When a gilt moves, it is important for her to have flexibility in the hock
and pasterns. She should have a level rump and a wide set to her legs.
3. What management problem would be represented if the dewclaw were touching
the surface when the gilt traveled?
If the dewclaw is touching the ground, it can tear off and cause the gilt
to become unsound. Thus, the gilt will not have the longevity
necessary to be productive.
True or False
T
4. A sow is expected to produce 4-5 litters in confinement situations.
F
5. Small toe size is desirable in replacement gilts.
A large toe is preferred for easy balance and sturdiness.
Livestock Judging: Breeding Gilt Selection
1
Answer Key for CEV #473
True or False
F
1. An up-turned vulva is desired when selecting replacement gilts.
An upturned vulva makes mating more difficult.
F
2. A short, thick, coarse head is an indicator of a feminine gilt.
A long and refined face is an indicator of a feminine gilt.
F
3. Inverted nipples are a non-heritable trait.
Inverted nipples tend to be inherited.
Short Answer
4. Name the three factors that indicate a gilt is feminine.
long fronted, long necked, long faced
5. Define the following terms (noting how it effects gilt evaluation):
a. Pin nippleAn extremely small nipple is non-functional and usually takes
the place of a functional nipple.
b. Small vulvaA small vulva is an indicator of a non-functional reproductive
tract.
c. Ideal nipple shapeThe nipple should be refined, and resemble a sharpened pencil
or small cone.
Discussion
6. Is the old quote, “you’re as useless as the teats on a boar hog,” true in livestock
evaluation? Why?
In livestock judging, this is a false statement. Underlines are
heritable, and the boar will pass this trait down to his offspring.
Livestock Judging: Breeding Gilt Selection
Answer Key for CEV #473
2
Discussion
1. Why is bone diameter and length important in breeding gilt selection?
When pigs are refined and light structured, they are usually not big
enough in kind. Gilts that are light boned and small statured are early
maturing.
True or False
T
2. Bolder ribbed, wider skeletoned gilts are usually heavier muscled.
T
3. Arch, spring, and curvature of the rib are qualities of an ideal breeding gilt.
T
4. Gilts should not be excessively deep bodied.
F
5. Breeding gilts should exhibit an extremely refined bone structure.
Too much refinement may mean bones that are too thin to support her
growth and weight.
Livestock Judging: Breeding Gilt Selection
Answer Key for CEV #473
3
Short Answer
1. Define composition.
the ration of muscling and leanness in swine
2. Where is fat depth measured?
at the last rib
3. What is the shape of an ideal breeding gilt?
An ideal breeding gilt will have an hourglass shape. She will have
muscular shoulders, a groove down her top, a square edge to her
loin, and flair in her ham and rump muscles.
True or False
T
4. Blade action is a direct indicator of both muscling and leanness.
T
5. A groove down the top is desirable in replacement breeding gilts.
Livestock Judging: Breeding Gilt Selection
Answer Key for CEV #473
4
True or False
T
1. A gilt with a backfat EPD of -.10 would be expected to produce offspring with .10
inch less backfat than the average gilt.
F
2. Positive EPD’s are more desirable for 21-day litter weights and days to 230.
While Positive EPD’s are desired for 21-day litter weights, Negative
EPD’s are desired for days to 230.
Short Answer
3. Define EPD.
EPD stands for Expected Progeny Difference. This is the predicted
difference in performance of future offspring of a sire or dam. This
predicted difference is compared to the performance of offspring from
parents of average genetic value with an EPD of zero.
4. Label the following EPD factors by indicating which are positive and negative
traits.
- (negative) * Days to 230
+ (positive) * 21-day Litter Weight
+ (positive) * Number Born Alive
- (negative) * Backfat
Discussion
5. How are EPD’s used as a tool to make sound management decisions?
Performance records are our best predictions of the future
performance of a gilt’s offspring. Performance records are utilized
with the visual appraisal to select the ideal gilt.
