Conditions stimulating neutral detergent fiber degradation by dosing branched-chain volatile fatty acids. I: Comparison with branched-chain amino acids and forage source in ruminal batch cultures

Three experiments assessed branched-chain volatile fatty acid (BCVFA) stimulation of neutral detergent fiber (NDF) disappearance after 24 h incubation in batch cultures derived from ruminal fluid inocula that were enriched with particulate-phase bacteria. In experiment 1, a control was compared 3 treatments isomolar doses all BCVFA (plus valerate), AA (BCAA), or half each and BCAA mix either alfalfa grass hays (50%) ground corn grain (50%). A portion the 13C, valerate (also 13C) added BCVFA. Although yielded similar production dosing BCVFA, equimolar substitution for decreased percentage N bacterial pellets when hay fed but increased fed. Substituting total (FA) concentration hay. Dosing did not affect FA, iso-FA, anteiso-FA percentages whereas numerous individual FA isomers their 13C enrichments affected by these treatments. Increasing recovery dose respective labeled primers indicated facilitated uptake incorporation into BCAA, bacteria pellet fraction suggested direct assimilation protein. The dosed varying combinations summed to 4 mM (experiment 2) had only 1 no matter what combination 3). general, more responsive NDF digestibility than hay, which attributed higher degradable protein latter. net (after subtracting dose) source Isovalerate tended increase its own production; contrast, isobutyrate seemed be used it alone, 2-methylbutyrate preferred over added. Results supported potential interactions, including feedback feed concentration-dependent competition cellular products. Under our conditions, appear readily available probably because regulated transport metabolism. Valerate consistently provided benefit. Using nonparametric ranking, isovalerate (both yielding iso-FA) should combined (yielding anteiso-FA) as opportunity improve rumen-degraded are limited diets decrease environmental impact waste.