Abstract: Estimation of body composition and water turnover rates can provide important indices of an animal's health and well-being. This data becomes especially important for a highly endangered species, such as the West Indian manatee (Trichechus manatus). Information on body composition and water turnover rates in nursing manatee calves is unavailable; therefore, the present study describes a unique opportunity to estimate, by isotopic dilution, body composition and water flux in vivo in bottle-fed calves of the West Indian manatee held in captivity. A calf held in fresh water was measured at 9 mo (124.8 kg) and 12 mo (152.6 kg) to examine the effects of growth. Over this 3-mo period, absolute fat mass (FM) increased 70.4% and absolute water turnover rate increased from 4.7 to 9.7 l/d, illustrating how these parameters change as a function of the animal's growth. To examine the effects of salinity on water flux, another calf (110.0 kg), held in salt water, was restricted from fresh water. During freshwater restriction, the calf's water turnover rate was 2.9 l/d and could be accounted for solely by dietary and metabolic water. When the animal was given access to fresh water, turnover rate increased to 4.0 l/d, for which 1.3 l/d could not be accounted, suggesting that nursing calves do not drink salt water. Collectively, the results provide a unique data set for nursing manatee calves and suggest that nursing calves, similar to adults, do not engage in mariposia. In addition, nursing calves will drink when given access to fresh water; however, the contribution of drinking fresh water to the growth and development of nursing calves remains to be examined. These data should provide useful information when implementing the proper husbandry and management plans for both fresh- and saltwater habitats of such a highly endangered species as the West Indian manatee.
Key Words: West Indian manatee, Florida manatee, Trichechus manatus, endangered species, marine mammals, sirenians, fat mass, deuterium oxide, isotopic dilution, D2O
Document Type: Research article
Page Numbers: 41-45