Abstract：
The aim of this study was to evaluate two cryoprotectants, dimethylformamide (DMF) and methylformamide (MF) in two concentrations (5 and 7 %) in vitro in donkey semen using a rapid freezing technique and the effect on pregnancy rates in mares. Twenty-four ejaculates from 8 jacks (n = 8; r = 3) were divided into 4 extenders: BotuSemen Gold with 5 % or 7 % MF and 5 % or 7 % DMF, all containing 11 % lactose, 20 % egg-yolk and 0.5 % Equex. Post-thaw evaluations included: sperm motility, membrane function and acrosome status. A linear mixed effect model was used to test the effect of different freezing media on semen parameters. No differences were observed between the 4 freezing media used, for any of the seminal parameters (P > 0.05). However, samples with 5 % DMF showed the highest percentages of sperm with acrosomes and functional membranes (DMF: 5 %: 53.67 ± 22.01; 7 %: 33.92 ± 23.4; MF: 5 %: 44.5 ± 20.46; 7 %: 38.75 ± 27.4) (Data: mean ± SD; P > 0.05). Hence, thirty mares were inseminated: 15 with 5 % DMF and 15 with 7 % DMF. The pregnancy rate was 46 % (7/15) and 0 % (0/15) using the extender with 5 % or 7 % DMF, respectively (P = 0.003). To conclude, the use of 5 % or 7 % of MF or DMF did not affect the in vitro parameters. Despite the lack of differences in vitro with the two DMF concentrations, in vivo results only showed pregnancies when using 5 % DMF. Thus, the results of this study demonstrate the importance of accompanying in vitro semen evaluations with studies that evaluate post-insemination pregnancy rates.
摘要：
这项研究的目的是评估两种冷冻保护剂，使用快速冷冻技术在驴精液中使用两种浓度（5％和7％）的二甲基甲酰胺（DMF）和甲基甲酰胺（MF），以及对母马妊娠率的影响。来自8个插孔（n=8;r=3）的24个射精分为4种补充剂：含5％或7％MF和5％或7％DMF的BotuSemenGold，都含有11%的乳糖，20％蛋黄和0.5％Equex。解冻后的评估包括：精子活力，膜功能和顶体状态。采用线性混合效应模型检验不同冷冻介质对精液参数的影响。使用的4种冷冻培养基之间没有观察到差异，对于任何开创性参数(P>0.05)。然而,含5％DMF的样本显示精子中具有顶体和功能膜的精子百分比最高（DMF：5％：53.67±22.01；7％：33.92±23.4；MF：5％：44.5±20.46；7％：38.75±27.4）（数据：平均值±SD；P>0.05）。因此，30只母马被授精:15只含有5%DMF,15只含有7%DMF。使用含有5%或7%DMF的补充剂，妊娠率为46%(7/15)和0%(0/15)，分别为(P=0.003)。最后，使用5%或7%的MF或DMF不影响体外参数。尽管两种DMF浓度在体外缺乏差异，体内结果仅在使用5％DMF时显示怀孕。因此，这项研究的结果证明了在评估授精后妊娠率的研究中进行体外精液评估的重要性.
