The use of the probiotic «Subtilis-C» in the breeding of the Nile tilapia (Oreochromis niloticus)

Abstract

With intensive cultivation technologies, fish are exposed to stress factors associated with intensive breeding. They reduce the immunity of cultivated objects. In addition, the aquatic environment is a good substrate for the development of microorganisms, including pathogenic ones, which aggravates the situation. Therefore, increasing the immunity of fish is an urgent task of their breeding. One of the ways to enhance the immune resistance of the body is the use of immunomodulators. The purpose of this work was to study the effect of the probiotic “Subtilis-S” on the productivity and hematological status of fish. At the beginning of the experiment, the tilapia females (7 heads per aquarium) were separated from the males. Males were kept individually. The fish of the experimental groups received the probiotic “Subtilis-S” as a feed additive for two months at the rate of 1 g/kg of feed. A month after the start of the experiment, the males were hooked up to the females (one male in each aquarium). After gestation, the larva was taken from the females and planted in separate containers. During the experiment, fertilization of eggs occurred in 80% of females in the experimental group and 50% in the control. The results of fish appraisal showed that the probiotic “Subtilis-S” had no effect on the growth and mass accumulation of tilapia: no significant differences in the main zootechnical parameters were found in the fish of the experimental and control groups. In the leukogram of tilapia treated with “Subtilis-S”, the proportion of lymphocytes increased due to a decrease in immature forms of the myeloid series; for rod-shaped neutrophils, the differences are significant. Which probably indicates the activation of a specific link of the immune defense. In the blood of experienced tilapia, in contrast to the control, there is a small percentage of eosinophils and basophils, that is, there is an increase in the nonspecific link of cellular immunity. The use of the probiotic “Subtilis-S” as a feed additive enhances the immunity of tilapia and increases the survival of fish in aquaculture, as well as increases their fertility.