科研之友
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摘要
The aim of the study was to investigate the effects of dietary lipid on growth, body and muscle proximate and fatty acid compositions in the juvenile redlip mullet (Liza haematocheila). Six iso-nitrogenous and iso-energetic experimental diets (protein: 30.7 +/- A 0.1 % and gross energy: 22.3 +/- A 0.1 MJ kg(-1)) with increasing lipid (2.0, 4.8, 7.5, 9.8, 12.0 and 14.6 % lipid on a dry matter basis) were fed to groups of juvenile mullet (initial weight 9.5 +/- A 0.3 g) for 60 days. The fish fed diets containing 7.5 and 9.8 % lipids had significantly higher weight gain (WG), lower feed conversion ratio and higher protein efficiency ratio compared to other groups (p < 0.05). Muscle and whole-body lipid concentration increased with increasing dietary lipid, and the opposite was observed for muscle and whole-body moisture. Polynomial regression analysis using a plot of WG against dietary lipid concentration gave 9.1 % lipid as the optimal dietary lipid level. Excess dietary lipid level should be avoided, because higher levels of dietary lipid (12.0-14.6 %) impaired growth and resulted in increased body lipid (fat) deposition. In each experimental treatment, docosahexaenoic acid (22:6n-3, DHA) concentration was always higher than eicosapentaenoic acid (20:5n-3, EPA) in specific tissues (muscle, liver and abdominal fat) and whole-body lipids, suggesting that DHA was probably more important in juvenile mullet live cycle than EPA.
