The nutritive value of the proteins of corn-gluten meal, linseed meal, and soybean-oil meal.

The results of previous experiments from this laboratory {22) ^ indicated no differences in the utilization by growing lambs of the proteins of alfalfa hay and clover hay when fed at a 10-percent level in rations which were presumably adequate in total digestible nutrients, minerals, and vitamins. F\u*thermore, no differences were observed between the biological value of the proteins of an alfalfa and corn ration and the proteins of a clover and com ration when both rations were fed at a 10-percent level of protein. The biological values of the proteins of the two latter rations were approximately the same as when each of the hays formed the only source of protein, hence showing no supplementary effect due to the addition of corn protein. The average of the biological values was 81 for clover protein, 79 for alfalfa protein, 80 for the protein in the combination of clover and corn, and 77 for the protein in the combination of alfalfa and com. These results were interpreted to indicate that alfalfa hay and clover hay are probably not deficient in quality of protein for sheep when fed in a balanced ration as regards protein and total digestible nutrients. Since there were no significant differences in protein utilization in these experiments, the question was raised in the minds of the writers as to whether or not there are any actual differences in the nutritive value of the proteins of common feeds for sheep, when the feeds in question are fed in rations which furnish sufficient of total digestible nutrients and other known dietary essentials, and when fed at the same level of protein intake. Very few data have been presented which show any marked differences in the efficiency of protein utilization when common feeds tuffs have been fed to ruminants in well-balanced rations (5, ö, 7, 11, 19). The common explanation given is that the ruminant has the ability to synthesize certain of the essential amino acids as a result of bacterial action in the digestive tract. This possibility has been frequently pointed out in the literature, especially with reference to the synthesis of cystine by sheep. These experimental results {22) have suggested the desirability of obtaining further data on the importance of the quality of protein for ruminants and of ascertaining whether differences in the biological value of proteins can be obtained with the sheep using the nitrogenbalance type of experimentation. Therefore, experiments have been conducted to determine the nutritive values for sheep of the proteins