Egg yolk, a major semen extender constituent, lacks a defined composition, therefore, there are biosecurity concerns with use of egg yolk. Cryopreservation of bull semen without inclusion of animal protein in the semen extender, therefore, is an important consideration. Cholesterol may be delivered and incorporated into the sperm plasma membrane by cyclodextrins to protect sperm during cryopreservation. The aim of this study was to determine suitability of a cholesterol-cyclodextrin semen extender, without inclusion of egg yolk, for cryopreservation of bull semen. Bull semen was collected and cryopreserved in either egg yolk or with inclusions of three different concentrations of cholesterol-cyclodextrin complex (0.5, 1 or 2 mg/mL semen) in Tris-glycerol (TG) extender. Sperm motion characteristics examined using the computer-assisted sperm analysis, and plasma membrane and acrosome integrity examined using flow cytometry, were similar for all extenders. The inclusion of the greatest concentration of cholesterol-cyclodextrin complex (2 mg/mL semen) followed by dilution in TG extender resulted in lesser pregnancy rates (P < 0.05). There was a pregnancy rate of as great as 56 % when sperm cryopreserved in 0.5 mg/mL cholesterol-cyclodextrin Tris-glycerol extender were used for artificial insemination following imposing of a hormonal treatment regimen for synchrony of timing of ovarian functions among cows for conducting fixed-time artificial insemination (FTAI). Results indicate cholesterol-cyclodextrin Tris-glycerol extender, with a chemically defined composition and without inclusion of egg yolk, may be used to cryopreserve bull sperm with there being acceptable pregnancy rates when this semen is used for FTAI.

蛋黄是一种主要的精液补充剂成分，缺乏确定的成分，因此，使用蛋黄存在生物安全问题。因此，在精液稀释剂中不包含动物蛋白的公牛精液冷冻保存是一个重要的考虑因素。胆固醇可以通过环糊精传递并结合到精子质膜中，以在冷冻保存过程中保护精子。本研究的目的是确定不包含蛋黄的胆固醇-环糊精精液补充剂是否适用于冷冻保存公牛精液。收集公牛精液并冷冻保存在蛋黄中或在 Tris-甘油 (TG) 增量剂中包含三种不同浓度的胆固醇-环糊精复合物（0.5、1 或 2 mg/mL 精液）。使用计算机辅助精子分析检查的精子运动特征，以及使用流式细胞术检查的质膜和顶体完整性，对于所有扩展剂都是相似的。包含最大浓度的胆固醇-环糊精复合物（2 mg/mL 精液），然后在 TG 稀释剂中稀释导致较低的妊娠率。P  < 0.05)。使用 0.5 mg/mL 胆固醇-环糊精 Tris-glycerol 补充剂冷冻保存的精子进行人工授精后，采用激素治疗方案以同步奶牛卵巢功能的时间进行固定，妊娠率高达 56%。 - 时间人工授精（FTAI）。结果表明，胆固醇-环糊精 Tris-甘油增量剂具有化学成分确定且不含蛋黄，可用于冷冻保存公牛精子，当该精液用于 FTAI 时，妊娠率可以接受。