OVULATION INDUCTION AND ARTIFICIAL INSEMINATION OF A CAPTIVE POLAR BEAR (URSUS MARITIMUS) USING FRESH SEMEN

Abstract

In 2008, polar bears were listed as a species threatened with extinction by the U.S. Endangered Species Act. Unfortunately, reproductive success has been poor despite breeding recommendations for almost every reproductively viable bear by the Species Survival Plan. Assisted reproductive technologies could complement breeding efforts by overcoming the challenges of behavioral incompatibilities and deficiencies, facilitating genetic management and increasing cub production. The goal of this study was to artificially inseminate a female polar bear after inducing ovarian activity and ovulation with exogenous hormones (equine chorionic gonadotropin and porcine luteinizing hormone). Fresh semen collected from an adult male via electroejaculation/urethral catheterization was used for the insemination. Fecal steroid monitoring indicated that the female ovulated following the exogenous hormone treatment. Progestin concentrations increased in late summer, at the time implantation was expected to occur; however, no cubs were produced. To the authors' knowledge, this is the first report of ovulation induction and artificial insemination in a polar bear.

Case Studies in Polar Bear (Ursus maritimus) Sperm Collection and Cryopreservation Techniques

“…Collections occurred both during the breeding season ( n = 27; 1 January–21 May) and the nonbreeding season ( n = 11; 22 May–31 December) [ 18 ]. Samples were collected from live bears via EEJ ( n = 6) [ 17 ] or UC ( n = 25) [ 17 , 19 ] and postmortem via SR ( n = 7) [ 12 , 20 ]. All protocols were reviewed and approved by the Cincinnati Zoo and Botanical Garden’s Animal Care and Use Committee (IACUC).…”

“…Testes were palpated and length and width were determined by holding the testes flush with the skin and using calipers to take measurements prior to collection. A rectal probe, 3.3 cm in diameter with three electrodes (7.5 cm × 0.5 cm) and an electroejaculator (P-T Electronics, Boring, OR 97009, USA) were used to administer stimuli (60–165) of 2–10 V over the course of 2–5 series [ 17 ]. Probe size was selected based on previous reports in polar bears [ 17 ] with consideration of similar species [ 21 ], and size and anatomy of the rectum to avoid forcible placement or damage to the rectal membrane.…”

“…UC was conducted a total of 25 times with 14 bears (1–5 procedures/individual) [ 17 ]. Testes were palpated and measured as described for EEJ.…”

“…Testes from hunted polar bears were examined though sperm characteristics were not reported [ 15 , 16 ]. Curry et al [ 17 ] briefly described the use of urethral catheterization (UC) and electroejaculation (EEJ) in polar bears for use in conjunction with artificial insemination; however, the sample size was limited, and further investigation is needed to optimize techniques.…”

Allee effect in polar bears: a potential consequence of polychlorinated biphenyl contamination

“…'the prime-aged males', and 15-19, 20-24, 25þ years) spent in pairs. Because polar bears are thought to be induced ovulators [31], it may be assumed that a male that spends a longer period with a female will have a greater probability of inducing ovulation and siring offspring. Therefore, we derived a potential age-category representation of males siring offspring from the proportions of the total number of days that healthy males in each category spent in pairs.…”