The effect of an experimental probiotic feed additive on some indicators of nonspecific immunity of fi ngerlings of the Russian Lena sturgeon

In industrial fi sh farming, the following indicators are important: the rate of reaching marketable weight, feed costs and survival. The latter directly depends on the level of antibacterial protection. In aquaculture, various feed additives, mainly probiotic preparations, are used to increase the level of non-specific protection of the body. They ensure the normalization of the intestinal microbiocenosis, which plays an important role in maintaining the level of non-specific protection. A study was conducted on the effect of probiotic preparations based on Enterococcus faecium and Pediococcus acidilactici bacteria, as well as neutralized exometabolites of pathogenic aeromonads, on the indicators of non-specific immunity of yearlings of the Russian-Lena sturgeon. The study was conducted from September to November at the Spetsrybzavod LLC, Republic of Adygea, Teuchezhsky District, Tugurgoy village. The pools were supplied with water from the Krasnodar Reservoir. The amount of incoming water directly depended on its level in the reservoir (the principle of communicating vessels). The water temperature in the pools at the beginning of the experiment was 18–20 °C, and by the end it dropped to 12–14 °C. This is due to seasonal climatic changes in the geographical area of the experiment. An insignifi cant effect of the additives on the studied indices of non-specific immunity was established. This is probably due to a decrease in temperature and the absence of pathogens in the water. During the experiment, no individuals with a positive level of C-reactive protein were recorded in the experimental and control fi sh. However, it is worth noting the reaction of non-specific immunity mechanisms to the drugs in the form of an increase in the level of IC and low indices of bacteriostatic activity of blood serum. Similar studies at a higher water temperature are required to establish the eff ectiveness of the influence of the additives on the immune system of fish.