Aflatoxin M1 (AFM1) is a metabolite of Aflatoxin B1 (AFB1) and is excreted through cow´s milk. AFM1 contamination of milk is extended geographically and there might be seasons-related variations for both prevalence and contents, with higher than average values in regions with long periods of drought like El Salvador. Therefore, this project quantified AFM1 levels in raw cow milk and AFs in cattle feedstuffs, during the transitional dry-rainy seasons of two consecutive years and it determined the variation of occurrence and contents associated to drought. Significant variations were shown from year to year in the prevalence of contamination (30% vs. 20%) and in the average levels of AFM1 in milk (0.056 vs 0.039 μg/kg), associated with drought and increased temperature. The AFs median levels raised significantly with the drought period (from 22.5 to 10.3 μg/kg). A significant relationship was demonstrated between AFs levels and those of AFM1, both in the year with drought and without that condition. AFM1 positive cases and its levels in milk increase in drought and hot conditions, AFs levels in the cattle feed tend to be higher with the same, as well. Both relationship between AFs and AFM1 levels and their association with drought were demonstrated. So that, heat and drought stress conditions can evoke raising effects on both Aflatoxins level and occurrence due to AFM1 in milk is a carryover from AFs contaminated feedstuffs ingested by dairy cows.
Key words: AFM1, Raw cow milk, ELISA, Drought-associated variation: total aflatoxins, Feedstuffs