饲用蛋白酶体外评价方法的建立

An in vitro method to evaluate the effects of proteases on broiler

在畜禽日粮中添加蛋白酶是提高其蛋白消化的重要手段,探明不同蛋白酶对饲料蛋白消化的影响及建立科学评价方法是饲用蛋白酶科学应用的关键。试验选用31日龄肉仔鸡,根据实际测定的消化道参数设定体外消化法中的p H值、消化酶和含水量水平,同时,通过比较3种产物分离方法的变异系数,筛选了用于评价蛋白酶作用效果的适宜参数,为了明确是否添加抗生素,还观测了微生物的生长情况。结果表明,适用于评价蛋白酶对31日龄肉仔鸡作用效果的最适参数为:嗉囊阶段p H值为4.91,含水量为80%;胃阶段p H值为3.39,含水量83%,胃蛋白酶水平54.89 U/g食糜鲜重;小肠段p H值为6.20,含水量97%,胰蛋白酶、糜蛋白酶、淀粉酶活性水平为10.21、0.76和2 381.36 U/g食糜鲜重;产物分离方式宜选用磺基水杨酸沉淀蛋白后离心测定粗蛋白体外消化率;为了抑制微生物的生长,有必要在消化体系中运用抗生素。试验建立了一套适合于评价饲用蛋白酶对肉仔鸡作用效果的体外评价方法。

It is important to verify different proteases effects on protein digestibility of animal feed anddevelop an in vitro method to evaluate protease. The in vitro method was built according to the actu-al value, p H, digestive enzyme and water content of broiler digesta. The digested products separatingway was also studied. The results showed the optimum p H of crop, gastric and intestine was 4.91,3.39, 6.20. Water content was 80%, 83%, 97%. Pepsin, trypsin, chymotrypsin, and amylase was54.89, 10.21, 0.76 and 2 381.36 U/g chyme fresh weight. Sulfosalicylic acid precipitated protein is su-perior to trichloroacetic acid in separating digested products. Antibiotic addition is necessary. In con-clusion, an in vitro method is built to evaluate the effect of protease on broiler.