Hamilton, 1970). When hens were fed diets with approximately 90 mg of aflatoxin per kilogram, egg production decreased quickly and a high rate of mortality ensued (Hamilton, 1971). At a level of 1.5 mg/kg feed, aflatoxins caused fatty livers, necrosis, and bile duct hyperplasia (Carnaghan et al., 1966). Hematological responses such as lowered serum protein, reduced hemoglobin, and lower levels of serum triglycerides, phospholipids, and cholesterol result from moderate aflatoxin doses (Tung et al., 1972).
Fusarium moniliforme is a fungus that may grow on grains. It is found to produce a thiaminase causing thiamin deficiency in chicks (Fritz et al., 1973). Mortality is increased if additional thiamin is not supplied in contaminated diets. Corn shown to contain F. moniliforme causes substantial mortality when fed to ducklings (Jeschke et al., 1987).
Tricothecenes constitute another group of fungal compounds that may decrease the performance of poultry. These compounds may be produced by several genera of fungi but are most commonly metabolites of Fusarium . Laboratory studies have shown that T-2 toxin at levels up to 20 mg/kg of diet may decrease weight gain and egg production (Wyatt et al., 1973b, 1975). Oral lesions and digestive disturbances are caused by toxic concentrations of T-2.
Other tricothecenes produced by Fusarium are deoxynivalenol (DON), nivalenol, and diacetylnivalenol. These toxins appear to be more toxic to swine, in which they may cause vomiting and feed refusal (Morehouse, 1985), than to poultry. Adverse effects of Fusarium toxins on turkey reproduction have been reported (Allen et al., 1983).
Mycotoxins such as ochratoxin A and zearalenone have also been identified and may cause deleterious effects on poultry. A review of their effects was done by the Council for Agricultural Science and Technology (1989).