Smith R L, Berndtson W E, Unal M B, Pickett B W
J Dairy Sci. 1979 Aug;62(8):1297-303. doi: 10.3168/jds.S0022-0302(79)83415-3.
The influence of percent egg yolk during cooling from 37 to 5 C on ability of sperm to withstand subsequent freezing was studied with semen from each of eight bulls. Treatments were arranged factorially and included .5, 1, 2, 4, 8, 16, and 32% egg yolk, cooling times of .5, 1, 2, and 4 h, and freezing in ampules and straws. Percent egg yolk did not influence motility or percent intact acrosomes when semen was frozen in ampules. For sperm in straws, both post-thaw percentages of motile sperm and intact acrosomes were similar for sperm cooled with .5, 1, 2, 4, or 8% egg yolk and greater than with 16 or 32% egg yolk. Optimal egg yolk during cooling was not dependent upon rate of cooling, regardless of how semen was packaged for freezing. The influence of percent egg yolk during freezing was investigated in a second study. Treatments included eight bulls; 1, 2, 4, 8, 16, and 32% egg yolk; freezing times from +5 to -130 C of 3.5, 20, and 40 min; and freezing in ampules or straws. Optimal egg yolk during freezing in either ampules or straws was independent of the rate of freezing. For sperm frozen in ampules, differences in motility or the percent intact acrosomes due to egg yolk were small. However, the use of only 1 or 2% egg yolk depressed motility whereas 16 or 32% egg yolk decreased the percentage of intact acrosomes. Thus, extremely high or low egg yolk should be avoided. For sperm in straws, survival was optimal when the extended semen contained 4 to 32% egg yolk during freezing.
用8头公牛的精液研究了从37℃冷却至5℃过程中蛋黄百分比对精子后续耐冻能力的影响。处理采用析因设计，包括0.5%、1%、2%、4%、8%、16%和32%的蛋黄、0.5小时、1小时、2小时和4小时的冷却时间，以及安瓿和细管冷冻。当精液在安瓿中冷冻时，蛋黄百分比不影响精子活力或完整顶体百分比。对于细管中的精子，用0.5%、1%、2%、4%或8%蛋黄冷却的精子，解冻后活动精子百分比和完整顶体百分比相似，且高于用16%或32%蛋黄冷却的精子。冷却过程中的最佳蛋黄百分比不取决于冷却速度，无论精液如何包装冷冻。在第二项研究中调查了冷冻过程中蛋黄百分比的影响。处理包括8头公牛；1%、2%、4%、8%、16%和32%的蛋黄；从+5℃至-130℃的冷冻时间为3.5分钟、20分钟和40分钟；以及安瓿或细管冷冻。安瓿或细管冷冻过程中的最佳蛋黄百分比与冷冻速度无关。对于安瓿中冷冻的精子，由于蛋黄导致的活力或完整顶体百分比差异较小。然而，仅使用1%或2%的蛋黄会降低活力，而16%或32%的蛋黄会降低完整顶体百分比。因此，应避免使用极高或极低的蛋黄。对于细管中的精子，当冷冻过程中精液稀释液含有4%至32%的蛋黄时，存活率最佳。
