Zearalenone

A mycotoxin from Fusarium species of mould growing pre harvest on cereal grains, mainly corn, barley and oats and also soybean. It is an endocrine disruptor mimicking the female hormone oestrogen. No clear clinical picture for toxicity in horses but by extrapolating from other species the expected signs may include prolonged oestrus or anoestrus, pseudopregnancy, mammary enlargement and abortion.

Fusarium moulds like warm humid environments to grow and the rapid drying and dry storage conditions typical of Australian grain production mitigates against them, so poisoning is likely to be rare. The maximum tolerable level for horses has been estimated at 2-3mg/kg DM of diet.

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