中文摘要：

本试验旨在用体外法研究不同蛋白质水平对杜长大肥育猪盲肠微生物发酵特性的影响。试验首先采集10头杜长大肥育猪大肠不同区段食糜,测定其主要养分含量,以确定食糜碳水化合物与粗蛋白质添加比例;然后以3头猪盲肠食糜为接种物,酪蛋白水解物为发酵底物进行体外发酵试验。试验组蛋白质水平分别为1.00、1.75和2.50 mg/m L,每组4个重复,37℃体外发酵24 h,测定产气量、p H以及氨态氮、菌体蛋白和短链脂肪酸含量。结果显示：1）猪盲肠食糜各养分含量在一定范围内变化,碳水化合物与粗蛋白质含量比范围为1.86~3.24,平均值为2.66。2）随着蛋白质水平的升高,产气量显著增加（P〈0.05）,氨态氮、总短链脂肪酸、支链脂肪酸、乙酸、丁酸、戊酸、异丁酸和异戊酸含量显著升高（P〈0.05）。以上结果表明：猪大肠食糜中碳水化合物与粗蛋白质含量比在一定范围内变化,而盲肠微生物对蛋白质的发酵能力随底物蛋白质水平的升高而增强。

英文摘要：

This study was conducted to estimate the effects of different protein levels on caecal microbial fermentation characteristics of Duroc × Landrace × Yorkshire finishing pigs in vitro.W e firstly analyzed the mainly nutrient content of chyme collected from different extents of large intestine of 10 pigs in order to confirm the adding ratio of carbohydrate to crude protein used in the following in vitro fermentation.Then in vitro fermentation experiment was carried out with cecum chyme of 3 pigs as inoculum and casein hydrolysate for fermentation substrates.The protein levels in experimental groups with 4 replicates each were 1.00,1.75 and2.50 mg/m L,respectively,for 24 h fermentation at 37 ℃.And gas production,p H and the contents of ammoniacal nitrogen,microbial protein and short-chain fatty acids were determined.The results showed as follows：1） nutrient contents in cecum chyme of pigs were changed within a certain range,and the ratio of carbohydrate to crude protein content was 1.86 to 3.24 with an average value of 2.66.2） W ith protein level increasing,the gas production was significantly increased（P 0.05）,and the contents of ammoniacal nitrogen,total short-chain fatty acids,branched-chain fatty acids,acetate,butyrate,valerate,isobutyrate and isovalerate were significantly significantly increased（P 0.05）.The results indicate that the ratio of carbohydrate to crude protein content in large intestine chyme of pigs changes within a certain range,and the caecal microbial fermentative capability is promoted with substrate protein level increasing.