Growth in juvenile pikeperch (Sander lucioperca L.) stimulated with yeast, Saccharomyces cerevisiae, extract

Thanks to the content of valuable bioactive substances, yeast, Saccharomyces cerevisiae, is finding wider applications in aquaculture and marine fish husbandry. Highly bio-available and bio-assimilable yeast extracts, which are obtained through processes that remove cell walls, are of special interest. The current study examined the impact of yeast extracts added to commercial feed at concentrations of 2% (group F2), 4% (group F4) and 6% (group F6) on growth, blood biochemistry parameters, liver and intestinal morphology, proximate body composition and the content of free amino acids in the muscle tissues of European pikeperch, Sander lucioperca (initial body weight = 10g). At the termination of the experiment that ran for 60 days, the highest increases in body weight were noted in all the groups of fish that had received yeast extract (final body weight approximate to 35g vs. control group approximate to 31g). The daily and specific growth rates indexes were the highest in group F6. The alanine aminotransferase activity in this group was half of that in the control group (group C) (p < .05). The lowest levels of plasma bilirubin were noted in groups F4 and F6, while these groups had the highest hepatosomatic indexes that differed significantly to those of group C (p < .05). Microscopic analysis of the intestines indicated significant growth in the enterocyte height and supranuclear zone, or the so-called absorption space, as the quantity of yeast extract added to the diets increased. Yeast supplementation was not noted to have a significant impact on the proximate body composition or the contents of free amino acids in the fish muscle tissues. In conclusion, the lowest analysed dose of yeast (i.e. 2% yeast extract) stimulates the growth of pikeperch.