FEEDING OF COMMON CARP ON FLOATING FEEDS FOR ENRICHMENT OF FISH FLESH WITH ESSENTIAL FATTY ACIDS.

Based on the formulations of the ingredient mixtures and setting up the details of the extrusion technology 4 floating complementary carp feeds were developed suitable for inclusion of high oil levels by vacuum coating technology. The experimental feeds were manufactured in pilot scale and the efficiency of oil supplementation after application of vacuum coating was checked by GC determination of feed fatty acid composition. The amounts of fortifying long chain polyunsaturated fatty acid (LcPUFA) containing oils - Mortierella alpine oil, containing 40% arachidonic acid in triglyceride form (ARA); eicosapentaenoic (EPA) and docosahexaenoic (DHA) ethyl esters - were as follows: Feed CF2: 6.0% Linseed oil (LSO); CF3: 3.5% LSO + 1.5% Arachidonic acid (ARA) + 1% DHA; CF4: 6.0% Fish oil (FO); CF5: 4.5% FO + 1.5% ARA. The control sinking feed (CF1) was supplemented with 6.0% Soybean oil (SBO). The fatty acid composition determined by capillary gas chromatography well reflected the fortification. The experimental feeds were tested in a feeding experiment with common carp under intensive RAS rearing conditions. The experimental feeds and the control sinking one were fed to fish in parallel groups at constant water temperature (average: 23.9±0.3 °C), with an average oxygen saturation of 90±2 %. Fish were grown steadily, the best growth rate (SGR) and feed conversion rate (FCR) both were found in the FO fed group (1.17±0.00 %/day and 2.02±0.12 g/g). In the feeds highest levels for 18:3n3, 20:4n6 and 22:6n3 were 27.6%, 9.2%, and 11.2%, respectively. Whereas for the above mentioned fatty acids the highest levels of 7.3%, 2.3%, and 2.3%, respectively, were found in the carp fillets, the estimated EPA+DHA contents of the fillet were 5 to 12 times higher in the fillets offish fed on fortified feeds than in those offish fed on control feed CF1. Fortified floating feeds can be applied as complementary feed along with sufficient levels of natural food in fish ponds in suitable feeding regimes. A suitable feeding regime was suggested to apply the complementary feeds. [ABSTRACT FROM AUTHOR]