Effect of grain vinegar feeding on milk production and fatty acid profile of Holstein cows.

Incorporating organic acids into cattle feed should be carefully considered because dietary organic acids may affect voluntary feed intake and rumen fermentation. We conducted a feeding trial for the practical evaluation of grain vinegar. Lactating Holstein cows (n = 19) were divided into two groups, then were subjected to each of two treatments in a crossover design. The rumen fermentation parameters, blood urea nitrogen and non-esterified fatty acids (NEFA), milk composition, and milk fatty acid content were analyzed. No notable changes were observed in rumen fermentation parameters or blood metabolites. Corn silage intake, milk production, and 4% fat-corrected milk (FCM) were not affected by vinegar supplementation. The proportions of fatty acids in milk originating from de novo synthesis in the mammary gland were 25.2% and 25.4% in control and vinegar-fed groups, respectively. The levels of branched-chain fatty acids iso-C14:0, iso-C15:0, and iso-C16:0 were substantially decreased by vinegar supplementation, are known to be related to rumen environmental stress. This study showed that feeding grain vinegar to lactating dairy cows had no effect on feed intake, rumen fermentation, or milk production, although the proportion of some branched-chain fatty acids in the milk decreased.