饲粮纤维水平对育肥羔羊瘤胃微生物组成及多样性的影响

试验旨在研究提高饲粮纤维水平对育肥羔羊瘤胃微生物组成及多样性的影响。试验选择健康无病、体重相近的2月龄杜湖杂交公羔，按照体重随机分为2组，每组38只，分别饲喂不同的饲粮，对照组（LW_CK）饲粮为精料+苜蓿，处理组（LW_EG）为精料+苜蓿+全株玉米青贮+花生秧；试验期150 d，其中预试期20 d，正试期130 d，试验结束后，每组随机选择5只羔羊屠宰取瘤胃内容物，通过16S rDNA高通量测序技术分析其微生物多样性及结构变化。结果表明，处理组羔羊瘤胃中细菌多样性显著高于对照组（P<0.05）。在门水平上，处理组羔羊瘤胃中优势菌门为拟杆菌门（Bacteroidetes）和厚壁菌门（Firmicutes），对照组优势菌门为拟杆菌门和变形菌门（Proteobacteria）。提高纤维水平后显著增加了育肥羔羊瘤胃中厚壁菌门的相对丰度（P<0.05）；显著降低了变形菌门的相对丰度（P<0.05）。在属水平上，对照组与处理组羔羊瘤胃菌群共鉴定出195个属，处理组优势菌属为普雷沃氏菌属（Prevotella_1）和解琥珀酸菌属（Succiniclasticum），对照组优势菌属为琥珀酸弧菌属（Succinivibrionaceae）和普雷沃氏菌属（Prevotella_7）。提高饲粮纤维水平，增加了育肥羔羊瘤胃中解琥珀酸弧菌属、密螺旋体属（Treponema_2）、疣微菌属（Ruminococcaceae）、月形单胞菌属（Selenomonas_1）的相对丰度，显著降低了琥珀酸弧菌属相对丰度（P<0.05）。综上所述，适量提高饲粮中纤维水平对育肥羔羊瘤胃微生物菌群结构有一定影响，能够促进部分纤维降解菌的增殖，有利于育肥羔羊的瘤胃发酵和养分消化利用。

Effects of Dietary Crude Fiber Level on Rumen Microbial Composition and Diversity of Fattening Lambs

This experiment was conducted to investigate the effects of dietary crude fiber level enhancement on rumen microbial composition and diversity of fattening lambs.In this study,healthy and disease-free male lambs were selected.All lambs with similar weight at the age of 2 months were randomly divided into two groups according to the body weight,38 males in each group were fed with different diets.The diets of control group were composed of concentrate and alfalfa hay,while the diets of the treatment group were composed of whole corn silage and peanut seedling based on control group diet.The period of trial lasted 150 d,including 20 d in the preliminary phase.After the end of the experiment,5 lambs from each group were slaughtered,and rumen contents were collected for the measurement of microbial diversity and structural changes by 16S rDNA high-throughput sequencing technology.The results showed that the bacterial diversity in the rumen of the treated lambs was significantly higher than that of the control group(P<0.05).At the level of phylum,the dominant bacteria in the rumen of the lambs in the treatment group were Bacteroidetes and Firmicutes,while the dominant bacteria in the control group were Bacteroidetes and Proteobacteria.After the addition of fiber,the relative abundance of Firmicutes in the rumen of the fattening lambs was significantly increased(P<0.05),the relative abundance of Proteobacteria was significantly reduced(P<0.05).At the level of genus,195 genera were identified from the rumen bacteria of the control group and the treatment group,and the dominant bacteria in the treatment group were Prevotella_1 and Succiniclasticum,while the dominant bacteria in the control group were Succinivibrionaceae and Prevotella_7.The relative abundance of Succiniclasticum,Treponema_2,Ruminococcaceae and Selenomonas_1 in the rumen of fattening lambs was increased by increasing the dietary fiber level,and the relative abundance of Succinivibrionaceae was significantly reduced(P<0.05).Therefore,the increase of dietary fiber level appropriately had a certain effect on the structure of rumen microbial flora of fattening lambs,which could promote the proliferation of some fiber-degrading bacteria,and was beneficial to rumen fermentation and nutrient digestion and utilization of fattening lambs.