低蛋白日粮添加新型毕赤酵母蛋白酶对肉鸡生长性能、胴体性状、机体免疫和氨基酸表观回肠消化率的影响

Effects of the addition of novel Pichia protease to low-protein diets on growth performance,carcass traits,immunity and apparent ileal digestibility of amino acids in broilers

为系统评估一种新型毕赤酵母蛋白酶在肉鸡低蛋白饲粮中的应用效果,试验选取180只1日龄爱拔益加(AA)健康公雏,随机分配到3个处理组,每组6个重复,每重复10只鸡。试验日粮包括基础日粮、低蛋白日粮(粗蛋白质水平降低两个百分点)以及添加500 mg/kg蛋白酶的低蛋白日粮。饲养周期42 d,采用1~21 d和22~42 d的两段制饲养模式。以重复为单位,记录并计算平均日采食量、平均日增重、死淘率和欧洲指数。试验结束时,每重复选一只接近平均体重的鸡,禁食后采血并屠宰,测定血清生化指标和肉鸡胴体性状。结果表明:低蛋白日粮添加蛋白酶可显著改善肉鸡生长性能,增加欧洲指数,起到节约饲粮蛋白的作用。低蛋白饲粮可显著增加肉鸡腿肌率和腹脂率,补充蛋白酶可有效降低腹脂率。低蛋白饲粮可显著改善肉鸡肝脏健康和机体氮代谢,补充蛋白酶可在一定程度上改善肉鸡免疫功能。饲粮粗蛋白质水平降低可提高肉鸡饲粮粗蛋白质和部分氨基酸的消化率,并且在补充蛋白酶后得到进一步增强。由此可见,此新型蛋白酶在肉鸡低蛋白饲粮中具有很好的应用潜力。

This study aimed to systematically evaluate the application effect of a novel Pichia protease in low-protein diet for broiler chickens.In the trial,1801-day-old AA healthy chicks were randomly assigned to 3 treatment groups with 6 replicates in each group and 10 chickens per replicate.The test diets were a basal diet,a low-protein diet(a two-percentage point reduction in crude protein level),and the low-protein diet supplemented with 500 mg/kg protease.The feeding trial lasted for 42 d and the two-stage feeding mode including 1~21 d and 22~42 d was adopted.Average daily feed intake,average daily gain,death and culling rate and European index were recorded or calculated for each replicate.At the end of the test,a bird close to the average weight was selected from each replicate.After fasting,blood was collected and birds were slaughtered to determine serum biochemical indicators and broiler carcass traits.The results showed that the addition of protease to low-protein diets could significantly improve the growth performance of broilers,increase the European index,and save feed protein.Low-protein diets could significantly increase the leg muscle rate and abdominal fat rate of broilers,and protease supplementation could effectively reduce the abdominal fat rate.Low-protein diets could significantly improve liver health and nitrogen metabolism in broilers,and protease supplementation could improve the immune function of broilers to a certain extent.Reduced levels of crude protein in feeds improve the digestibility of crude protein and part of amino acids in broiler feeds,which was further enhanced by protease supplementation.It could be seen that the novel protease had good application potential in broiler low-protein diet.