Study of the effectiveness of using the antioxidant astaxanthin in the composition of feeds for valuable aquaculture objects

Abstract

The “Enzymsporin” is one of these preparations, which is a probiotic feed additive for optimizing digestion processes, increasing the productivity and safety of fish. Second year rainbow trout grown in cages at the cooling pond of the Smolensk NPP were used as the objects of study. Specialized domestic feed “Trout growth 44/23” was used as the main diet (MD) for feeding the fish. The main diet with the addition of 0,5 g of “Enzymsporin” per 1 kg of feed was used as an experimental variation. An increase of the body girth index (66,7% versus 61,9% at p < 0,05) in the experimental group of the trout was founded. A tendency to increase the coefficient of fatness and the relative length of the stomach and intestines were noted, but the difference was not significant. The relative weight of fish without chyme (gastric and intestinal contents) in the control (without the use of the preparation) was significantly higher by 2,6% (p < 0,05), that indicates its lower nutritional activity. Significant differences in the content of moisture and minerals in the experimental and control groups won’t founded, but the fat content in the body of fish when using a probiotic was 1,5% higher then in control. Therefore, trout meat in this variant was more nutritious. An improvement in rearing results was achieved in the experimental group, especially the average daily growth gain increased by 6,8%, survival — by 6,7%, standing crop of the fish per unit area in a body water — by 9,2%, with a reduction of feed conversion ratio by 10,2%. The trout meat of the experimental group after heat treatment had a more pleasant taste, juiciness and tender texture. The average score of its overall average degustation evaluation significantly exceeded the control (8,0 versus 7,5 at p < 0,05). An economic effect in the experimental variant of feeding was 98257,5 rubles for the 80 m2 cage.