Kushniryk O. The biotechnology of live feeds for sturgeon juveniles

The scientific work is devoted to the study of a problem of biotechnology correction the nutrient composition of live feeds, considering the needs of juvenile sturgeons. The carotenogenic yeast Rhodotorula are used at the first time in the technology of freshwater zooplankton enrichment with carotenoids in terms of live feed for fish. It ise22 shown that the most effective dose of a yeast capable to carotenogenesis is 0.5 g/l, that corresponds to a concentration of 1,5?1011 CFU/l. It was found that the technology of live feed bioencapsulation with carotenoids does not lead to changes in the content of main nutrients. It is noted that the use of waste water from RAS as an alternative medium for zooplankton cultivation enhances the density of S. vetulus and M. macrocopa cultures in 5 times and 38 times, respectively, without leading to a deterioration of their nutritional value. The first time usage of ?-crotonolactone-containing preparation DON-1R for increase in freshwater zooplankton productivity was the most effective at a concentration of 66,8?10-6 µl/l of the cultural medium. It is shown that the live feed, grown with using of DON-1R, is characterized by a high part of certain essential amino acids, namely valine, methionine and isoleucine. Despite the established advantages of DON-1R using, it was revealed its inhibitory effect on the enzymatic hydrolytic activity in feed organisms. An increase in the content of linolenic acid, EPA and DHA in the diet of fish larvae can be reached under conditions of applied technology of their bioencapsulation into Artemia nauplii. It was found that the use of emulsions did not cause a decrease in nutritional value of nauplii and is accompanied by an increase in hydrolytic activity.