| Summary: | Estrus was synchronized in a wood bison herd using Syncro-mate B implants either with estradiol valerate (n = 9) or Estrumate (n = 9). The efficacy of Folltropin-V (n = 5) compared to pregnant mares' serum gonadotropin (n = 5) for inducing superovulation was evaluated. Based on behavioural and ultrasonographic observations, Syncro-mate B with Estrumate resulted in a tighter synchrony of estrus and only a single female per superovulation treatment produced multiple follicles. Pregnancy in wood bison was monitored using steroid enzyme immunoassays. Gestation was 268.3 $\pm$ 1.0 days (n = 6) with calving occurring from April-July. Using urinary and fecal estrogens, pregnancy could be detected between 4-13 weeks of gestation. Similar to the sheep fecal and urinary progestin levels elevated during the second trimester, and declined 3-5 weeks before parturition, respectively; whereas, estrone conjugate concentrations increased markedly 4 weeks prior to parturition, similar to domestic cattle. Urinary cortisol levels remained unchanged throughout pregnancy, peaking just prior to parturition.
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