Effect of Carbon-4 and Carbon-5 Volatile Fatty Acids on Digestion of Plant Cell Wall In Vitro

Publisher Website
Google Scholar
Abstract
When mixed ruminal bacteria were incubated in an artificial medium with isolated plant cell walls, cell wall digestion and ammonnia utilization were increased by low concentrations (< 0.30 mM) of C-4 and C-5 volatile fatty acids (isobutyric, isovaleric, valeric and 2-methylbutyric). C-4 and C-5 acid supplementation also increased cell wall digestion of intact forages. No pattern was observed between protein content of the fed and responses to C-4 and C-5 volatile fatty acids. Only the branch-chain acids (isovaleric, isobutyric and 2-methlbutyric) stimulated bacteria growth and plant cell wall digestion. No synergisms were observed among the branched-chain acids, they could replace each other. Valeric acid, a straight chain compound, was without effect, and phenylpropionic and phenylacetic acids did not improve digestibility. The peptide source, trypticase, enhanced cell wall digestion more than C-4 and C-5 volatile fatty acids alone, and this observation suggested that fiber digesting bacteria may have been stimulated directly by amino acids or peptides.