An examination of gossypol toxicity in broilers and laying hens and the development of a novel use for cottonseed meal in poultry diets and of a rapid assay for quantifying gossypol in cottonseed meal
Lordelo, Maria Madalena
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Gossypol is a toxic compound found in cottonseed meal. Experiments were conducted to determine the relative toxicity of the (+) and (-) enantiomers of gossypol in poultry. The individual pure gossypol enantiomers were added to nutritionally complete diets and then fed to broilers, laying hens, and broiler breeder hens. The (-) enantiomer of gossypol was detrimental to feed intake in broilers and broiler breeder hens while the (+) enantiomer of gossypol inhibited feed intake in laying hens. Severe egg yolk discoloration was caused by (+)-gossypol in both laying and broiler breeder hens. Since both (-)- and (+)-gossypol have toxic effects in chickens, the development of a cotton strain containing only one gossypol enantiomer would not be beneficial for the poultry industry. To determine if cottonseed meal could replace soybean meal in broiler breeder pullet diets, pullets were fed a diet containing either cottonseed meal or soybean meal as the major protein source from 2 to 18 weeks of age. Flock body weight uniformity during the rearing period was improved in pullets consuming cottonseed meal as the major protein source. Furthermore, subsequent reproductive performance was not affected in broiler breeder pullets fed cottonseed meal during the rearing period. Therefore, cottonseed meal has advantages over soybean meal in broiler breeder pullet diets. To determine if near infrared reflectance spectroscopy could be successfully utilized to rapidly measure free gossypol concentration in cottonseed meal, a near infrared calibration equation for gossypol was developed. There was a high correlation between the values of gossypol determined by the conventional chemical-based reference method and by the near infrared reflectance spectroscopy method. The results suggest that there are no apparent advantages for poultry in altering the enantiomeric ratio of the cotton plant, but that cottonseed meal can be successfully utilized by the poultry industry in broiler breeder pullet diets and that the poultry industry could use near infrared reflectance spectroscopy technology to determine the free gossypol content of cottonseed meal.