The Nutritive Value of the Proteins of Alfalfa Hay and Clover Hay When Fed Alone and in Combination with the Proteins of Corn

The great importance of legume hay is recognized by everyone interested in livestock production. Because of this importance, it is highly desirable to obtain data on the nutritive value of the proteins in these hays when they are fed alone and when fed in combination with the protein of corn and other farm-grown grains. It is apparent that the great value of legume hays in stock feeding is largely due to their heavy yield per acre, their high protein content, and their palatability. From the good results which are obtained with legume hay, even when animals are given little or no other feeds in addition, as is sometimes the case in the alfalfa districts of the West, it might also be assumed that the protein of legume hay has a high quality or high biological value. The results of experiments thus far reported, however, do not seem to bear out this assumption. Practically all experiments in which alfalfa hay furnished the principal or sole source of protein have indicated that the crude protein possesses a low nutritive value. Sotóla {20Y found the protein of alfalfa hay to have a biological value of only 56 when fed alone to lambs. This was considerably lower than values for corn silage or even for sunflower silage. A later report by Sotóla {21) indicated still lower biological values for alfalfa protein when fed to lambs. This report gave the protein of the alfalfa stems a value of 64, while for the protein in the leaves it was only 44 and for the protein in the whole hay it was 51. Haag (3) made a study of the factors limiting the nutritive value of the crude protein of alfalfa for rats, and reported a deficiency of cystine, one of the essential amino acids, in the proteins of this hay. Nevens {17) fed alfalfa to rats at a 10 percent level of intake and obtained an average biological value of 62. His results further indicated no supplementary effect of the corn-grain proteins with alfalfa proteins, since the combination gave biological values averaging bS. Very few data reported show any marked differences in efficiency of protein utilization when common feeding stuffs have been fed to ruminants. Experiments by Hart, Humphrey, and Morrison (7) to determine the nutritive value of nonprotein nitrogen for dairy heifers indicated that the total nitrogen of alfalfa hay possesses approximately the same efficiency for growth and milk production as the nitrogen of corn grain plus corn stover. Hart and Humphrey {4) showed that milk protein is more efficient than corn or wheat protein when fed with corn stover. These same investigators {6) also found that both