Freshwater Aquaculture Collaborative Innovation Center in Hubei Province

Wuhan, China

Freshwater Aquaculture Collaborative Innovation Center in Hubei Province

Wuhan, China
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Dong G.F.,Anhui Agricultural University | Dong G.F.,Wuhan Polytechnic University | Dong G.F.,Freshwater Aquaculture Collaborative Innovation Center in Hubei Province | Yang Y.-O.,Anhui Agricultural University | And 8 more authors.
Journal of Applied Ichthyology | Year: 2015

A 30-day growth trial was conducted to investigate the individual variations in feeding rate, growth rate, spontaneous activity, and their possible interrelationships in hybrid tilapia (Oreochromis niloticus × O. aureus) reared individually at feeding frequencies of one and two meals daily. Results show that the feeding rate in energy (FRe), specific growth rate in energy (SGRe), and food conversion efficiency (FCE) of fish fed twice a day were significantly higher than that of fish fed only once. However, no significant differences in distance or in time spent swimming were observed between the groups. SGRe was positively correlated with FRe in fish fed only once daily, and SGRe was positively correlated with food conversion efficiency in energy (FCEe) between the two groups. SGRe was only inversely correlated with the distance that fish swam when fed once daily. The results suggest that the individual growth differences of hybrid tilapia could be attributed mainly to variations in FRe, and that the energy costs of spontaneous activity play an important role in the differences at feeding frequency of one meal a day. However, at feeding frequencies of two meals a day, individual growth differences in fish may be caused by variations in FCEe, and energy costs of spontaneous activity have only marginal effects on the differences. © 2014 Blackwell Verlag GmbH.


Dong G.-F.,Wuhan Polytechnic University | Dong G.-F.,Freshwater Aquaculture Collaborative Innovation Center in Hubei Province | Zou Q.,Wuhan Polytechnic University | Wang H.,Wuhan Polytechnic University | And 6 more authors.
Aquaculture | Year: 2014

Conjugated linoleic acid (CLA) has been shown to decrease body fat and increase lean tissue in mammals. However, limited data is available about the effect of CLA on the lipid content in fish tissue, and the mechanisms underlying the beneficial effects of CLA in fish are unknown. We hypothesized that dietary CLA may induce lipid-lowering effects in grass carp (Ctenopharyngodon idella) tissue, and the fat reduction effect was modulated by the expression of genes involved in the lipid metabolism. A 65-day growth trial was conducted to investigate the effect of CLA on the growth, tissue lipid deposition, and gene expression involved in the lipid metabolism of grass carp. Seven isonitrogenous and isolipidic diets were formulated: 0% CLA (control); 0.5% CLA (CLA0.5); 1% CLA (CLA1); 1.5% CLA (CLA1.5); 2% CLA (CLA2); 2.5% CLA (CLA2.5); and 3% CLA (CLA3).Results showed that only fish fed the CLA3 diet exhibited a significant reduction in feeding rate and specific growth rate than those of fish fed the control diet (P<. 0.05). Significant decreases in the lipid content in the liver, intraperitoneal fat, and muscle were observed in fish fed with 2.5% to 3% CLA, 1.5% to 3% CLA, and 2% to 3% CLA diets, respectively (P<. 0.05), compared to those fed with the control diet. Dose- and tissue-dependent changes were found in the mRNA expressions of fatty acid synthetase (FAS), acetyl-CoA carboxylase (ACC), lipoprotein lipase (LPL), hormone-sensitive lipase (HSL), peroxisome proliferator-activated receptor α (PPARα), peroxisome proliferator-activated receptor γ (PPARγ), and sterol regulatory element binding protein-1c (SREBP-1c). The mRNA expressions in most of the genes examined in the liver, foregut, intraperitoneal fat and muscle were highly sensitive to dietary CLA. Our results suggested that a dose-dependent effect on the reduction of fish growth induced by CLA supplementation should be carefully considered in intensive aquaculture, although lipid reduction is nutritionally important for fatty liver control in grass carp. Furthermore, our results raise the possibility that the lipid-lowering effects of dietary CLA were modulated by the gene expressions in lipogenesis (such as FAS and ACC), lipoprotein transport (such as LPL), and lipolysis (such as HSL) primarily in the liver, foregut, intraperitoneal fat, and muscle. The activation of transcription factors (such as PPARα, PPARγ, and SREBP-1c) may also be responsible for the lipid-lowering effects of dietary CLA. © 2014.


Dong G.-F.,Hubei Key Laboratory of Animal Nutrition and Feed Science | Dong G.-F.,Freshwater Aquaculture Collaborative Innovation Center in Hubei Province | Liu W.-Z.,Hubei Key Laboratory of Animal Nutrition and Feed Science | Wu L.-Z.,Hubei Key Laboratory of Animal Nutrition and Feed Science | And 5 more authors.
Fish Physiology and Biochemistry | Year: 2014

Fatty liver syndrome is a prevalent problem of farmed fish. Conjugated linoleic acid (CLA) has received increased attention recently as a fat-reducing fatty acid to control fat deposition in mammals. Therefore, the aim of the present study was to determine whether dietary CLA can reduce tissue lipid content of darkbarbel catfish (Pelteobagrus vachelli) and whether decreased lipid content is partially due to alterations in lipid metabolism enzyme activities and fatty acid profiles. A 76-day feeding trial was conducted to investigate the effect of dietary CLA on the growth, tissue lipid deposition, and fatty acid composition of darkbarbel catfish. Five diets containing 0 % (control), 0.5 % (CLA0.5), 1 % (CLA1), 2 % (CLA2), and 3 % (CLA3) CLA levels were evaluated. Results showed that fish fed with 2–3 % CLA diets showed a significantly lower specific growth rate and feed conversion efficiency than those fed with the control diet. Dietary CLA decreased the lipid contents in the liver and intraperitoneal fat with the CLA levels from 1 to 3 %. Fish fed with 2–3 % CLA diets showed significantly higher lipoprotein lipase and hepatic triacylglycerol lipase activities in liver than those of fish fed with the control, and fish fed with 1–3 % CLA diets had significantly higher pancreatic triacylglycerol lipase activities in liver than those of fish fed with the control. Dietary CLA was incorporated into liver, intraperitoneal fat, and muscle lipids, with higher percentages observed in liver compared with other tissues. Liver CLA deposition was at the expense of monounsaturated fatty acids (MUFA). In contrast, CLA deposition appeared to be primarily at the expense of MUFA and n-3 polyunsaturated fatty acids (PUFA) in the intraperitoneal fat, whereas in muscle it was at the expense of n-3 PUFA. Our results suggested that CLA at a 1 % dose can reduce liver lipid content without eliciting any negative effect on growth rate in darkbarbel catfish. This lipid-lowering effect could be in part due to an increment in the activity of lipid metabolism enzymes and an extensive interconversion of fatty acids. Although CLA deposition in muscle (0.66–3.19 % of total fatty acids) are higher than presented in natural sources of CLA, EPA (C20:5n-3) in fish muscle appears simultaneously expendable, when the fish fed with 2–3 % CLA. © 2014, Springer Science+Business Media Dordrecht.

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