Background: Cereal grains are important ingredients of ruminant diets, but their rapid degradation seriously impairs rumen fermentation and the host's health. The goal of this study was to evaluate whether processing of barley grain with 1 or 5% lactic acid (LA) and 1 or 5% tannic acid (TA), without or with an additional heat treatment (1% LAH or 1% TAH), may affect microbial ruminal abundance, fermentation profile, and nutrient degradation in vitro.
Results: Processing with LA lowered (P < 0.05) the concentration of short-chain fatty acids (SCFAs), proportions of branched-chain SCFA, and the acetate-to-propionate ratio. Treatment with 1% TAH and 1% LAH lowered (P < 0.05) gene copy numbers of total protozoa, rumen lipopolysaccharide, and degradation of crude protein, and tended (P = 0.08) to lower the proportion of the genus Prevotella. Treatment of barley grain with 1% LA or 1% LAH stimulated Clostridium cluster XIV. Degradation of fibre was enhanced (P < 0.05) by all LA and TA treatments.
Conclusion: Chemical and heat treatment of barley grain modulated the ruminal fermentation profile and enhanced fibre degradation; however, processing of grain with LA seems to be superior because this effect was not associated with a concomitant depression in ruminal degradation of organic matter.
Keywords: grain cereal processing; lipopolysaccharide; rumen ecology; rumen health; short-chain fatty acids.
© 2015 Society of Chemical Industry.