Ruminal Bypass of Dietary Soybean Protein Treated with Heat, Formalin and Tannic Acid

Abstract

Diets containing either commercial, solvent-extracted soybean meal or the same soybean meal treated with heat, formalin or tannic acid were fed to steers fitted with permanent abomasal cannulas to determine the effect of treatment on ruminal bypass of dietary protein. Based on the nutrient to chromic oxide ratio technique, steers consuming formalin-treated soybean meal had more protein nitrogen reaching the abomasum per day, although no difference (P < .05) between diets was found in the total nitrogen reaching the abomasum. Heat and formalin treatment increased the quantity of amino acids presented to the abomasum daily, whereas tannic acid treatment had no effect on increasing either ruminal bypass of dietary protein or the quantity of amino acids presented to the abomasum. However, the total concentration of plasma amino acids was not affected by treatment. Trends in the proportion of individual amino acids found in abomasal digesta were not as evident in the plasma. Plasma amino acid ratios of glycine to the branch chain amino acids (valine, leucine and isoleucine) were lower (P < .05) in steers fed heat- and formalin-treated soybean meal than in steers fed normal soybean meal. The lower ratios also indicate more digestible protein reached the abomasum when normal soybean meal was heated or treated with formalin. Copyright © 1974. American Society of Animal Science . Copyright 1974 by American Society of Animal Science.