Comparison of satiate feeding and restricted feeding of channel catfish with various concentrations of dietary protein in production ponds

Abstract

A 2 × 3 factorial experiment was conducted with channel catfish ( Ictalurus punctatus) using satiate or restricted feeding with 26, 32 or 38% dietary protein concentrations in practical catfish diets. The diets were similar to commercial catfish feeds, with major ingredients being soybean meal, ground corn, fish meal and wheat middlings, and small amounts of vitamin and mineral supplements. The protein concentration of the diets was increased by substituting a fixed ratio of soybean meal to fish meal (5 : 1) for corn. Essential amino acids in all diets were adequate. Energy concentration of the diets was not regulated. Fish were grown from 60 g to marketable size at a stocking density of 13 590 fish per ha in 400-m 2 earthen ponds. Fish in the satiation feeding group were fed as much as they would consume each day for the 125-day spring-summer experimental period. Fish in the restricted feeding group were not fed more than 60 kg/ha day −1; this rate was reached at approximately day 70 of the experiment. There was a significant interaction between feeding regime and dietary protein concentration on weight gain. Weight gain of fish fed to satiation decreased linearly as dietary protein content increased, while weight gain of fish under restricted feeding increased linearly with increasing dietary protein percentage. Weight gain of fish fed to satiation was positively correlated with feed consumption, which decreased linearly as dietary protein concentration increased. Dietary protein concentration had no influence on feed conversion under satiate feeding, but had a positive effect on feed conversion under restricted feeding. Feed conversion of fish fed to satiation was higher than that of fish under restricted feeding. Dietary protein had a quadratic effect on dressing percentage; it increased as dietary protein increased from 26 to 32% and decreased as dietary protein increased from 32 to 38% for both satiate and restricted feeding. Body fat content of fish in both feeding regimes was negatively correlated with the protein/digestible energy ratio of the diets. Body fat content of fish fed to satiation was higher than that of fish fed at the restricted rate. These results indicate that feeding rate significantly influences weight gain and body composition of channel catfish. In addition, channel catfish can obtain sufficient nutrients from a 26%-protein, amino-acid-balanced practical diet for maximum weight gain with satiate feeding, but when fed to less than satiation higher-protein diets are required.