Roles of Diet Protein and Temperature in the Growth and Nutritional Energetics of Juvenile Slider Turtles, Trachemys scripta

• Published in: Physiological zoology 1993-11, Vol.66 (6), p.902-925
• Main Authors: Avery, Harold W., Spotila, James R., Congdon, Justin D., Fischer, Robert U., Standora, Edward A., Avery, Susan B.
• Format: Article
• Language: English
• Subjects: Animal digestion; Biological and medical sciences; Chelonia; Diet; Digestion; Feces; Food; Food consumption; Freshwater; Fundamental and applied biological sciences. Psychology; Lizards; Protein digestion; Thermoregulation. Hibernation. Estivation. Ecophysiology and environmental effects; Trachemys scripta; Turtles; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Young animals
• ISSN: 0031-935X; 1937-4267
• DOI: 10.1086/physzool.66.6.30163746

We determined the effects of dietary protein and$T_{a}$on growth rates, food consumption rates, digestion rates, and digestive efficiencies of juvenile slider turtles (Trachemys scripta). Results from this study provide a clearer understanding of how these environmental factors interact in influencing body sizes and growth rates of individuals in wild slider turtle populations. Changes in plastron length, carapace length, and body mass were significantly greater for T. scripta eating 25% and 40% crude protein diets than for those eating 10% crude protein. Those consuming 10% crude protein showed significant decreases in body mass and plastron length over a 13-wk period. Individuals at$T_{a}'s$of 15°, 22°, 28°, or 34° C had food ingestion rates (kJ wk⁻¹) that increased markedly with an increase in$T_{a}$. Increasing dietary crude protein concentration increased turtle ingestion rates and influenced the positive effect of$T_{a}$. Increasing dietary crude protein concentration alone did not significantly affect turtle consumption rates but did significantly influence the positive effect of$T_{a}$. Digestive efficiencies were very high (because of the pelleted diet). Those turtles that ate at 15° C had a digestive efciency of 99.5%, as compared with 98.3% at 22° C, 94.8% at 28° C, and 95.8% at 34° C. Dietary protein concentration did not influence the digestive efficiencies of T. scripta. These data suggest that dietary protein is an important nutritional component to the growth of juvenile slider turtles and that elevated thermal conditions, combined with a high dietary protein availability, may explain the very high growth rates of slider turtles in some wild populations.