2 CIRCULAR 80 4, U. S. DEPARTMENT OF AGRICULTURE 



Much of this range is grazed by cattle and horses, but sheep also 

 use a considerable part of it. Although wool and feeder lambs are 

 the chief market products of the local sheep industry, the development 

 of ewe lambs and yearling ewes into breeding animals by grazing them 

 for several months to a year on the range is becoming an increasingly 

 important type of range sheep husbandry in the northern Great 

 Plains. 



In this area the low production of supplemental hay and the high 

 cost of imported feeds, plus generally open winters and the relatively 

 good forage value of cured range herbage, encourage range grazing 

 for long periods annually. It is a common practice to graze sheep 

 on the range continuously for 9 to 1 1 months and even year long when 

 forage is available and weather is not too severe. One of the major 

 problems which northern Great Plains sheepmen face is how to stock 

 their ranges to get the greatest possible production year after year 

 without deterioration of the forage and soil upon which their continued 

 and successful operation depends. The effect of past grazing use and 

 the frequent occurrence of severe drought contribute to the wide 

 variations in stocking which occur in the region. 



It has been most difficult to determine the acreage of range per 

 sheep per month; i. e., the rate of stocking that will give best results 

 over a long period. A common but questionable practice has been to 

 stock heavily during favorable years and then attempt to adjust down- 

 ward when unfavorable weather and forage conditions occur. This 

 has led many operators into financial ruin because, unfortunately, a 

 crisis may develop more rapidly than adjustments can be made during 

 unfavorable seasons. Furthermore, the range deteriorates severely 

 under heavy stocking. On the other hand, stocking so light as to 

 entirely avoid heavy sales of livestock during drought years is not 

 practical because heavy carrying charges and other expenses make such 

 a practice unprofitable. The urgent need for information on how to 

 stock northern Great Plains sheep range for sustained production 

 led to the study here reported. 



HOW THE PROBLEM WAS STUDIED 



The Northern Pocky Mountain Forest and Range Experiment 

 Station in cooperation with the Bureau of Animal Industry and the 

 Montana Agricultural Experiment Station conducted a study of sheep 

 grazing from 1936 through 1941 to determine and develop guides to 

 proper stocking of northern Great Plains range for sustained sheep 

 production without deterioration of the forage and soil resource. The 

 study centered on lands of the United States Range Livestock Experi- 

 ment Station, about 10 miles southwest of Miles City, Mont. This 

 location is typical of northern Great Plains range. Three experimental 

 pastures (fig. 1) of 332, 476, and 847 acres were established and stocked 

 with yearling ewes to provide 9.5, 13.6, and 24.2 acres of range per 

 head in 1936, the first grazing season. During that first season, 1936, 

 the range pastures received 0.48, 0.34, and 0.19 sheep-months of graz- 

 ing use per acre, respectively. The smallest pasture was stocked 

 heavily, the next larger one conservatively, and the largest pasture 

 lightly throughout the entire test. 



Because of favorable weather after late 1937 and substantial re- 

 covery of the range from the severe droughts of 1934 and 1936, it was 

 necessary to increase the number of sheep in each pasture to maintain 



