Determination of Oxidative Energy Metabolism and Plasma LDH Isoenzyme Patterns of Dolphins

In this study, oxidative energy metabolism was determined in 5 captive bottlenose dolphins (Tursiops truncatus), and subsequently compared to 6 Thoroughbred riding horses, and 12 lactating Holstein cows in order to assess symmorphosis of each animal species. Plasma metabolites profile, plasma MDH (M) and LDH (L) activities, M/L ratio, and plasma LDH isoenzyme distribution patterns were all examined. Overall, dolphins appear to have the greatest level of oxidative energy metabolism amongst horses and cows, due to having the greatest levels of plasma MDH activity. In addition, dolphin energy production/usage efficiency, via oxidative metabolism, was considered to be second (M/L ratio = 0.49) behind that of horses (M/L ratio = 0.79), possibly due to an increased reliance of non-oxidative energy metabolism over horses. In spite of demonstrating the lowest oxidative energy production/usage efficiency (M/L ratio = 0.15), cows also demonstrated the highest plasma LDH activity amongst all animal species. Although all animal groups displayed differing plasma LDH isoenzyme distribution patterns, dolphins and horses demonstrated a similarity with LDH-3 isoenzyme predominating in plasma; whereas LDH-1 isoenzyme predominates in cow plasma, thus inferring differences in oxidative/non-oxidative metabolism for energy generation/usage. Therefore, plasma MDH and LDH activity levels, M/L ratio, and plasma LDH isoenzyme pattern can all be useful indicators for better understanding oxidative energy metabolism and monitoring of captive animals’ health. As it is not easy to obtain tissue samples from animals, the development of blood indicators for evaluating whole body metabolic state is necessary.