Seasonal description and comparison of the vagina, milk and colostrum microbiota in transhumant ewes
Milk, colostrum, and vaginal microbiota could have an important role in animal health,  and studies on its composition in ruminants are lacking particularly in ovine species. For this reason, a total of eight transhumant Segureña ewes were sampled in each season to describe and compare the fluctuations of the vaginal and milk microbiota over a year in Spain. Moreover, colostrum samples from eight ewes were taken in winter and eight other ewes in summer during the lambing season. Samples were analysed by 16S rRNA gene metabarcoding. Regarding alpha diversity, colostrum and vaginal samples were richer in winter pastures than in summer pastures (Sierra del Segura) (P < 0.01). For beta diversity, differences were observed between the different types of samples, especially for vaginal samples. In milk and vagina samples, there were significant differences between seasons, including seasons within the same location. In regard to taxonomic composition, Bacillota was the most abundant phylum in milk and vagina samples while Pseudomonadota was the most abundant in colostrum samples. Ureaplasma, Histophilus and Oceanivirga were the most abundant genera in the vagina while Sphingomonas was the most abundant genus in colostrum and Corynebacterium in milk. In these last two types of samples, the following most abundant genera were Staphylococcus and Lactobacillus. Seasonal changes were observed in colostrum including a higher abundance of Proteobacteria in summer (P < 0.001), more specifically of Enterobacteriaceae (P < 0.05). In vaginal samples Proteobacteria were also significantly higher in summer compared to spring (P < 0.05) while in autumn and summer (Sierra Morena) Lactobacillales were significantly lower than in spring and winter (P < 0.05). Similarly, in milk samples, Proteobacteria was more important in summer than in winter (P < 0.05), however, there were more lactobacilli in autumn than in winter (P < 0.05) and more enterococci in every season compared to winter (P < 0.05). Nevertheless, there were more Atopostipes, also a lactic acid bacterium, in winter compared to autumn (P < 0.05).
Milk, colostrum, and vaginal microbiota could have an important role in animal health,  and studies on its composition in ruminants are lacking particularly in ovine species. For this reason, a total of eight transhumant Segureña ewes were sampled in each season to describe and compare the fluctuations of the vaginal and milk microbiota over a year in Spain. Moreover, colostrum samples from eight ewes were taken in winter and eight other ewes in summer during the lambing season. Samples were analysed by 16S rRNA gene metabarcoding. Regarding alpha diversity, colostrum and vaginal samples were richer in winter pastures than in summer pastures (Sierra del Segura) (P < 0.01). For beta diversity, differences were observed between the different types of samples, especially for vaginal samples. In milk and vagina samples, there were significant differences between seasons, including seasons within the same location. In regard to taxonomic composition, Bacillota was the most abundant phylum in milk and vagina samples while Pseudomonadota was the most abundant in colostrum samples. Ureaplasma, Histophilus and Oceanivirga were the most abundant genera in the vagina while Sphingomonas was the most abundant genus in colostrum and Corynebacterium in milk. In these last two types of samples, the following most abundant genera were Staphylococcus and Lactobacillus. Seasonal changes were observed in colostrum including a higher abundance of Proteobacteria in summer (P < 0.001), more specifically of Enterobacteriaceae (P < 0.05). In vaginal samples Proteobacteria were also significantly higher in summer compared to spring (P < 0.05) while in autumn and summer (Sierra Morena) Lactobacillales were significantly lower than in spring and winter (P < 0.05). Similarly, in milk samples, Proteobacteria was more important in summer than in winter (P < 0.05), however, there were more lactobacilli in autumn than in winter (P < 0.05) and more enterococci in every season compared to winter (P < 0.05). Nevertheless, there were more Atopostipes, also a lactic acid bacterium, in winter compared to autumn (P < 0.05).