Effects of dietary lipid levels on growth performance, feed utilization and fatty acid composition of juvenile Japanese seabass (Lateolabrax japonicus) reared in seawater

Abstract

Triplicate groups of 40 Japanese seabass Lateolabrax japonicus (initial weight, 11.3 ± 0.4 g) reared in seawater (salinity, 30.0-33.0 g L -1 ) were fed with five isonitrogenous (41.3 ± 0.2% crude protein) and isoenergetic (18.5 ± 0.3 MJ kg -1 ) experimental diets formulated with increasing lipid levels (4.3, 8.4, 12.2, 15.8 and 20.1% lipid) for 10 weeks. Survival throughout the feeding experiment ranged from 87.5 to 100%, but the survival of fingerlings fed with the 4.3% lipid diet was significantly lower than the rest of the diets. At the end of the feeding experiment, fish fed with 12.2% lipid diet showed optimal growth performance (P \ 0.05). Lipid contents of whole body, liver and muscle increased in parallel with the increase in dietary lipid levels. Viscerosomatic index (VSI), hepatosomatic index (HSI) and muscle lipid content were higher in 20.1% lipid group than those in the rest of the lipid level groups indicating that viscera and muscle tissues played important contributions to body lipid deposition. High proportions of 18:1n-9, eicosapentaenoic acid (20:5n-3; EPA) and docosahexaenoic acid (22:6n-3; DHA), and low concentrations of n-6 polyunsaturated fatty acids (PUFAs) occurring in liver and muscle, to some extent, reflected fatty acid (FAs) composition in the experimental diets.

Effects of dietary lipid levels on growth performance, whole body composition and fatty acid composition of juvenile gibel carp (Carassius auratus gibelio)

“…Thus, a diet of 11.6% lipids was an optimal concentration for growth performance of juvenile gibel carp. These findings are consistent with previous reports on juvenile Japanese seabass ( Latelabrax japonicus ; Xu, Qin, Yan, Zhu & Luo ), tiger puffer (Kotaro, Takeshi, Nakahiro, Kazue & Tamo ), pike perch ( Sander iucioperca L.; Molna′r, Szabo′, Szabo′, Szabo′ & Hancz ) and juvenile GIFT tilapia ( Oreochromis niloticus ; Wang, Han, Feng, Yang, Guo, Wang & Xu ). In addition, we found that the WG in the high lipid group was the lowest, indicating that high dietary lipid levels have detrimental effects on juvenile gibel carp growth.…”

“…), red drum ( Scienops oceelatus ; Ellis & Reich ), halibut ( Hippoglossus hippoglossus L.; Nortvedt & Tuene ) and Japanese seabass ( Lateolabrax japonicus ; Xu et al . ). The negative association between high dietary lipid levels and growth may be the result of lower feed intake (Tocher ; Xu et al .…”

“…The negative association between high dietary lipid levels and growth may be the result of lower feed intake (Tocher ; Xu et al . ). In this study, we also found that fish in the high lipid group had a significantly lower DFI than those in the other dietary groups.…”

“…) and Japanese seabass (Xu et al . ). Excessive dietary lipid levels may result in excessive fat deposition in the visceral cavity and liver and muscle tissues, all of which increase whole body lipid concentrations (Tocher ).…”

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“…Its occurrence and development are closely related to lipid metabolism key factors. It is well known that dietary lipid plays a key role in the growth of fish and the unreasonable lipid level could cause the physiological disorders of lipid metabolism (Xu, Qin, Yan, Zhu, & Luo, 2011), so we suspect that the unreasonable lipid level might lead to the massive fat deposition by regulating some key factors of lipid metabolism in fish body, especially in liver.…”