Air temperature and diet influence body composition and water turnover in zoo-living African elephants (Loxodonta africana)

Abstract

African elephants, the largest land animal, face particular physiological challenges in captivity and the wild. Captive elephants can become over- or under-conditioned with inadequate exercise and diet management. Few studies have quantified body composition or water turnover in elephants, and none to date have examined longitudinal responses to changes in diet or air temperature. Using the stable isotope deuterium oxide ( 2 H 2 O), we investigated changes in body mass, estimated fat-free mass (FFM, including fat-free gut content) and body fat in response to a multi-year intervention that reduced dietary energy density for adult African elephants housed at the North Carolina Zoo. We also examined the relationship between air temperature and water turnover. Deuterium dilution and depletion rates were assayed via blood samples and used to calculate body composition and water turnover in two male and three female African elephants at six intervals over a 3-year period. Within the first year after the dietary intervention, there was an increase in overall body mass, a reduction in body fat percentage and an increase in FFM. However, final values of both body fat percentage and FFM were similar to initial values. Water turnover (males: 359 ± 9 l d −1 ; females: 241 ± 28 l d −1 ) was consistent with the allometric scaling of water use in other terrestrial mammals. Water turnover increased with outdoor air temperature. Our study highlights the physiological water dependence of elephants and shows that individuals have to drink every 2–3 days to avoid critical water loss of approximately 10% body mass in hot conditions.

Anatomical, physiological, and behavioral mechanisms of thermoregulation in elephants

“…It was recorded that shaded areas covered approximately 11% of the enclosure and helped to reduce the radiant heat load to 278 Wm -2 , or 36% of the calculated maximum heat reduction of 766 Wm -2 (Thaker et al 2019) mention that shade provided by dense vegetation supports thermoregulation and constitutes a naturalized environment for elephants. Water bodies are essential for elephants to meet their daily physiological demands and to perform thermoregulatory behaviors to moisten and cool the skin (Pontzer et al 2020). In recent years, elephant tourist camps have implemented activities promoting the coexistence of people and wildlife.…”

The provisioned primate: patterns of obesity across lemurs, monkeys, apes and humans

“…Obesity and cardiometabolic health are common concerns for captive primate populations [8,[11][12][13][14]. Many species are known to develop obesity in zoo and laboratory settings, where overweight and obesity are typically tracked by body weight and visual determinations of body condition by veterinary staff.…”