Abstract
This study aimed to evaluate the fat deposition pattern and lipid metabolic strategies of grass carp in response to dietary lipid levels. Five isonitrogenous diets (260gkg-1 crude protein) containing five dietary lipid levels (0, 20, 40, 60, 80gkg-1) were fed to quadruplicate groups of 15 fish with initial weight 200g, for 8weeks. The best growth performance and feed utilization was observed in fish fed with lipid level at 40gkg-1. MFI and adipose tissue lipid content increased with increasing dietary lipid level up to 40gkg-1, and higher lipid level in diet made no sense. Fish adapted to high lipid intake through integrated regulating mechanisms in several related tissues to maintain lipid homeostasis. In the present study, grass carp firstly increased PPARγ and CPT1 expressions in adipose tissue to elevate adipocyte differentiation and lipolysis to adapt to high lipid intake above 40gkg-1. In liver, fish elevated hepatic lipid uptake but depressed biosynthesis of hepatic FAs, resulted in no difference in HSI and liver lipid content among the groups. Only in muscle, fish showed a significant fat deposition when the lipid intake above 40gkg-1. The excess lipid, derived from enhanced serum TC and TG contents, was more likely to induce deposition in muscle rather than lipid uptake by adipose tissue in grass carp fed with high dietary lipid, indicating the muscle of grass carp might be the main responding organ to high lipid intake.
Published Version
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