Degradation of protein in the rumen of the sheep. 2. The action of rumen micro-organisms on amino-acids

Publisher Website
Google Scholar
Abstract
The amino acids of an acid hydrolysate of casein were attacked under anaerobic conditions at similar relative rates by sheep rumen contents and by washed suspensions of micro-organisms therefrom. L-Proline was reduced when other amino acids were present; the resulting delta-aminovaleric acid was isolated and characterized. The main reaction products from casein hydrolysate and washed suspensions were ammonia, CO2 and volatile fatty acids in roughly equimolecular proportions; there was no significant formation of H2, methane or non-volatile organic acids. The volatile fatty acids were straight- and branched-chain Cg -C5 acids. The capacity of washed suspensions of rumen microorganisms to deaminate amino acids depended on the diet of the animal. The probable origin of the branched-chain acids by Stickland reactions from valine, leucine and isoleucine, and the nutritional significance of the deamination reactions for the animal are discussed.