Characterizing the hindgut microbiome in healthy and ketotic cows

Ketosis is a prevalent metabolic disease in the peripartum period of dairy cows, that causes considerable losses in milk production. In particular, the changes in the gut microbiome influence the occurrence of cow ketosis. In this study, the hindgut microbial communities of ketotic and healthy cows were compared and analyzed using 16S rRNA sequencing. Community composition analysis reveal that the predominant phyl in both groups were Bacteroidetes and Firmicutes. At the genus level, Bifidobacterium were more abundant in healthy cows than in ketotic cows. Conversely, the ketotic group exhibited a greater abundance of Bacteroides and Treponema than the healthy group. Differential hindgut fecal bacterial taxa in healthy and ketotic cows were identified by linear discriminant analysis effect size, with increases in Treponema, Bacteroides, and Peptococcaceae and decreases in Christensenellales, Chloroflexi, and Paenibacillaceae in ketotic cows. A distance-based redundancy analysis was conducted to further explore the connection between the gut microbiome, blood β-hydroxybutyrate levels, and milk production traits. The results suggested that the hindgut microflora was significantly correlated with blood β-hydroxybutyrate concentration and somatic cell score. These results improve our understanding of rectal microbes, and may help prevent ketosis in cows.