Effects of dietary astaxanthin and xanthophylls on the growth and skin pigmentation of large yellow croaker Larimichthys croceus

A 9-week feeding trial was conducted to investigate the effects of dietary astaxanthin and xanthophylls on the growth and skin coloration of large yellow croaker Larimichthys croceus (mean initial weight: 33.33±1.67g). There were five experimental diets: CD (control diet without carotenoid), AST37.5 (diet with 37.5mg/kg of astaxanthin), AST75 (diet with 75mg/kg of astaxanthin), X37.5 (diet with 37.5mg/kg of xanthophylls) and X75 (diet with 75mg/kg of xanthophylls). Results showed that the growth and feed efficiency ratio were not significantly affected by dietary treatments (P>0.05). With the feeding period increased, the lightness (L*) in the dorsal skin showed a slight increase. However, it decreased in the ventral skin (P>0.05). Treatments of X37.5 and X75 had lower redness (a*) in the dorsal skin. As to a* values in the ventral skin, fish fed with carotenoid supplemented diets were higher than that in the CD group. Yellowness (b*) values in the ventral and dorsal skins of fish fed with the carotenoid supplemented diets were elevated as the feeding period increased. Fish in the X37.5 and X75 groups had higher b* values in the ventral and dorsal skins than those in the AST37.5 and AST75 groups (P