Biological efficiency of rainbow trout meat lipids depending on the levels of amino acids in fodder

Abstract

In trout farms of Ukraine, when using compound fodder for their production, the question arises of clarifying the requirement of rainbow trout in energy, protein and amino acids to achieve the maximum realisation of its biological productivity potential. Accordingly, the research explored the effect of using complete fodder with various levels of lysine and methionine on the biological efficiency of rainbow trout meat lipids. The purpose of the experiment was to determine the effect of different levels of amino acid nutrition of commercial rainbow trout on the fatty acid composition of meat lipids and their biological efficiency. For this purpose, five experimental groups were established by the method of analogues. The experiment lasted 210 days and was divided into two periods: equalising (10 days) and main (200 days). During the equalisation period, the feeding diet was the same for the fish of the control and experimental groups. During the main period, the level of lysine and methionine in the experimental fodders for different experimental groups of trout ranged from 2.5 to 2.9% and from 0.8 to 1.0%, respectively. Feeding of rainbow trout during the study period was performed 4-6 times a day, during the daytime at regular intervals. The required amount of fodder was calculated according to the individual weight of the fish and the temperature of the environment during feeding. Cultivation of marketable two-year-olds was performed in ponds with an area of 100 m2 at a planting density of 50 specimens/m2 and a water level of 1 m. The total number of trout in the experimental studies was 25 thousand specimens. It is established that the main share of fatty acids of lipids of rainbow trout meat is saturated fatty acids and monounsaturated fatty acids. As a result of the research, it was determined that using feed with increased levels of lysine and methionine for fish of the 4th experimental group was accompanied by an increase in the content of the sum of saturated fatty acids in meat by 5.84% compared to the control. With the growth of amino acid nutrition of the fodder, there is an increase in the content of linoleic acid in trout m′eat by 0.19-0.24% compared to the control. The practical value of the scientific work is to substantiate approaches to the technological bases of increasing the efficiency of using fodder nutrients in trout farming to ensure high fish productivity, which is of great economic importance