The Influence of Autoclaving Soybean Oil Meal on the Digestibility of the Proteins

Chicks were raised to 4 weeks of age on diets supplemented with raw soybean oil meals which had received the following treatments: none, autoclaved for 30 minutes at 100, 110, 120, 130°C. or autoclaved for 60 minutes at 130°C. The percentages of total protein, organic sulfur, cystine and methionine in the soybean oil meals not digested by the chick, by pepsin, trypsin and erepsin in vitro, or by trypsin and erepsin in vitro were determined. The soybean oil meals which had been autoclaved at temperatures between 100°C. and 120°C. for 30 minutes were more completely digested by the chick or by trypsin and erepsin in vitro than the raw meal or the meals which had been autoclaved at 130°C. using undigested total protein, or sulfur, cystine, or methionine in the undigested protein as criteria. Raw soybean oil meal was in most cases more readily digested by pepsin, trypsin and erepsin in vitro than the autoclaved meals. Significant correlations were obtained between in vitro trypsin and erepsin digestion, and chick digestion of these soybean oil meals for undigested protein, organic sulfur and cystine. No significant correlations between chick digestion and in vitro pepsin, trypsin and erepsin digestion values were obtained. Of especial interest is the relatively high percentage of cystine in the soybean oil meals that was not digested by the chick or by either of the in vitro enzyme digestions made.