Semen cryopreservation is not available for massive use in South American Camelids (SACs) due to the lack of an efficient protocol and the low pregnancy rates obtained with artificial insemination (AI). The use of a single cryoprotectant (CP) is commonly used in SACs frozen semen. The objective of the study was to evaluate the combined cryoprotective capacity of two permeable CPs at different stages of the cryopreservation protocol in llama semen. Sixteen ejaculates from 4 llama males were analysed, and sperm quality was assayed in raw semen, at 5°C, after equilibration of samples with the CPs and when samples were thawed. The following CPs and combination were used: 6% glycerol (GL), 6% dimethylformamide (DMF) and the combination of both CPs: 3% GL and 3% DMF. A Kruskal–Wallis test and an experimental factorial design, considering one factor with four levels (raw semen, 6% GL, 6% DMF and GL/DMF), were used. Total sperm motility and live sperm with intact acrosomes remained unchanged after equilibration of samples (p > .05). A significant decrease in the percentage of functional membrane, motile and live sperm with intact acrosomes was observed when samples were thawed (GL, DMF and GL/DMF). Nevertheless, the cryopreservation protocols used preserved sperm DNA quality; thus, sperm chromatin condensation and DNA fragmentation were unaffected (p > .05) when GL, DMF and GL/DMF were used. To conclude, no superiority was found between the use of a single or a combination of permeable cryoprotectants to freeze llama semen.

中文翻译：

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使用可渗透冷冻保护剂的组合冷冻保存美洲驼精液

由于缺乏有效的协议和人工授精 (AI) 获得的低妊娠率，精液冷冻保存无法在南美骆驼 (SAC) 中大量使用。在 SAC 冷冻精液中通常使用单一的冷冻保护剂 (CP)。该研究的目的是评估两种可渗透 CP 在低温保存方案的不同阶段对美洲驼精液的联合冷冻保护能力。分析了来自 4 只美洲驼雄性的 16 份精液，并在 5°C、样品与 CP 平衡后以及样品解冻后在原始精液中检测精子质量。使用了以下 CP 和组合：6% 甘油 (GL)、6% 二甲基甲酰胺 (DMF) 和两种 CP 的组合：3% GL 和 3% DMF。Kruskal-Wallis 检验和实验因子设计，考虑使用具有四个水平（原始精液、6% GL、6% DMF 和 GL/DMF）的一个因素。样本平衡后，总精子活力和具有完整顶体的活精子保持不变（p  > .05）。当样品解冻（GL、DMF 和 GL/DMF）时，观察到具有完整顶体的功能膜、活动精子和活精子的百分比显着降低。尽管如此，冷冻保存方案使用了保存精子 DNA 质量的方法。因此， 当使用 GL、DMF 和 GL/DMF 时，精子染色质凝聚和 DNA 断裂不受影响 ( p > .05)。总而言之，在使用单一或组合的渗透性冷冻保护剂冷冻美洲驼精液之间没有发现优势。