Occurrence of Aflatoxin in Dairy Cow Feed Ingredients and Total Mixed Ration

Abstract

Abstract. The level of aflatoxin B1 (AFB1) in dairy cow feed ingredients and Total Mixed Rations (TMRs) procured at two farms for low- and high-yielding dairy cows were surveyed. Raw milk from the two groups of cows at each farm was sampled 24 h after feeding the cows with examined feedstuffs during both the rainy and the non-rainy season. The aflatoxin M1 (AFM1) level in the raw milk samples was measured 12-24 h later. The levels of AFB1 in feed and AFM1 in milk were determined by validated enzyme linked immunosorbent assay (ELISA). The influence of farm management and type of feeding system on aflatoxin occurrence were considered. AFB1 and AFM1 were detected in 100% of feed and milk samples, respectively. The average level of AFB1 in the feed ingredients and TMRs were in the range of 1.6-104.7 µg/kg and 11.0-56.0 µg/kg, respectively. The average level of AFM1 in milk samples was 77.0 ng/L. The average concentrations of AFB1 in feeds and AFM1 in milk procured in the rainy season were significantly greater than those procured in the non-rainy season (p<0.05). Of the studied feed, maize silage was determined as the most contaminated feed ingredient in terms of AFB1 content. Furthermore, the AFM1 in 75% of milk samples obtained from high-yielding dairy cows and 25% of milk samples obtained from low-yielding dairy cows indicated AFM1 level higher than the maximum allowable Europe Commission limit of 50 ng/L. The results also showed that the occurrence of AFB1 in feed varied with farm feed management. The extent of translocation to AFMI in milk samples was dependent on type of cow, whether low- or high- milk yielding. This study suggests regular risk analysis and using good farm management practices are important to control aflatoxin contamination in feed and milk. Keywords: Aflatoxin B1, Aflatoxin M1, Dairy cows, Feed, Milk yield.