Biological Value of Casein as a Supplement to the Proteins of Barley in Rations for Pigs

It has been shown at the California Agricultural Experiment Station by Thompson and Voorhies (7) ^ and by Hughes (2) that barley, when fed as the only source of protein, does not produce optimum growth in pigs. Protein-rich concentrates like fish meal and tankage or dairy byproducts when used as supplements to barley, produce more rapid growth. Such concentrates, however, contain other nutrients than protein, which makes it unsafe to conclude that the protein is responsible for the results obtained. Casein, since it has been used by biologists in similar studies with smaller animals than the pig, and since it is relatively low in cost, was used as a supplement in the studies reported here to determine whether or not the proteins of barley are present in amounts necessary for the rapid development of the pig.