Effects of dietary carotenoid source and level on growth, skin pigmentation, antioxidant activity and chemical composition of juvenile olive flounder Paralichthys olivaceus

Abstract

Abstract A feeding trial was conducted to investigate the effects of dietary carotenoid source and level on growth performance, feed utilization, skin pigmentation, antioxidant responses and fatty acid composition of juvenile olive flounder, Paralichthys olivaceus . Three carotenoid sources derived from Carophyll-pink (AX), paprika extract (PE) and either Haematococcus pluvialis extract (HE) or raw H. pluvialis (HR) were evaluated at 100 or 200 mg/kg carotenoid, respectively. These dietary treatments were designated AX100, AX200, PE100, PE200, HE100, HE200 or HR100. The CON diet without supplementation of carotenoid was considered as the control diet. Juvenile olive flounder (average body weight, 9.5 ± 0.2 g) were randomly distributed in a flow-through tank system. Each experimental diet was fed to three replicate groups of fish to visual satiation twice per day for 8 weeks. Survival, weight gain and daily feed intake were not different to control group. Fish fed the HE200 diet showed higher feed efficiency and protein efficiency ratios compared to those of fish fed the CON, AX100, PE100, PE200 and HE100 diets. Total carotenoid in the dorsal muscle, skin and whole body of fish fed the diets containing carotenoids was higher than that of fish fed the CON diet. L * and b * values of the fish skin were not altered by dietary carotenoid sources and levels. However, a * values of fish fed the diets containing carotenoids were significantly higher than that of fish fed the control diet. Liver and plasma SOD activities of the fish fed diets containing carotenoids were lower than those of the control group. Radical scavenging activities of dietary carotenoids were increased in the muscle, liver, and plasma by dietary carotenoid source, except for the liver and plasma of AX100 and AX200 diets. The present results suggest that dietary inclusion of paprika and H. pluvialis extract at a concentration of approximately 100 mg/kg carotenoid could increase total carotenoid, antioxidant activities and skin pigmentation of olive flounder as efficiently as commercial synthetic astaxanthin.