Abstract: | The objective of the present study was to estimate the dietary thiamine (vitamin B1) requirement of juvenile soft‐shelled turtles, Pelodiscus sinensis. Eight experimental diets containing 0, 1.90, 3.63, 5.65, 7.51, 9.62, 11.37 and 13.64 mg thiamine/kg diet were fed to 160 soft‐shelled turtles reared individually for 10 weeks. The turtles had an average weight of 5.33 ± 0.21 g. Among all the dietary groups, weight gain, feed utilization and tissue thiamine were the lowest in the turtles fed with a thiamine‐free diet. The variables increased when dietary thiamine increased and then levelled off beyond 3.63 mg/kg diet. In contrast, plasma pyruvate and lactate concentrations in turtles decreased when dietary thiamine increased and then levelled off beyond 3.63 and 5.65 mg/kg diet respectively. Estimation using a broken‐line regression model, the vitamin B1 requirement of soft‐shelled turtles was 3.2 mg thiamine/kg diet based on weight gain and plasma lactate concentration. When tissue thiamine and plasma pyruvate concentrations were used as the indicators, the estimated requirement was 5.4–6.5 mg/kg diet. |