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&lt;0.001) (adonisAdonis:; R2=0.16;, p&lt;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&lt;0.05) contribution of Succinivibrionaceae in Farm12 compared to Farm9. Furthermore, in Farm12, this bacterial populations was higher (p&lt;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. <br><br>

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，且每个牧场均拥有独特的微生物指纹图谱。

本研究纳入了来自两个牧场的85头荷斯坦（Holstein）奶牛：牧场12（305天标准产奶量M305为12324 kg；样本量n=47，其中初产奶牛24头、经产奶牛23头）与牧场9（305天标准产奶量M305为9693 kg；样本量n=38，其中初产奶牛19头、经产奶牛19头）。本研究采用离子激流（Ion Torrent）PGM测序平台，通过16S rRNA基因测序对瘤胃样本的细菌多样性进行了表征。

不同牧场间的微生物群落差异（p<0.001；置换多元方差分析Adonis：R²=0.16，p<0.001）显著大于牧场内部的群落差异。研究观察到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，48%~51%）、拟杆菌目（Bacteroidales，10%~12%）、未分类细菌（5%~8%）、琥珀酸弧菌科（Succinivibrionaceae，1.4%~6.6%）以及普雷沃氏菌科（Prevotellaceae，3.8%~4.7%）。

一项显著发现为：相较于牧场9，牧场12的琥珀酸弧菌科（Succinivibrionaceae）相对丰度显著更高（p<0.05）。此外，在牧场12中，两个胎次组的高产奶牛体内的该细菌类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（Prevotella）、S24-7以及琥珀酸弧菌科（Succinivibrionaceae）与乳脂校正奶产量及饲料转化率呈正相关；多数厚壁菌门（Firmicutes）菌属与乳脂率（%）及乳蛋白率（%）呈正相关。

本研究得出结论：需对优质牧场的瘤胃微生物群进行表征，以在产奶量各异的牧场中鉴定出特异性瘤胃微生物。