【摘要】 文章旨在评估包被蛋氨酸对低蛋白质日粮奶牛泌乳性能、养分消化、血清生化及瘤胃发酵性能的影响。试验将体重为(634±38)kg、泌乳量为40 kg的20头荷斯坦奶牛随机分为2组,每组5个重复,每个重复2头奶牛。对照组奶牛饲喂低蛋白的基础全混合日粮,处理组奶牛饲喂低蛋白的基础全混合日粮+0.4 g/kg包被蛋氨酸。结果 :对照组与处理组对奶牛采食量、泌乳量、4%脂肪校正乳及脂肪、蛋白质和乳糖产量的影响无显著差异(P> 0.05),同时两组奶牛乳中蛋白质和乳糖成分也无显著差异(P> 0.05)。处理组奶牛的乳尿素氮产量、乳中脂肪和尿素氮含量较对照组分别显著提高7.43%、3.87%和4.32%(P <0.05)。低蛋白质日粮添加包被蛋氨酸对奶牛养分表观消化率无显著影响(P> 0.05)。与对照组相比,处理组奶牛血清尿素氮浓度及瘤胃氨氮浓度分别显著提高8.45%和18.56%(P <0.05),但血清谷氨酰转肽酶活性及瘤胃p H和异戊酸浓度分别显著降低16.28%、2.38%和32.35%(P <0.05)。结论 :低蛋白质日粮补充0.4 g/kg包被蛋氨酸对奶牛泌乳量、采食量和养分消化均无负面影响,但可改善乳脂肪和尿素氮含量,降低瘤胃p H。更多还原

【Abstract】 This experiment was conducted to evaluate the effects of coated methionine on lactation performance,nutrient digestion,serum biochemistry and rumen fermentation performance of dairy cows fed low protein diet. Twenty Holstein dairy cows with a body weight of(634±38)kg and a milk yield of 40 kg were randomly divided into 2 groups with 5 replicates per group and 2 dairy cows per replicate. Cows in control group were fed basal total mixed diet,and cows in treatment group were fed basal total mixed diet +0.4 g/kg coated methionine. Results :There were no significant differences in feed intake,milk yield,4% fat corrected milk and the yield of fat,protein and lactose between control group and treatment group(P > 0.05),and there were no significant differences in milk protein and lactose components between control group and treatment group(P > 0.05). Milk urea nitrogen yield,milk fat and milk urea nitrogen content of cows in treatment group were significantly increased by 7.43%,3.87% and 4.32% compared with control group(P < 0.05),respectively. Low protein diet supplemented with coated methionine had no significant effect on nutrient apparent digestibility of dairy cows(P > 0.05). Compared with the control group,the serum urea nitrogen concentration and rumen ammonia nitrogen concentration in treatment group were significantly increased by 8.45% and 18.56%(P < 0.05),respectively,but the serum glutamyl transferase activity,rumen pH and isovalenic acid concentration in treatment group were significantly decreased by 16.28%,2.38% and 32.35%(P < 0.05),respectively. Conclusion :Low protein diet supplemented with 0.4 g/kg coated methionine has no negative effects on milk yield,feed intake and nutrient digestion,but can improve milk fat and urea nitrogen contents,and reduce rumen pH value.更多还原