Relative Toxicity of Cottonseed Gossypol Enantiomers in Broilers

ABSTRACT

In cottonseed meals gossypol exist as a mixture of (+)- and (-)-enantiomers. Because of limited data on the effects of specific gossypol enantiomers on poultry and variation in (-)-gossypol in seed of Upland [34 to 47% (-)-gossypol] and Pima cotton cultivars [52 to 57% (-)-gossypol], the relative toxicity of these enantiomers to broilers was evaluated. Seeds of three cotton cultivars differing in the proportion of (-)-gossypol (35.2, 52.2 and 66.3 %) were included in three different diets at levels to give a final concentration of 400 mg/kg of total gossypol [259 and 141; 161 and 209; 135 and 265 mg/kg of (+)- and (-)-enantiomers respectively]. A total of 72 One-Day-Old, male broilers were placed in 12 Petersime battery brooder pens at 6 birds per pen and randomly assigned to the three cottonseed meat diets and a soybean meal based control. All diets were formulated to fulfill the NRC (1994) suggested requirements for essential amino acids and poultry metabolizable energy for starting broiler chickens. Gossypol enantiomers were determined in plasma, liver, heart, kidney, breast muscle and pancreas collected at 21 days of age. BW was significantly depressed as the relative dietary concentration of the (-)-enantiomer increased (P<0.01). Relative liver weight significantly increased with the use of all three cottonseeds. Body weights were negatively associated with the concentration of (-)-gossypol in plasma, liver, heart, kidney and muscle. These results clearly indicate the toxic effects of gossypol in broilers are due primarily to the (-)-enantiomer.

Keywords: