INCREASING FORAGE YIELDS ON INTERMOUNTAIN WINTER RANGES 45 
grazing was somewhat lighter than in succeeding years. Average 
utilization of the various forage species for the period of the study was 
practically the same as that reported in table 1. Although adjustments 
in stocking were made, apparently they were not adequate to fully 
compensate for the wide fluctuations in production. As a result, 
utilization of the forage species was greater in years of low herbage 
yields than in years when production was above average. 
For the heavily grazed allotment exact records of stocking or grazing 
use are not available because during the first 4 years of comparison the 
allotment was used in common by several herds which grazed in mi- 
gratory fashion over wide areas of winter range. Utilization during 
this period was extremely heavy, the palatable species receiving prob- 
ably one-third greater use than those on the moderately grazed allot- 
ment. During the last 5 years the heavily grazed allotments were 
assigned to individual sheep operators. Although this brought about 
some reduction in grazing intensity, utilization of the palatable species 
was still fairly heavy. The average intensities of grazing for the entire 
period were estimated to be about one-fourth heavier than 1 in the mod- 
erately grazed allotment. 
In 1942 about half of the herd assigned to the heavily grazed range 
was sold, leaving about 1,500 sheep. Because the two herds were no 
longer comparable in size the detailed comparisons were discontinued 
although some general phases of the study were carried on for a few 
more years. 
Sheep in both horde were range-bred Rambouillets of good quality 
and essentially similar. The herds belonged to two brothers and had 
been previously owned and operated jointly by their father. Operating 
methods for both herds, designated A and B, were closely similar. 
During the winter of 1935-36 herd A was placed on the moderately 
_ grazed allotment within the experimental range and herd B was assigned 
to the heavily grazed range. In succeeding winters the assignments 
were reversed annually. 
This alternating arrangement in grazing was used to eliminate dif- 
ferences due to management, herd performance, and the cumulative 
effects of previous grazing treatment which might be peculiar to the 
individual herds. 
Management practices for the two herds differed throughout the 
period of observation. In the moderately grazed experimental allot- 
ment they were as follows: (1) The allotment was divided into units 
which were grazed at predetermined periods; (2) sheep were bedded in 
a new location each night; (3) herding was carefully controlled to permit 
quiet grazing and to check unnecessary trailing; and (4) water was 
supplied every day or every second day when snow was not readily 
available. 
On the unfenced range, sheep were managed according to practice 
customarily used on many of the winter ranges in the Intermountain 
region: (1) The entire range area was grazed repeatedly as a single unit; 
(2) sheep were bedded on established bedgrounds, often for several 
nights in succession and often after trailing as much as 3 miles to reach 
a particular site; (3) trailing and movement were seldom checked by the 
herders; and (4) animals were primarily dependent on snow or reservoir 
supplies for water, and sometimes had to be trailed as much as 4 miles 
to get water during dry periods in early or late winter. 
