Bacteriological survey of bulk tank milk from dairy farms in Montero, Santa Cruz, Bolivia

BACKGROUND AND AIM: Recently, bacterial surveys for mastitis-causing pathogens in bulk tank milk (BTM) have been conducted in several countries worldwide. However, no such surveys have been reported from Bolivia. Therefore, the present study aimed to estimate the prevalence of mastitis pathogens in BTM from dairy farms in Montero, Santa Cruz, Bolivia. MATERIALS AND METHODS: Between July 2016 and August 2017, a total of 43 BTM samples were collected from 3264 cows to determine bulk tank somatic cell counts (BTSCC) and identify mastitis-causing bacteria. BTSCC was classified as follows: <100×10(3), 100-500×10(3), 500-1000×10(3), and >1000×10(3) cells/mL. RESULTS: Mastitis-causing pathogens identified by agar medium cultures included Bacillus spp., coagulase-negative staphylococci (CNS), coliforms, Staphylococcus aureus (SA), streptococci, and other species. The proportions of BTSCC of <100×10(3), 200-500×10(3), 500-1000×10(3), and >1000×10(3) cells/ml were 0%, 37%, 51%, and 12%, respectively. The proportions of coliforms, streptococci, CNS, Bacillus spp., SA, and others detected in BTM were 33%, 30%, 16%, 7%, 2%, and 16%, respectively. CONCLUSION: Although the herd prevalence of contagious mastitis-causing pathogens, such as SA, in BTM was low, increased BTSCC were identified in Montero, Santa Cruz, Bolivia.