EFFECT OF SUNFLOWER AND LINSEED OIL SUPPLEMENTATION IN THE DIET ON THE CHEMICAL AND FATTY ACID COMPOSITION OF RAINBOW TROUT (ONCORHYNCHUS MYKISS W.), CULTIVATED IN RECIRCULATING SYSTEM

The aim of this study was to determine the infl uence of the dietary linseed and sunfl ower oil supplementation on the chemical and fatty acid composition in the meat of rainbow trout (Oncorhynchus mykiss W.), cultivated in recirculating system. The fi sh in the experiment received extruded pellets and were divided in control (CG) and two experimental groups – EL and ES. The feed of the rainbow trout of EL group was supplemented with 5% linseed oil and that of the group ES contained additionally 5% sunfl ower oil. The fi sh of the control group did not receive any of the above mentioned oils as additives. At the end of the 60 day trial period, four fi sh of each group were randomly selected for evaluation of the chemical and fatty acid composition in the fi llet. Signifi cant infl uence of the vegetable oils in the diet on the water content of the fi llets was found (P ≤ 0.05) as the group fed linseed oil showed the highest value of this parameter in comparison with the fi sh of the control group and the group receiving sunfl ower oil. Supplementation with both oils led to signifi cantly higher protein content in the meat of the two experimental groups, compared to this one of the fi sh of the control (Р ≤ 0.001), while the value of the dry matter was lower in the fi llets of the group with the linseed oil in the diet, compared to this parameter of fi sh from C and ES (Р ≤ 0.05). The linseed and sunfl ower oils in the diet of the rainbow trout infl uenced signifi cantly the contents of С16:0 (P ≤ 0.05), С18:2 (P ≤ 0.01) and С18:3 (P ≤ 0.001) in the fi llets. The fi sh receiving sunfl ower oil as feed additive displayed highest levels of С18:2, compared to these parameters in the fi sh of C and EL groups. The group with linseed oil supplementation in the diet had lower content of C16:0 and higher value of C18:3 content than the fi sh fed pellets supplemented with sunfl ower oil and the control group. The changes in the individual fatty acids in the fi sh of experimental groups EL and ES corresponded to those of their total amounts – the content of n-6 PUFA was highest in the group fed with added sunfl ower oil (Р ≤ 0.05), while the rainbow trout receiving diet, supplemented with linseed oil had highest total content of n-3 PUFA (Р ≤ 0.01). The vegetable oils infl uenced the values of n-6/n-3 ratio (P < 0.001) which were signifi cantly higher in the fi sh of ES group, when compared to these ones in the fi llets from the control and linseed oil groups.