Effects of dietary β-carotene levels on growth and liver vitamin A concentrations of the soft-shelled turtle, Pelodiscus sinensis (Wiegmann)

摘要

A feeding trial was conducted to evaluate the effect of dietary β-carotene level on the growth and liver vitamin A concentrations in soft-shelled turtles, Pelodiscus sinensis, fed a vitamin A-free diet. Soft-shelled turtles were fed diets containing 0, 14.5, 26.5, 47.5, 87.3, 112.8 and 163.8?mg β-carotene?kg?1 for 10 weeks. Although it was not statistically significant due to high deviation within each group, mean weight gain of soft-shelled turtles fed the diet without β-carotene supplementation was the lowest among all test groups. Vitamin A concentrations in liver of turtles significantly (P<0.05) increased when dietary β-carotene level reached 47.5?mg?kg?1 indicating that soft-shelled turtles were capable of converting β-carotene to vitamin A. Analysed by regression modelling, dietary β-carotene levels for optimal growth and maximal liver vitamin A contents of juvenile soft-shelled turtles fed the vitamin A-free diets were 49.1 and 88.7?mg?kg?1 respectively.