The optimal protein requirements of juvenile mangrove red snapper, Lutjanus argentimaculatus fed isoenergetic diets
2012
Abbas, G. (Karachi Univ. (Pakistan). Centre of Excellence in Marine Biology) | Siddiqui, P.J.A. (Karachi Univ. (Pakistan). Centre of Excellence in Marine Biology) | Jamil, K. (Pakistan Council of Scientific and Industrial Research Labs., Karachi (Pakistan))
In order to investigate optimum dietary protein requirement, juvenile mangrove red snapper Lutjanus argentimaculatus (body weight 8.0 plus minus 0.3 g) were reared in seawater tanks (125 liters each) and fed one of the experimental diets at a daily ration of 2% body weight for 90 days. Six isoenergetic (22.4 kJg-1) diets were formulated contain protein levels of 20%, 25%, 30%, 35%, 40% and 45%. Fish fed diets of 40% and 45% protein produced higher weight gain and growth rate than those of the other diets. Broken line regression analysis yielded an optimal protein level of 42.8%. Fish whole body, muscle, liver and visceral composition showed that moisture content of fish fed diets of 40% and 45% protein was significantly higher than that of fish fed diets containing protein levels of 20% to 35% in 5% increments, although the lipid contents were lower. No significant difference was observed in protein and ash contents of whole fish or body organs for the diets of 20% to 45% protein. Fish fed 40% and 45% protein diets showed higher nitrogen gain and nitrogen retention efficiency than those fed on other diets. The mesenteric fat, hepato- and viscerosomatic indices of fish fed diets of 40% and 45% protein were significantly higher than those of fish fed diets of 20%, 25%, 30% and 35% protein. Based on the biological data, it was estimated that the optimal level of protein for L. argentimaculatus weighing between 8.0 g and 110 g was 40% to 42.8%.
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