发酵杂粕型饲粮中添加小肽对肉牛瘤胃发酵参数及微生物区系的影响

Effects of Small Peptide Supplementation in Diets with Fermented Mixed Meals on Rumen Fermentation Parameters and Microflora of Beef Cattle

本试验旨在研究发酵杂粕型饲粮中添加小肽对肉牛瘤胃发酵参数及微生物区系的影响。选取初重为(481.43±36.36)kg、健康状况良好的肉牛28头,随机分为4组,每组7个重复,每个重复1头牛。4组肉牛分别饲喂小肽添加水平为0(Ⅰ组,作为对照组)、0.5%(Ⅱ组)、1.0%(Ⅲ组)和1.5%(Ⅳ组)的发酵杂粕型全混合日粮。预试期15 d,正试期60 d。结果显示:1)随着小肽添加水平的增加,丁酸的比例呈二次曲线变化(P=0.037),异戊酸的比例有线性降低的趋势(P=0.080),丙酸的比例有二次曲线变化的趋势(P=0.082)。2)随着小肽添加水平的增加,Ace指数和Chao指数呈二次曲线变化(P=0.030、0.036)。3)门水平上,各组的优势菌门均为拟杆菌门、厚壁菌门和变形菌门,随着小肽添加水平的增加,厚壁菌门、柔膜菌门和Saccharibacteria的相对丰度有二次曲线变化的趋势(P=0.097、0.074、0.077)。属水平上,普雷沃氏菌属1为优势菌属,随着小肽添加水平的增加,普雷沃氏菌属1的相对丰度有二次曲线变化的趋势(P=0.089);理研菌科RC9肠道群的相对丰度随着小肽添加水平的增加呈二次曲线变化(P=0.042),与丙酸(r=-0.489,P=0.029)和戊酸比例(r=-0.529,P=0.016)显著负相关;Ⅱ组克里斯腾森菌科R7群的相对丰度显著高于其余组(P<0.05),与乙酸(r=0.678,P=0.001)、丁酸比例(r=0.481,P=0.032)和乙酸/丙酸(r=0.729,P<0.001)显著正相关,与丙酸比例(r=-0.723,P<0.001)显著负相关。综上所述,发酵杂粕型饲粮中添加小肽影响了肉牛瘤胃菌群的丰富度和多样性,影响了门和属水平菌群组成,改善了挥发性脂肪酸的组成和比例。

This experiment aimed to investigate the effects of small peptide supplementation in diets with fermented mixed meals on rumen fermentation parameters and microflora of beef cattle.Twenty-eight healthy Simmental crossbred cattle with(481.43±36.36)kg of initial weight were randomly divided into 4 groups with 7 replicates per group and 1 cattle in each replicate.Cattle in the 4 groups were fed fermented mixed meal total mixed rations with small peptide supplemental levels of 0(groupⅠ,as control group),0.5%(groupⅡ),1.0%(groupⅢ)and 1.5%(groupⅣ),respectively.The pre-test period lasted for 25 days and the trial lasted for 60 days.The results showed as follows:1)with the increase of small peptide supplemental level,the proportion of butyrate showed a quadratic curve change(P=0.037),the proportion of isovalerate tended to decrease linearly(P=0.080),and the proportion of propionate had a tendency of quadratic curve change(P=0.082).2)Ace index and Chao index had a quadratic curve change with the increase of small peptide supplemental level(P=0.030,0.036,respectively).3)At phylum level,the dominant phyla were Bacteroidetes,Firmicutes,and Proteobacteria,and with the increase of small peptide supplemental level,the relative abundances of Firmicutes,Tenericutes and Saccharibacteria presented a tendency of quadratic curve change(P=0.097,0.074,0.077,respectively).At genus level,the relative abundance of Prevotella_1 was the dominant genus,and with the increase of small peptide supplemental level,the relative abundance of Prevotella_1 had a tendency of quadratic curve change(P=0.089);the relative abundance of Rikenellaceae_RC9_gut_group showed a quadratic curve change with the increase of small peptide supplemental level(P=0.042),and its was negatively correlated with the proportions of propionate(r=-0.489,P=0.029)and valerate(r=-0.529,P=0.016);the relative abundance of Christensenellaceae_R7_group of groupⅡwas significantly higher than that of other groups(P<0.05),it was positively correlated with the proportions of acetate(r=0.678,P=0.001),butyrate(r=0.481,P=0.032)and acetate/propionate(r=0.729,P<0.001),and was negatively correlated with the proportion of propionate(r=-0.729,P<0.001).In conclusion,on the conditions of the present study,supplementing small peptides to diets with fermented mixed meals can affect the rumen microbial richness and diversity,alter the microbial composition at phylum and genus levels,and optimize the composition and proportions of volatile fatty acids in the rumen of beef cattle.