Proveden je hranidbeni pokus u trajanju od 43 dana u kojem je istraživan utjecaj oligosaharida iz proizvoda NatramuneTM na oksidacijski stres kod juvenilne kategorije klena (Squalius cephalus Linnaeus, 1758) inicijalne prosječne težine od 7,4 g. Granuliranoj hranidbenoj smjesi (28,7% SP) pridodan je imunostimulans u koncentracijama od 1%, 3% i 5%. Rezultati provedenog istraživanja ukazuju da je uključenje imunostimulansa u hranidbu varijabilno utjecalo na koncentraciju malonaldehida u mišićnom tkivu riba. Najniža razina MDA u tkivima uočena je u grupi hranjenoj s 1% (D1). Izloženost stresu, oboljenja u fazi pokusa, loša adaptacija na hranu, te mortaliteti kod riba u pokusu mogući su uzroci visoke varijabilnosti rezultata unutar i između hranidbenih skupina.

A forty three day feeding trial was conducted on evaluating the effects of different concentrations of oligosaccharides derived from NatramuneTM on juvenile chub (Squalius cephalus Linnaeus, 1758) (initial weight 7,4 g). In the basal diet (28,7% CP) was added NatramuneTM at levels of 1%, 3% and 5% to determine the effects on levels of malondialdehyde (MDA) in muscle tissue. The research results indicate that the inclusion of immunostimulans in the feed variably affected malondialdehyde concentrations in muscle tissue of fish. The lowest level of MDA was observed in the group fed with 1% (D1) of immunostimulans. Exposure to stress, disease in the experimental stage, poor adaptation to feed and mortality of fish during the feeding trials could be related to the high variability of results within and between experimental groups.