Effects of Dietary Lipid Level on Growth Performance,Body Composition and Liver Histological Structure of Red Drum( Sciaenops ocellatus)

A 57-day feeding experiment was conducted to determine the effects of dietary lipid level on growth performance,body composition and liver histological structure of red drum( Sciaenops ocellatus). Five isonitrogenous diets( contained 47% crude protein) were designed to contain five dietary lipid levels( 7. 19%,9.17%,10.94%,13.04%,14.20%,respectively),and each diet was randomly assigned to 4 replicates of 30 red drum [average body weight of( 19.88 ± 0. 26) g]. The results showed that the final average body weight( FBW),weight gain rate( WGR) and specific growth rate( SGR) in the 7.19% group were significantly higher than those in the 13.04% and 14.20% groups( P 0.05),and no significant differences were found among the three lower level groups( 7. 19%,9. 17% and 10. 94% groups). W ith the increase of dietary lipid level,the protein efficiency ratio( PER) showed a descending trend,while conversely the feed conversion ratio( FCR) showed a rising tendency,and the FCR in the 7.19% and 9.17% groups was significantly lower than that in the 13.04% and 14.20% groups( P 0.05). Moreover,viscerasomatic index( VSI) and mesenteric fat index( MFI) in the 13.04% and 14.20% groups were significantly higher than those in the other three groups( P0.05). Lipid content in whole body and liver was increased with the increase of dietary lipid level,which of 7.19% group came to be the lowest,though the crude protein content in whole body of 9.17% group seemed to be the highest. Histological examinations indicated that the severity of fatty degeneration in liver cells of red drum had a positive relationship with the dietary lipid level. In conclusion,the dietary lipid level in artificial formulated feed for red drum is recommended to be 7.19% to 9.17%.