INCREASING FORAGE YIELDS ON INTERMOUNTAIN WINTER RANGES 51 
I-wes that wintered on moderately grazed range usually produced 
more lambs the following spring than those that wintered on heavily 
grazed rarge. Following the winter grazing seasons of 1937-38, 
1939-40, and 1948-44 more lambs were docked from the herd which 
wintered on heavily grazed range. In spite of this disadvantage the 
herd on moderately grazed winter range produced, on the average, 11 
percent more lambs than the herd that wintered on heavily grazed 
range. Lambs at market time were also slightly heavier. 
SUPPLEMENTAL FEEDING 
Practices in regard to the feeding of supplements vary somewhat 
on the winter range. A few herds are fed supplements throughout each 
winter. Most herds, however, are fed for a short time only in the late 
winters when forage is unusually scarce and the condition of sheep is 
noticeably poor. Occasionally entire herds are fed in this manner, but 
in most cases only the poorer sheep are given supplements in separate 
bands. 
As arule such feeding begins about January 15 and continues through 
March or April or until green forage becomes available. Sheep are 
usually fed 14 to 1 pound per day of cottonseed cake, grain pellets, or 
corn. 
During the period of study, sheep within the moderately grazed 
experimental allotment wintered in good condition even in severe 
winters without any supplemental feed. Sheep on the heavily grazed 
range were fed some supplements for short periods during a few of the 
severe winters. The usual practice was to feed only the poorer sheep. 
Although they received this supplemental feed, many of the animals 
still lost weight and death losses were heavy. Several other herds on 
adjacent heavily grazed range were fed considerable amounts of cot- 
tonseed cake or corn during 3, 4, or 5 years to help carry the sheep 
through periods when range forage was inadequate. In the fairly 
severe winter. of 1936-37, these herds were fed cottonseed cake during 
a period of 4 to 6 weeks. Nevertheless, many of the ewes remained 
in poor condition and death losses were high. 
Studies in recent years have shown that many of the winter range 
forage plants are low in nutritional and mineral content (3, 5, 6). It 
is therefore probably desirable to feed supplements in most years to 
supply dietary deficiencies even for sheep on moderately grazed areas. 
Some experiments to determine what supplements may be necessary 
are being conducted at the Desert Experimental Range in cooperation 
with the Utah State Agricultural College. These studies show that 
most of the forage plants are deficient in phosphorus and that condition 
of sheep is markedly improved when they are fed supplements contain- 
ing this element. 
INCOME 
Financial and operational data were obtained for herds A and B 
covering 8 years. These data were combined for each type of grazing 
treatment. Since the herd sizes varied, figures were recomputed on the 
basis of 3,000 head to make them directly comparable (table 15). 
