The Effect of Distiller’s Dried Grains with Solubles on Carcass Composition, Fatty Acid Composition, Skin and Fillet Coloration of Rainbow Trout (Oncorhynchus mykiss)

Abstract

The aim of the study was to evaluate the effects of distiller’s dried grains with solubles (DDGS) as an alternative protein source on carcass composition, fatty acid composition, skin, and fillet coloration of rainbow trout (Oncorhynchus mykiss). Four isoproteic (45.5% crude protein) and isocaloric (17.42 MJ/kg) diets were formulated using DDGS (0, 10, 20 and 30%) for a feeding trial of 84 days. Fish (mean initial weight of 19.88 g) were distributed into triplicate treatments at a rate of 25 fish per 200 L tanks and fed to satiation with the experimental diets three times a day. The results of the present study show that the coloration of experimental fish was not modified negatively by the use of DDGS protein sources in diets. Carcass composition values were also not affected by increased DDGS, although some fatty acids were affected. Total saturated fatty acids, total monounsaturated fatty acids, total n-3 polyunsaturated fatty acids (Σn-3 PUFA) and Σn-3 PUFA/total n-6 polyunsaturated fatty acids (Σn-6 PUFA) values of the fish in the experimental groups were found to be statistically similar. On the other hand, palmiteloic acid, docosahexaenoic acid and Σn-3 PUFA decreased, while linoleic acid, Σn-6 PUFA and ΣPUFA increased significantly. In conclusion, the fatty acid composition of fish muscle was affected by the use of DDGS up to a rate of 30% in rainbow trout diet, while no negative effect on the skin and fillet coloration could be found.