40 CIRCULAR 925, U. S. DEPARTMENT OF AGRICULTURE 
Although the usable forage was slightly greater on the adjacent 
heavily grazed range in 1937, 10 years later the estimated usable forage 
produced within the enclosure was 373 pounds per acre as compared 
with 224 pounds outside it. The heavily grazed range had the greater 
total herbage yield in 1947, but more than half of this was the low- 
value Russian-thistle, which showed a striking increase, largely because 
of the unusually favorable precipitation during the preceding year. 
TABLE 1|1.—Herbage production per acre in an ungrazed enclosure and on 
adjacent heavily grazed range within a winterfat subtype at three intervals 
after establishment of the enclosure in 1937 
Ungrazed Heavily grazed 
Species eee ee ee ee aan 
1937 | 1940 | 1946 | 1947 | 1937 | 1940 | 1946 | 1947 
Shrubs: Lb: Lbs |b. | 26. ibe) bs | be ae 
Winterfat__.-------- 35.8 |171.4 |121.2 [428.1 | 49.0 | 29.1 | 61.7 | 213.8 
Others ie ae [eb | ON | 22.47] 67 3312 a Oe 
All shrubs_____- 36.3 |171.4 1123.6 [434.8 | 52.3 | 31.8 | 64°7 | 225.2 
Grasses: | | = | | 
Indian ricegrass _ _ _ -- £0) 18716 45-07 13274 del ae ea eae 
Galleta: 12:1 | 49:8: 5.8 | 21-91 9:3 2.7.6 | 3 5 ease 
Others = se 8 See) 2 150-|- 2.5 | 3) le a0 eae 
All grasses ___ | 16.5 | 68.4 | 51.0 [155.3 | 14.9| 12.0 | 12.7] 84.0 
Forbs: | | 
Russian-thistle_____- 73.3} °2\ 0 | 18.9 1113 21143 0 | 78 a0ieG 
Giicr = os 3.21 10:4 4118 0 118-20 oe eee 
AM forbs == = s)\27665.1 1006 4 | 31.9 [115.0 [145.7 | 2.5 | 438.9 
otal 8 129.3 |250.4 |175.0 622.0 [182.2 |189.5 | 79.9 | 748.1 
Usable forage ?__| 38.0 141.2 |109.7 |372.7 | 49.1 | 39.5 | 44.8 | 223.6 
1 Less than 0.1 pound. 
2 Caleulated from utilization records. 
INFLUENCE OF GRAZING INTENSITY 
ON SHEEP PRODUCTION 
Concurrently with the studies of herbage yields and vegetal changes, 
data on sheep production were maintained. Records of body weight 
were made for all ewes assigned to the experimental range pastures. 
Additional data on body weights of ewes together with information on 
wool vields, death losses, lamb crops, and income were obtained for the 
two herds (designated as A and B) that grazed in alternate years on the 
experimental range allotments and on nearby unfenced range. Further 
records included observations on supplemental feeding of both these 
herds as well as others grazing in the vicinity of the experimental range. 
