Characterization of Preprandial and Postprandial Plasma Bile Acid Concentrations in Krefft’s River Turtles (Emydura macquarii krefftii)

Abstract Enterohepatic circulation and prandial influence of plasma bile acid (BA) concentrations in reptiles are unknown, and discrepancy occurs in BA diagnostic utility in reptiles. This study determined pre- and postprandial BAs in Krefft’s river turtles ( Emydura macquarii krefftii ), a representative freshwater chelonian, to investigate digestive influences on plasma concentrations. Seventeen clinically healthy turtles were fasted for 10 days before preprandial blood was collected. Shrimp gruel was then gavage fed to all turtles, and blood was collected over 10 days (0.25, 0.5, 1, 2, 4, 6, 8, 10, 12, 24 h and every 24 h thereafter until 240 h). Plasma BA was determined using a colorimetric assay. A significant change in BAs was demonstrated, depending on time, sex, and the interaction of sex and time. Compared with other venipuncture time points, BA concentrations were consistently elevated at 24 and 48 h, and it is recommended to use these time points to sample BAs postprandial in this species. Overall, mean male BAs were higher than female BAs, and, for both sexes, multiple elevations in BAs were found throughout the sampling timeline. Median (interquartile range) BAs and associated times for maximum values were 3.3 µmol/L (2.7–5.45 µmol/L) at 24 h (7.5 h–48 h) for females and 9.4 µmol/L (4.8–20.73 µmol/L) at 11 h (9.5–24 h) for males. In conclusion, the digestive timeline of Krefft’s river turtles appears to influence BAs; however, sex and fasting status should be determined for the best interpretation of BA results in a clinical setting.