This study was conducted to investigate the effects of lysine (Lys) , methionine ( Met) and threonine ( Thr) supplementation on growth performance and serum biochemical parameters of calves. Twenty-four neonatal Holstein calves were selected and assigned randomly to 4 treatments according to the body weight and date of birth. The study lasted for 8 weeks. Four amino acids models in milk replacers ( MR) were applied in each treatment, which were consisted of balanced amino acids model ( PC group) , Lys, Met and Thr deduction models ( PC-Lys, PC-Met and PC-Thr group, repectively) . The deduction levels were all 30％ of PC group. The results showed as follows: 1) compared to the deduction models, calves fed with balanced amino acids model significantly decreased the feed to gain ratio ( P ＜ 0. 05) , significantly increased the average daily gain aged from 2 to 4 weeks (P ＜ 0. 05), and significantly increased the thorax girth change ratio and body oblique length change ratio aged from 0 to 2 weeks (P ＜0. 05) ; 2) compared to the deduction models, calves fed with balanced amino acids model significantly increase the serum albumin content aged from 0 to 8 weeks and at 8 weeks old ( P ＜0. 05) , significantly decreased serum globulin content at 8 weeks old ( P ＜0. 05) , but significantly increased serum glucose aged from 0 to 8 weeks ( P ＜ 0. 05) ;3) with the growing of calves, serum total protein increased, serum glucose increased at first and then decreased. In conclusion, the partial deductions of Lys, Met and Thr have negative effects on growth performance and serum biochemical parameters of calves. [ Chinese Journal of Animal Nutrition ,2011 ,23 ( 2 ) : 226-233 ]%本试验旨在研究赖氨酸、蛋氨酸和苏氨酸对犊牛生长性能和血清生化指标的影响.选取24头新生荷斯坦犊牛进行8周饲养试验,按照体重和出生时间相近原则分为4组,采用4种氨基酸模式的代乳粉,分别为氨基酸平衡组(PC组)、扣除赖氨酸组(PC-Lys组)、扣除蛋氨酸组(PC-Met组)、扣除苏氨酸组(PC-Thr组),扣除量均为对照组的30%.结果表明:1)与采食扣除氨基酸饲粮相比,犊牛采食氨基酸平衡饲粮显著降低了料重比(P＜0.05),增加了2～4周龄平均日增重、0～2周龄胸围变化率和体斜长变化率(P＜0.05);2)与采食扣除氨基酸饲粮相比,犊牛采食氨基酸平衡饲粮显著提高了0～8周龄平均血清白蛋白含量及8周龄血清白蛋白含量(P＜0.05),降低了8周龄血清球蛋白含量(P＜0.05),提高了0～8周龄平均血清葡萄糖含量(P＜0.05);3)犊牛血清总蛋白含量随着周龄的增长而提高,血清葡萄糖含量随周龄的增长先下降后上升.结果提示,部分扣除赖氨酸、蛋氨酸和苏氨酸对犊牛的生长性能和血清生化指标均有负面影响.
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