Farm management has a significant impact on microbial composition and may affect the quality of raw buffalo milk. This study involved a diversity analysis and traceability of the microbial communities in raw buffalo milk from three buffalo farms at different management ranks in Guangxi Province, China. The microbial composition of the raw buffalo milk and its environmental sources were investigated using 16S rRNA gene sequencing and bioinformatics analysis. The results demonstrated that different management ranks significantly influenced microbial composition in milk, with the primary sources of contamination varying across farms. The env.OPS_17 was the predominant differential bacterium in farm rank A, whereas Enterobacteriaceae, Aerococcaceae, and Planococcaceae were dominant in farm rank B. The Fast Expectation–Maximization for Microbial Source Tracking model revealed that while the sources of microbial contamination varied across farms at different management ranks, the teat and teat liner consistently emerged as the primary sources of microbial contamination in raw buffalo milk. This study provides important insights into how different farm management ranks affect the microbial composition of raw buffalo milk, highlighting the importance of improved management practices during milk production, particularly in cleaning the milking equipment and farm environment, as these are key factors in ensuring the quality and safety of raw buffalo milk.

Subclinical mastitis (SCM) is one of the most common and detrimental diseases affecting dairy cows, causing lower milk yield and quality. Identification of pathogenic bacteria of subclinical mastitis (PSM) in dairy cows is crucial for selecting suitable antibiotic treatments and implementing effective prophylactic measures. This paper highlights the first systematic study to investigate the PSM in buffalo farms in Guangxi, China. It also analyzes the antibiotic resistance and virulence characteristics of typical PSM. The bacteriological characteristics of 132 milk samples collected from buffaloes with SCM across 3 representative buffalo farms in Guangxi, China were investigated. A total of 1659 bacterial strains were isolated and classified into 46 genera and 183 species, where 1058 bacterial strains were identified as PSM, representing 64% of the total isolates. The frequently isolated PSM in total samples were coagulase-negative Staphylococci (55.30%), Enterococcus faecalis (51.52%), Escherichia coli (31.82%), and Klebsiella pneumoniae (28.03%). All PSM strains showed multiple antibiotic resistance. Notably, E. faecalis and Lactococcus garvieae were resistant to all 12 antibiotics, whereas Staphylococcus chromogenes (95.24%), E. coli (89.19%), K. pneumoniae (83.87%), and Staphylococcus epidermidis (83.33%) were sensitive to levofloxacin (LEV). Additionally, E. coli exhibited the strongest mortality of Galleria mellonella. This study concluded that multiple PSM are present in the milk of buffaloes suffering from SCM in Guangxi, China. LEV may be a suitable antibiotic for the treatment of PSM. In the future, it is necessary to monitor the prevalence of PSM in buffalo farms and develop control strategies to prevent their spread.