Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2006
Publication Date: 5/27/2006
Citation: Bosworth, B.G., Wolters, W.R., Silverstein, J., Li, M.H., Robinson, E.H. 2006. Family, strain, gender, and dietary protein effects on production and processing traits of norris and NWAC103 strains of channel catfish, Ictalurus punctatus. North American Journal of Aquaculture 69:106-115. Interpretive Summary: Feed costs are a major expense for catfish producers, and diet costs generally increase as the protein level of the diet increases. Recent trends in commercial catfish diets have been towards lower cost, lower protein diets. Given the trends toward lower protein diets it is important to determine if fish being bred for improved performance when fed current diets will perform well on potentially lower protein diets that may be used in the future. Performance of NWAC103 strain channel catfish fed 32% and 22% protein diets were compared to performance of Norris strain catfish fed 32%. NWAC103 strain fish fed 32 and 22% diets were larger at harvest than Norris strain fish fed 32% diet. There was no difference in growth between NWAC103 strain fish fed 32% or 22% diet. However, NWAC103 fish fed 22% diet were fatter and had lower fillet yield than NWAC103 fish fed 32% diet. Performance rankings (growth, fillet yeild etc.) of NWAC103 families were very consistent across 32% and 22% diets (the same families that grew fastest when fed 32% also grew fastest when fed 22%) suggesting that fish bred for improved performance on 32% diet will retain superior performance if they are fed 22% diet. Results suggest improvements in performance achieved through selective breeding will be realized on lower protein diets that may be used by catfish producers in the future.
Technical Abstract: Juvenile NWAC103 and Norris strain channel catfish (from 32 and 29 full-sib families, respectively) were stocked into 0.04 ha ponds at approximately 14,400 fish/ha. Four ponds each of NWAC103 and Norris strain fish were fed a 32% protein diet and four ponds of NWAC103 fish were fed a 22% protein diet to satiation once daily for 150 - 178 days. Fish were harvested, counted, sexed, weighed, and measured for yield and composition of various body components. NWAC103 strain fish were larger at stocking and harvest than Norris strain fish. Strain-diet combinations did not differ for survival, feed conversion ratio, or percent weight gain. NWAC103 and Norris strain fish fed 32% diet did not differ for body component yield or composition. NWAC103 strain fish fed 32% and 22% diets did not differ for growth, but NWAC103s fed 22% diet had lower processing yield (carcass, total fillet, shank fillet) and higher visceral fat and fillet fat than NWAC103s fed 32% diet. Compared to females, males grew faster, had lower fillet yield and fillet fat. Family within strain was a significant source of variation (accounting for 10 - 45% of total variation) for all traits except fillet protein. NWAC103 family rankings for most traits were consistent across diets (correlations generally > 0.70 among family BLUP values across diets). Results suggest potential for improving growth and processing yield traits through selective breeding and that improvements achieved through selection would be realized on either of the diets used.