Sexton T J
Poult Sci. 1980 Dec;59(12):2765-70. doi: 10.3382/ps.0592765.
Optimal rates for cooling chicken semen from +5 to -196 C were determined. Semen was diluted 1:5 with Beltsville Poultry Semen Extender and held at 5 C for 2 hr before adding dimethylsulfoxide (DMSO), 4% v/v. The semen-DMSO mixture was allowed to equilibrate for 2 hr at 5 C before it was placed in a plastic freeze straw of .5 cc capacity. A two step controlled-rate procedure was used to test the various cooling rates (1 to 50 C/min) through certain temperature ranges (+5 to -20 C and -20 to -180 C) and to determine the optimal semen temperature for making the transition of cooling in alcohol (Step 1) to cooling in liquid nitrogen (LN2) vapor (Step 2). Fertilizing capacity of spermatozoa was maximal when semen samples were cooled from +5 C to -20 C at a rate of 1 C/min (Step 1), then transferred to LN2 vapor (Step 2) and cooled to -80 C at 30 C/min before the samples were plunged in liquid nitrogen. After storage in LN2 for 24 hr and subsequent thawing at +2 C, the fertilizing capacity of the sperm was 47%.
确定了将鸡精液从+5℃冷却至-196℃的最佳速率。精液用贝尔茨维尔家禽精液稀释液按1:5稀释，并在添加4%（v/v）的二甲基亚砜（DMSO）之前于5℃保存2小时。精液-DMSO混合物在5℃平衡2小时后，放入0.5毫升容量的塑料冷冻细管中。采用两步控速程序来测试在特定温度范围（+5℃至-20℃和-20℃至-180℃）内的各种冷却速率（1至50℃/分钟），并确定从酒精冷却（步骤1）过渡到液氮（LN2）蒸汽冷却（步骤2）时精液的最佳温度。当精液样本以1℃/分钟的速率从+5℃冷却至-20℃（步骤1），然后转移至LN2蒸汽（步骤2）并以30℃/分钟的速率冷却至-80℃，再将样本投入液氮中时，精子的受精能力最大。在液氮中储存24小时并随后在+2℃解冻后，精子的受精能力为47%。
