燕麦草在奶牛瘤胃中的降解规律与黏附细菌区系变化

Degradation Regularity of Oat Grass in Rumen of Dairy Cows and Changes of Attached Bacterial Flora

本试验旨在研究燕麦草在奶牛瘤胃内随时间变化的降解规律和黏附在燕麦草上的细菌区系的变化。采用3头装有永久瘤胃瘘管的中国荷斯坦奶牛,用尼龙袋法分别在2、6、12、24、48和72 h测定燕麦草的营养成分动态降解率,并采集降解残渣用于分析黏附细菌区系变化。结果表明:1)燕麦草干物质(DM)降解呈现2个阶段(快速降解期和慢速降解期),中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)呈现3个阶段(快速降解期、滞后期和慢速降解期),其中NDF和ADF滞后期分别为2~12 h和6~12 h。2)燕麦草在瘤胃中2 h时,厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes)取代变形菌门(Proteobacteria)成为燕麦草中的优势菌门。培养时间具有影响黏附在燕麦草上细菌群落alpha多样性的趋势(P>0.05)。经瘤胃培养2 h后,在门水平上,燕麦草黏附相关细菌趋于稳定,仅观察到轻微变化;在属水平上,燕麦草残渣黏附细菌以普雷沃氏菌属1(Prevotella_1)、理研菌科RC9肠道群(Rikenellaceae_RC9_gut_group)、克里斯滕森菌科R-7群(Christensenellaceae_R-7_group)、瘤胃球菌属1(Ruminococcus_1)和解琥珀酸菌属(Succiniclasticum)等为主,且绝大多数来源于瘤胃内容物。除克里斯滕森菌科R-7群和丁酸弧菌属2(Butyrivibrio_2)等外,大多数优势菌属的相对丰度随时间变化显著(P<0.05)。3)黏附在燕麦草上的细菌群落组成和结构与燕麦草残渣营养成分组成呈强相关。综上所述,本研究揭示了燕麦草在瘤胃中的降解特性以及黏附细菌区系的相应变化,发现宿主瘤胃微生物群落对燕麦草附着细菌产生一定影响。

The purpose of this experiment was to study the degradation regularity of oat grass in rumen of dairy cows over time and the changes of attached bacterial flora.Three Chinese Holstein cows with permanent rumen fistulas were used to determine the dynamic degradation rates of nutrients in oat grass at 2,6,12,24,48 and 72 h,respectively,and the degradation residue was collected to analyze the changes of attached bacteria flora.The results showed as follows:1)there were 2 stages of dry matter(DM)degradation(rapid degradation stage and slow degradation stage),3 stages of neutral detergent fiber(NDF)and acid detergent fiber(ADF)degradation stage(rapid degradation stage,lag stage and slow degradation stage),and the lag stage of NDF and ADF was 2 to 12 h and 6 to 12 h,respectively.2)When oat grass was in rumen for 2 h,Firmicutes and Bacteroidetes replaced Proteobacteria as the dominant bacteria in oat grass.The culture time had a tendency to affect the alpha diversity of bacterial community attached to oat grass(P>0.05).After rumen culture for 2 h,at the phylum level,the related bacteria attached to oat grass tended to be stable,and only slight changes were observed;at the genus level,the dominant bacteria attached to oat grass residue were Prevotella_1 and Rikenellaceae_RC9_gut_group,Christensenellaceae_R-7_group,Ruminococcus_1,Succiniclasticum and so on,and most of them were derived from rumen contents.Except for Christensenellaceae_R-7_group and Butyrivibrio_2,etc.,the relative abundances of most dominant bacteria genera change significantly with time(P<0.05).3)The composition and structure of bacterial community attached to oat grass were strongly correlated with the nutrient composition of oat grass residue.In summary,this study reveals the degradation characteristics of oat grass in rumen and the corresponding changes in the attached bacterial flora,finding that the host rumen microbial community has a certain impact on the bacteria attached to oat grass.