不同粗蛋白和氨基酸组合日粮对实验兔氮代谢和免疫功能的影响

选用100日龄成年日本大耳白兔36只，随机分为6组（Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ和Ⅵ组），分别喂以6种不同粗蛋白和氨基酸组合的日粮。其中Ⅰ-Ⅲ组日粮粗蛋白水平为12％，赖氨酸含量分别为0．72％，0．9％和1．08％，含硫氨基酸含量分别为0．52％，0．65％和0．78％：Ⅳ—Ⅵ组日粮粗蛋白水平为16％，赖氨酸与含硫氨基酸组成分别与Ⅰ-Ⅲ组相同。通过饲养试验、氮代谢试验和免疫学实验。观察这6种粗蛋白和氨基酸组合日粮对实验兔的氮代谢和免疫功能的影响。试验结果表明，动物的日增重和氮利用率以Ⅲ、Ⅳ组最高，Ⅰ、Ⅵ组最低，Ⅲ、Ⅳ组分别与Ⅰ、Ⅵ差异显著（P〈0．01），但Ⅲ组的总氮排泄量明显低于Ⅳ组（P〈0．01）。Ⅲ、Ⅳ组动物的脾脏指数和胸腺指数也都高于其他4组动物，Ⅳ组动物的脾脏指数分别与Ⅰ、Ⅱ、Ⅴ和Ⅵ组差异显著（P〈0．01）。抗卵苛白蛋白抗体阳性的动物数以Ⅲ组最多，分别与Ⅱ、Ⅴ和Ⅵ组差异显著（P〈0．05）。血清总蛋白含量随日粮氨基酸水平提高有上升趋势，血清尿素氮含量以Ⅴ和Ⅵ组最高，与其他各组差异显著（P〈0．01，P〈0．05）。综上所述，Ⅲ、Ⅳ组日粮粗蛋白和氨基酸组合比较适宜，考虑到Ⅳ组氮排放量较高，故以Ⅲ组最佳。

Effects of Diets with Different Combinations of Crude Protein and Amino Acids on Nitrogen Metabolism and Immune Function in Experimental Rabbits

A series of experiments （feeding trial, nitrogen metabolism trial and immune function test） were carried out to assess the effects of diets with different combinations of crude protein and amino acids on immune function and nitrogen metabolism in rabbits. 36 adult Japanese White rabbits （100 d old） were randomly divided into 6 groups（ Ⅰ, Ⅱ, Ⅲ,Ⅳ, Ⅴ and Ⅵ ）according to 6 diets. The crude protein levels in groups Ⅰ , Ⅱ and Ⅲ were 12%, while those in group Ⅳ,Ⅴ and Ⅵ were 16%. From group Ⅰ to group Ⅲ or group Ⅳ to Ⅵ, contents of lysine were 0.72%, 0.9% and 1.08%, and contents of methionine plus cystine were 0.52%, 0.65% and 0.78%, respectively. Results showed that both daily weight gain and total nitrogen utilization were significant higher in group Ⅲ and Ⅳ than those in group Ⅰ or Ⅵ （P〈0.01）.While compared with the group Ⅳ, the content of total nitrogen excretion in group Ⅲ significandy decreased from 2.07 to 1.59 g·d^-1 （P 〈0.01）. Combinations of crude protein and amino acids had significant effects on immune function, with the highest level of antibody response to ovalbumin in group Ⅲ, which was significant higher than group Ⅱ, Ⅳ and Ⅴ （P〈 0.05）. Both indices of spleen and thymus in group Ⅲ and Ⅳ were higher than those in the other 4 groups, although there were no significant differences among them except the spleen index in group Ⅳ. The serum total protein （TP） was increased with the increasing amino acids content. The contents of blood urea nitrogen （BUN） were highest in group Ⅴ and Ⅵ （5.1 mmol·L^-1）, which had significant differences between the two groups and the other d groups （P〈0.01, P〈0.05 ）. In summary, the suitable combinations of crude protein and amino acid were the diets in group Ⅲ and Ⅳ, but as the total nitrogen excretion concerned, group Ⅲ was optimal.