[Objective] The objective of the present study was to determine the effect of exogenous protease supplementation on the in vitro dry matter digestibility (DMD) and enzymatic hydrolysate gross energy (EHGE) using a computer-controlled simulated digestion system (CCSDS) and obtain the optimum protease supplementation into a corn-soybean meal-based diet for broilers.It would provide a reference for the establishment of in vitro method for efficacy evaluation of exogenous enzyme.[Method] A single factor completely randomized design with 8 treatments was adopted and each treatment contained 5 replicates with 1 digestion tube per replicate was adopted in the present study.The control diets for starter and finisher phrases (24.29％ and 21.72％ of crude protein,respectively,dry matter basis) of broilers were formulated to meet or exceed the nutrient requirements forbroilers,and the test diets were supplemented with 0,15 000,75 000,and 150 000 PROT·kg-1 exogenous protease (90 000 PROT·g-1)into the control diets for starter and finisher phrases of broilers,respectively.The DMD,in vitro gross energy digestibility (GED) and EHGE of the diets were determined using a CCSDS (SDS-Ⅱ).The correlation between DMD or EHGE and protease supplementation (PS) of diets were also analyzed.[Result] The results showed as follow:1) The in vitro total tract DMD,GED and EHGE of diets increased as the level of exogenous protease supplementation in the control diet for starter and finisher phrases of broilers increased(linear,P＜ 0.01).2) The in vitro gastric DMD and GED of diets decreased as the level of exogenous protease supplementation in thecontrol diet for starter phrases of broilers increased (linear,P＜0.01).However,the in vitro gastric DMD and GED of diets were notaffected by the exogenous protease supplementation in the finisher control diet (P＞0.05).3) A linear regression analysis,taking into account protease supplementation (g·kg-1),explained the DMD (％) of starter and finisher diets for DMD =2.56 PS-0.82 PS × PS + 73.90 (R2 =0.82,RSD =0.42,P＜0.001) and DMD =3.56 PS-1.46 PS × PS + 75.20 (R2 =0.70,RSD =0.60,P＜0.001),respectively.A linear regression analysis,taking into account protease supplementation (g·kg-1),explained the EHGE (MJ·kg-1) of starter and finisher diets for EHGE =0.75 PS-0.30 PS × PS + 15.02 (R2 =0.89,RSD =0.07,P＜0.001) and EHGE =0.61 PS-0.30 PS × PS + 15.67 (R2=0.79,RSD =0.06,P＜0.001),respectively.There was greatest EHGE when protease supplementation was 112 500 PROT·kg-1 in a starter diet and 91 800 PROT·kg-1 in a finisher diet,respectively.[Conclusion] In conclusion,the in vitro gastrointestinal DMD,GED and EHGE were increased by the protease supplementation into a corn-soybean diets for broilers.However,the effect of protease supplementation on nutrition digestibility in different intestinal segments was not simple consistent with a dose-response pattern.The 112 500 PROT·kg-1 of protease supplementation in a starter diet and 91 800 PROT·kg-1 of protease supplementation in a finisher diet for broilers may improve more effectively in the present study.%[目的]研究外源蛋白酶对肉鸡饲粮体外干物质消化率(DMD)和酶水解物能值(EHGE)的影响,并使用仿生法获取饲粮中外源蛋白酶的最适添加量,为饲用酶制剂效价快速评价方法的建立提供理论参考.[方法]试验采用单因素完全随机设计,对照组分别为肉鸡前期和后期基础饲粮(粗蛋白质水平分别为:24.29％和21.72％,干物质基础),试验组分别在肉鸡前期和后期基础饲粮中添加0、15 000、75 000和150 000 PROT·kg-1的外源蛋白酶,试验共8种饲粮样品,每种饲粮样品设5个重复,每个重复1根仿生消化管,使用单胃动物仿生消化系统(SDS-Ⅱ)分别模拟饲粮在鸡的胃和胃—肠道的消化过程,测试并计算饲粮样品的DMD、体外能量消化率(GED)和EHGE,分别建立DMD和EHGE与蛋白酶添加量(protease supplementation,PS)的回归方程,并分析DMD和EHGE与PS的相关关系.[结果]随着外源蛋白酶添加剂量的增加,肉鸡前期和后期基础饲粮全消化道DMD、GED和EHGE也随之增加(P＜0.01).随着在肉鸡后期基础饲粮中外源蛋白酶添加剂量的增加,胃消化阶段的DMD和GED随之降低(P＜0.01).而在肉鸡前期基础饲粮中添加外源蛋白酶,对胃消化阶段的DMD、GED和EHGE影响不显著(P＞0.05).肉鸡前期基础饲粮全消化道DMD(％)和PS(g·kg-1)的关系为:DMD(％)=2.56 PS-0.82 PS×PS+73.90(R2=0.82,RSD=0.42,P＜0.001);EHGE (MJ·kg-1)和PS (g·kg-1)的关系为:EHGE (MJ·kg-1)=0.75 PS-0.30 PS×PS+15.02 (R2 =0.89,RSD=0.07,P＜0.001);当外源蛋白酶添加剂量为112 500 PROT·kg-1时,肉鸡前期基础饲粮全消化道EHGE达到最大值.肉鸡后期基础饲粮全消化道DMD(％)和PS(g·kg-1)的关系为:DMD(％)=3.56PS-1.46 PS×PS+75.20 (R2=0.70,RSD=0.60,P＜0.001);EHGE (MJ·kg-1)和PS(g·kg-1)的关系为:EHGE (MJ·kg-1)=0.61PS-0.30 PS×PS+15.67 (R2=0.79,RSD=0.06,P＜0.001),当外源蛋白酶添加剂量为91 800 PROT·kg-1时,肉鸡后期基础饲粮全消化道的EHGE达到最大值.[结论]玉米-豆粕基础饲粮中添加外源蛋白酶,可显著提高肉鸡基础饲粮体外全消化道DMD、GED和EHGE.但外源蛋白酶的添加剂量对不同消化道阶段和不同营养指标消化率的影响并不呈单纯一致的剂量反应规律.本试验条件下,肉鸡前期和后期基础饲粮中分别添加112 500和91 800PROT·kg-1的蛋白酶时EHGE提升效果最好.
展开▼
