Family, Strain, Gender, and Dietary Protein Effects on Production and Processing Traits of Norris and NWAC103 Strains of Channel Catfish

Juvenile National Warmwater Aquaculture Center 103 (NWAC103) and Norris strain channel catfish Ictalurus punctatus (from 32 and 29 full‐sib families, respectively) were individually tagged and stocked into 0.04‐ha ponds at 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 d. Fish were harvested, counted, sexed, and weighed. Fish larger than 0.40 kg were processed and measured for yield and composition of various body components. The NWAC103 strain fish were larger at stocking than Norris strain fish; however, none of the strain‐diet combinations differed with respect to survival, feed conversion ratio, or percent weight gain. The NWAC103 strain fish fed the 32% protein diet were larger at harvest and had faster growth at unit size (a) than Norris strain fish. Norris and NWAC103 strain fish fed the 32% protein diet did not differ in body component yield or composition. The NWAC103 strain fish fed the 22% and 32% protein diets did not differ in growth, but NWAC103 strain fish fed the 22% protein diet had lower processing yield (carcass, total fillet, and shank fillet) and higher visceral fat and fillet fat than NWAC103 strain fish fed the 32% protein diet. Compared with females, males had higher stocking weight, harvest weight, a, percent weight gain, head yield, fillet moisture, and nugget yield but lower visceral yield, carcass yield, 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. The NWAC103 family rankings for most traits were consistent across diets (correlations generally >0.70 among best linear unbiased predictor values across diets). These results suggest that there is potential for improving growth and processing yield traits through selective breeding and that the improvements achieved through selection would be realized on either of the diets used.