16 CIRCULAR 925, U. S. DEPARTMENT OF AGRICULTURE. 
TABLE 3.—Percentage utilization of total herbage production of forage 
plants on a moderately grazed range allotment during 10-day intervals 
in a 40-day grazing period of a rather typical winter 
Species Jan. 5-14 | Jan. 15-24 eee Feb. 4-13 Total 
Percent Percent Percent | Percent | Percent 
Globemallow____-___-_- 45 30 | al 5 85 
Black sagebrush _ - - _ _-- 40 30 10 0 | 80 
Indian ricegrass________ 35 30 5 a 75 
Bud sagebrush_________ a 10 | 40 15 | 70 
Winteriat sss ss. = 10 10 15 | 25 | 60 
Gallets = a 10 10 5 | 30 55 
Sand dropseed________- 0 5 5 15 25 
Shadscale= S22 5 5 10 5 25 
Frequently sheep ate only the central portions of galleta tufts, leaving 
the coarser growth around the edges. They also ate some individual 
patches but left adjacent ones untouched. 
Sheep definitely preferred the tops of Indian ricegrass and the seed- 
stalks and foliage of small plants to the herbage produced by large 
plants. Utilization of this species was also heavier in years when late 
summer rains stimulated the growth of the basal leaves and freshened 
up the herbage. 
During short periods throughout the winter when melting snow 
softened the otherwise dry vegetation, sheep often ate galleta, sand 
dropseed, blue grama, and Russian-thistle in preference to other nor- 
mally more palatable species. 
In some years many forage species such as spiny hopsage, bud sage- 
brush, squirreltail, Indian ricegrass, and Salina wildrye began to grow 
in March and April, during the late winter grazing period. Sheep 
relished this green succulent growth and ate it in preference to herbage 
of other species which was still dry and dormant, thus altering the 
utilization pattern during this period. 
INFLUENCE OF RELATIVE PRODUCTION OF THE SPECIES 
In general the percentage utilization of the herbage varied with the 
amount and relative production of the different species. The grazing 
of a given species tended to increase with a decrease in its relative 
production (table 4). 
Data from moderately grazed range pastures show this inverse rela- 
tion. In pasture 6, where winterfat production averaged 4 pounds per 
acre and made up only 2 percent of the total herbage, 77 percent of the 
herbage was utilized. In pasture 16 with 118 pounds of winterfat 
herbage, 51 percent of the total yield, average utilization was only 48 
percent. 
Utilization of several other species also followed the same general 
pattern. Grazing of Indian ricegrass, galleta, and sand dropseed was 
greater on range pastures where yields were small and less on those 
where yields were high. This relation was less pronounced for galleta, 
which was fairly evenly distributed on the range. 
