Effects of dietary protein concentration on production characteristics of pond-raised channel catfish fed once daily or once every other day to satiation

摘要

We evaluated the effects of dietary protein and feeding regime on the production characteristics, processing yield, and body composition of channel catfish Ictalurus punctatus. Stocker-size fish with an average weight of 93 g/fish were stocked into twenty-four 0.4-ha ponds at a rate of 11,115 fish/ha. Fish were fed once daily or every other day (EOD) to apparent satiation with three commercial diets containing 28, 32, or 35% protein in a 2 x 3 factorial arrangement for 110 d. Compared with daily feeding, EOD feeding resulted in lower average net production, feed consumption, weight gain per fish, and feed conversion ratio and produced fewer marketable fish. The EOD ponds required less aeration than ponds with fish fed daily. Fish fed EOD bad lower visceral fat and fillet fat, carcass yield, and fillet yield compared with fish fed daily. Dietary protein levels had no effect on net production, aeration time, processing yield, fillet composition, and feed consumption and weight gain per fish. However, the feed conversion ratio was higher for fish fed the 28% protein diet than for fish fed the other two diets, which was unexpected because we have not observed this in other studies. Neither dietary protein nor feeding regime had an effect on pond water total ammonia nitrogen, un-ionized ammonia, or nitrite-nitrogen concentrations; these nitrogenous compounds were highly variable among ponds and time. The results from the present study demonstrated that dietary protein levels in the range of 28% to 35% had no effect on channel catfish growth or production whether the fish were fed once daily or once EOD to satiation. Feeding EOD may improve feed efficiency and reduce feed cost and aeration time but will also reduce production and processing yield and extend the production cycle compared with feeding daily.