Association of residual feed intake with peripartal ruminal microbiome and milk fatty acid composition during early lactation in Holstein dairy cows

Feed efficiency in peripartal Holstein cows is associated with differences in ruminal bacterial profiles and milk FA composition during the transition period. Compared with L-EFF, M-EFF cows had greater relative abundance of carbohydrate-fermenting and acetate-producing bacteria during early lactation, suggesting a better capacity for utilizing complex carbohydrates in the rumen. In contrast, L-EFF cows had greater DMI and lactate-producing bacteria, indicating they were more susceptible to developing acidosis. The concentrations of LCFA and MUFA in the milk of M-EFF cows were greater than L-EFF cows, whereas MCFA and SFA were lower. Acetate-producing bacteria and Prevotellaceae had opposite correlations with 16:1 cis-9 and 17:1 cis-10 concentrations in milk. Concentration of 15:0 in milk might reflect the population of bacteria related to butyrate metabolism in the rumen during the transition period. Overall, the data provide support for additional studies during the transition period to expand our understanding of the consequences of selective breeding based on RFI.围产期荷斯坦奶牛的饲料效率与泌乳过渡期的瘤胃细菌群落特征及牛乳脂肪酸（Fatty Acid, FA）组成密切相关。与低饲料效率组（L-EFF）相比，中饲料效率组（M-EFF）奶牛在泌乳早期的碳水化合物发酵菌与产乙酸菌相对丰度更高，提示其瘤胃利用复杂碳水化合物的能力更强。与之相反，低饲料效率组奶牛的干物质采食量（Dry Matter Intake, DMI）与产乳酸细菌相对丰度更高，表明其更易罹患瘤胃酸中毒。中饲料效率组奶牛牛乳中的长链脂肪酸（Long-Chain Fatty Acid, LCFA）与单不饱和脂肪酸（Monounsaturated Fatty Acid, MUFA）浓度高于低饲料效率组，而中链脂肪酸（Medium-Chain Fatty Acid, MCFA）与饱和脂肪酸（Saturated Fatty Acid, SFA）浓度则更低。产乙酸菌与普雷沃氏菌科（Prevotellaceae）与牛乳中顺-9-十六碳一烯酸（16:1 cis-9）和顺-10-十七碳一烯酸（17:1 cis-10）的浓度呈相反相关性。牛乳中十五烷酸（15:0）的浓度或可反映围产期瘤胃内与丁酸代谢相关的细菌种群数量。总体而言，本研究数据为泌乳过渡期的后续研究提供了支撑，有助于拓展我们对基于剩余采食量（Residual Feed Intake, RFI）开展选择性育种所产生后果的认知。