Electroejaculation and Semen Characteristics of the Captive Hokkaido Brown Bear. (Ursus arctos yesoensis)

Abstract

ABSTRACT. 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 2.7 ml, 471.6 × 10 6 cells/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. -KEY WORDS: brown bear, electroejaculation, seminal trait.J. Vet. Med. Sci. 60(8): 965-968, 1998 domestic animal diets and some vegetables were provided, and the bears were housed in indoor/outdoor enclosures under the natural light cycle. All males were separated from females by a grid wall, but had visual, aural, and/or olfactory contacts during the experimental periods. A surgical plane of anesthesia was induced with an intramuscular (i.m.) injection of tiletamine HCl-zolazepam (Zoletil; 100 mg/ml, Virbac, Carros, France) at a dose of 3 mg/kg body weight by pole syringe in 19 trials. For male D (Trial no. 11), 0.01 mg/kg atropine sulfate (Atropine sulfate injection, Tanabe, Osaka, Japan) was given before the injection of tiletamine HCl-zolazepam. Male A (Trial no. 5) was preanesthetized by an i.m. injection of 0.25 mg/kg midazolam (Dormicum, Roche, Basel, Switzerland) and immobilized by an i.m. injection of 5.0 mg/kg ketamine HCl (Ketalar, Sankyo, Tokyo, Japan). With the anesthetic plane with midazolam and ketamine HCl, the animal was less immobilized than in the other trials.

Electroejaculation and Semen Cryopreservation of Free-Ranging Japanese Black Bears (Ursus thibetanus japonicus)

“…In recent years, their habitats have become fragmented and shrunken by human activity, and this species even faces extinction in some areas [7]. What is worse, bears have been killed to protect forestry, agriculture, livestock and humans from damage caused by them.Endangered and threatened wild animals are now attracting attention as a genetic resource and for species conservation, and semen has been recovered from various captive non-domestic animals, including fat-tailed dunnarts, koalas, brushtail possums, long-footed potoroos, northern brown bandicoots and ring-tailed possums [32] [4,20,22,24], Hokkaido brown bears [13,14] and Japanese black bears [16]. However, these studies were done with captive animals, and there are no reports on semen collection and cryopreservation in free-ranging bears.…”

Cryopreservation of the Semen Collected by Electroejaculation from the Hokkaido Brown Bear(Ursus arctos yesoensis).

“…An assisted reproductive technology like artificial insemination could contribute to the maintainance of their genetic diversity. We previously reported a successful semen collection of the Hokkaido brown bear by electroejaculation [7]. Semen cryopreservation is an essential procedure for assisted breeding; however, there are only a few reports on cryopreservation of the bear semen [2,9].…”

“…The semen was assessed by determining ejaculate volume, pH, sperm concentration and the percentage of abnormal sperm as described elsewhere [7]. The percentage of viable spermatozoa was determined by an eosin-nigrosin staining method [7] before and after freezing. Small aliquot of raw and frozen-thawed semen was taken for the assessment of sperm motility.…”

“…The electrical stimulation with 60 Hz alternative current, sine wave and 5 V was repeated till ejaculates were obtained. The semen was assessed by determining ejaculate volume, pH, sperm concentration and the percentage of abnormal sperm as described elsewhere [7]. The percentage of viable spermatozoa was determined by an eosin-nigrosin staining method [7] before and after freezing.…”

“…A total of 10 trials of electroejaculation were conducted during the breeding season (May to July) in 1996 and 1997. Electroejaculation was conducted as described previously [7]. Briefly, bears were immobilized with tiletamine HClzolazepam HCl (Zoletil; Virbac S. A., Carros, France) in 8 trials, and with midazolam (Dormicum; F. Hoffman-La Roche Ltd., Basel, Switzerland) and ketamine HCl (Ketalar; Sankyo Co., Ltd., Tokyo, Japan) in 2 trials.…”