Optimum feeding frequency of juvenile blunt snout bream Megalobrama amblycephala

An 8-week experiment was conducted to determine the optimal feeding frequency of juvenile blunt snout bream Megalobrama amblycephala. Fish (8.87 ± 0.03 g) were randomly assigned to one of six feeding frequencies (1, 2, 3, 4, 5 and 6 times daily) and hand-fed at 8% of the biomass per day for the first 4 weeks and 6% for the remaining 4 weeks. The results showed that maximum final weight (29.75 ± 0.73 g) and weight gain (20.86 ± 0.77 g) was observed in fish fed 3 times daily. Whole-body lipid content increased significantly (P < 0.05) as feeding frequency increased from 1 to 5 times daily, whereas moisture content showed an opposite trend. The activities of intestinal α-amylase and Na+, K+-ATPase increased significantly (P < 0.05) as feeding frequency increased from 1 to 3 times daily, but decreased with further increasing feeding frequency. In addition, growth hormone (GH) mRNA expression level in the brain of fish fed 1 and 2 times daily significantly higher (P < 0.05) than fish fed in other groups. Hepatic insulin-like growth factor-I (IGF-I) expression increased significantly (P < 0.05) as feeding frequency increased from 1 to 3 times daily, but decreased significantly with further increasing feeding frequency. In conclusion, both low and high feeding frequency could result in growth retardation, poor feed efficiency, decreased intestinal enzyme activities and low hepatic IGF-I expression of juvenile blunt snout bream. The optimal feeding frequency for this species at the juvenile stage is 3 times daily.