Dietary protein requirement for juvenile Chinese sucker (<i>Myxocyprinus asiaticus</i>)

Abstract

This study was conducted to determine the dietary protein requirement for juvenile Chinese sucker, Myxocyprinus asiaticus. Six fishmeal-based experimental diets containing various crude protein levels ranging from 300 to 500 g kg−1 were fed to triplicate groups of 20 fish each (initial weight 13.5 ± 1.1 g) for 56 days at a temperature of 28 ± 1°C (tank size 400 × 45 × 40 cm, linked to a recirculation system). Survival was not affected by dietary protein level (overall survival 71 to 90%). Weight gain (WG) and specific growth rate (SGR) increased with an increasing dietary protein level up to 460 g kg−1. The feed conversion rate (FCR) generally showed a decline at higher protein levels (from 1.62 in 300 g protein kg−1 to 1.13 in 500 g protein kg−1 feed). Protein efficiency ratio (PER) showed gradual improvements with increasing dietary protein up to 460 g kg−1. A similar trend was found for the protein productive value (PPV). Among the proximate compositions of the fish, crude protein content increased significantly with increasing dietary protein levels. Based on broken-line regression analysis of SGR against dietary protein levels, the optimal dietary protein requirement for juvenile Chinese sucker was estimated to be close to 465 g kg−1.