Degradation of aflatoxin by poultry litter

Two trials were conducted to determine whether deep stacking of contaminated corn with poultry litter destroys aflatoxin. Contaminated corn was ground and mixed with litter to carbon:nitrogen ratios of 30:1. Moistures were adjusted by adding tap water just prior to incubation or stacking. The initial laboratory trial included only broiler litter at 40% moisture, whereas the subsequent field trial involved a 2 x 2 factorial design with litter type (turkey or broiler) and moisture (20 or 40%) as main effects. Aflatoxin assays were reduced in the laboratory trial from 433 and 402 to 54 and 8 ppb in Containers 1 and 2, respectively, after 35 d of incubation at 28 C. In the field trial, aflatoxin disappeared from broiler and turkey litter mixtures with projected moistures of 20% after 10 and 6 wk of storage, respectively, whereas disappearance in mixtures containing projected moistures of 40% required 5 and 3 wk, respectively. Differences in moisture appear to account for differences in the ability of turkey and broiler litter to detoxify aflatoxin. Hence, turkey and broiler litter would appear equal with respect to the ability to detoxify aflatoxin-contaminated corn. Disappearance of aflatoxin during storage with litter could have occurred as a result of ammonia release during storage or microbial detoxification mechanisms. However, nitrogen values suggest that microbial action was responsible for much of the detoxification, as aflatoxin disappeared from mixtures with little apparent ammonia release.