Plasma biochemistry, gene expression and liver histomorphology in common carp (Cyprinus carpio) fed with different dietary fat sources

Demand for omega-3 long chain polyunsaturated fatty acids has become global challenge for aquaculture and
different components have been used to increase nutritional value of fillets. The aim of this study was to evaluate
influences of feeds on zootechnical parameters, biochemical plasma parameters, expression of lipid-dependent
genes, hepatocyte histomorphologies, and fatty acid profiles in common carp fillets. We compared a control diet
(CTRL), mimicking a commercial feed formulation for common carp, with three diets containing blends of
vegetable oils and a DHA-rich alga (Schizochytrium sp.) included at 3.125% (CB1) or 1.563% (CB2), and 2.1%
salmon oil (CB3). The study revealed no differences in final body weight of fish fed CB1-3 diets in comparison
with significantly lower CTRL. Concentrations of all biochemical parameters in plasma increased gradually in
fish fed CB1-3 diets when compared to CTRL diet, with exception of triacylglycerol levels. Expression of hepatic
fas, elovl-5a and pparα genes increased significantly in fish fed CB1 and CB2. Additionally, eicosapentaenoic
(EPA) and docosahexaenoic acid (DHA) accumulation in muscle tissue was directly proportional to the amounts
supplied in the diets. Our study revealed that carp fillet profiles can be manipulated for DHA and EPA-contents
using enriched diets, depending on the source of fat.