Research Overview:
Artificial insemination (AI) is increasingly utilized to maintain genetic diversity in bottlenose dolphin populations in human care, maximizing the gene pool without the risks and social disruption of transporting animals between facilities for breeding loans. But, for successful AI to occur there must be a way to identify when a female dolphin ovulates.
Luteinizing hormone (LH) is a hormone produced in the body that is thought to trigger ovulation. Before ovulation occurs, a preovulatory follicle (POF) develops, which houses the egg until ovulation. To better understand the relationship between POF development, the ovulatory LH surge and ovulation, Holley Muraco, a PhD student in Reproductive Physiology at Mississippi State University, worked with Dolphin Research Center’s Medical Director, Pat Clough, to characterize dolphin ovulatory estrous cycles by using multiple daily sampling of conditioned dolphins at several different facilities, including Dolphin Research Center. Non-invasive, voluntary techniques, including ultrasound and voluntary urine collection, were used.
The study concluded that bottlenose dolphins have brief measurable ovulatory LH surges lasting approximately 6 hours, followed by ovulation within 24-48 hours, and that during the LH surge the POF remained an intact significant round structure with an average diameter of 1.9cm, observable by trans abdominal ultrasound. Gaining a better understanding of these ‘fleeting’ processes will assist in the planning for artificial insemination and maximize controlled natural breeding programs.
