The effects of dietary supplement of rounded brittle fern weed (Laurencia obtusa) (hudson) (j.v.lamouroux, 1813) as a natural carotenoid on pigmentation in rainbow trout (oncorhynchus mykiss)

Abstract

The aim of this study was to determine the effects of Laurencia obtusa (Hudson) as a natural carotenoid on the growth performance, biochemical composition and skin and fillet pigmentation in rainbow trout (Oncorhynchus mykiss). Laurencia obtusa was collected manually from the shores of Sinop (The Black Sea-Turkey) and included in the diet at two different ratios as 30 (L30) and 60 (L60) mg/kg diet. The fish with an average weight of 248.9±6.1 g were fed by the experimental diets for 6 weeks. The best growth performance was determined in L0. The differences between protein, fat and ash values of fish were not significant (P>0.05). At the end of the study, the L* value was highest in the L0 group (59.94±1.28) and lowest in the L60 group (53.43±1.98) and, in fillet, it decreased in all experimental groups compared to the initial values (P<0.05). The a* values of skin and fillet were determined between 4.48±0.31 and 4.68±0.41, 1.45±0.42 and 1.73±0.39, respectively (P>0.05). The b* value increased in all groups in skin (P<0.05), whereas it was decreased in fillet (P>0.05).