34 CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE 



This experiment produced only limited information concerning the 

 effects of degree of grazing on the calf crop. Percentage pregnancies 

 and calf crops for supplemented cows (table 9) did not differ significantly 

 between experimental pastures. Supplements received during the fall 

 and winter apparently offset the effects of differences in degrees of grazing 

 during the remainder of the year. Yet stocking to a degree closer than 

 moderate during late winter, spring, and early summer did affect repro- 

 duction from unsupplemented cows. As stated by the animal husband- 

 men (4), there is a good indication "that the lower percentage of preg- 

 nancies and calf crop of group B (unsupplemented) cows in pastures 3 

 (close) and 1 (moderate to close) is related to the lower gains and 

 weights of these cows." 



The experiment shows, too, that net gain per acre is not a good ex- 

 pression of efncienc3 T of operation for a breeding herd. The average yearly 

 gain of all cattle per grazable acre was greatest under close grazing and 

 decreased with increase in the amount of grazable land available per 

 animal unit: from 43.1 pounds in pasture 3 to 23.4 pounds in pasture 6, 

 with pasture 2 as an exception at 32.5 pounds per grazable acre. But, as 

 stated by the animal husbandmen (4), "while pasture 3 shows the highest 

 return in pounds of gain per grazable acre, it should not be concluded 

 that this is the most profitable use. The cattle were always thinner, the 

 gains contained less energy because of lack of fat, the calves weighed 

 less at weaning time, had less bloom, and were worth less per pound. 

 Efficiency of production for those not receiving supplemental feed was 

 further reduced because of lower calf crops. . . . Thus there are limita- 

 tions of greatest return in pounds of beef per acre as a criterion of most 

 profitable rate of stocking. Rather, the criteria should be the maximum 

 returns per acre compatible with maximum gains of the cattle, high 

 percentage calf crops and optimum weaning weights. . . . That animals 

 do not thrive where they do not get enough to eat is not news to most 

 livestock men. Some cling to large numbers poorly fed and thus use 

 too high a proportion of feed resources for maintenance. This leaves too 

 little for production and sacrifices efficiency through lower weights, calf 

 crops, value per pound, and increased death loss." 



Effects of Different Degrees of Grazing on Herbage 



Production 



Grazing to a moderate degree which gave efficient cattle production 

 also maintained satisfactory herbage production. On the other hand, 

 close grazing reduced range forage production as well as efficiency of 

 cattle production. The effects of degree of grazing were apparent in the 

 winter growth of forage and in yield of mature herbage. 



EFFECTS ON PLANT GROWTH DURING WINTER 



Close grazing consistently reduced winter plant growth. Even though 

 the closely grazed range appeared greener, the new plants were shorter 

 than on areas grazed moderately or lightly. This difference was found 

 in measurements made along fence lines and on permanent sample plots 

 in the grazing-intensity pastures, and it is well illustrated by intensive 

 measurements made in January 1943 on 100 square-foot quadrats in 



