Use of human chorionic gonadotropin in a male Pacific walrus (Odobenus rosmarus divergens) to induce rut and achieve a pregnancy in a nulliparous female.

摘要: Walrus in US zoos have a very low reproductive rate of 11 births 80 years, and little is known about Pacific walrus (Odobenus rosmarus divergens) biology. To address this, we initiated program which detailed biological data were recorded on captive walrus. As part 7-year study, 1 male female 16-year-old carefully monitored with weekly serum hormone analysis, daily glans penis smears for spermatozoa, abdominal ultrasound pregnancy. The ovulated once annually from late December through mid-January then exhibited 9 months sustained elevated progesterone. This nonconceptive estrous cycle profile consistent reports wild females. In contrast, the male's seasonal rut routinely occurred February May testosterone peak March. differed reported adult November During period female's ovulation, had nadir levels was consistently azoospermic. Likewise, during spermatogenic spring, anovulatory On this basis, treated 14 weeks human chorionic gonadotropin (hCG) an attempt to increase synchrony annual ovulation. treatment successfully induced characterized by production spermatozoa. bred, became pregnant. Upon discontinuation hCG treatment, resumed baseline levels. We theorize that lack synchronization ovulatory cycles primary reason failure these