Comparison of rumen microbial communities in dairy herds of different production

In the US, there is a substantial difference in annual milk production between dairy herds. We hypothesized that the rumen microbial composition will be different between higher and lower yielding dairy herds and that each dairy herd will have a distinct microbial fingerprint. This study included 85 Holstein dairy cows from two farms: Farm12 (M305;, 12,324 kg; n=47; primiparous cows: 24, multiparous cows: 23) and Farm9 (M305;, 9,693 kg; n=38; primiparous cows: 19, multiparous cows: 19). Bacterial diversity from rumen samples was characterized using 16S rRNA gene sequencing using Ion Torrent (PGM)Ion Torrent platform. Differences in microbial communities between farms were greater (p<0.001) (adonisAdonis:; R2=0.16;, p<0.001) than within farm. Five bacterial lineages namely Prevotella (48-51 %), Bacteroidales (10-12 %), Unclassified bacteria (5-8 %), Succinivibrionaceae (1.4-6.6 %) and Prevotellaceae (3.8-4.7 %) were observed to differentiate the community clustering patterns between the two farms. A notable finding is the greater (p<0.05) contribution of Succinivibrionaceae in Farm12 compared to Farm9. Furthermore, in Farm12, this bacterial populations was higher (p<0.05) in the high yielding cows compared to low yielding cows in both parity groups. Prevotella, S24-7 and Succinivibrionaceae were found to be positively correlated with fat corrected milk and feed efficiency, and a majority of Firmicutes genera were found to be positively correlated with milk fat ( %) and protein ( %). It was concluded that characterizing ruminal microbiota across elite herds is required to identify specialist rumen microbes across herds varying in milk production.

在美国，不同奶牛牧场的年牛奶产量存在显著差异。本研究假设，高产与低产奶牛牧场的瘤胃微生物组成存在差异，且每个牧场均具有独特的微生物指纹图谱。本研究选取来自两个牧场的85头荷斯坦奶牛作为研究对象：牧场12的305天标准产奶量（M305）为12324 kg，共47头奶牛，其中头胎奶牛24头、经产奶牛23头；牧场9的305天标准产奶量（M305）为9693 kg，共38头奶牛，其中头胎奶牛19头、经产奶牛19头。采用Ion Torrent（PGM）测序平台对瘤胃样本进行16S rRNA基因测序，以解析细菌多样性。牧场间微生物群落差异（p<0.001；置换多元方差分析Adonis：R²=0.16，p<0.001）显著大于牧场内部差异。分析发现，5个细菌类群可区分两个牧场的群落聚类模式，分别为普雷沃氏菌属（Prevotella，占比48%~51%）、拟杆菌目（Bacteroidales，占比10%~12%）、未分类细菌（Unclassified bacteria，占比5%~8%）、琥珀酸弧菌科（Succinivibrionaceae，占比1.4%~6.6%）以及普雷沃氏菌科（Prevotellaceae，占比3.8%~4.7%）。一项重要发现为，相较于牧场9，牧场12中琥珀酸弧菌科的相对丰度显著更高（p<0.05）。此外，在牧场12中，无论是头胎还是经产奶牛群体，高产奶牛体内的琥珀酸弧菌科菌群丰度均显著高于低产奶牛（p<0.05）。研究发现，普雷沃氏菌属、S24-7类群以及琥珀酸弧菌科与乳脂校正乳产量及饲料转化率呈显著正相关；而多数厚壁菌门（Firmicutes）菌属与乳脂率（%）及乳蛋白率（%）呈显著正相关。本研究得出结论：若要在产奶量各异的牧场中鉴定出特异性瘤胃微生物，需对优质牧场的瘤胃微生物群进行表征分析。