饲粮非纤维性碳水化合物/中性洗涤纤维对藏羊瘤胃发酵参数及菌群结构的影响

Effects of Dietary Non Fibrous Carbohydrate/Neutral Detergent Fiber on Rumen Fermentation Parameters and Flora Structure of Tibetan Sheep

【目的】旨在研究不同非纤维性碳水化合物/中性洗涤纤维(NFC/NDF)对藏羊瘤胃发酵参数及微生物区系多样性的影响。【方法】选取2月龄健康、平均体重为(21.27±0.38)kg的断奶母羔15只,随机分为3组,每组5只。分别饲喂粗蛋白水平相似,NFC/NDF水平为2.20(Ⅰ组)、1.39(Ⅱ组)和0.92(Ⅲ组)的全混合饲粮。试验期持续119 d,其中预试期7 d,正试期112 d。试验结束后采集瘤胃液测定细菌多样性及各类细菌相对丰度。【结果】①随着NFC/NDF水平的降低,瘤胃液pH显著增加,瘤胃液中氨态氮浓度、丙酸和异丁酸占总挥酸含量的百分比以及总挥发酸含量逐渐降低,乙酸百分比及乙酸丙酸比逐渐增加(P<0.05)。②3组共产生347种操作分类单元(OTU),其中共有OTU为269种,占总OTU的77.52%。③Ⅰ组的Shannon指数、ACE指数和Chao1指数均显著低于Ⅲ组(P<0.05)。④门水平上,拟杆菌门(Bacteroidetes)相对丰度Ⅱ组显著高于其余两组(P<0.05),厚壁菌门随NFC/NDF降低而降低(P<0.05);⑤科水平上,毛螺菌科(Lachnospiraceae)Ⅰ组显著高于Ⅱ组(P<0.05),瘤胃球菌科(Ruminococcaceae)Ⅰ组和Ⅱ组显著高于Ⅲ组(P<0.05);韦荣氏菌科(Veillonellaceae)Ⅱ组显著高于Ⅰ组和Ⅲ组(P<0.05)。⑥属水平上,丁酸弧菌属(Butyrivibrio)Ⅱ组显著高于Ⅰ组和Ⅲ组(P<0.05);瘤胃球菌属(Ruminococcus)相对丰度有降低趋势,且Ⅰ组和Ⅱ组显著高于Ⅲ组(P<0.05)。⑦主坐标分析瘤胃细菌第一主成分和第二主成分贡献率分别为63.93%和57.63%,各组间瘤胃液细菌群落结构差异明显,Ⅰ组与Ⅱ组明显分隔。【结论】饲喂不同NFC/NDF水平饲粮,改变了瘤胃发酵模式,显著影响了育肥藏羊瘤胃中微生物的种类和丰富度,并影响门、科和属水平上细菌的组成。

【Objective】The purpose of this study was to analyze the effects of different NFC/NDF levels on rumen microbial diversity of Tibetan sheep.【Method】Fifteen healthy weaned Tibetan lambs with an average weight(21.27±0.38)kg were randomly divided into three groups,with 5 lambs per group.Lambs in each group were fed total mixed rations with NFC/NDF levels of 2.20(groupⅠ),1.39(groupⅡ)and 0.92(groupⅢ)respectively.The experimental period was 119 days,including 7 days of pre-test and 112 days of formal test.At the end of feeding experiment,the rumen fluid samples were collected to deter⁃mine the diversity and relative abundance of rumen bacterial.【Result】The results showed that:①With the decrease of NFC/NDF level,the ruminal fluid pH increased significantly.Besides,the concentration of NH_(3)-N in ruminal fluid,the percentage of propionate and isobutyric acid in total volatile acid content and total volatile acid content decreased gradually.However,the percentage of acetate and the ratio of ac⁃etate to propionate increased gradually(P<0.05).②A total of 347 OTU were generated,of which 269 OTU were shared by the three groups,accounting for 77.52%of the total.③The Shannon index,ACE index and Chao1 index of rumen bacteria in groupⅠwere significantly lower than that in groupⅢ.④At phylum level,the relative abundance of Bacteroidetes in groupⅡwas significantly higher than that in the other two groups(P<0.05),and the relative abundance of Firmicutes decreased with the decrease of NFC/NDF(P<0.05);⑤At family level,the relative abundance of Lachnospiraceae in groupⅠwas sig⁃nificantly higher than that in groupⅡ(P<0.05),and the relative abundance of Pachnospiraceae in groupsⅠandⅡwas significantly higher than that in groupⅡ(P<0.05).The relative abundance of Ru⁃minococcus was significantly higher than that of groupⅢ(P<0.05).The relative abundance of Veillonel⁃laceae in groupⅡwas significantly higher than that of groupⅠand groupⅢ(P<0.05);⑥At the genus level,the relative abundance of Butyrivibrio in groupⅡwas significantly higher than that of groupⅠand groupⅢ(P<0.05).The relative abundance of Ruminococcus had a decreasing trend,and the relative abundance of groupⅠand groupⅡwas significantly higher than that of groupⅢ(P<0.05).⑦Principal coordinate analysis showed that the contribution rates of the first principal component and the second principal component of rumen bacteria were 63.93%and 57.63%,respectively.There were significant differences in rumen fluid bacterial community structure among groups,and the difference between groupⅠand groupⅡwas significant.【Conclusion】In conclusion,feeding different levels of NFC/NDF changed the rumen fermentation mode,significantly affected the rumen microbial species and richness,and influenced the composition of bacteria at phylum,family and genus levels.