饲粮中添加海南霉素对奶牛瘤胃发酵及甲烷产量的影响

摘要

本试验旨在研究海南霉素对荷斯坦奶牛瘤胃发酵模式及甲烷产量的影响.试验选用3头装有永久性瘤胃瘘管、体况相近的中国荷斯坦奶牛,采用3×3拉丁方试验设计,试验分为3期,每期15 d,试验设负对照组(不添加任何添加剂)、正对照组(添加10 mg/kg莫能菌素)和海南霉素组(添加7.2 mg/kg海南霉素).结果表明:饲粮中添加海南霉素后,除在采食后2h显著提高奶牛瘤胃内pH(P ＜0.05)外,其他时间均无显著影响(P＞0.05)；采食后0、2、8和10 h,海南霉素组氨态氮(NH3 -N)浓度均显著低于负对照组(P＜0.05),而采食后6h,海南霉素有抑制NH3 -N释放的趋势(P=0.06)；采食后0、2、4和6h,海南霉素组乙酸浓度及乙酸与丙酸的比值与负对照组相比均显著降低(P＜0.05),丙酸浓度显著升高(P＜0.05),总挥发性脂肪酸和丁酸浓度没有显著变化(P＞0.05).海南霉素显著抑制了瘤胃甲烷的产生(P=0.02),海南霉素组的奶牛甲烷呼出量为216.50 L/d,比负对照组降低了14.03％.由此得出结论:饲粮中添加海南霉素可以改变奶牛瘤胃的发酵类型,使其更趋向于丙酸型发酵,并显著降低动物的甲烷呼出量.%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 x 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 hainamy-cin 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 (P <0. 05) , but had no significant effects at all other times after feeding (P >0. 05). Dietary hainanmycin decreased rumen ammonia (NH3-N) concentration at 0, 2, 8 and 10 h after feeding (P <0. 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 (P <0. 05) , and increased rumen propionate concentration (P <0. 05) , but had no significant effects on rumen butyrate and total volatile fatty acid (TVFA) concentration (P >0. 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.