Abstract
The use of probiotics in aquaculture has become a necessity to increase disease resistance. Probiotics are also capable of increasing feed digestion and conversion, decreasing sensitivity to stress, and improving the health of the fish. The aim of this study was to analyse the effect of probiotics on survival, welfare, growth indices and blood composition in Siberian sturgeon (Acipenser baerii), reared in a recirculating system. Diets were supplemented with Lactobacillus acidophilus (FLa) and Saccharomyces boulardii (FSb), separately and combined (FLa + Sb). The effect of probiotics was investigated on 2000 fish with a mean weight of 8.82 ± 0.29 g/specimen. Fish were fed for eight weeks with four different diets: a control without probiotics, one with the addition of lactic acid bacteria (La), one with the addition of yeast (Sb), and one with a mixture of bacteria and yeast in equal proportions (50% La + 50% Sb). FLa + Sb showed a better condition factor (Fulton coefficient, K = 0.39%) and significantly higher growth performance in terms of individual growth (WGi = 35.56 g), total growth gain (WGt = 15.30 g), specific growth rate (SGR, 2.70%/day), and feed conversion ratio (FCR = 1.58), compared to the control. The concentration of lymphocytes, monocytes, and neutrophils was higher in the tanks fed with probiotics compared to the control. The presence of probiotics caused a decrease in cholesterol and glucose. There were significant differences between the Immunoglobulin M values identified in the tank fed with FLa + Sb and the control tank. The results showed that the addition of lactic acid bacteria and yeasts, introduced as probiotics in the diets of Acipenser baerii, reared in a recirculating system, improved the growth indicators, survival, and welfare of the fish.