Relative toxicity of dietary free gossypol concentration in ducklings from 1 to 21 d of age

The aim of this study was to investigate the toxic effects of gossypol from cottonseed meal on the growth performance, serum characteristics and tissue gossypol residues in Shanshui White Ducklings. A total of 750 1-d-old ducklings (375 males and 375 females) was randomly divided into 5 dietary treatments with 5 replicate pens per treatment and 30 birds in each pen (15 males and 15 females). The experimental diets were formulated with raw cottonseed meal, de gossypol cottonseed meal and cottonseed powder as free gossypol (FG) sources. The final FG concentrations in the 5 diets were 0, 80, 160, 240 and 320 mg/kg feed. Feeding the diet with 320 mg FG/kg decreased (P < 0.0003) body weight (BW), average daily gain (ADG) and average daily feed intake (ADFI) of ducklings during the periods of d 1-10 and 1-21, and increased (P < 0.0003) feed: gain ratio (F:G) of ducklings during the period of d 1-10. Gossypol concentration in liver and muscle of ducklings measured at d 10 and 21 linearly increased (P < 0.001) with the increase of dietary FG levels. Notably, the diet containing 320 mg FG/kg increased (P < 0.05) liver index and serum alanine aminotransferase and aspartate aminotransferase activities at d 10, as well as decreased (P < 0.05) thymus index and serum total protein and albumin contents at d 10 and the body protein deposition at d 21. Our results indicated that ducklings fed the diet with 320 mg FG/kg resulted in an accumulation of gossypol in liver and then induced hepatic damage in the ducklings at d 10. Subsequently, the serum total protein concentrations and body protein deposition were reduced and growth rate were depressed in the ducklings at d 10 and 21 (or from d 10 to 21). Therefore, dietary FG concentration should be controlled at below 320 mg/kg to prevent an economic loss from the toxicity of FG in Shanshui White ducklings from 1 to 21 d of age.