Low optimal temperatures for food conversion and growth in the big-headed turtle, Platysternon megacephalum |
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Authors: | Yong-Pu Zhang Wei-Guo Du Jian-Wei Shen Lin Shu |
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Affiliation: | aCollege of Life and Environmental Sciences, Wenzhou University, 325027, Wenzhou, Zhejiang, People's Republic of China;bDepartment of Environmental Sciences, School of Life Sciences, Hangzhou Normal University, 310036, Hangzhou, Zhejiang, People's Republic of China;cQuzhou College, 324000 Quzhou, Zhejiang, People's Republic of China |
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Abstract: | We held juvenile big-headed turtles, Platysternon megacephalum, from eastern China, at temperatures from 20 to 29.4 °C to determine effects on feeding, growth and food conversion. Food intake increased significantly from 20 to 22.4 °C, remained high until 27.1 °C, and then decreased dramatically at 29.4 °C. Digestive efficiency for energy decreased as temperature increased, whereas the digestive efficiency of protein increased from 20 to 25 °C, and decreased at higher temperatures. The relationships between specific growth rate (SGR), food conversion coefficient (Cc) and temperature (T) were curvilinear, and could be described by quadratic equations: SGR = −0.01 T2 + 0.47 T − 5.24 and Cc = −0.37 T2 + 17.20 T − 181.85. Maximum growth was estimated to occur at 23.9 °C, with 90% of the maximum being achieved within the range of 21.9–25.8 °C; maximal food conversion occurred at 23.2 °C, with a 90% range from 21.0 to 25.4 °C. The temperature range (22–25 °C) found to promote best growth and food conversion in juvenile P. megacephalum is lower than for many other freshwater turtles. Temperatures of 22–25 °C are recommended for use in culture of this species to maximize growth and food conversion. |
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Keywords: | Digestive efficiency Growth rate Nutritional energetics Platysternon megacephalum Thermal requirements Turtle culture |
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