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United States Department of Agriculture

Agricultural Research Service

Research Project: VACCINOLOGY AND IMMUNITY OF AQUATIC ANIMALS

Location: Aquatic Animal Health Research

Title: Histologic changes in channel catfish, Ictalurus punctatus Rafinesque, fed diets containing graded levels of gossypol-acetic acid

Authors
item Evans, Joyce
item Pasnik, David
item Aksoy, Mediha
item Lim, Chhorn
item Klesius, Phillip

Submitted to: Aquaculture Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 2, 2009
Publication Date: July 1, 2010
Repository URL: http://handle.nal.usda.gov/10113/55434
Citation: Evans, J.J., Pasnik, D.J., Aksoy, M., Lim, C.E., Klesius, P.H. 2010. Histologic changes in channel catfish, Ictalurus punctatus Rafinesque, fed diets containing graded levels of gossypol-acetic acid. Aquaculture Nutrition. 16:385-391.

Interpretive Summary: Gossypol is a naturally-occurring yellow pigment in the cotton plant, and the free form of the pigment is toxic to animals. Cottonseed contains free gossypol, potentially hindering the use of cottonseed as a protein source in fish feed. Gossypol appears to have detrimental effects on select growth and feed efficiency parameters, but nonetheless may enhance catfish immune responses and increase their resistance to Edwardsiella ictaluri. Our laboratories are further examining different gossypol concentrations to determine if a certain concentration would minimize the negative and maximize the positive effects of dietary gossypol. The objective of this study was to evaluate the histologic changes among juvenile channel catfish (I. punctatus) fed purified diets containing graded levels of gossypol from gossypol–acetic acid. The catfish were maintained on diets with 0, 300, 600, 900, 1200 or 1500 mg gossypol kg-1 diet for 12 weeks, and samples for histologic examination of the stomach, proximal and distal intestines, pancreas, liver, and spleen were obtained from fish in all groups. Stomach sections exhibited statistically significant gastric gland necrosis in fish fed 600 mg gossypol kg-1 diet or higher. Non-existent-to-mild enterocyte vacuolization loss, inflammatory cell infiltration, and hyperplastic lamina propria were noted in the intestinal sections from gossypol-fed fish, but no statistically significant differences in severity scores were noted among the different diet groups or between the groups and the control group. The pancreas from fish fed doses of gossypol above 600 mg gossypol kg-1 diet exhibited statistically significant mild-to-severe necrosis, and livers from fish fed 900 and 1500 mg gossypol kg-1 diet exhibited statistically significantly higher pigment deposition. No other statistically significant histologic differences were observed. The data in this study indicates that at least 600 to 900 mg gossypol kg-1 purified diet can cause statistically significant histologic changes in the stomach, pancreas, and liver of fingerling channel catfish within 12 weeks. The findings presented here suggest that gossypol should remain at concentrations below 600 mg gossypol kg-1 diet.

Technical Abstract: A study was performed to evaluate the histologic changes among fingerling channel catfish (Ictalurus punctatus) fed purified diets containing graded levels of gossypol from gossypol–acetic acid. The catfish were maintained on diets with 0, 300, 600, 900, 1200 or 1500 mg gossypol kg-1 diet for 12 weeks, and samples for histologic examination of the stomach, proximal and distal intestines, pancreas, liver, and spleen were obtained from fish in all groups. Stomach sections exhibited statistically significant gastric gland necrosis in fish fed 600 mg gossypol kg-1 diet or higher. Non-existent-to-mild enterocyte vacuolization loss, inflammatory cell infiltration, and hyperplastic lamina propria were noted in the intestinal sections from gossypol-fed fish, but no statistically significant differences in severity scores were noted among the different diet groups or between the groups and the control group. The pancreas from fish fed doses of gossypol above 600 mg gossypol kg-1 diet exhibited statistically significant mild-to-severe necrosis, and livers from fish fed 900 and 1500 mg gossypol kg-1 diet exhibited statistically significantly higher pigment deposition. No other statistically significant histologic differences were observed. The data in this study indicates that at least 600 to 900 mg gossypol kg-1 purified diet can cause statistically significant histologic changes in the stomach, pancreas, and liver of fingerling channel catfish within 12 weeks. The findings presented here suggest that gossypol should remain at concentrations below 600 mg gossypol kg-1 diet.

Last Modified: 4/23/2014
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