engleski

Effect of Vetregard on the immunological parameters in the reared European seabass

Vetregard (Pharmaq) is a natural food component comprised of yeast (Saccharomyces cerevisiae) that contains a blend of beta 1.3 and 1.6 glucan, suggested to have beneficial effect when administered in fish feed at a rate of 0.1%. To our knowledge there are no studies that assessed the physiological response of the reared European sea bass (Dicentrarchus labrax) to the supplementation of feed with Vetregard. Moreover, practical trials on the farm have suggested that fish indeed exhibit better growth rate and resistance to the farm strains of Tenacibaculum maritimum. This for we have fed fsea bass (N=60 per trial) for 4 weeks by 4 different feeding regimes: 1.) Vetregard administered daily in feed by 0.1% ; 2.) Vetregard administered in feed by 0.1% on every 4th day of feeding ; 3.) Vetregard administered daily in feed by 0.1% for 2 weeks, followed by regular feed the next 2 weeks ; 4.) control fish fed by regular feed without Vetregard. Prior to the feeding trial (day 0) and further on 1st, 4th, 7th, 14th, 21st and 28th day of trial, different physiological parameters were sampled: fish length and weight ; serum and whole blood for lysozyme activity and macrophage respiratory burst ; gills, gut and hematopoietic organs for histological analysis as well as for expression of interleukin-10. After a 4-weeks experiment, all 4 categories of fish were subjected to experimental challenge with sublethal doses of two pathogens: local Adriatic strain of T. maritimum and Mediterranean strain of virus of encephalopathy and retinopathy (VER). One week after the challenge, all fish were sacrificed and same samples as before were taken for analysis, in addition to serum immunoglobulin and tissues for pathogen isolation and identification by PCR (brain for VER and gills for T. baculum). Our preliminary results show that although Vetregard did not significantly affect fish growth, different feeding regimes induced different levels of innate immunity reaction.

European seabass; Dicentrarchus labrax; immunostimulation; Vetregard

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