Study on the occurrence of fungi and aflatoxina B-1 in the diet of dairy cattle in Sao Paulo, Brazil

The quality of the diet offered to lactating cows is a concern to health officials the possibility of detecting mycotoxins harmful to human and animal health. The objectives were to evaluate the profile of mycoflora, determine the water activity (Aw) and the natural occurrence of aflatoxin B-1 (AFB(1)) in diets offered to lactating cows from dairy farms in the state of Sao Paulo, Brazil. Samples of the diets were taken directly from the troughs batch of 15 cows, on two consecutive days at intervals of 24 hours and every 15 days with a period of 45 sampling days per farm. Purification and determination of AFB(1) were performed on immunoaffinity columns and High Performance Liquid Chromatography (HPLC). The study of mycobiota present in samples of diets (288) revealed that yeast cells were predominant in all diets (83.97 to 99.98%). 15 genera were isolated from filamentous fungi, with Aspergillus spp (20.09%), Fusarium spp. (14.16%) and Penicillium spp. (11.48%) the most prevalent. The counts of colony forming units per gram of food (UFC.g(-1)) ranged from 10(2) a10(11). The water activity of the samples ranged from 0.91 to 0.98. We have detected the presence of AFB(1) in 31.44% of samples with levels between 1.68 a 194.51 mu g.kg(-1). Measures of good production, storage and use should be taken to reduce the occurrence of aflatoxin B-1 in the diet offered to lactating cow.