Effects of Different Protein Levels of Feed on Growth and Feed Conversion of Juvenile Lateolabrax japonicus

The present study was conducted to investigate the effects of different protein levels of feed on the growth performance and feed conversion of juvenile Lateolabrax japonicus. Five protein levels of feeds were formulated by using fish meal as main protein source,and the juvenile Lateolabrax japonicus with the average initial body weight of(84. 81 ± 0. 92) g was fed for 75 days,in order to determinate the suitable protein level of the feed for juvenile Lateolabrax japonicus. The results showed that the relative weight gain rate,specific growth rate,fatness,feed conversion rate and protein efficiency rate in the group of 39. 85% protein content were the highest. The relative weight gain rate,specific growth rate and feed conversion rate in the group of 39. 85% protein content were very significantly higher than those in the groups of 34. 76% and 37. 54% protein content(P 0. 01),but they were not significantly different from the 42. 34% group(P 0. 05). The protein efficiency rate in the 39. 85% group was significantly higher than that in the 34. 76%,42. 34% and 45. 03% groups(P 0. 05),while it had no significant difference with the 37. 54%group. Under the conditions of this experiment,based on regression analysis and indicators such as specific growth rate and protein efficiency rate,it was concluded that the growth performance and feed utilization rate of juvenile Lateolabrax japonicus were the best when the protein content in the feed was 38. 87% ~ 41. 50%.