Effects of feeding frequency and dietary moisture content on growth, body composition and gastric evacuation of juvenile Korean rockfish ( Sebastes schlegeli)

Abstract

A 7-week feeding experiment was conducted to determine the optimum feeding frequency for growth, body composition and gastric evacuation of the juvenile Korean rockfish. Three replicate groups of the fish (average weight of 5.7 g) were fed to visual satiety either dry pellets (DP) or moist pellets (MP), at different feeding frequencies (two meals a day, one meal a day or one meal every 2 days). At the end of the feeding trial, gastric evacuation rate of the fish was monitored after feeding. Weight gain and daily feed intake of the fish were not affected by dietary moisture content, whereas they were significantly affected by feeding frequency ( P<0.05). Weight gain and daily feed intake of the fish fed DP or MP once a day and twice a day were significantly higher than once every 2 days ( P<0.05). Feed efficiency and protein efficiency ratio in the fish fed MP were not affected by feeding frequency ( P>0.05), but these variables in the fish fed DP once every 2 days were significantly higher than once a day or twice a day ( P<0.05). As feeding frequency decreased, moisture content of muscle and liver increased. Both feeding frequency and dietary moisture content had no significant effect on protein content of muscle and viscera ( P>0.05). As feeding frequency increased, lipid content of muscle, viscera and liver significantly increased ( P<0.05). Gastric contents peaked at 4 h after feeding, then gradually decreased until the 20th h and reached the pre-feeding level within 24 h. It is concluded that one meal a day is more effective than two meals a day or one meal every 2 days for improving growth performance of juvenile Korean rockfish grown from 6 to 20 g.