The effect of using pro- and prebiotics in feed on the physiological parameters of tilapia larvae

The effect of the use of pro- and prebiotics in feed on some physiological (fish-biological and hematological) parameters of tilapia larvae has been studied. The object of the study was the larvae of the Nile tilapia (Oreochromis niloticus), which switched to active nutrition. The fish were divided into 4 groups: control – feed without the addition of a probiotic drug; experiment 1 – feed with the addition of the prebiotic inulin; experiment 2 – feed with the addition of a probiotic drug + inulin; experiment 3 – feed with the addition of a probiotic drug. The experiment was conducted at the Laboratory of Aquaculture and Aquatic Bioresources of the Southern Scientific Centre of the Russian Academy of Sciences. Experimental batches of feed, including feed with the addition of a probiotic drug containing strains of Bacillus velezensis bacteria and possessing enzymatic activity, as well as the inulin prebiotic, were manufactured at the Don State Technical University. During the first 6 weeks of the experiment, weight gain was higher in the еxperiment 3. At this stage, we can talk about early effects on the microflora of larvae and the prospects of using a probiotic drug to increase survival and growth rate at the initial stages of cultivation. Then the weight gain in the experiment 3 decreased slightly, which may indicate that probiotics can modulate the intestinal microflora and cause negative effects over time, but these data have not been confirmed by hematological parameters, which in all groups were within the limits of the reference values typical for this species. Sufficiently high levels of hemoglobin, the number of red blood cells and platelets, and the leukocyte intoxication index according to V.K. Ostrovsky testified to the positive effect of inulin and a probiotic drug on tilapia's health. Thus, the use of the prebiotic inulin and a probiotic drug containing bacterial strains of Bacillus velezensis had a positive effect on the health and immunity of juvenile tilapia.