Department of Animal and Dairy Science, University of Georgia, Athens, GA, United States of America.
Department of Environmental Health Science, University of Georgia, Athens, GA, United States of America.
PLoS One. 2020 Apr 13;15(4):e0231533. doi: 10.1371/journal.pone.0231533. eCollection 2020.
Most of the research efforts involving the bovine gastrointestinal microbiota have focused on cattle's forestomach, particularly the rumen, so information concerning the bovine fecal microbiota is more scarce, especially in young beef cattle. The present study was performed to evaluate the ruminal and fecal microbiotas of beef calves as they reached the end of their nursing phase. A total of 18 Angus cow/calf pairs were selected and assigned to one of two treatment groups for the last 92 days of the calves' nursing period, as follows: 1) calves were supplemented with concentrate in a creep feeding system; or 2) control group with no supplementation of calves. After 92 days, ruminal and fecal samples were individually obtained from calves in both groups, and their microbiotas were evaluated using 16S rRNA gene sequencing. Ruminal samples were predominated by Prevotella (18 to 23% of the total bacterial abundance), regardless if calves received supplementation or not; however, in the feces, Prevotella was only the seventh most abundant genus (0.6 to 2.1% of total bacterial abundance). Both the rumen (P = 0.01) and the feces (P = 0.05) of calves that received supplementation had greater abundance of Firmicutes. In addition, calves that were supplemented had lower abundance of Fibrobacteres (P = 0.03) in their rumens. Regardless if the calves were supplemented or not, Faith's Phylogenetic Diversity index (P ≤ 0.007) and total concentration of short chain fatty acids (P < 0.001) were both greater in the rumen than in the feces of calves. In summary, the ruminal and fecal microbiotas of weanling beef calves were considerably distinct. Additionally, supplementation with creep feed caused some significant changes in the composition of the gastrointestinal microbiota of the calves, especially in the rumen, where supplementation caused an increase in Firmicutes and a decrease in abundance of Fibrobacteres.
大多数涉及牛胃肠道微生物群的研究都集中在牛的前胃，特别是瘤胃，因此有关牛粪便微生物群的信息更为稀缺，尤其是在小牛中。本研究旨在评估育肥牛犊在结束哺乳期时的瘤胃和粪便微生物群。总共选择了 18 对安格斯牛/犊牛，并将它们分配到犊牛哺乳期的最后 92 天的两种处理组之一，如下所示：1）犊牛在放牧饲养系统中补充浓缩饲料；或 2）对照组不补充犊牛。92 天后，从两组中的犊牛中分别获得瘤胃液和粪便样本，并使用 16S rRNA 基因测序评估其微生物群。瘤胃液样本以普雷沃氏菌为主（占总细菌丰度的 18%至 23%），无论犊牛是否接受补充；然而，在粪便中，普雷沃氏菌仅为第七大丰富属（占总细菌丰度的 0.6%至 2.1%）。接受补充的犊牛的瘤胃（P=0.01）和粪便（P=0.05）中厚壁菌门的丰度更高。此外，补充的犊牛瘤胃中拟杆菌门的丰度较低（P=0.03）。无论犊牛是否接受补充，补充的犊牛瘤胃的Faith 系统发育多样性指数（P≤0.007）和短链脂肪酸的总浓度（P<0.001）均高于粪便中的。总之，断奶肉牛犊牛的瘤胃和粪便微生物群有很大的不同。此外，补充放牧饲料会导致犊牛胃肠道微生物群的组成发生一些显著变化，特别是在瘤胃中，补充会导致厚壁菌门增加，拟杆菌门丰度减少。
