Efficacy and tolerance of lutein as colourant in diet of juvenile soft‐shelled turtle Pelodiscus sinensis

The effects of dietary supplementation of lutein on the growth, haematological profile and pigmentation in target tissues of the soft‐shelled turtles were investigated. Five experimental diets were prepared with lutein levels at 1.16 (D1, control), 70.3 (D2), 132 (D3) and 239 (D4) mg kg^?1, and one more high inclusion level of 3410 mg kg^?1 (D5) was included for tolerance test. Each diet was fed to 24 juvenile turtles for 8w. Specific growth rate (SGR) in D2, D3 and D4 was significantly higher than that of group D1 and D5. Skin yellowness (b*) and chroma (C*) of both carapace and plastron skin were all significantly increased with higher dietary lutein levels. Dietary lutein supplementation turned the H° values of skins into yellowness. The accumulation of lutein in skin and muscle also augmented significantly with increasing lutein levels and fit a logarithmic correlation with dietary lutein levels. There were almost no differences in haematological parameters of all turtles. Lutein is an efficient and safe colourant in diet of soft‐shelled turtle. The optimal inclusion levels for the highest SGR and desired skin colour in carapace and plastron of soft‐shelled turtle were 162, 142 and 143 mg kg^?1, respectively.