|Yildirim, Mediha - AUBURN UNIVERSITY|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 24, 2003
Publication Date: September 22, 2003
Citation: Lim, C.E., Yildirim, M., Wan, P.J., Klesius, P.H. 2003. Growth performance and disease resistance of channel catfish (Ictalurus punctatus) fed diets containing graded level of gossypol acetate. 10th International Symposium on Nutrition and Feeding of Fish. June 2-7, 2002, Rhodes, Greece. p. 62. Technical Abstract: Previous studies at our laboratory suggested that gossypol or other compounds present in cottonseed meal (CSM) improved the resistance of channel catfish against enteric septicemia of catfish (ESC). A more recent study showed that gossypol from gossypol-acetic acid may be of little benefit in improving the resistance of catfish against ESC since the dietary level found to improve the disease resistance was much higher than that affecting the growth performance. However, gossypol from gossypol¿acetic acid may not function the same in catfish diets as natural free gossypol present in CSM. Thus, this study was conducted to evaluate the effect of free-gossypol from glanded-cottonseed meal (natural free gossypol) or gossypol from gossypol-acetic acid on growth performance, body composition, hematology, immune response and resistance of channel catfish to Edwardsiella ictaluri challenge. A soybean meal-based diet supplemented with 0, 100, 200, 400, and 800 mg/kg free gossypol from glanded-cottonseed meal (G-CSM) or gossypol-acetic acid were fed to juvenile channel catfish in triplicate aquaria to apparent satiation twice daily for 12 weeks. Results showed that neither sources nor levels of dietary gossypol significantly (P>0.05) influenced the final weight gain, feed intake, feed efficiency and survival of channel catfish. Similarly, whole body proximate composition, hematological parameters (red blood cell, white blood cell counts, hemoglobin and hematocrit), serum protein concentration, macrophage chemotaxis ratio, phagocytic activity and antibody production against E. ictaluri 21-day post-infection were likewise not affected by dietary sources or levels of gossypol. Gossypol concentrations in liver were linearly related to dietary levels of gossypol but the retention rate varied dependent on the source of dietary gossypol. At dietary gossypol levels of 400 or 800 mg/kg, total gossypol concentrations in liver of fish fed dietary gossypol from G-CSM were significantly higher (P<0.05) than fish fed the corresponding levels of dietary gossypol from gossypol-acetic acid. The (+)-isomer of gossypol was predominantly retained in liver regardless of dietary sources of gossypol. The ratio of (+)- to (-)-isomers in liver decreased with increasing dietary concentrations of gossypol. Serum lysozyme activity of fish fed diets containing gossypol at levels of 200 mg/kg or higher, either from G-CSM or gossypol-acetic acid, was significantly higher than that of the control. At a level of 800 mg/kg diet, gossypol from G-CSM stimulated significantly higher lysosyme activity than gossypol from gossypol-acetic acid. Fish fed diets containing 400 mg/kg gossypol or higher from G-CSM or 800 mg/kg gossypol from gossypol-acetic acid had significantly increased superoxide anion (O2¿) production. However, neither the sources nor the levels of dietary gossypol influenced the resistance of juvenile channel catfish to E. ictaluri infection.