Farm management factors with potential effect on culturable microbiota in bulk tank milk from sheep farms

Introduction Ensuring high microbiological quality in sheep milk is crucial for public health, product quality, and the sustainability of traditional dairy systems. This study investigated the association between the bacteriological quality of bulk tank milk and key management and productive factors. Methods A total of 308 sheep’s milk samples from 77 farms were analyzed for major microbial groups using culture methods, and a farm survey was conducted to characterize management practices. Factor analysis identified four distinct groups of culturable bacteria that collectively explained 64.9% of the total variance in the model. These groups were characterized as: (i) environmental and hygienic bacterial counts, (ii) thermotolerant bacterial counts, (iii) bacterial counts associated with udder health, and (iv) spore-forming bacteria counts. Results The first factor, which accounted for the largest proportion of explained variance, showed strong positive associations among lactic acid bacteria, Gram-positive cocci, Pseudomonas spp., Escherichia coli , coagulase-negative staphylococci, and coliforms counts. The study also revealed that flock and seasonal variations are statistically associated with the distribution of groups of culturable bacteria, highlighting their potential use in the qualitative monitoring of bulk tank milk for cheesemaking. Conclusion Higher culturable bacteria prevalence was observed in smaller, low-producing flocks, particularly those exposed to environmental contamination or suboptimal hygiene. Microbial counts decreased with regular replacement of milking filters. Feeding practices were also associated with culturable bacteria, with higher counts in hay-fed flocks and greater contamination linked to the use of wet by-products. These findings highlight how seasonality and farm management practices shape the microbial quality of milk intended for cheesemaking.