desert and salt desert ranges usually furnish 
adequate energy in the dormant stage (Boh- 
man et al. 1961; Cook and Harris 1968) Cheat- 
grass (Cook and Harris 1952) and California 
annual range (Van Dyne 1965) also furnishes 
enough energy, except after extensive leaching 
by winter rain (Wagnon et al. 1959). Dormant 
browse plants tend to be deficient in energy, 
but these are good sources of protein and caro- 
tene (Cook and Harris 1968). A high-energy 
supplement is recommended for wintering 
sheep on sagebrush range, and as a substitute 
feed during deep snow emergencies (Harris 
1968). Energy values of range forage and ani- 
mal diets vary markedly with species, range 
condition, degree of use, and other factors 
which can be influenced through management. 
Skillful handling of these factors is generally 
the most practical approach to meeting energy 
requirements of livestock on Western ranges. 
In the South, however, digestible energy ap- 
pears to be the main limitation of range for- 
age. On bluestem forest range in Louisiana, es- 
timates from composite samples representing 
cattle diet indicated adequate energy only dur- 
ing the young-leaf stage. Indications were that 
a 700-pound lactating cow would need 1 to 1.8 
pounds of supplemental TDN per day during 
the full-leaf and mature-green stages, and 
about 3 pounds on winter rough (Campbell et 
al. 1954). However, feeding small amounts of 
energy supplement (in addition to protein and 
minerals) during winter was not profitable 
(Duvall and Whitaker 1963). 
On wiregrass forest range in Georgia, diges- 
tion trials with indicator techniques showed 
TDN at only 44 to 48 percent in April and 
June, 42 to 48 percent in September, and 32 to 
338 percent in December (Halls et al. 1957; 
Hale et al. 1962). In the spring and summer, 
these levels approximate requirements for 
maintenance of mature cattle without weight 
gains (as recommended for economic winter- 
ing), but they fall far short of the standards 
for nursing cows—60 percent TDN (table 1). 
This explains why cows lose weight while 
suckling calves and tend to have small calf 
crops when this kind of range is supplemented 
with only protein and minerals (Halls and 
Southwell 1956; Shepherd et al. 1953). Inte- 
gration of improved pasture with wiregrass 
range in summer, to provide about half the 
diet, offers one economical method of providing 
adequate energy levels to obtain good calf 
crops (80 percent) and weaning weights 
(400-450 pounds) from low-quality wiregrass 
range (Southwell and Hughes 1965). 
Protein 
Protein supplementation is often a practical 
means of improving livestock production and 
effective utilization of range forage, especially 
74 
in fall and winter when mature grass is defi- 
cient in protein. Although vital to animal 
health, vigor, growth, and _ reproductive 
efficiency, digestible protein only need comprise 
a relatively small proportion of the diet—4 to 
5 percent for most classes of sheep and cattle 
except rapidly growing young animals (table 
1). Also, supplying deficient protein may in- 
crease the digestibility of other nutrients 
(Harris 1968). 
Common protein concentrate meal feeds for 
cattle and sheep—cottonseed, soybean, meal, 
and peanut meal—usually have 41 to 45 per- 
cent total protein, and 33 to 43 percent digesti- 
ble protein. Consequently, relatively small 
amounts will satisfy the daily requirement of 
common classes of range livestock (NAS-NRC 
19638, 1964): 
43 percent 
Digestible digestible 
protein protein 
(Lb./animal 
Class of livestock daily requirement) 
Normal growth, young 
cattle (400-800 lb.) _____- 0.9 2.1 
Wintering weanling calves 
(500-600 lb.) ~______- as 8 1.8 
Wintering yearling cattle. 
(600-900 Ib.) __-________- i sth 1.6 
Wintering pregnant cows 
(900-1,200 lb.) ________-- 8 1.8 
Cows nursing young calves 
(900-1,100 Ib.) ___.-___-- 1.4 3.2 
Ewes (120 lb.) last 6 weeks 
Sestatlonerd sone wee 19 A 
Ewes (120 lb.) early 
lactationos- =. ceca oe ieee 23 5 
Replacement lambs and 
yearlings (80 lb.) _-_____- 15 3 
Fattening lambs 
(80=100°Ib.) 22-2 .20 5 
Urea and some other nonprotein nitrogen 
compounds, including diammonium phosphate, 
can replace part of the costlier protein in live- 
stock feeds, but their use as range supplements 
has not been thoroughly investigated. Rumen 
bacteria can convert urea and other nitrogen- 
ous compounds into proteins for the animal. 
About one-third of the total protein require- 
ment may be met in this way under suitable 
conditions (NAS-NRC 1963), including ample, 
readily available carbohydrates, phosphorus, 
trace minerals, and sulfur. Fifty-percent re- 
placement of protein with urea and with diam- 
monium phosphate has been successful in fat- 
tening steers (Brown et al. 1967; Gallup et al. 
1953). Pelleted protein supplement with 25 
percent of its nitrogen as urea was as good as 
cottonseed meal for supplementing winter 
range in Oklahoma (Gallup et al. 1953). Biuret, 
a new source of nonprotein nitrogen, may be 
better than urea as a protein substitute (Ral- 
eigh and Turner 1968). 
In general, protein supplementation is prof- 
itable when it increases the reproductive rate 
