Effect of Two Natural Carotenoid Sources in Diets for Gilthead Seabream, Sparus aurata, on Growth and Skin Coloration

Abstract

To improve the unnatural fade-pigmented skin of cultivated gilthead seabream, Sparus aurata, (if shown) the present study was initiated. The effects of either red bell-pepper (Capsicum annum) meal or carrot (Daucus carota) meal as a natural dietary carotenoid source, on growth and skin coloration of gilthead seabream growers were investigated. A basal/control diet (D1/CTR) was firstly formulated to contain 48% crude protein and 14% lipids, with no added-carotenoids. With this basal diet, two other test diets were similarly prepared and supplemented each with about 40mg/Kg total carotenoids from either red-pepper meal (D2) or carrot meal (D3). In a feeding trial, fish (mean IW, 94.86±0.3g) were fed one of the three diets (D1, D2, D3), in triplicates for each treatment, for 6 weeks in light-blue background PVC tanks supplied with natural seawater flow. Total carotenoids content of skin was determined spectrophotometerically at initiation and end of the experiment. Neither growth nor feed utilization were significantly (P<0.05) affected by the red pepper-added diet (D2) as compared to CTR diet. However, the carrot fed fish recorded the lowest and significant (P<0.05) weight gain (g/fish) and specific growth rate (SGR, %/d) among dietary treatments. There were no considerable (P>0.05) differences in major nutrients composition between fish fed the experimental diets. Total carotenoids content was significantly (P<0.05) increased, in the skin-opercle area, of fish fed the red pepper diet (D2) as compared to initial fish and to either carrot fed fish or CTR fish. Results have suggested that gilthead seabream can effectively bio-absorb natural carotenoid pigments (mainly capsansin and capsorbin) in red-pepper but not in carrot (mainly β-and α-carotene).