Effects of short-term feed restriction on production, processing and body shape traits in market-weight channel catfish, Ictalurus punctatus (Rafinesque)

Abstract

The effects of feed restriction on channel catfish production, processing yield (carcass and fillet), visceral composition and body shape traits were determined. Channel catfish (initial mean weight =0.77 kg) were stocked into six 0.04-ha ponds at ∼5775 kg ha−1. Two ponds were assigned to each of three feeding regimes for a 4-week trial: fed daily to satiation, fed once weekly to satiation and not fed. Fish were measured for weight, processing yield and visceral components after 2 and 4 weeks, and for body shape after 4 weeks. Growth was fastest in fish fed daily, intermediate in fish fed weekly and slowest in unfed fish. There were no differences in survival among feeding regimes. After covariate adjustment for weight differences, fish fed daily had shorter, thicker bodies, and smaller heads than fish from feed-restricted treatments. Carcass yield was higher for females than males and higher at week 2 than at week 4, but was not affected by feeding regime. Fillet yield was higher for females than males, higher at week 2 than at week 4, and higher for fish fed daily than for feed-restricted fish (fed once weekly and not fed). Viscerosomatic index (VSI), visceral fat-somatic index (VFI) and hepatosomatic index were higher at week 2 than at week 4, and highest for fish fed daily, intermediate for fish fed weekly and lowest for unfed fish. Hepatosomatic index and VSI were higher for females than males, but VFI was not different between genders. The female gonadosomatic index increased over time but was not affected by feeding regime. Short-term feed restriction had negative impacts on growth and fillet yield. Processors could benefit by marketing severely feed-restricted channel catfish as carcasses rather than fillets since fillet yield declined but carcass yield was unchanged by feed restriction.