Evaluation of Nutritional and Health Status in Captive Eastern Indigo Snakes (Drymarchon couperi) in Response to Formulated Sausage Diet

The federally threatened eastern indigo snake (EIS; <i>Drymarchon couperi</i>) is an active ophiophagous snake once found throughout the southeastern US that is now restricted to southeastern Georgia and peninsular Florida. There are concerns regarding the potential impact of overconditioning or nutrient imbalances on the reproductive fitness of breeding programs due to the occurrence of dystocia in nulliparous dams and the differing nutritional profiles of domestic and free-range prey species. We examined the blood cell counts, plasma biochemistry, and circulating plasma levels of nutrients in snakes consuming standard or experimental diets over a one-year period. Treatments included mixed whole laboratory animal prey (rodents, birds), whole prey ground into sausage, or a sausage with similar nutrient profiles measured in prey found in free-ranging EIS stomach contents. Plasma concentrations of vitamin E (maximum = 0.80 mg/mL) and selenium (maximum = 371 ng/mL) were within range of and exceeded values reported in free-ranging EIS (0.0365 mg/mL and 107.45 ng/mL), while plasma vitamin D₃ concentrations (maximum = 64.1 ng/mL) were typically below minimum values observed in free-ranging EIS (46 ng/mL). Additional dietary studies initiated on juvenile subjects throughout reproductive maturity would provide an ideal experimental design for studying the linkage between reproductive health and nutrition.