Enhancing Reproduction in White Rhinos

The southern white rhinoceros captive population is facing a looming crisis. Although reproduction among founders was moderately successful, most females born in captivity have not reproduced.

The objective of this collaborative research project is to determine the root causes of failed reproduction and to make recommendations for improved management of the captive population. From previous research, we have been able to identify several factors that may explain reproductive failure, including diet, body condition, social experience, enclosure size, animal density, early age at weaning, and transfers, premature copulations, long non-reproductive periods, and reproductive pathologies.

We are developing a comprehensive dataset to evaluate histories of individuals reared in various captive environments, including an array of captive conditions in small South African game reserves that lie on a continuum between wild and captive. In a multi-disciplinary approach, veterinary reports will be reviewed to glean information about reproductive pathologies and other insights.

We have begun an exciting new program to evaluate the possible effects of diet on reproduction. For example, the captive diet may contain phytoestrogens that can elicit an estrogenic response in vertebrates. Many of these plant compounds are found in legumes such as clover, soy, and alfalfa - species that have been associated with infertility in livestock. We are developing assays to screen dietary extracts for activation of white rhino estrogen receptors. These cell-based assays will allow us to identify compounds in the diet of captive rhinos that could mimic estrogen signaling and lead to developmental abnormalities of the female reproductive tract.