Apparent Biological Value of Pelleted and Autoclaved Torula Yeast Measured in Various Ways

TORULA yeast appears to be a good source of protein for chicks fed practical type diets. Klose and Fevold (1945) reported that 80% of the fish meal in a cereal ration could be replaced by torula without decrease in the rate of gain, methionine being the limiting amino acid in the yeast. Ringrose (1949) and Vedvik (1952) showed that 50–60% of the soybean oil meal in a corn-soy diet could be effectively replaced by torula. On purified diets, however, chicks grow very poorly when fed torula yeast as the sole source of protein (Vedvik, 1952; Gitler, 1956). The present studies deal with attempts to improve the protein quality of torula yeast by pelleting, autoclaving, or extracting with alkali. The products were tested in chicks by ordinary growth studies, and measurements were also made in rats by a spaced feeding technique. METHODS Chick experiments. In all series day old chicks, . . .