Effects of Season and Hygienic Factors on Milk Microbiological and Physicochemical Characteristics in Livestock Communities of Ayacucho, Peru

Climatic changes can influence milking practices and the dairy production chain, thereby influencing the microbiological safety and physicochemical quality of raw bovine milk (RBM), with potential implications for public health. The present study aimed to evaluate the effects of seasonal variability on the hygienic factors and characteristics of RBM produced in livestock communities in the Socos district, Ayacucho, Peru. For mesophilic aerobic bacteria (MAB) and total coliform bacteria (TCB), the compact dry plate method was used. Sixty random samples were collected during the rainy season (RS) and the dry season (DS). Samples were taken from milkers' hands (six in the RS and six in the DS), rags (six in the RS and six in the DS), buckets (six in the RS and six in the DS), receiving tanks (eight in the RS and eight in the DS), and distribution centers (four in the RS and four in the DS). To evaluate physicochemical characteristics, including density, fat, protein, total solids, lactose, pH, and mineral salts, eight samples of Brown Swiss cattle RBM were collected directly from the tanks (four in the RS and four in the DS) of two distribution point centers. The present results indicated that the MAB count for hygienic factors was lower in the DS than in the RS, except in the milker's hands and distribution centers. For the TCB count related to hygienic factors, the values were lower in the DS than in the RS, except in receiving tanks and distribution centers. In the RS, the physicochemical qualities complied with the Peruvian Technical Standard (PTS), except for protein content and mineral salt levels. In the DS, the physicochemical quality did not comply with the PTS; however, these properties were within acceptable limits in the receiving tanks for MAB and on the milker's hands for TCB. As a result, the bacterial load on inert surfaces and the characteristics of RBM were lower in the DS compared to the RS. Still, contamination during milking and at distribution centers was greater.