36 CIRCULAR 870, I". S. DEPARTMENT OF AGRICULTURE 



was three times as great as in pasture 3, and more than 50 percent greater 

 than in pasture 1. Production was uniformly low on all sites in the two 

 more closely grazed pastures. Grasses produced about 75 to 90 percent 

 of the available new growth in each of the pastures. 



The differences between pastures were only about 50 pounds of air-dry 

 forage per acre, but even such small differences in the production of new 

 forage are important in this period when cattle have difficulty in obtaining 

 sufficient green forage for their minimum requirements. Furthermore, 

 at this stage the forage is a "watery concentrate;" air-dry, it is comparable 

 to many commercial concentrate feeds. Fifty pounds of air-dry forage 

 per acre represent a considerable bulk of green material. 



Close grazing also delayed the date when new forage was adequate, thus 

 lengthening the time that expensive supplemental feeding was necessary. 

 Each year when the cattle entered the six grazing-intensity pastures, the 

 new forage was considered adequate in each of the four pastures grazed 

 from moderate to light the previous year. But it was not considered 

 adequate in pasture 3, grazed close, and pasture 1, grazed moderate to 

 close in preceding years. Observations during 3 years on some 200 small 

 temporary enclosures that were relocated each year and protected from 

 cattle grazing until May, indicated that the forage in the closely grazed 

 pasture would not have been ready until shortly before the start of the 

 spring growth period. Since spring growth started about the first week 

 in March on the average, close grazing caused an average delay of about 

 3 weeks in the date when the forage was ready to graze without supple- 

 ments. The delay in the pasture grazed moderate to close was about 

 half that in the closely grazed pasture. 



This delay in growth of late-winter forage was reflected in weight gains 

 of the cows for the first few weeks they were in the pastures. First weighed 

 when they moved into experimental pastures, the cows were weighed 

 again when the forage in all pastures was abundant enough to provide a 

 fill. By that date, averaging March 21 during 9 years, cattle had been 

 in the pastures an average of 51 days. That period included the end of 

 slow winter forage growth and the start of accelerated spring growth. 

 For the entire 51-day period, which included some time when forage was 

 adequate in all six pastures, average gains 8 of cows with calves at side 

 were : 



Supplemented Unsupplemented 



Pasture (degree of grazing) : cows (pounds) cows (pounds) 



3 Close 2.5 46.5 



1 Moderate to close : 26.8 65.6 



5 Moderate 67.1 117.2 



4 Light to moderate 63.9 106.0 



6 Light 51.0 100.6 



2 do 68.1 110.6 



Cows which received supplemental feeds before entering the grazing- 

 intensity pastures as well as those that had not been supplemented gained 

 much less in the two pastures that had been most closely grazed than 

 did cows of the same group in more lightly grazed pastures. 



Better winter growth of green forage under light or moderate grazing 

 is undoubtedly related to the amount of dry vegetation left ungrazed. 

 The dry vegetation left on the range at the beginning of the fall-winter 



8 From unpublished data in files of Division of Animal Husbandry, University 

 of California, at the San Joaquin Experimental Range. 



