Characteristics of the milk microbiota of healthy goats and goats diagnosed with clinical mastitis in Western China.

Guanzhong dairy goats, a breed indigenous to the Guanzhong region of China, offer several advantages; however, they are particularly vulnerable to mastitis, a common disease affecting their health and productivity. In this study, we collected milk samples from healthy goats (designated as healthy goat milk samples, n = 13) and goats affected by clinical mastitis (designated as mastitis goat milk samples, n = 24) from two distinct dairy goat farms located in Shaanxi and Gansu (Shaanxi n = 25, Gansu n = 12). We employed 16S rRNA amplicon sequencing to identify the dominant bacterial communities present in both healthy and mastitis-affected goat milk samples. Our findings revealed differences in bacterial populations between the two groups. The alpha diversity of the microbiota in healthy goat milk samples was significantly greater than that in the mastitis-affected samples. Beta diversity analysis demonstrated the presence of pathogen-associated microbiota in healthy goat milk samples, highlighting notable differences in the core microbiota between the two sample groups. Achromobacter was identified as the dominant bacterial genus in healthy goat milk samples, whereas it was either absent or present in minimal quantities in the mastitis samples. In contrast, the mastitis-causing goat milk samples exhibited a more homogeneous microbiota composition, marked by the loss of beneficial probiotic flora. Furthermore, the microbiota structure in goats with severe clinical symptoms, such as gangrenous and streptococcal mastitis, was simplified and comprised exclusively of pathogenic bacteria. Through this study, we identified both probiotic and pathogenic bacteria in healthy and mastitis-affected goat milk samples, providing essential microbiological insights that could inform effective prevention and treatment strategies for mastitis in dairy goats. These findings underscore the importance of understanding the microbial dynamics in dairy goats to enhance herd health and productivity.