Nutrient Requirements of Livestock and Game 
LOWELL K. HALLS? 
This paper reports data mainly for beef cat- 
tle, sheep, and deer—the largest consumers of 
food from forests and rangelands of the United 
States. When available, information is included 
for other mammals and birds such as elk, ante- 
lope, goats, rabbits, squirrels, wild turkeys, and 
quail. 
Maynard and Loosli (1956) cautioned against 
the use of the term “requirement” because 
it implies an exactness which does not exist. 
Strictly speaking, a requirement is the mini- 
mum amount of a nutrient that will pro- 
mote a given body function to the optimum in a 
perfectly balanced ration. This minimum var- 
ies among animals and environments. An 
amount that is adequate in closely controlled 
experiments may not be sufficient in an envi- 
ronment that is not controlled. Despite limita- 
tions, nutrient-requirement standards are use- 
ful in selecting forage species, in formulating 
feeds, in evaluating the carrying capacity of 
ranges and pastures, and in determining the 
adequacy of a particular ration. 
Much of the information on nutrition of do- 
mestic livestock is taken from the reports of 
the Committee on Animal Nutrition of the Na- 
tional Academy of Science—National Research 
Council (NAS-NRC). Unfortunately, similar 
appraisals are not available for game. 
DRY WEIGHT OF FEED 
The dry weight of food consumed by an ani- 
mal normally is closely related to body size. 
For range livestock and big game, daily con- 
sumption is roughly 2 to 4 percent of live 
weight. Small mammals and birds eat up to 10 
percent of their weight. In table 1, feed intake 
of several species is related to condition and 
body weight. 
Consumption is influenced by many factors 
other than body weight. Grazing sheep require 
an average of 80 to 90 percent more feed for 
maintenance than sheep fed indoors (Joyce 
1968). Older animals eat less per unit of body 
weight than younger animals (NAS-NRC 
1963). Consumption also varies with food qual- 
ity. Diets low in protein cause lowered food 
consumption (Madsen 1939). In south Georgia 
the daily intake of dry forage was 20 pounds 
per cow when forage was of relatively high 
quality but only 12 pounds per cow when qual- 
ity was low (Hale et al. 1962). Even when 
‘Principal Ecologist, Wildlife Habitat and Silvicul- 
ture Laboratory, Nacogdoches, Tex. The Laboratory is 
maintained by the Southern Forest Experiment Station 
in cooperation with Stephen F. Austin State Univ. 
10 
quality is constant, food intake of some ani- 
mals may vary seasonally (Fowler et al. 1968; 
Long et al. 1965). Feed intake may also differ 
among animals grazing apparently comparable 
forages. McCullough and Sell (1952) reported 
a daily intake of 16 pounds of dry matter by 
cattle on fescue pasture as compared to 26 
pounds on a mixed-species pasture of similar 
quality. In extremely cold weather, wild ani- 
mals may consume very little food (Silver and 
Colovos 1957). The amount of acetic acid in 
the rumen, the content of undigested feed resi- 
dues in the digestive tract, and thermostatic 
mechanisms influenced food intake of rumi- 
nants (Conrad 1966). 
To be most meaningful, information on in- 
take should include species, size, age, and con- 
dition of animal; quality of food; and season of 
use. Data are not available for many wildlife 
species under the various conditions in which 
they live. Where information is extrapolated 
from one species and from one condition to an- 
other, care should be taken to compare only an- 
imals with similar metabolism and _ similar 
digestion capacity. For example, under like 
conditions, the food intake of goats, deer, and 
antelope may be similar. Domestic and wild 
turkeys probably have similar requirements, as 
do domestic and wild sheep and white rats and 
squirrels. 
ENERGY * 
Since all organic nutrients contain energy, 
it provides a common expression of the nutri- 
tive value of foods (Maynard and Loosli 1956). 
Lack of digestible energy (DE) was the 
most common deficiency in the diets of sheep 
and cattle (NAS-NRC 1963, 1964). With the 
possible exception of a lack of protein and a 
lack of phosphorus, it is probably the most 
common nutritional deficiency of deer (Dietz 
important to other kinds of range livestock 
and wildlife. Low-energy intake causes reduced 
or halted growth, loss of weight, failure to 
conceive, increased mortality, and lowered res- 
istance to parasites and disease. 
Digestible-energy measurements do _ not 
consider energy losses from urine, combusti- 
ble gases, and heat increment during digestion. 
As these losses are larger for roughages than 
for concentrates, a pound of DE in roughage 
has considerably less value than a pound in 
concentrates. On shrub ranges the use of DE 
* This section is abstracted in part from Short and 
Golley (1968). 
