32 



CIRCULAR 870, IT. S. DEPARTMENT OF AGRICULTURE 



dicated a degree that was nearer to moderate than to close, while "close 

 to moderate" indicated utilization was nearer to close. 



Effects of Different Degrees of Grazing on Cattle 



Production 



A brief consideration of how different degrees of grazing affect cattle 

 production will aid in interpreting the effects on sustained forage pro- 

 duction. Members of the Division of Animal Husbandry, University of 

 California, who were in charge of the cattle phases of the experiment, 

 have reported the findings for 1937-43 (4)- Their results, summarized 

 here, show that heavy stocking, even for only part of the year, on annual- 

 plant ranges means lowered efficiency of production from a breeding-cow 

 herd. 



Average gains and weaning weights of calves were low in closely grazed 

 pasture 3, particularly for calves from the "B" herd which received no 

 supplements, but also for calves from the "A" herd which received supple- 

 ments while out of the grazing-intensity pastures (table 7). Variations 

 in gains and weaning weights of calves in the other five pastures were 

 not related to degree of grazing; the variations were apparently caused 

 by other factors. The lower calf gains in pasture 3 emphasize the im- 

 portance of having an adequate forage supply for cows during the nursing 

 period. 



Table 7. — Average gains and weaning weights of calves from supplemented 

 and unsupplemented herds grazed in six pastures, 1937-43 *■ 



Pasture 

 number 



Degree of grazing 



Calves from supple- 

 mented "A" herd 



Calves from unsupple- 

 mented "B" herd 





Gains in 

 pasture 



Weaning 

 weight 



Gains in 

 pasture 



Weaning 

 weight 



3 



Close 



Pounds 

 265 



Pounds 

 459 



Pounds 

 241 



Pounds 

 378 



1 



Moderate to close 



292 



504 



291 



447 



5 



Moderate 



281 



459 



286 



432 



4 



Light to moderate 



284 



490 



285 



435 



6 



Light 



268 



462 



299 



453 



2 



____do 



292 



493 



300 



447 



1 Source: H;irt, Wagnon, and Guilbert (4). 



The cows in closely grazed pasture 3, from the unsupplemented "B" 

 herd, always gained less than did the cows from this herd in the other 

 five pastures and were always thinner at the time they left the pasture 

 (table 8). Cows from the supplemented herd also gained less in the 

 closely grazed pasture than did their mates in the other pastures. For 

 the unsupplemented cows, gains and final weights were also lower in 



