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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Natural Free Gossypol and Gossypol-Acetic Acid on Growth Performance and Resistance of Channel Catfish (Ictalurus Punctatus) to Edwardsiella Ictaluri Challenge

Authors
item Yildirim-Aksoy, Mediha - AUBURN UNIVERSITY
item Lim, Chhorn
item Wan, Peter
item Klesius, Phillip

Submitted to: Aquaculture Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2003
Publication Date: August 1, 2004
Citation: Yildirim-Aksoy, M., Lim, C.E., Wan, P.J., Klesius, P.H. 2004. Effect of natural free gossypol and gossypol-acetic acid on growth performance and resistance of channel catfish (Ictalurus punctatus) to Edwardsiella ictaluri challenge. Aquaculture Nutrition. 10:153-165.

Interpretive Summary: Previous studies at our laboratory suggested that gossypol or other compounds present in cottonseed meal 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 level found to improve the disease resistance was much higher than the level found to be toxic to catfish. However, gossypol from gossypol¿acetic acid may not function the same in catfish diets as natural free- gossypol present in glanded-cottonseed meal (CSM). Thus, this study was conducted to evaluate the effect of free-gossypol from G-CSM 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 G-CSM or gossypol-acetic acid were fed to juvenile catfish in triplicate aquaria to apparent satiation twice daily for 12 weeks. Results showed that neither sources nor levels of dietary gossypol significantly influenced the final weight gain, feed intake, feed efficiency, survival, body proximate composition, blood parameters and serum protein content of catfish. Additional compounds, such as minerals, present in practical diets may counteract with free gossypol and reduce its toxicity to juvenile catfish. The ratio of the number of phagocytic cell migration in the presence and absence of the bacterial protein, antibody production and the number of bacteria engulfed by phagocytic cells were also not affected by dietary sources or levels of gossypol. Gossypol accumulation in liver were linearly related to dietary levels of gossypol but the retention rate in fish fed diets containing 400 or 800 mg gossypol/kg from G-CSM were significantly higher than fish fed the corresponding levels of gossypol from gossypol-acetic acid. The activity of a serum enzyme (lysozyme) and superoxide anion production were enhanced at dietary levels of gossypol ranging from 200 to 800 mg/kg depending on the source. The enhancement effect of these immune parameters by free gossypol from G-CSM appeared to be better than that from gossypol-acetic acid. However, neither the sources nor the levels of dietary gossypol improved the resistance of juvenile channel catfish to E. ictaluri infection. Further studies to identify compounds other than gossypol present in CSM and evaluate the mechanisms in which these compounds affect immune response and disease resistance in fish is needed.

Technical Abstract: A study was conducted to evaluate the effect of free-gossypol from glanded-cottonseed meal (natural free-gossypol) or gossypol-acetic acid on growth performance, body composition, hematology, immune response and resistance of channel catfish (Ictalurus punctatus) to Edwardsiella ictaluri challenge. A soybean meal-based diet supplemented with 0, 100, 200, 400, and 800 mg kg-1 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. Neither sources nor levels of dietary gossypol significantly 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 not significantly affected at either dietary sources or levels of gossypol. Gossypol concentrations of liver were linearly related to dietary level of gossypol but the retention rate varied dependent on sources of the dietary gossypol. At dietary gossypol levels of 400 or 800 mg kg-1, total gossypol concentrations in liver of fish fed dietary gossypol from G-CSM were significantly higher than those of 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 (-) gossypol isomers in liver decreased with increasing dietary concentrations of gossypol. Serum lysozyme activity of fish fed dietary gossypol levels of 200 mg kg¿1 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¿1 diet, gossypol from G-CSM stimulated significantly higher lysosyme activity than gossypol from gossypol-acetic acid. Fish fed diets containing 400 mg kg-1 gossypol or higher from G-CSM or 800 mg kg-1 gossypol from gossypol-acetic acid had significantly increased superoxide anion (O2¿) production. However, neither the sources nor the levels of dietary free-gossypol influenced the resistance of juvenile channel catfish to E. ictaluri infection challenge.

Last Modified: 9/2/2014
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