Effects of Dietary Hainanmycin on Rumen Fermentation and Methane Production in Dairy Cows

The effects of dietary hainanmycin on rumen fermentation and methane production in dairy cows were observed in this study.Three ruminally fistulated cows with similar body condition were used in a 3×3 Latin square experiment consisting of three 15-day periods.The treatments were negative control group(without any supplementation),positive control group(supplementation with 10 mg/kg monensin),and hainamycin supplementation group(supplementation with 7.2 mg/kg hainanmycin),respectively.The results showed that dietary hainanmycin significantly increased the rumen pH at 2 h after feeding(P0.05),but had no significant effects at all other times after feeding(P0.05).Dietary hainanmycin decreased rumen ammonia(NH3-N) concentration at 0,2,8 and 10 h after feeding(P0.05) compared with the negative control group.There was a tendency that rumen NH3-N concentration at 6 h after feeding was also decreased(P=0.06).Hainanmycin supplementation significantly declined rumen acetate concentration and acetate/propionate ratio(P0.05),and increased rumen propionate concentration(P0.05),but had no significant effects on rumen butyrate and total volatile fatty acid(TVFA) concentration(P0.05) at 0,2,4 and 6 h after feeding compared with the negative control group.Dietary hainanmycin inhibited ruminal methane emissions(P=0.02).Daily methane production in cows receiving hainanmycin was 216.50 L/d,which was 14.03% lower than that of the negative control group.It is concluded that dietary hainanmycin can change rumen fermentation in a tendency of propionate-type fermentation,and significantly reduce methane emissions from rumen fermentation.