Effect of Peptides and Amino Acids on Efficiency of Rumen Bacterial Protein Synthesis in Continuous Culture

Five species of rumen bacteria were grown in continuous culture to study effects of peptides and amino acids on efficiency of energy utilization for microbial protein synthesis. Decreasing the source of amino acids from .5 g/liter to 0 g/liter with glucose at .5 g/liter caused the yield of bacterial protein to decrease, but the most dramatic effects were from concentrations of amino acid source below .062 g/liter. Whereas the highest concentration of peptides and amino acids always resulted in the highest yields of bacterial protein, conversion of amino acids to cell protein was usually poor. Amino acids were converted most efficiently to bacterial protein at concentrations of amino acid source below .031 g/liter. Concentrations of dietary protein needed to maximize synthesis of rumen bacterial protein may not be associated necessarily with the most efficient utilization of dietary protein in the ruminant animal.