chemical composition and acceptability of aquatic plants in diets of
CHEMICAL COMPOSITION AND ACCEPTABILITY OF AQUATIC PLANTS
IN DIETS OF SHEEP AND PREGNANT GOATS 1
C. L. Heffron 2 , J. T. Reid 2 , W. M. Haschek 3 , A. K. Furr s , T. F. Parkinson 6 ,
C. A. Bache 4, W. it. Gutenmann 4 , L. E. St. John, Jr. 4 and D. J. Lisk 4
Cornell University, Ithaca 14853 and Virginia Polytechnic Institute, Blacksburg 24061
studied and reviewed (Boyd, 1972). A few investigators
have studied nutrient availability in
Aquatic plants harvested from Cayuga Lake
when included in dry pelleted
in New York were dried, milled and incorpocattle rations (Stephens et al., 1973; Hentges
rated into a pelleted ration replacing 35% by
et al., 1972; Stephens et al., 1972) or ensiled
weight of alfalfa meat. The ration was fed to
and fed to sheep or cattle (Linn et al., 1975;
pregnant goats and to sheep for 130 days.
Byron et al., 1975) for periods up to about 2
Analysis of the aquatic plants for 40 elements
weeks. Aquatic plants have also been included
and polychlorinated biphenyls showed no toxic
in the diet for chicks from 1 day old to 4 weeks
concentrations. There were no significant difof age (Muztar et al., 1976).
ferences (P>.05) in feed intake, rate of weight
There are advantages and disadvantages to
gains or ration digestibility between the aniutilizing aquatic plants in farm animal rations.
mals fed the aquatic ration and those fed the
When properly prepared they are accepted by
control ration. The aquatic ration was notably
animals and appear to be comparable nutritionhigher in ash and lower in fat, fiber and energy
ally to field-grown forage crops. Harvesting of
than was the control ration. All kids born were
aquatic plants obviates the need for aquatic
normal. Gross pathologic and histologic examination of animal tissues revealed no notable dif- herbicides, dredging and other methods for
their control. Several cuttings per year are usuferences between animals fed the aquatic and
ally available depending on their geographical
location. Conversely, aquatic plants are high in
(Key Words: Aquatic Plants, Sheep, Pregnant
moisture and the cost of drying is the single
Goats, Digestibility, Weight Gain.)
biggest expense. They can be ensiled, however,
to offset the cost of complete drying. Pigs will
also accept aquatic plants without drying. The
Aquatic plant growth interferes with trans- expense o f cutting and loading would probably
be similar to that for field crops. When harportation and water sports in many areas of the
vested, the drying operation must begin immeUnited States. Control measures have included
chemical, mechanical, physical and biological diately or aquatic plants rapidly spoil. The
water in which they are growing must be free
methods (Hall, 1961; Bates and Hentges, 1976).
of contaminants. The possible presence of
Harvesting and processing aquatic plants as a
natural toxicants in them must be considered.
source of methane for fuel (Chem. Eng. News,
The number of plant species represented and
1976) and protein (Boyd, 1972, 1968) has been
their nutritive value will vary with the time
(Boyd, 1968) and location of sampling.
In the work reported here, aquatic weeds
from Cayuga Lake in New York were harThe authors thank J. w. Wilbur, W. A. English,
T. H. Kuntz, W. F. Miller, J. Hotaling, H. G. Knight, vested, dried, milled and incorporated into a
L. F. Armitage, G. F. Rickey, T. G. Wright, J. C.
pelleted ration replacing 35% by weight of
Palermo, W. D. Youngs, E. J. tlarris, R. Karcher, H. T.
alfalfa meal. The ration was then fed to lambs
Greweling and C. Burda for their assistance during the
and pregnant goats for 130 days. Digestibility
course of this investigation.
2Department of Animal Science.
of the ration was determined and analysis of
3Department of Veterinary Pathology.
the aquatic plants for 40 nutrient and toxic
4Pesticide Residue Laboratory, Department of
elements and polychlorinated biphenyls was
performed. Adult and newborn animals were
s Office of Occupational Health and Safety.
autopsied and tissues studied histologically.
6Nuclear Reactor Laboratory.
