Purified Diet Studies with Sheep

Abstract

Four protein sources; urea, casein, soybean oil meal and isolated soy-protein were individually included in a semi-purified ration and compared in a 48-day sheep growth experiment. Gains of sheep receiving the isolated soy-protein ration were greater (P<.05) than those of sheep consuming the urea or casein rations and sheep consuming the isolated soy-protein ration required less feed per pound of gain (P<.05) than those consuming the urea ration. Sheep consuming the casein ration had essentially the same rate of gain as those on the urea ration while those receiving the soybean oil meal ration had gains intermediate between the urea and isolated soy-protein rations. The addition of 0.4% DL-methionine or 4% ground polyethylene to a purified diet in which urea supplied the dietary nitrogen did not affect gains or feed efficiencies of sheep during a 54-day experiment. Sheep receiving the isolated soy ration made greater (P<0.01) and more efficient gains (P<0.01) than sheep consuming any of the urea-containing rations. A rumination apparatus was described and used to determine the amount of time that sheep spent ruminating. The addition of 1, 2 and 4% of polyethylene to the urea basal ration, increased the time spent ruminating and the response did not differ significantly from linearity (P>0.05). The addition of 1, 2 or 4% ground polyethylene to the isolated soy ration increased rumination time (P< 0.01) over that obtained on the isolated soy control ration but the different levels did differ from linearity. The addition of 0.2% DL-methionine, 1 mg. diethylstilbestrol per lb. of ration, 0.2% DL-methionine plus 1 mg. diethylstilbestrol per lb. of ration, or 0.2% DL-alanine to the urea basal ration did not significantly affect gains or feed efficiency of sheep during a 50-day growth trial.