Assimilation of exogenous fatty acids in tissues of rainbow trout Parasalmo mykiss (Walbaum, 1792) in aquaculture

Abstract

A comparative study of the fatty acids composition in the feed and food lump from the rectum, and in muscles and internal fat of rainbow trout Parasalmo mykiss (Walbaum, 1792) grown on various diets in June and Septem-ber was carried out. Differences in content of dietary fatty acids in diet 1 and diet 2 were found. Monounsaturated fatty acids predominated in diet No. 1. A significantly higher level of saturated and ω3 polyunsaturated fatty acids in diet No. 2 was recorded. Concentration of ω6 polyunsaturated fatty acids in diets was equal. Despite the differences in the fatty acid composition of the diet, a decreased concentration of fatty acids in the intestines for the two groups of fish was similar and did not depend on the month of the study. Polyunsaturated fatty acids were absorbed more effectively in rainbow trout. Monounsaturated fatty acids showed a low level of assimilation. Significant differences in the content of saturated fatty acids in the food lump from the rectum and in feed was not stated. Monounsaturated fatty acids dominated in muscles and visceral fat of rainbow trout compared to other fatty acids. In June concentration of ω3 polyunsaturated fatty acids increased in the muscles of trout species of group No. 2 (143.9 ± 8.9 mg/g lipids), while concentration of monounsaturated fatty acids increased in the internal fat of the fish of group No. 1 (310.8 ± 10.8 mg/g lipids). This fact corresponded to the predominance of these classes of fatty acids in the feed of the fish. Concentration of mono- and polyunsaturated fatty acids in the tissues of the two groups of the fish increased by the end of the exper-iment. Monounsaturated fatty acids were mainly stored in the internal fat of trout, while polyunsaturated fatty acids were deposited in the muscles of the fish.