JOURNAL OF ANIMAL SCIENCE, Vol. 45, No. 5 (1977)
PERFORMANCE OF RUMINANTS FED AQUATIC PLANTS
A b o u t 20 tons (fresh weight) of aquatic
plants were harvested in the northeast portion
of Cayuga Lake in the vicinity of Cayuga, New
York, during July and August, 1975. Seven
plant species were identified: clasping leaf
pondweed (Potamogeton ricbardsonii), coontail
pondweed (Potamogeton crispus), sago pondweed (Potamogeton pectinatus), water milfoil
(Myriopbyllum spicatum), water stargrass
(Heterantbera dubia), and wild celery (Vallisneria americana). Plants were cut at a depth of
1.5 meters, removed by a raking boat and dried
on slotted wagons using heated air (38 C). The
dried material was milled to a fine powder and
thoroughly mixed. The estimated percentages
(dry weight) of each of the above species in the
final mixed sample were: clasping leaf pondweed, 25; coontail, 10; curly-leafed pondweed,
10; sago pondweed, 25; water milfoil, 25; water
stargrass, 2.5 and wild celery, 2.5. The percentage (dry weight) of protein in each of the
aquatic plants (determined as Kjeldahl N •
6.25) was, respectively, 13.7, 23.4, 15.3, 14.2,
13.1, 15.7 and 15.3. The mixed aquatic plants
were incorporated into a pelleted (.4 cm pellets) ration replacing 35% by weight of alfalfa
meal. The composition of the pelleted aquatic
and control rations is listed in table 1.
Four, 3-month-old Dorset wethers and four
recently bred 1-year-old French Alpine goats
were used in the feeding trial. Two lambs and
two goats were fed the aquatic rations and the
remaining animals were fed the control diet.
The animals were located in individual metabolism stalls throughout the feeding period. All
animals were first adapted from a ration of hay
and grain to a diet of hay and control pellets
during a period o f 14 days. They were then
adapted to a ration of control pellets alone during the next 37 days. An additional 10 days
were used to adapt two sheep and two goats
from a diet of control pellets to pellets containing 35% aquatic plants. The feeding continued
for 130 days (129 days for the goats) beginning
with their receipt of the complete pelleted 35%
aquatic plant ration. Salt (without iodine or
trace minerals) and water was provided ad libiturn. The digestibility of the rations was measured by total collection over a 9-day period
during the last 2 weeks of the feeding trial. At
the end of the feeding period the animals were
sacrificed, autopsied and tissue samples taken
for histologic examination.
The individual aquatic plants were analyzed
for 40 nutrient and toxic elements. Samples of
the dried plant tissues were analyzed for 29 elements by nondestructive neutron activation
analysis using the procedure described previously (Furr et al., 1976). After dry ashing the
samples at 475 C, cadmium, lead, copper and
zinc were determined by conventional stripping
voltammetry using a po'arographic analyzer
(Princeton Applied Research Corp. Model 174)
(Gajan and Larry, 1972). Nickel and chromium
were determined in the ashed samples by graphite furnace atomic absorption analysis using a
Perkin Elmer Model 303 equipped with an
HGA-2000 furnace (Zachariasen et al., 1975;
Cary and Olson, 1975). Mercury was determined by flameless atomic absorption spectrophotometry following combustion of the dry
sample using an oxygen flask (Bache et al.,
1973). The determination of selenium was ac-
TABLE 1. COMPOSITION OF TIlE COMPLETE
PELLETED ANIMAL RATIONS
Composition, percent dry wt
Vitamin supplements (A, D, E)
HEFFRON ET AL.
PERFORMANCE OF RUMINANTS FED AQUATIC PLANTS
complished by a modification of the method
Olsen (1969) employing wet digestion of the
sample and measurement of the fluorescence of
piazselenol resulting from reaction of selenium
with 2,3-diaminonaphthalene. Arsenic analysis
was performed by dry ashing, distillation of
arsine and determination using the silver diethyldithiocarbamate spectrophotometric procedure (Evans and Bandemer, 1954; Fisher
Scientific Co., 1960). Boron was determined by
the curcumin spectrophotometric procedure
(Greweling, 1966). Fluorine was determined by
combustion of the dried sample in an oxygenfilled polypropylene flask and detection using
the fluoride specific ion electrode. A subsample
of the dried mixed aquatic plants was analyzed
for the Aroclor 1254 polychlorinated biphenyls
(PCB's). The method involved extraction, isolation using petroleum ether-acetonitrile partitioning, column chromatography on Florisil
and final determination using electron affinity
gas chromatography (Pesticide Analytical Manual, 1971). Fat, fiber, ash, calcium and phosphorus were determined by the procedures
cited, respectively, in Official Methods of Analysis (1975).
