Effects of Dietary Protein Level and Feeding Regimen on Growth and on Fattiness of Channel Catfish,Ictalurus punctatus

Two studies were conducted to evaluate the effects of (I) high-protein (38%) finisher feed fed to satiation for 30,45,60, or 90 days prior to harvest and (2) dietary protein (32 vs. 38%) and feeding regimen (satiation or restricted) on growth and fattiness of channel catfish. Each study was conducted for two years in earthen ponds stocked with channel catfish at a rate of 13,590 fish/ha (35 to 40 g initial weight) for year 1 and 6,800 fish/ha (0.45 to 0.6 kg initial weight) for year 2. Years refer to year of experiment and not fish age class. There were no significant differences in total yield, dressed yield, or muscle fat, regardless of diet or feeding regimen within year. Year-one fish (study 2) fed to satiation tended to gain more weight and appeared to convert feed better than fish fed at a restricted rate. In study 2 there were significant interactions between year and feed, and between year and feeding regimen. Percentage visceral fat was reduced by feeding a high-protein feed during year 1 (study 1). Females also generally had a higher percentage visceral fat than males, regardless of diet. Year-two-fish generally contained a higher percentage of visceral fat as compared to year-one fish. In study 2, there was a significant interaction effect between year, feed, feeding regimen, and sex on visceral fat. Increasing dietary protein or restricting feed appeared to have only marginal effects on fattiness in channel catfish. Fish size and/or age appeared to influence fattiness more than diet or feeding regimen.