SEASONAL CHANGES IN THE LIPID COMPOSITION OF TISSUES OF RAINBOW TROUT RARASALMO MYKISS (WALBAUM, 1792), GROWN ON DIFFERENT FEEDSTUFFS
The paper presents and analyzes data on the annual dynamics of the content of lipid components in tissues of rainbow trout Rarasalmo mykiss (Walbaum, 1792) and its dependence on the composition used in the cultivation of the fish fodder. Every month, from March to November, tissue samples from two groups of rainbow trout, cultivated on different combined feed, were collected. A biochemical analysis of tissue samples and compound fish fodder, which determined the level of triacylglycerols, cholesterol, cholesterol esters, general and individual phospholipids was performed. The combined feed for salmon differed in ratio of structural and replacement substances. The content of total lipids, triacylglycerols, sphingomyelin in muscles, in the inner fat and in the liver of rainbow trout depended upon fish fodder composition. The increase of cholesterol and phosphatidylcholine during summer months and the reduction of these components in winter were registered. The concentration of phosphatidylethanolamine, on the contrary, increased in cold weather.