Aflatoxins in feeds: Issues and concerns with safe food production

Abstract

Aflatoxin is a category of mycotoxin produced by the fungal species Aspergillus flavus mainly, besides Aspergillus parasiticus, Aspergillus pseudocaelatus, Aspergillus pseudonomius and Aspergillus nomius. The hot-humid tropical climatic conditions predispose certain crops to mould growth, especially maize, peanuts, cottonseed and dairy products. Aflatoxin contamination of animal feeds causes huge economic loss to the feed-food industry throughout the world. Aflatoxin-B 1 is the most hazardous toxin and can be transferred from the feed to the milk of ruminant animals as aflatoxin-M 1 and ultimately poses a significant human health hazard owing to its hepatotoxic, immunosuppressive and carcinogenic effects. In India, the Bureau of Indian Standards has set a maximum permissible level of 20 ppb (aflatoxin-B 1) in all animal feeds; however, the Food Safety and Standards Authority of India recommends a permissible limit of 0.5 ppb in human foods. Aflatoxins can be transferred (0.8-6.5%) from the feed to the milk of animals as aflatoxin-M 1 and ultimately pose a significant human health hazard. Not only in milk, but the presence of aflatoxin in other dairy products, eggs and edible animal products also pushed the formulation of regulations to minimize the exposure of aflatoxin to food animals. Pre-and post-harvest prevention of aflatoxin production in agricultural products is necessary with improvement in management protocols for reducing the susceptibility of mould growth. Proper storage conditions, avoiding mechanical and insect damage, maintaining temperature, aeration and moisture are important for reducing aflatoxin contamination of feeds. Various acids, viz. sorbic acid and propionic acid, are used commercially at adequate levels to reduce aflatoxin contaminations in products. Gamma-irradiation, chemical degradation, microbial inactivation and reduction of toxin bioavailability by selective chemisorption with clays are few techniques to reduce the aflatoxin levels in animal feeds. Provision of good quality protein balanced diet with supplementation of N-acetylcysteine, choline, methionine and vitamin E is advantageous for reducing the severity of aflatoxicosis. Sustainable preventive strategies for pre-and post-harvest management of food-feed crops need to be taken up to reduce aflatoxin exposure to animals for the production of safe foods of animal origin.