Abstract

Experiments were conducted with male weanling rats to determine the effect of high dietary protein (40% casein), alfalfa (25%), protein + alfalfa (25% casein + 25% alfalfa), or anion-exchange resin (5%) on the relative proportions of free and conjugated zearalenone and zearalenols excreted in urine and feces following a single oral dose of zearalenone. About 90% of the dose was excreted in feces after 48 h while the remaining 10% was excreted in urine. Zearalenone and metabolites were excreted mainly in free form with conjugates being found only in urine. Rats fed high-protein diets excreted more free zearalenone and alpha-zearalenol in urine than did controls (16.3% casein). The feeding of protein + alfalfa also resulted in increased urinary losses of free zearalenone. A reduction in urinary losses of conjugated zearalenone and alpha-zearalenol was seen when 5% anion-exchange resin was fed. Fecal excretion of zearalenone and alpha- and beta-zearalenol increased when alfalfa + protein was fed. Residual zearalenone and zearalenols were measured in liver and kidney 18 h after dosing. All treatments except high protein reduced residues of zearalenone and alpha-zearalenol in liver when compared with controls. Renal residues of zearalenone were lowered only by supplements of protein + alfalfa or anion-exchange resin. Each of the treatments fed has been shown to reduce zearalenone toxicosis in rats, but it was concluded that each does so by a different mechanism.