Differences in milk microbiota between healthy cows and cows with a high incidence of Klebsiella mastitis

Klebsiella mastitis remains a disease with a high economic impact on the dairy industry, causing clinical mastitis of long duration, recurrent infections, and poor response to antimicrobials. Therefore, it is crucial to investigate the root reasons for its recurrent infections in dairy cows. In this study, we aimed to use high-throughput DNA sequencing to characterize the milk microbiota of healthy cows (H) and cows with a high incidence of Klebsiella mastitis (KLB) and to identify potential pathogenic genera affecting recurrent Klebsiella infections in cows. According to our research, the relative abundance of Firmicutes and Faecalibacterium was much higher in the KLB group than in the H group. However, Proteobacteria and Labrenzia were significantly less abundant than in the H group. Although the two groups' species compositions differed, the communities' diversity and richness were similar. Based on LEfSe analysis and random forest analysis, the majority of the differential genera in the KLB group were intestinal-associated genera, which suggested that even though the cows were currently healthy, there was a high risk of mastitis reoccurring once the cows were in a contaminated environment. The milk microbiota of each group was also compared at various parties, between different quarters, and between the first three handfuls of milk and milk. We discovered that while there were minor differences in species composition between the groups, all of them shared a relatively similar level of diversity, except for primiparous cows' alpha diversity, which was higher than that of multiparous cows' milk microbiota. Our research offers a powerful tool for reducing Klebsiella mastitis on this dairy farm.