The Risk of Feed and Milk Contamination by Mycotoxins on Smallholder Dairy Farmers in Kenya

Mycotoxins are toxic secondary metabolites produced by fungi in warm environments. Due to the warm climate highly favourable for growth of moulds, the threat of mycotoxin poisoning (livestock and human) is real and of major concern in Kenya. This is further compounded by the general preference for foods that are highly susceptible to mycotoxins contamination. This paper attempts to highlight the risk of mycotoxin contamination of dairy feeds and products’ serious animal and human health implications. Available information clearly indicates that, aflatoxin is one of the most widely occurring and dangerous of all mycotoxins known. The term aflatoxin refers to a closely related group of metabolites produced by toxigenic strains of Aspergillus flavus and A. parasiticus. Aflatoxins are potent carcinogenic, mutagenic, teratogenic, and immunosuppressive agents. Four different aflatoxins, B1, B2, G1 and G2, have been identified with M1 (a metabolite of B1) being the most toxic. Their contamination of agricultural feed grains poses a serious threat worldwide. Although occurrence and magnitude of mycotoxin contamination varies with geographical and seasonal factors and also with the conditions under which a food or feed crop is grown, harvested, and stored, those grown under tropical and subtropical conditions are more prone to contamination than those in temperate regions due to favourable humidity and temperaturelevels for mould growth (10 – 40oC, pH range of 4 – 8 and above 70% equilibrium relative humidity). Incidences of mycotoxin poisoning are more common on smallholder farms due to lack of appropriate control skills and knowledge. Dairy cattle on these farms often get poisoned as result of continuous exposure to contaminated feeds. Virtually all feeds are susceptible to mycotoxin contamination, so long as conditions permit mould colonisation. Poor storage and the general tendency to offer mouldy feed resources (protein supplements, poultry manure, cereal grains and crop residues) to livestock are the primary factors exacerbating mycotoxin related risks on smallholder farms in Kenya. Because of the greater rolethey play as milk producers, control of mycotoxins in dairy diets on smallholder farms would not only reduce the likelihood of livestock poisoning, but also significantly improve public health and consumer confidence, with positive impact on economic returns at household level.