Department of Reproduction and Clinic of Farm Animals, Wrocław University of Life and Environmental Science, Wrocław, Poland.
Reprod Biol Endocrinol. 2011 Mar 8;9:31. doi: 10.1186/1477-7827-9-31.
European bison is the largest mammal in Europe with the population of approximately 4000 individuals. However, there is no report of post-mortem spermatozoa collection and cryopreservation from this species and the aim of this study was to test if the epididymal spermatozoa collected post-mortem from European bison are suitable for cryopreservation and artificial insemination (AI).
Epididymides were collected post-mortem from two European bison bulls at age of 8 (bull 1) and 11 year (bull 2). Epididymal sperm was harvested by making multiple incisions in caudae epididymidis, which were then rinsed with extender. The left epididymis of bull 1 was rinsed with BioXcell (IMV, France), whereas the right epididymis of bull 1 and the right and left epididymides of bull 2 were rinsed with the extender based on Tris, citric acid, glucose, egg yolk, glycerol, antibiotics and distilled water (extender II). The diluted semen was cooled to 5 degrees C, and frozen in liquid nitrogen vapour. Then, properties of the frozen/thawed semen were examined with the use of computer-assisted semen analysis system, and thirty cows and nine heifers of domestic cattle were artificially inseminated.
Motility of fresh spermatozoa collected from the right epididymis of bull 1 was 70% (spermatozoa diluted with extender II), and from the left one was 60% (spermatozoa diluted with BioXcell), whereas motility of fresh spermatozoa collected from bull 2 was 90% (spermatozoa diluted with extender II). Spermatozoa motility just after thawing were 11 and 13% in bull 1, respectively for spermatozoa collected from the left and right epididymis and 48% in bull 2. As a result of AI of domestic cows and heifers with the frozen/thawed European bison spermatozoa, two pregnancies were obtained in heifers. One pregnancy finished with a premature labour after 253 days of pregnancy, and the second one after 264 days of pregnancy.
This is the first report showing pregnancy in the domestic cattle following AI with frozen-thawed European bison spermatozoa collected post-mortem. The protocol of spermatozoa collection, dilution, and cryopreservation presented in this paper may be useful for the creating genetic resource bank in the European bison.
欧洲野牛是欧洲最大的哺乳动物，数量约为 4000 头。然而，目前尚无关于从该物种采集死后精子并进行冷冻保存的报道，本研究的目的是测试从欧洲野牛死后采集的附睾精子是否适合冷冻保存和人工授精（AI）。
从两头 8 岁（公牛 1）和 11 岁（公牛 2）的欧洲野牛公牛死后收集附睾。通过在尾部附睾上做多个切口收集附睾精子，然后用扩展剂冲洗。公牛 1 的左附睾用 BioXcell（IMV，法国）冲洗，而公牛 1 的右附睾和公牛 2 的右附睾和左附睾用基于 Tris、柠檬酸、葡萄糖、蛋黄、甘油、抗生素和蒸馏水的扩展剂冲洗（扩展剂 II）。稀释后的精液冷却至 5°C，在液氮蒸气中冷冻。然后，使用计算机辅助精液分析系统检查冷冻/解冻精液的特性，并对 30 头奶牛和 9 头小母牛进行人工授精。
公牛 1 右附睾采集的新鲜精子活力为 70%（用扩展剂 II 稀释的精子），左附睾采集的新鲜精子活力为 60%（用 BioXcell 稀释的精子），而公牛 2 右附睾采集的新鲜精子活力为 90%（用扩展剂 II 稀释的精子）。公牛 1 左附睾和右附睾采集的精子解冻后即刻活力分别为 11%和 13%，公牛 2 为 48%。用冷冻/解冻的欧洲野牛精子对家牛和小母牛进行人工授精后，有两例妊娠。一例在妊娠 253 天后早产，另一例在妊娠 264 天后。
这是首例报道称用死后采集的冷冻解冻欧洲野牛精子进行人工授精可使家牛怀孕。本文提出的精子采集、稀释和冷冻保存方案可能有助于建立欧洲野牛的遗传资源库。
