Estimation of dietary vitamin K requirement of juvenile Chinese soft-shelled turtle, Pelodiscus sinensis

A 10-week feeding trial was conducted to estimate the dietary vitamin K requirements of juvenile Chinese soft-shelled turtles, Pelodiscus sinensis, using menadione sodium bisulphite (MSB) as the vitamin K source. Juvenile soft-shelled turtles with 6.1 +/- 0.1 g body weight were individually reared and fed diets containing seven levels of MSB (0.0, 5.0, 8.9, 12.3, 16.6, 20.7 and 41.0 mg/kg). Turtles fed with an MSB-free diet exhibited the lowest feed utilization, carapace Ca concentrations, carapace strength or liver menaquinone (MK-4) concentrations among all dietary groups. Weight gain (WG) in the turtles tended to increase with increase in dietary MSB until a dietary MSB level of 16.6 mg/kg, where WG levelled off. Total plasma prothrombin concentrations, an indicator for blood clotting function, in the turtles fed on MSB supplemented diets were significantly (p < 0.05) lower than those in turtles fed on MSB supplemented diets. Liver MSB concentrations increased with increase in dietary MSB. Using broken-line or sigmoidal regression model, the vitamin K requirements of juvenile Chinese soft-shelled turtles based on WG, total plasma prothrombin concentrations and liver vitamin K were 21.5, 25.8 and 29.9 mg MSB per kg, respectively.