Reproductive Physiology and Development of Artificial Insemination Technology in Killer Whales (Orcinus orca)
Research was conducted to define the basic reproductive physiology of killer whales ( Orcinus orca ) and to use this knowledge to facilitate the development of artificial insemination procedures. The specific objectives were 1) to determine the excretory dynamics of urinary LH and ovarian steroid me...
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Veröffentlicht in: | Biology of reproduction 2004-08, Vol.71 (2), p.650-660 |
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Zusammenfassung: | Research was conducted to define the basic reproductive physiology of killer whales ( Orcinus orca ) and to use this knowledge to facilitate the development of artificial insemination procedures. The specific objectives were
1) to determine the excretory dynamics of urinary LH and ovarian steroid metabolites during the estrous cycle; 2) to evaluate
the effect of an exogenously administered, synthetic progesterone analog on reproductive hormone excretion; 3) to validate
the use of transabdominal ultrasound for ovarian evaluation and timing of ovulation; 4) to examine the quality of semen after
liquid storage and cryopreservation; and 5) to develop an intrauterine insemination technique. Based on urinary endocrine
monitoring of 41 follicular phases and 26 complete cycles from five females, estrous cycles were 41 days long and comprised
a 17-day follicular phase and a 21-day luteal phase. A consistent temporal relationship was observed between peak estrogen
conjugates and the LH surge, the latter of which occurred approximately 0.5 days later. Two animals placed on oral altrenogest
(three separate occasions for 30, 17, and 31 days, respectively) excreted peak urinary estrogen concentrations 25 days after
withdrawal that were followed by sustained elevations in urinary pregnanediol-3α-glucuronide excretion. Mean preovulatory
follicle diameter was 3.9 cm (n = 6), and ovulation occurred 38 h (n = 5) after the peak of the LH surge. Based on visual
estimates of motility, liquid-stored semen maintained 92% of its raw ejaculate sperm motility index (total progressive motility
à kinetic rating [0â5 scale, where 0 = no movement and 5 = rapid progressive movement]) when held at 4°C for 3 days postcollection.
Semen cryopreserved using a medium freezing rate demonstrated good postthaw total motility (50%), progressive motility (94%),
and kinetic rating (3.5). Insemination during eight estrous cycles resulted in three pregnancies (38%), two from liquid-stored
and one from cryopreserved semen. Two calves were delivered after gestation lengths of 552 and 554 days, respectively. These
data demonstrate the potential of noninvasive endocrine monitoring combined with serial ultrasonography to improve our understanding
of the reproductive biology of cetaceans. This fundamental knowledge was essential for ensuring the first successful conceptions,
resulting in live offspring, using artificial insemination in any cetacean species. |
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ISSN: | 0006-3363 1529-7268 |
DOI: | 10.1095/biolreprod.104.027961 |