牦牛和黑白花牛瘤胃内饲料蛋白质降解率的比较研究

Differences of Ruminal Dietary Protein Degradation Between Yaks and Holsteins

用瘤胃尼龙袋技术研究了青藏高原８种常见饲料在牦牛和黑白花牛瘤胃内的粗蛋白（ＣＰ）和干物质（ＤＭ）降解率，分析了２个动物品种间的降解率的差异性。装有永久性瘤胃瘘管的牦牛（平均体重１００ｋｇ）和黑白花牛（平均体重１７０ｋｇ）各２头，，以１．５×ＭＥｍ水平饲喂同一基础日粮（精粗比为５０∶５０），瘤胃食糜的外流速度估计为０．０６７／ｈ（精料）和０．０２／ｈ（粗料）。待测料在瘤胃内的培养时间为２ｈ，４ｈ，６ｈ，８ｈ，１２ｈ，２４ｈ和３６ｈ。用最小二乘法计算饲料在瘤胃内的潜在降解率常数。试验结果表明，牦牛瘤胃内饲料ＣＰ的快速降解部分（ａ）低于黑白花牛瘤胃的快速降解部分，除个别饲料外，牦牛瘤胃内饲料ＣＰ的潜在降解部分（ｂ）却高于黑白花牛瘤胃内的潜在降解部分。饲料ＣＰ在牦牛瘤胃内的有效降解率低于同等饲养条件下同一饲料在黑白花牛瘤胃内的有效降解率。

The objectives of this study was to determine ruminal dry matter(DM) and crude protein(CP) degradation of 8 foodstuffs in yaks and Holsteins and to study the possible differences of the degradation between the two breeds,using In Situ incubation in nylon bag method.Two yaks and two Holsteins,fitted with permanent ruminal cannulae,weighting 100 kg and 170 kg,reps,were fed the same basal diet composed of 50% hay and 50% concentrate at 12-h intervals,with a feeding level of 15MEm.Potential degradations of CP and DM were measured according to different incubation times.The constant a and c were lower,while constant b was higher for CP in yaks than in Holsteins.The proportion of potentially degraded CP (b),which degraded with the ratio c,was higher in yak than in Holstein.Effective CP degradability of the 8 foodstuffs,based on passage rate (K) of 0067/h for concentration and 002/h for roughage,were lower in yaks than in Holsteins.