Study of growth and body composition of red snapper Lutjanus erythropterus fed diets containing Escherichia coli expressing recombinant tilapia insulin-like growth factor-I

摘要

To examine the effects of insulin-like growth factor (IGF)-I on the growth performance of fish, juvenile red snapper Lutjanus erythropterus with an initial body weight of approximately 12 g were fed diets containing different amounts of IGF-I containing Escherichia coli BL21 powder (BL21-tlGF-I). The growth of fish was enhanced by lower doses (0.25, 0.5 and 1%), but deteriorated at higher amounts (2.5 and 5%). The best results were obtained with 0.5% BL21-tlGF-I supplementation, which resulted in 154 and 85% weight gain and feed efficiency, respectively. In addition, muscle proteins appeared to be elevated, but muscle lipids were reduced except for in the 1% BL21-tlGF-l group. In contrast, liver lipids were reduced at 0.25, 0.5 and 1%, but increased at 2.5 and 5% BL21-tlGF-l. Furthermore, to examine the effects of BL21-tlGF-l on later-stage red snapper, we selected fish of approximately 23–24 g weight and fed them a diet either with or without 0.5% BL21-tlGF-l for 12 weeks. Results showed that the growth performance of later-stage fish was better with BL21-tlGF-l than those without supplementation after 6 weeks of feeding. The average body weight of fish that did not receive BL21-tlGF-l during the first 6 weeks, but were fed BL21-tlGF-l in weeks 7–12, was significantly higher than those fed without BL21-tlGF-l for the entire experiment. These results suggest that a continuous supply of BL21-tlGF-l may be beneficial for the growth performance of red snapper.