Abstract: 【Objective】The effects of different simulated hindgut enzymes on the in vitro dry matter digestibility (DMD) and enzyme hydrolysate gross energy (EHGE) of feedstuffs were determined using a computer-controlled simulated digestion system (SDS), and the correlation between non-starch polysaccharides (NSP) content and in vitro gross energy digestibility (GED) of feed ingredients were also analyzed to provide reference for in vitro method to simulate digestion in the stomach, small intestine and large intestine. 【Method】After the simulated digestion in the stomach and small intestine of 6 feed ingredients, 4 groups including 3 simulated hindgut enzymes (cellulase, Viscozyme and bionic enzyme) and the control with deionized water were used to stimulate the hindgut digestion with a SDS. Bionic enzymes included cellulase, xylase, β-glucanase and pectinase. Each treatment contained 5 replicates with 1 digestion tube per replicate, the DMD, GED and EHGE of corn, soybean meal, wheat bran, corn DDGS, alfalfa and soybean hull were determined. The NSP contents of these feed ingredients were measured using a gas-liquid chromatography with aiditol acetates derivatives and were also related with DMD and GED. 【Result】 The DMD (81.51 %) and EHGE (15.39 MJ·kg^-1) of corn were the highest in all ingredients, whereas the DMD (10.60 % ) and EHGE (2.42 MJ·kg^-1) of soybean hull were the lowest in the 6 feedstuffs. The DMD of corn, soybean meal and soybean hull and the EHGE of soybean meal and soybean hull were greater in the 3 simulated hindgut enzymes than in the control group (P＜0.01). The DMD and EHGE of alfalfa and DDGS were not affected by the inclusion of cellulase and the DMD and EHGE of wheat bran and DDGS were also not affected by the inclusion of Viscozyme (P＞0.05). The DMD of 6 feedstuffs and the EHGE of 6 feedstuffs with the exception of DDGS were increased with the bionic enzyme to simulate digestion in the hindgut (P＜0.01). The promotion degree of simulated hindgut enzymes on the DMD and EHGE were varied with feedstuffs. In the cellulase group, the increased DMD and EHGE were greatest in the wheat bran by 5.89% and 1.03 MJ·kg^-1, whereas were the lowest in the soybean meal by 1.26% and 0.36 MJ·kg^-1, respectively. The increasing DMD and EHGE in the Viscozyme group were the greatest in the soybean hull by 6.01% and 1.02 MJ·kg^-1, respectively, and the DMD and EHGE in the bionic enzyme group were the greatest in wheat bran by 6.59% and 1.37 MJ·kg^-1, respectively. The soluble NSP content was less than the insoluble NSP of 6 feedstuffs. Total NSP content of corn was the lowest (8.59%), whereas the total NSP content of soybean hull was the highest (75.72%). The main components of NSP included arabinose, xylose, mannose and glucose, but the 4 monosaccharide content varied in the feed ingredients. The NSP content was negatively related with the DMD, GED of feedstuffs (P＜0.05).The relationship between the DMD and TNSP contents of the 6 feedstuffs in the bionic enzyme group (R²=0.95, P＜0.01) was higher than in the cellulase group (R²=0.94, P＜0.01) and in the Viscozyme group (R²=0.93, P＜0.01). The relationship between the GED and TNSP contents of the 6 feedstuffs in the bionic enzyme group (R²=0.89, P＜0.01) was also higher than in the cellulase group (R²=0.86, P＜0.01) and in the Viscozyme group (R²=0.81, P＜0.01). 【Conclusion】 In conclusion, the inclusion of bionic enzyme to simulate hindgut digestion has a significant effect on the in vitro energy digestion of feedstuffs than the inclusion of cellulase and Viscozyme. The bionic enzyme can be used to simulate the hindgut digestion using the SDS.

Key words: in vitro, hindgut enzyme, non-starch polysaccharide, digestibility, enzyme hydrolysate gross energy, simulated digestion system