Autopsies were performed on all adults and
neonates. Nineteen tissues from each animal,
including bone, were sectioned at 6 microns,
stained with hematoxylin and eosin, and examined microscopically.
RESULTS A N D DISCUSSION
The results of elemental analysis of the
individual aquatic weeds are given in table 2.
Cowgill (1973a,b) reported relatively high
concentrations of rare earth elements such as
cerium and lanthanum in aquatic plants in
Connecticut but these were found in this study.
Certain of the elements of toxicologic significance and PCB's were also determined in the
complete pelleted aquatic and control diets.
These results are listed in the lower portion of
table 3. With the exception of chromium and
fluorine, the concentrations of elements in the
control and aquatic rations were not gready different. PCB's were not detected in either ration.
Animal tissues and organs were not analyzed
for chromium or fluorine. Chromium is not accumulated by animal tissues (Browning, 1969).
Some fluorine may have deposited at higher
concentrations in bone and teeth of the animals
on the aquatic ration than in the control animals.
HEFFRON ET AL.
TABLE 3. ANALYSIS OF PELLETED RATIONS
FOR ASII, NUTRIENTS, FIBER,
SELECTED ELEMENTS AND PCB'S
possible. All o f t h e kids p r o d u c e d were n o r m a l
in a p p e a r a n c e .
G r o s s lesions c o n s i s t e d of several mild parasitic lesions in lungs a n d intestines. No lesions
a t t r i b u t a b l e to t h e a q u a t i c diet were present.
T h e r e were no significant d i f f e r e n c e s ( P > . 0 5 )
b e t w e e n a n i m a l s receiving t h e a q u a t i c or control r a t i o n s w h e n weights o f livers, k i d n e y s a n d
h e a r t s were expressed as p e r c e n t a g e s o f t o t a l
b o d y weights of respective a d u l t animals.
T h e u p p e r p o r t i o n o f t a b l e 3 lists t h e levels
of various n u t r i e n t s a n d o t h e r e n d o g e n o u s cons t i t u e n t s in t h e diets. T h e a q u a t i c r a t i o n was
n o t a b l y higher in ash a n d l o w e r in fat, fiber a n d
e n e r g y t h a n t h e c o n t r o l diet. Calcium a n d magn e s i u m in w a t e r p r e c i p i t a t e o u t as t h e carbon a t e s o n a q u a t i c plants and t h u s t h e y are very
high in ash c o n t e n t . Since t h e foliage of a q u a t i c
p l a n t s p r o b a b l y does n o t require a w a x y cuticle
to p r e v e n t desiccation, t h e fat c o n t e n t e x p e c t edly w o u l d be lower. Higher ash a n d l o w e r fat
c o n t e n t s w o u l d c o n t r i b u t e to a lower e n e r g y
T a b l e 4 s u m m a r i z e s d a t a on feed i n t a k e ,
w e i g h t gains, milk p r o d u c t i o n , k i d d i n g a n d rat i o n digestibility during t h e f e e d i n g trial. T h e
in vivo digestibility c o e f f i c i e n t s were determ i n e d for each of t h e r a t i o n s a n d are also listed
in t a b l e 4. No significant d i f f e r e n c e s @ > . 0 5 )
in average daily feed intake, w e i g h t gain or
digestibility were n o t e d b e t w e e n t h e diets.
Since o n e o f t h e goats fed t h e a q u a t i c r a t i o n s
was f o u n d l a t e r n o t to b e p r e g n a n t (see t a b l e 4)
a m e a n i n g f u l statistical c o m p a r i s o n of milk prod u c t i o n b e t w e e n goats on t h e r a t i o n s was n o t
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