Mycotoxins have become an important issue for the grain industry and animal producers with a growing interest in the decontamination and remediation of highly contaminated feedstuffs. Practical methods to detoxify mycotoxin-contaminated grain on a large scale and in a cost-effective manner are essential but not currently available. The most recent and promising approach to detoxify mycotoxin-contaminated grain is the use of non-nutritive adsorbents, which bind the aflatoxin and thereby reduce their absorption from the gastrointestinal tract. Humic acids are products of chemical and biological transformations of animal and plant residues and are widely distributed in nature. Humic acids have some therapeutic characteristics and a strong binding affinity for several compounds. A South African company developed an effective large-scale regeneration process for humic acids from coal, called oxihumate. This study evaluated the effectiveness of oxihumate to adsorb mycotoxins, for the purpose of developing it as a commercial mycotoxin binder to be used in the preventative management of contaminated poultry feedstuffs. The in vitro affinity and adsorption capacity of oxihumate to aflatoxin was evaluated and the efficacy of oxihumate as an aflatoxin binder in broiler feeds in vivo was determined. The data showed adsorptions of about 10.3, 7.4 and 11.9 mg aflatoxin B1/g oxihumate at pH 3, 5 and 7, respectively. Oxihumate adsorbed 1.2, 2.6 and 8.5 mg aflatoxin G2/g at pH 3, 5 and 7, respectively. Oxihumate supplementation at a concentration of 3.5 g/kg feed was effective in diminishing the growth inhibitory effects of aflatoxin and apparent protection was noted for some of the organ, haematological and serum biochemical changes associated with aflatoxicosis. These results suggest that oxihumate could alleviate some of the toxic effects of aflatoxin in growing broilers, and when used with other sound mycotoxin management practices, might prove beneficial in the preventative management of aflatoxin-contaminated feedstuffs for poultry. The improvement observed during this specific study was, however, not satisfactory enough to recommend oxihumate as a commercially available product.
Thesis (PhD (Animal and Wildlife Sciences))--University of Pretoria, 2007.