Effects of Feeding Rates on Growth Performance and Apparent Digestibility Coefficients of Nutrients for Grouper Epinephelus coioides Juveniles

摘要

An experiment was conducted to determine effects of feeding rates on growth performance and apparent digestibility coefficients(ADCs) of nutrients for juvenile E.coioides(initial weight:10.3±0.4 g).Grouper were fed a practical diet(containing 51.7% crude protein,9.0% lipid and 18.8 kJ g-1) from 0(starvation) to 3.5%(at 0.5% increments) body weight per day(bw d-1) in triplicates for 8 weeks.Growth performance,feed utilization,body composition and ADCs of dry matter,protein and energy were significantly(P < 0.05) affected by feeding rates.Survival was the lowest for the starvation and 0.5% bw d-1 groups.Final body weight,weight gain,specific growth rate and metabolic growth rate increased significantly with increasing feeding rate from 0 to 2.5% bw d-1 and showed no significant differences above the level.Feed conversion rate was lowest and protein efficiency ratio highest in those fed 2.0% bw d-1.Lipid contents of whole body,muscle and liver increased with increasing feeding rates from 0 to 3% bw day-1 and showed a slight decline at the feeding level of 3.5% bw d-1.Protein contents of body composition,muscle and liver remained relatively stable with feeding rates.Condition factor,viscerosomatic index and hepatosomatic index were the lowest for fish fed 0.5% bw d-1 and tended to increase with the increasing feeding rates.ADCs of dry matter,protein and energy were significantly and negatively correlated with the feeding rates.Based on the broken-line regression analysis using WG data,the optimum and maintenance feeding rates for grouper were 2.5% bw d-1 and 0.25 bw d-1,respectively.