Effects of tannins source (Vaccinium vitis idaea L.) on rumen microbial fermentation in vivo

Four rumen cannulated Polish Holstein-Friesian dairy cows were used in a crossover study to determine effects of source of tannins on rumen microbial fermentation. Cows were in their 4th month of lactation at the initiation of the study and were fed 20 kg/d of DM of a 600:400 forage:concentrate diet. Treatments were either no supplemental tannin or supplemental Vaccinium vitis idaea (VVI). The dose of VVI was 140 g of extract containing the equivalent of 2 g of tannins/kg dietary DM. The VVI reduced rumen CH4 production (P=0.006), ammonia concentration (P<0.001) and protozoa microbial populations (P<0.001) (protozoa and methanogens), respectively by 8, 46, and 35 and 21%, while tending (P<0.001) to reduce the acetate to propionate ratio although the proportion of total VFA was not affected. The tannin sources used demonstrated antimicrobial activity by decreasing protozoal numbers thereby reducing rumen CH4 production and ammonia concentration. Results suggest that Vaccinium vitis idaea, as a source of tannins, has the potential to reduce rumen CH4 production and ammonia concentration.