grass ranges during the growing season and 
black grama ranges in the dormant season in 
the Southwest (Paulsen and Ares 1962). A 
mixture of browse and grass range is desirable 
in the West during the dormant season when 
good browse has adequate protein and grass 
has adequate energy (Cook and Harris 1968). 
Where appropriate, seasonal range types do 
not exist naturally; they often can be estab- 
lished through seeding or other management 
practices. 
Range improvement practices offer promis- 
ing alternatives to supplementation, especially 
when they also increase forage yield. It is well 
known that seasonal forage quality often can 
be increased, or the period of adequate quality 
extended, by altering the botanical and chemi- 
cal composition through range seeding, fertil- 
ization, burning, mechanical or chemical treat- 
ments, and grazing management. In western 
range seeding, extension of adequate forage 
quality has long been a major consideration in 
selecting species to be seeded. In some situa- 
tions, profitable fertilization can correct phos- 
phorus deficiency and replace supplementation, 
as in southern Texas (Reynolds et al. 1953). 
Prescribed burning improves forage quality 
and cattle gains in the southern pine region, 
but its effects are short-lived. Also, it does not 
eliminate deficiencies nor the need for supple- 
mentation in this region (Halls et al. 1952; 
Campbell et al. 1954). 
Early weaning of calves can reduce the need 
for supplementation on ranges when forage 
quality drops below adequate levels during late 
summer; this frequently occurs in dry years in 
the West (Skovlin 1967). Because require- 
ments for protein and digestible nutrients of 
lactating beef cows are more than 50 percent 
greater than for dry cows, and because about 
2.5 pounds of TDN are required to produce 1 
pound of TDN in milk form through the cow, 
it is more efficient to feed calves directly than 
through the dams. Calves weaned at about 4 
months of age have gained as well as calves 
weaned when they are 6 months older (Frisch- 
knecht 1968). Following early weaning, dry 
dams tend to gain in condition and were re- 
ported to graze farther into rough range than 
when they had calves at their sides.” 
Practical Levels 
Short periods of deficient diet are not serious 
if followed by high-quality diets. In Montana 
and California, breeding herds that were al- 
lowed to lose 150 to 200 pounds during the 
winter calving season, but were gaining weight 
and condition rapidly during the following 
breeding season, produced calf crops approach- 
*McArthur, J. A. B. Personal correspondence, Oreg. 
State Univ., Eastern Oreg. Exp. Sta., Union, Oreg., 
1968. 
72 
ing 90 percent (Reed and Peterson 1961; Wag- 
non et al. 1959). Sheep in the West success- 
fully tolerate deficient diets and weight loss on 
winter range when they make rapid gains on 
spring range; supplementing at levels that 
fully maintain weight in winter is not consid- 
ered economical (Harris 1968). 
However, where the range diet does not per- 
mit lactating cows to gain weight and to breed 
successfully, as in the Southeast, alternate- 
year calving and 50-percent calf crops tend to 
be the rule (Shepherd et al. 1953; Southwell 
and Halls 1955). Thus, for breeding herds, the 
percentage of calf crop can reflect major sup- 
plement needs. In the South, supplementation 
involves more than the wintering period (Du- 
vall and Whitaker 1963; Southwell and 
Hughes 1967). 
Apparently young animals also can be win- 
tered successfully at nutritional levels that 
scarcely maintain weight if the subsequent diet 
is of a high quality. Studies have shown that 
young beef cattle can recover from severe un- 
dernutrition (one-sixth of the protein and 
two-fifths of the energy allowances for rapid 
growth) lasting as long as 6 months without 
impairing subsequent growth or quality when 
finished on a liberal diet, and without reducing 
their overall efficiency of feed utilization (total 
feed per pound of gain) (Winchester et al. 
1967; Winchester and Ellis 1957). This work 
verifies the common observation that animals 
show greater efficiency in feed utilization and 
gain faster after undernutrition. It also sup- 
ports the common practice of providing only 
enough supplement on winter range to prevent 
serious loss in livestock condition (Harris 
1968; Morrison 1954). 
DEFICIENCIES AND SUPPLEMENTATION 
The most commonly recognized deficiencies 
in range forage for livestock are energy, pro- 
tein, phosphorus, and carotene (vitamin A). 
Customary salting practices usually satisfy re- 
quirements for sodium and chlorine. In the 
South, deficiencies also occur in calcium and 
several minor elements, including iron, copper, 
and cobalt (Cunha et al. 1964). Iodine defi- 
ciency occurs in several Western states (Stod- 
dart and Smith 1955). 
Supplement requirements can be estimated 
from NAS-NRC nutritional standards devel- 
oped by its Committee on Animal Nutrition 
(NAS-NRC 1968, 1964). However, confident 
estimating requires specific information about 
the digestibility and the chemical composition 
of the range diet. Such information is scarce, 
but some inferences can be drawn from availa- 
ble data on chemical composition by assuming 
levels of digestibility. As a guide to judging 
forage adequacy, table 1 summarizes livestock 
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