L-proline has been reported to be useful in semen cryopreservation. However, its use has rarely been reported in the freezing of boar semen. The objective of this study was to evaluate the effects of different concentrations of L-proline (0, 10, 30, 50, and 90 mM) on the quality of boar semen after freezing and thawing. Semen samples from boars (n = 6) were frozen using freezing extenders with added concentrations of L-proline. Total sperm motility, progressive motility, survival time at 37 °C, acrosome integrity, mitochondrial activity, DNA integrity, the content of the lipid peroxidation product malondialdehyde (MDA), total antioxidant capacity (T-AOC) and, expression levels of apoptosis protein (cleaved caspase 3 and Bax) were evaluated after thawing. The results showed that total sperm viability (73.96% vs. 63.58%) and progressive motility (56.88% vs. 47.26%) after thawing were significantly higher in the 10 mM L-proline treatment group than in the control group. The survival time at 37 °C and the total motility of sperm in the 10 mM group within one hour after thawing were significantly higher than in the control group. Acrosome integrity and mitochondrial activity of sperm in the 10 mM group were significantly higher than those in the control, 50 mM, and 90 mM groups. The DNA integrity rate in the 10 mM group was significantly higher than in the control group. The L-proline treatment did not affect sperm MDA content or T-AOC. The expression levels of apoptosis protein (cleaved caspase 3 and Bax) in the 10 mM L-proline supplemented group were lower than those in the control group. In conclusion, the freezing extender containing 10 mM L-proline improved semen quality after freezing and thawing and thus would be a useful reagent for boar semen cryopreservation.

据报道， L-脯氨酸可用于精液冷冻保存。然而，其在公猪精液冷冻中的应用却鲜有报道。本研究的目的是评估不同浓度的L-脯氨酸（0、10、30、50和90 mM）对冻融后公猪精液质量的影响。 使用添加了L-脯氨酸浓度的冷冻稀释剂冷冻公猪 ( n = 6) 的精液样本。精子总活力、前进活力、37℃存活时间、顶体完整性、线粒体活性、DNA完整性、脂质过氧化产物丙二醛（MDA）含量、总抗氧化能力（T-AOC）、凋亡蛋白表达水平（裂解的 caspase 3 和 Bax）在解冻后进行评估。结果显示，10 mM  L-脯氨酸处理组解冻后的总精子活力（73.96% vs. 63.58%）和前向运动力（56.88% vs. 47.26%）显着高于对照组。10 mM组在37℃下的存活时间以及解冻后1小时内的精子总活力均显着高于对照组。10 mM组精子顶体完整性和线粒体活性显着高于对照组、50 mM和90 mM组。10 mM组的DNA完整性率显着高于对照组。L-脯氨酸处理不影响精子MDA含量或T-AOC。10 mML-脯氨酸补充组中凋亡蛋白（cleaved caspase 3和Bax）的表达水平 低于对照组。总之，含有10 mM  L-脯氨酸的冷冻稀释剂改善了冷冻和解冻后的精液质量，因此将成为公猪精液冷冻保存的有用试剂。