LAUSR

Abstract The present study was conducted to investigate the effects of extruded and pelleted feeds at various feeding rates on growth and nutrient utilization of grass carp (Ctenopharyngodon idellus). Two fish meal-free feeds with the same formula were prepared as pelleted feed and extruded feed, and fed to eight treatments of fish (37.0 ± 0.2 g) with feeding rates of 100%, 90%, 80% and 70% satiation. During the feeding period, the fish of 100% satiation group were fed to apparent satiation, and then the other fish were fed with diets equal to 90%, 80% and 70% of 100% satiation group, respectively. After 10 weeks of feeding, the fish fed pelleted and extruded feeds showed no differences in feed intake (P > 0.05). At the same feeding rate, the fish fed extruded feed showed higher weight gain (WG), protein retention efficiency (PRE), lipid retention efficiency (LRE) and lower feed conversion ratio (FCR) than those fed pelleted feed (P