Distribution of molds and aflatoxins in dairy cattle feeds and raw milk

Ninety six feedstuffs given to daily cattle from four milk producing areas of the Sao Paulo state, Brazil (Sorocaba, Cotia, Vale do Paraiba and Itupeva) were analyzed over a one-year period (June 1992 to August 1993) for the presence of contaminating fungi, toxigenic or not, and aflatoxins. In addition, the occurrence of aflatoxins aflatoxins M-1 and M-2 in raw milk from the studied dairy cows was evaluated in 144 milk samples. Fungal species were isolated on potato-dextrose agar and identified by routine mycological techniques. Detection and quantification of aflatoxins were done by thin layer chromatography (TLC). The most frequent fungi recovered from feeds were Fusarium spp. (67.7%; main isolate: F. moniliforme), Aspergillus spp. (58.3%: main isolate: A. flavus) and Penicillium spp. (52.0%), followed by eight other fungi genera. The numbers of colony forming units (CFU/g) ranged from 3.5 x 10(3) to 1.1 x 10(6) (Fusarium spp.), 3.0 x 10(2) to 7.8 x 10(3) (Aspergillus spp.) and 1 x 10(2) to 3.1x x 10(5) (Penicillium spp.). Twelve (46.1%) of the 26 A. flavus isolates were group B aflatoxins producers and 3 of the A. pal asiticus isolates were group B and G aflatoxins producers. The presence of aflatoxins B-1 and B-2 was observed in 14 (14.6%) of the feed samples analyzed at levels that ranged between 11.5 and 287 mu g/kg (AFB(1)) and 19 and 40 mu g/kg (AFB(2)). No carryover of mycotoxins to raw milk was observed. Nonetheless, despite these negative results under the experimental conditions used, the continuous evaluation of levels of aflatoxin M-1 and M-2 in dairy products is always necessary since either favorable or unfavorable conditions for mycotoxin production may vary over different periods.