Theses and Dissertations


Title: GROWTH PERFORMANCE AND DISEASE RESISTANCE OF CHANNEL CATFISH (Ictalurus punctatus) FED DIETS CONTAINING NATURAL GOSSYPOL AND GOSSYPOL-ACETIC ACID

Name: Yildirim-Aksoy, Mediha

Degree: PhD

Chair: Chhorn Lim

Resides:

University: Auburn University

Location: Auburn, Alabama

Date: 2003

Pages: 150

Keywords: gossypol,growth performance,disease resistance,channel catfish

Abstract:

Two experiments were conducted to determine the effect of dietary gossypol on growth performance, hematology, immune response, and disease resistance of channel catfish to Edwardsiella ictaluri challenge. Fish averaging 6.22 ± 0.25 g and 6.47 ± 0.04 g were fed purified diets supplemented with gossypol (0, 100, 200, 400, 800 and 1600 mg/kg) from gossypol-acetic acid (G-AA) and practical diets containing natural free-gossypol (0, 100, 200, 400 and 800 mg/kg) from glanded-cottonseed meal (G-CSM) or G-AA, respectively, twice daily to apparent satiation for 12 weeks. Weight gain, feed intake and feed efficiency of fish fed purified diets linearly (P < 0.001) decreased with increasing dietary gossypol levels. When practical diets were used, neither the sources nor the levels of dietary gossypol influenced these response criteria. Whole body moisture, fat, and ash, hematological values and serum protein linearly (P < 0.001) decreased with increasing dietary gossypol levels in fish fed purified diets but not in fish fed practical diets. These data indicate that gossypol supplemented to purified diets appeared be more toxic than gossypol supplemented to practical diets. Chemotaxis ratio was enhanced in fish fed purified diets containing 277 mg/kg dietary gossypol (break point analysis) but not in fish fed practical diets. Gossypol accumulation in liver was linearly (R2=0.99) related to dietary levels of gossypol. The accumulation rate was higher in fish fed purified diets than in fish fed practical diets. Higher liver gossypol contents also were observed in fish fed practical diets containing gossypol from G-CSM as compared to those fed corresponding levels of gossypol from G-AA. These results indicate that part of the portion of total gossypol, besides free gossypol present in G-CSM, may be absorbed and deposited in the liver of catfish. Serum lysozyme activity significantly increased in fish fed dietary gossypol levels of 900 and 200 mg/kg or higher in purified and practical diets, respectively. Significantly increased superoxide anion (O2) production was observed in fish fed practical diets containing gossypol at levels of 400 mg/kg from G-CSM or 800 mg/kg from G-AA. Antibody titer against E. ictaluri was not affected by type of diet and sources and levels of gossypol. Post-challenge mortality significantly decreased in fish fed purified diets containing gossypol at levels of 900 mg/kg or higher. When practical diets were used, neither the sources nor the levels of gossypol influenced the resistance of fish against E. ictaluri infection. Gossypol, even supplemented to purified diets, is of little or no benefit in improving the resistance of fish against E. ictaluri infection because the levels observed to enhance some immune parameters and survival of fish post-challenged with E. ictaluri were much higher than those found to be toxic to juvenile catfish.

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