42 BULLETIN 1170, U. S. DEPARTMENT OF AGRICULTURE. 



per cent more cattle can be grazed on the same area. This will in 

 a short time more than pay for the extra cost of fences. This sys- 

 tem of grazing could be readily applied on many farms or ranches. 

 It often happens that the land for pastures is divided by roads, so 

 that it is necessary to operate independent pastures. When such a 

 condition exists the system of deferred and rotation grazing can be 

 put in operation at once without additional cost. 



SALIENT POINTS REVEALED BY THE GRAZING EXPERIMENT. 



Of more than 250 species of plants at the Northern Great Plains 

 Field Station, less than a dozen play a dominant role in grazing. 



Bouteloua gracilis (blue grama grass) is the species least injured 

 by heavy grazing and apparently is benefited by moderate to close 

 grazing. 



Stipa comata (western needle grass) is the species most injured by 

 heavy grazing. 



Artemisia frigida (pasture sage) is the best indicator of over- 

 grazing, because cattle do not like it, and it is able to take advantage 

 of the weakened condition of other plants and increase in number 

 and size per unit area. 



The range vegetation makes 75 per cent of its growth during May 

 and June. 



The total gains that can be made on native pastures in this area 

 of the Great Plains have never been fully realized by stockmen or 

 those interested in grazing problems. 



In a grazing experiment it is equally important to know what is 

 happening to the cattle and to the vegetation. 



Cattle make their largest gains during the early season on green 

 grass and not in the fall on mature grass. This is true as long as the 

 quantity of feed early in the season is not a limiting factor. 



Cattle grazing on a short range may appear to be doing well when, 

 in fact, they are no more than maintaining their weight. 



Grazing longer than four months has not increased the gains per 

 head, but has resulted in a better " finish." 



Under a system of continuous grazing it requires 7 acres to graze 

 one 2-year-old steer for five months. 



Between 4 and 5 acres will graze a 2-year-old steer for five months 

 under a sj'stem of deferred and rotation grazing. 



The highest gain per head of cattle is not correlated with the 

 highest gain per acre. 



The lowest gain per head made on the lowest acreage is correlated 

 with the highest individual gain per acre, provided the cattle are not 

 forced to remain on a short pasture for too long a period. 



The measure of efficiency of a pasture or system of grazing is not 

 determined by one factor but by several of equal importance. 



CONCLUSIONS AND SUMMARY. 



The cooperative grazing experiment reported upon in this bulletin 

 was established at the Northern Great Plains Field Station, near 

 Mandan, N. Dak., in 1915. Its objects were to determine the grazing 

 capacity of the native range and the effects of different systems and 

 intensities of grazing upon the native vegetation. 



