飼育下のエゾヒグマにおける電気刺激射精法を用いた精液採取と射出精液の特徴(短報) Electroejaculation and Semen Characteristics of the Captive Hokkaido Brown Bear(Ursus arctos yesoensis)
性成熟に達した10頭の飼育下の雄エゾヒグマを不動化した後, 電気刺激射精法により, 延べ21回の精液採取試験を行った.運動精子を含む射出精液は, 21回のうち14回から得られ, 採取された精液の量およびpHは, 平均2.7mlおよび7.4であった.また, 精子の濃度, 運動性, 生存率および奇形率は, それぞれ平均471.6×10^6個/ml, 80.2%, 89.7%および21.8%であった.
An electroejaculation technique was applied to the Hokkaido brown bear(Ursus arctos yesoensis)for semen collection and characterization of their seminal traits. Ten captive sexually mature bears were anesthetized and subjected to 21 electroejaculation trials during their mating season in 1995 and 1996. Spermic electroejaculates were recovered from 6 of the 10 bears(14 of 21 trials). The semen was characterized by serous fluid of semitransparent white color and a neutral pH. The mean values of ejaculate volume, sperm concentration, percentage of sperm motility, percentage of live spermatozoa, and percentage of pleiomorphic forms were 2.7ml, 471.6×10^6cells/ml, 80.2%, 89.7% and 21.8%, respectively. Although there was considerable variation among the seminal traits of the individual bears, the electroejaculation technique was effective in obtaining ejaculates from captive bears.