Effects of Formulated Diet Co-fed with Minced Fish on Growth, Digestion, Metabolism, and Appetite Regulation, of Mandarin Fish Hybrid (Siniperca chuatsi ♀× Siniperca scherzeri ♂)

Abstract

This study examined the effects of a formulated diet combined with minced fish at ratios of 1:1 (Diet 1), 1:3 (Diet 2) and 0:1 (Diet 3) on growth, digestion, metabolism, and appetite of juvenile mandarin fish (initial weight, 10.63 ± 0.29 g). Fish were hand fed to satiation for 194 days. Weight and growth rate of the fish in the first 97 days were negatively correlated to decreased ratio of minced fish. The weight of fish fed Diet 2 (97 days) was significantly higher than that of fish fed Diet 1. There was no significant difference in the growth of fish fed Diets 2 or 3. The activities of pepsin in the stomach, alanine transminase (ALT), and aspartate transminase (AST) in the liver, significantly increased in relation to the enhanced formulated diet ratio. The mRNA level of leptin in the liver and ghrelin in the stomach increased as the minced fish ratio decreased. The mRNA level of neuropeptide Y (NPY) in the brain increased as formulated diet ratios increased. Combined feeding strategies increased the appetite of the mandarin fish hybrid, improved digestion and metabolism of formulated diets, and improved fish growth.