Effects of ammoniation on aflatoxins in rations fed lactating cows

A multifaceted cooperative research program involving industry, government and universities was initiated to determine the effects of feeding lactating dairy cows rations containing various levels of cotton-seed and cottonseed meal that had been naturally contaminated with aflatoxins. Evidence is presented that ammoniation of aflatoxin-contaminated cottonseed and cottonseed meal eliminates the aflatoxins, producing a product safe for feeding to ruminants. The aflatoxin M1 content of milk samples of individual cows receiving rations containing (a) prime cottonseed meal, (b) aflatoxin contaminated meal, and (c) aflatoxin contaminated meal that had ammoniation treatment is reported. Data comparing results with (d) prime cottonseed, (e) aflatoxin contaminated seed, and (f) aflatoxin-contaminated seed that had ammoniation treatment are also reported. None of the milk samples from cows fed ammoniated rations contained any detectable M1 by the modified Jacobson et al. methodology used. The sensitibity of the method in this laboratory is 0.1 μg M1/liter of milk. Under the conditions of this study, aflatoxin M1 levels are related to the levels of aflatoxin B1 consumed in the diet of the cows. Conversion ratios are reported. Aflatoxin M1 levels in the milk, relative to the time of the cows’ initial ingestion of aflatoxin B1, the persistence of M1 in the milk after discontinuing ingestion of B1, and disappearance of M1 under the conditions of the analytical methodology used relative to storage time and temperatures, are reported for liquid milk and for frozen milk. Milk containing the highest level of aflatoxin M1 was treated with rennet. An 80:20 partion of aflatoxin M1 was observed between curd and whey, respectively.