Dietary choline requirement of juvenile Chinese sucker (Myxocyprinus asiaticus)

Abstract

An 8-week growth experiment was conducted to quantify the appropriate dietary choline requirement of juvenile Chinese sucker (Myxocyprinus asiaticus). Each of seven semi-purified diets containing choline at a level of 44.79 (basal), 164.95, 278.70, 574.29, 1076.52, 2124.29 or 4477.72 mg/kg diet was fed to three replicates with 30 fish (5.52 g per fish). The results showed that weight gain and specific growth rate increased significantly with the increase of dietary choline levels from 44.79–574.29 mg/kg, and then decreased above these levels. Fish fed the basal diet had the lowest survival rate and feed efficiency. Choline contents in whole body and muscle tissues showed an increasing trend and then stabilized with increasing dietary choline supplementation. Dietary choline had no significant effects on whole-body moisture, crude protein, crude lipid and ash contents, but had a significant effect on muscle crude lipid content. Liver aspartate aminotransferase and alanine aminotransferase activities increased firstly and then decreased with the increase in dietary choline levels, whereas the changes in liver triglyceride content exhibited an opposite trend. Broken-line regression analysis showed that dietary choline requirement for juvenile Chinese sucker was 493.8 and 549.7 mg/kg based on specific growth rate and muscle choline content, respectively.