AUTHOR=Kojima Miyu , Liu Hong , Takemoto Satoshi , Suda Yoshihito , Inoue Ryo , Watanabe Gen , Jin Wanzhu , Nagaoka Kentaro TITLE=Temporal changes in the fecal microbiome and blood metabolites of early neonatal calves JOURNAL=Frontiers in Animal Science VOLUME=3 YEAR=2022 URL=https://www.frontiersin.org/journals/animal-science/articles/10.3389/fanim.2022.934204 DOI=10.3389/fanim.2022.934204 ISSN=2673-6225 ABSTRACT=

The initial colonization and early development of the intestinal microbiome are important stages in the growth of calves during pre-weaning. This study investigated temporal changes in the diversity and composition of the fecal microbiota, focusing on the first 2 weeks after birth, with the aim of identifying intestinal bacteria and blood metabolites that are associated with calf diarrhea. In this study, 10 calves were fed colostrum on day 0 after birth, whole milk from days 2 to 5, and milk replacer from day 6. Six calves showed mild diarrhea in the second week (i.e., from day 8 to 14). We observed dramatic changes in the development of the fecal microbiome from day 2 to 14 and found several bacterial species, such as Lactobacillus and Collinsella, changing significantly in abundance during the milk transition (i.e., from day 4 to 10). In investigating whether there is an association between the microbiome and the milk transition, we found the level of hypotaurine and D-xylose to be significantly higher in whole milk from days 4 and 5 than in milk replacer. A comparison of four healthy calves and six diarrheal calves revealed that the diarrheal calves had a low abundance of Collinsella on day 10. Furthermore, we explored plasma metabolites statistically correlated with the change of fecal Collinsella and found a high level of dimethylglycine in healthy calves. Taken together, these findings suggest a possible link between temporary changes in the fecal microbiome and neonatal diarrhea during the milk transition in calves.