肉牛真胃灌注不同水平的葡萄糖和酪蛋白对日粮氮代谢调控的研究

３头带有瘤胃和真胃瘘管的肉牛（３７５±２５ｋｇ）饲喂全羊草以满足维持需要，设计３个对比试验，每个试验均向瘤胃内持续灌注高乙酸摩尔比例（７５％）的混合ＶＦＡ。试验１，真胃每天持续灌注１００ｇ，２５０ｇ和４００ｇ葡萄糖；试验２，真胃每天持续灌注２００ｇ，３００ｇ和４００ｇ酪蛋白；试验３，真胃每天持续灌注２５０ｇ葡萄糖与２００ｇ，３００ｇ，４００ｇ酪蛋白组成的混合物。连续７天灌注后测定氮平衡。试验结果表明，真胃灌注葡萄糖、酪蛋白及两者的混合物均能增加氮沉积和可消化氮转化为沉积氮的效率（ＲＮ／ＤＮ），经回归分析，可消化氮转化为沉积氮的效率（ｙ，％）与真胃葡萄糖灌注量（ｘ，ｇ／天）之间存在线性正相关，回归方程为ｙ＝２５．０８２＋０．１０６９ｘ（ｒ＝０．９８９，ｎ＝４）；与真胃酪蛋白灌注量（ｘ，ｇ／天）之间存在曲线正相关，回归方程分别为ｙ＝３３．４７０＋３．３８２１ｎｘ（ｒ＝０．９７０，ｎ＝４）；与真胃葡萄糖和酪蛋白混合物的灌注量（ｘ，ｇ／天）之间也存在曲线正相关，回归方程为：Ｙ＝３５．８７０＋４．０７９ｌｎｘ（ｒ＝０．９８５，ｎ＝４）。真胃灌注葡萄糖和酪蛋白的混合物比单独灌注葡萄糖时氮的转化效率提高了１９．４１％（Ｐ?

Effect of Intra-abomasal Infusion of Glucose, Casein or Glucose and Casein Mixture on Nitrogen Metabolism in Beef Cattle

In 3 single factorial design experiments, 3 steers(BW,375±25kg) fed a maintenance diet consisted of 100% chinese wildrye hay were intra-ruminally infused VFA mixtures (acetic,propionic and butyric acid in the molar proportion of 75,15 and 10) at the 0.3 maintenance level.The treatments were intro-abomasal infusion of glucose(100,250,and 400 g/d) for experiment 1, of casein(200,300,and400 g/d) for experiment 2,and of glucose-casein mixture (250+200,250+300,and 250+400 g/d) for experlment 3. Nitrogen balance was measured after 7 days of infusion. Abomasal infusion of glucose, casein and both mixtures resuited in an increase nitrogen retention and the efficency of digestible nitrogen conversion to nitrogen retention (RN/DN). RN/DN had a positive linear relation to infusion levels of glucose (y=25.08+0.106x, r=0.989,n=4),a positive curve relation to infusion levels of casein (y=33.47+3.381nx,r=0.970,n=4), and also a positive curve relation with infusion levels of glucose and casein (y=35.87+4.08lnx,r=0.985,n=4).Compared with the infusion of glucose or casein alone, Infusion of different mixtures of glucose and casein increased RN/DN by 19.41%(P<0.05)or 16.86%(P<0.05)respectively. It was concluded that intra-abomasal infusion of glucose, casein and glucose-casein mixtures can increase nitrogen retention of beef cattle.