Few controlled studies have been conducted to determine nutrient requirements of sea mammals; so, military researchers have looked at basic nutritional challenges. Specifically, the effects of high and low fat diets were compared with weight, body condition, and metabolism. Dolphin populations were divided into groups based on gender, age, and activity.
Older mammals require fewer calories for maintenance than do younger animals because the body becomes fatter with age. Animals fed high fat diets had higher body fat than did animals fed the same amount of calories from other sources. Metabolic rate decreases with age, but low fat diets increase metabolic rate.
Free ranging aquatic animals cannot be put in a metabolic chamber to measure energy expenditure; so, stable isotopes of water, deuterium, and 18O, must be administered orally. This method is effective but expensive—an average dose costs $6,000. This technique allows very accurate measurements of energy expenditure, and metabolic rate can be calculated in free ranging animals.
More research needs to be conducted on the nutrient requirements of marine mammals. Dolphins are specialized mammals and fill a unique military service and ecological niche. Early evidence suggests that bioenergetic principles in marine mammals mimic the bioenergetic principles in terrestrial mammals, supporting the concept of evolution and underscoring the relationship among all living animals.
The use of animals in the military has been a significant and critical component of our nation’s protection and defense throughout history. These animals serve in specialized capacities, working closely with their human counterparts. Defining and meeting their nutrient needs continues to be of the utmost importance to ensure that the non-human members of our military forces are well cared-for and given the necessary tools for optimum performance.