EFFECT OF A COMMERCIAL PROBIOTIC ON THE CHEMICAL AND FATTY ACID COMPOSITION AND LIPID QUALITY INDICES OF EUROPEAN CATFISH Silurus glanis GROWN IN A RECIRCULATING AQUACULTURE SYSTEM

This experiment evaluated the effect of a commercial probiotic on the chemical composition and meat nutritional quality indices of European catfish (Silurus glanis L.) grown in a recirculating aquaculture system. To conduct the experiment, the European catfish were placed in two separate tanks containing 45 fish each. The growing conditions for the fish in the two tanks were identical. The only difference was that 1 ml of a commercial probiotic was added to the water in one tank every other day. The meat of 6 catfish from each tank was examined.

The difference in the chemical composition of the catfish meat in the control and probiotic groups is statistically significant (P<0.05) (Table 1) .  During this experiment, 25 fatty acids were identified. Statistically significant differences in the saturated fatty acids  (SFA), monounsaturated fatty acids

(MUFA) and polyunsaturated fatty acids in the two groups were observed (P<0.05). The group raised with probiotics had higher amounts of SFA and MUFA than those in the control group.

The fatty acid n-3/n-6 ratio was closer to the recommended value (<0.25) in the probiotic group. Indices of atherogenicity and thrombogenicity were higher in the probiotic group, while higher flesh-lipid quality and hypocholesterolemic (acid) were found in the control group. There are no specific recommendations concerning the most beneficial AI and TI values; it is only stated that lower levels are more beneficial; however, it is advised that in the human diet these indices should be lower than 1. The AI and TI values measured in this experiment were lower than 1 (Table 2).

This experiment showed that when catfish are reared in recirculating aquaculture systems containing probiotics, the meat is suitable for human consumption as a source

of omega-3 and omega-6 fatty acids.