Serum 25(OH)D Analysis in Captive Pachyderms (Loxodonta africana , Elephas maximus , Diceros bicornis , Rhinoceros unicornis , Tapirus indicus) in Europe.

Simple Summary: This study aimed to determine the serum levels of vitamin D in captive pachyderms in Europe, and whether there were any seasonal differences. For some species, comparing the temperature and UVB irradiation of the current captive locations with the wild-ranging areas, the required conditions may be met in summer. In contrast, for other species, this might not be the case. Therefore, the animals may be unable to endogenously produce vitamin D, leading to calcium and phosphorus imbalances that were only reported in captive pachyderms. For some of the pachyderms, it is known that they can absorb cholecalciferol from the digestive tract, but this is not the case for all studied pachyderms. Tapirs had very low vitamin D levels, similar to horses. The higher vitamin D levels of elephants and rhinoceroses could indicate that they are capable of producing vitamin D or absorb more cholecalciferol from their diet. When comparing both rhinoceros and elephant species in this study, differences with regard to their capability in endogenous production of vitamin D were shown. Indian rhinoceroses seem capable of producing enough endogenous vitamin D year-round, while both elephant species and the black rhinoceros are not. This study aimed to detect seasonal and species differences in serum 25-hydroxy vitamin D (25(OH)D) concentrations during summer and winter months in captive pachyderms in Europe. Both elephant species had low 25(OH)D while African elephants did not show a seasonal variation. Asian elephants had significantly higher 25(OH)D compared to their African counterparts but also did not show a seasonal difference. Both rhinoceros species investigated had higher 25(OH)D compared to both elephant species; the Indian rhinoceros had high circulating levels year-round, while the black rhinoceroses showed significantly lower 25(OH)D in winter. Malayan tapirs have very low 25(OH)D, comparable to horses. The higher 25(OH)D of elephants and rhinoceroses could indicate that elephants and rhinoceroses are capable of producing vitamin D. This might indicate that the Indian rhinoceroses are capable of producing enough endogenous vitamin D year-round at latitudes around 52° N, while both elephant species and the black rhinoceros are not. This study also showed that it is likely that both elephant species and rhinoceros species are capable of absorbing cholecalciferol from the digestive tract, according to the existing literature, while tapirs may not. [ABSTRACT FROM AUTHOR]