Reduction of Mutagenic Potentials in Milk: Effects of Ammonia Treatment on Aflatoxin-Contaminated Cottonseed

Milks obtained from cows fed rations containing aflatoxin-contaminated cottonseed, ammonia-treated aflatoxin-contaminated cottonseed, and uncontaminated cottonseed were tested for mutagenic potential using the Salmonella /mammalian microsome mutagenicity assay using Salmonella typhimurium strains TA98 and TA100. Standard assay protocol was used with S-9 liver homogenate added. Samples including whole milk, nonfat dry milk powder, cream, and reconstituted whole milk were applied directly to the plates in triplicate. As a control, samples of whole milk, reconstituted whole milk, and nonfat dry milk powder from cows fed uncontaminated feed were spiked with aflatoxin B₁ and tested for mutagenic activity. High levels of mutagenic activity were observed in all samples from cows exposed to aflatoxin-contaminated cottonseed and the aflatoxin-spiked milks. This high activity was not evident in whole milk and whole milk component samples from cows fed the ammonia-treated aflatoxin-contaminated cottonseed or nonaflatoxin containing cottonseed. A low level of mutagenic potential was evident in whole milk from the ammonia treated group using TA100 tester strain.