Billy Lee LasleyPromoting propagation

Published in 1978

Captive breeding is the last hope for some endangered birds. American Billy Lee Lasley was working as a research endocrinologist at the San Diego Zoo when he developed a non-invasive method for determining the sex of birds.

locationUnited States

Forty years ago breeding programmes for endangered birds often foundered on the difficulty of identifying fertile breeding pairs. Therefore it was necessary to develop a non-invasive method to determine the gender and reproductive status of birds that have no plumage variation between the sexes. Billy Lasley understood that a simple gender-assigning method that was economical and stress-free was required and developed a system (now superseded by more specific genetic testing) based on the fecal monitoring of sex steroid ratios.

The development of hormone metabolite monitoring for determining the sex life of birds has led to broad applications in both animal and human studies.

While early years of research were directed towards the application of the technology as an adjunct in propagating exotic species in zoos and managing the reproduction of free-ranging animals, that work has expanded into other scientific arenas, including the understanding of early pregnancy loss in humans, detecting adverse effects of environmental hazards on reproduction and monitoring reproductive health in the context of ageing. Funding for this technology became common when it was extended to human studies.

The current focus of Lasley’s study is now focused mainly on human reproduction and infertility with an emphasis on women’s reproductive health and women’s healthy ageing. These studies are currently conducted at the University of California, Davis where Lasley is Professor Emeritus at the California National Primate Research Center.


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