The expediency of special prewinter feeding of sturgeon females in industrial conditions

The technology of keeping and preparing for spawning of sturgeon producers in installations with a closed water supply provides for a relatively short (10–14 days) period of temperature reduction amid feeding cessation and subsequent wintering before spawning. This approach does not take into account the specificity of the nutritional needs of producers, due to the seasonal characteristics of their metabolism, including generative exchange. In experimental work carried out in aquarium conditions and in sturgeon farming of the industrial type, confirmation was obtained of the advisability of supplementing the technologyof keeping sturgeon producers in the RAS, with a new stage — prewinter feeding of females. Its essence is the replacement of the traditionally used short period of reducing the water temperature to wintering values, a longer period of “autumn feeding” with a decrease in water temperature for 30–35 days while maintaining feeding. At 54 females of the Aksai bester and 49 females of the Siberian sturgeon, it was shown that pre-winter feeding of females (compared to starving fish) helps to improve the maturation of oocytes, as evidenced by an increase in their diameter and a more effective decrease in their polarization ratio (1.5–3 times). Feeding not only has a positive effect on the quality of preparation of females for spawning, but also makes it possible to ensure the production of more eggs. At the same time, the fertilization of eggs obtained from females fed increases by 10–17 %, the development of embryos by 10–20 %. The results of experiments under production conditions, which demonstrated an increase in the production of caviar (by more than 35 %) in Siberian sturgeon females that fed in the pre-winter period, convincingly confirmed the feasibility of feeding them in a period of decreasing temperature. It was also shown that there were no significant differences in the period of the “autumn feeding” in the effect on females of high-energy feeds and the proposed specialized feeds with a reduced content of protein and lipids.