饲粮添加海南霉素和莫能菌素对奶牛瘤胃发酵特性和氮平衡的影响

本研究旨在探究饲粮添加海南霉素和莫能菌素对奶牛瘤胃发酵特性和氮平衡的影响.选用3头体重为(460.0±20.6)kg、装有永久性瘤胃瘘管的成年荷斯坦奶牛,采用3×3拉丁方试验设计,对照组饲喂基础饲粮,试验组分别饲喂在基础饲粮添加20 mg/d海南霉素和350 mg/d莫能菌素的试验饲粮.结果表明:饲粮添加海南霉素和莫能菌素没有显著影响瘤胃液pH和丁酸含量(P＞0.05),但显著降低了瘤胃液总挥发性脂肪酸浓度、乙酸含量、乙酸/丙酸和氨态氮浓度(P＜0.05).与对照组相比,海南霉素组和莫能菌素组丙酸含量分别提高了16.26％和15.79％(P ＜0.01).饲粮添加海南霉素和莫能菌素显著降低了尿囊素排出量、尿嘌呤衍生物排出量和微生物氮产量(P＜0.05).饲粮添加海南霉素和莫能菌素也降低了粪氮量和尿氮量(P＜0.05),提高了沉积氮量(P＜0.01).与对照组相比,海南霉素组和莫能菌素组的表观氮消化率分别提高了5.61％和7.05％(P =0.03).总之,与莫能菌素相似,饲粮添加海南霉素可以改变瘤胃发酵模式,使其更趋向于丙酸型发酵,并且能够提高氮利用效率.

Effects of Dietary Hainanmycin and Monensin on Ruminal Fermentation Characteristics and Nitrogen Balance in Dairy Cows

This study was conducted to evaluate the effects of dietary hainanmycin and monensin on ruminal fermentation characteristics and nitrogen balance in dairy cows.Six Holstein dairy cows with an average body weight of(460.0±20.6) kg fitted with permanent rumen cannula were used in a 3×3 Latin square design.Cows in the control group were fed a basal diet,and those in experimental groups were fed the basal diet supplemented with 20 mg/d hainanmycin and 350 mg/d monensin,respectively.The results showed as follows: rumen fluid pH and butyrate content were not affected by dietary hainanmycin and monensin(P>0.05),but total volatile fatty acids concentration,acetate content,acetate/propionate and NH3-N concentration were significantly decreased(P<0.05).Compared with the control group,propionate content of hainanmycin and monensin groups was increased by 16.26% and 15.79%,respectively(P<0.01).Dietary hainanmycin and monensin significantly reduced allantoin extraction,urinary purine derivatives extraction and microbial nitrogen yield(P<0.05).Dietary hainanmycin and monensin significantly reduced fecal nitrogen and urinary nitrogen(P<0.05),and significantly increased nitrogen retention(P<0.01).Compared with the control group,apparent nitrogen digestibility of hainanmycin and monensin groups was increased by 5.61% and 7.05%,respectively(P=0.03).In conclusion,similarly to monensin,dietary hainanmycin tends to change rumen fermentation into propionate-type fermentation,and can improve efficiency of nitrogen utilization.