Section 5 ends with an example of Oral Reasonings concerning the scenario Yorkshire
gilts. The Oral Reasonings are given by Ryan Sites of the 1995 Livestock Judging Team
of Oklahoma State University.
Livestock Judging: Breeding Gilt Selection
Answer Key for CEV #473
Scenario: These Yorkshire gilts will be bred to Landrace boars to produce Landrace
x Yorkshire crossbred gilts. These Landrace x Yorkshire gilts will be the sow line to be
5
mated to terminal line boars in a terminal crossbreeding system with all offspring
marketed. Structural soundness and maternal traits are emphasized. Consider all
underlines to be sound.
No.
1
2
3
4
Number
Born Alive
- .3
+ .4
+ .5
+ .6
21-Day
Litter Weight
- 1.0
+ 5.1
+ 7.4
+2.3
Back fat
+ .01
- .02
- .03
+ .02
Day/230
+ 2.5
- 7.0
+ 1.0
- 4.0
Short Answer:
1. Which gilt was the most structurally sound?
2
2. Which gilt ranked first in sex character?
3
3. Which gilt ranked first in size and scale?
2
4. Which gilt was superior in composition?
2
5. Between 1 and 4, which gilt had the most desirable performance data?
4
6. To what breed of boars will these gilts be bred?
Landrace
7. Which gilt is the most structurally unsound?
4
8. Between 3 and 1, which gilt had the most desirable performance data?
3
9. Between 2 and 4, which gilt had the most extension of skeleton?
2
10. Between 3 and 4, which gilt was the most feminine?
3
Livestock Judging: Breeding Gilt Selection
Answer Key for CEV #473
Short Answer:
6
1. List the major factors in breeding gilt evaluation.
1. Structural Soundness
2. Sex Characteristics
3. Size and Volume
4. Composition
5. Performance Records
2. In terms of structural soundness, describe the ideal breeding gilt.
Very level from her shoulder, back through her hip and rump
structure. She should move freely, with ease and mobility. She
should have cushion at her knees and front pasterns, as well as
flexibility in her rear hocks.
3. In relation to production and longevity, why is structural soundness important?
The breeding gilt is expected to produce 4 to 5 litters in confinement
situations. For this reason, she should have ample cushion to her
pasterns and correct angulations in her shoulder and hocks to
provide longevity.
4. What problems may arise from a fat uddered gilt?
A fat uddered gilt will have problems producing and lactating more
than just a few times. The fat uddered section will break down and be
more prone to mastitis.
5. List the common defects/flaws that arise in underlines.
1. Pin nipple
2. Blind nipple
3. Inverted nipple
4. Fat udder
5. Inadequate spacing
6. Coarse Underline
6. With the wide use of artificial insemination in modern pork production, why is it
important to discriminate against vulva defects?
If the producer does not select against vulva defects, the problem will
not be eliminated. As long as these gilts are reproduced, the vulva
defects will be carried on to the next generation.
7. Why are performance records an integral element in the swine industry?
Performance records are the best predictions of the future
performance of the progeny. Producers use these records to produce
the ideal pig.
8. What factors are considered when discussing size and volume?
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The size and volume of the gilt is the indicator of growth and maturity.
Durable skeletons are desired to carry the gilt to a heavier weight.
Also, wider skeletoned gilts are more apt to be heavier muscled.
9. Why is breeding gilt evaluation important?
The gilt is important to the profitability of the swine industry.
Producers must be able to buy, sell, keep, and cull.
10. How did you place the Yorkshire gilt class? Defend your placing.
2-3-1-4 - accept logical defense responses that support the 2-3-1-4
placing.
11. Why is it imperative for EPD’s to be negative in back fat and days to 230?
The goal of the producer is to produce a hog that is lean and
muscular, yet fast-growing and profitable. For these reasons, the final
product should have limited back fat, and should take less time to
reach desired weight.
12. With both performance and phenotypic traits considered, why did 1 place over 4
in the Yorkshire gilt class?
4 was stronger in performance data than 1; however, 4 was
structurally incorrect. 1 was sounder and would be more functional
as a gilt.
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