l-Carnitine (LC) plays a key role in sperm metabolism, easily providing energy through β-oxidation, which positively affects motility. The objective of this study was to investigate the association between blood plasma and seminal plasma LC levels, as well as the effect of LC as an additive in a skimmed milk-based extender during sperm storage at 5°C. In the first experiment, semen and blood samples from 14 Quarter Horse stallions were used. The LC content in blood plasma and seminal plasma was determined by spectrophotometry and their relationships with seminal parameters were evaluated. In the second experiment, ejaculates (n = 16) from four Quarter Horses were used. Each ejaculate was split into four treatment groups with different LC concentrations: 0 (control), 0.5, 1.0, and 2.0 mM. Sperm motility, integrity of plasma and acrosomal membranes, intracellular reactive oxygen species content, and plasma membrane stability were evaluated immediately after samples reached 5°C (0 hour) and after 24, 48, and 72 hours. There was a positive correlation (p < 0.05) between LC levels in seminal plasma with both sperm concentration and plasma and acrosomal membrane integrity. Furthermore, the addition of LC (1 and 2 mM) preserved the motility of equine sperm stored at 5°C. It was concluded that the concentrations of LC with seminal plasma present correlate to semen parameters and the addition of LC to skimmed milk-based extender preserves the motility of equine sperm stored at 5°C for up to 48 hours.

中文翻译：

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左旋肉碱对液体储存期间马精液质量的影响。

l -肉碱 (LC) 在精子代谢中起着关键作用，很容易通过 β-氧化提供能量，从而对运动产生积极影响。本研究的目的是研究血浆和精浆 LC 水平之间的关联，以及在 5°C 精子储存期间，LC 作为脱脂牛奶补充剂中的添加剂的影响。在第一个实验中，使用了 14 匹 Quarter Horse 种马的精液和血液样本。通过分光光度法测定血浆和精浆中的LC含量并评估它们与精液参数的关系。在第二个实验中，射精（n = 16) 来自四匹夸特马。每个射精被分成具有不同 LC 浓度的四个处理组：0（对照）、0.5、1.0 和 2.0 mM。在样品达到 5°C（0 小时）后和 24、48 和 72 小时后立即评估精子活力、质膜和顶体膜的完整性、细胞内活性氧含量和质膜稳定性。呈正相关（p < 0.05) 在精浆中的 LC 水平与精子浓度和血浆和顶体膜完整性之间。此外，添加 LC（1 和 2 mM）可保持储存在 5°C 下的马精子的活力。得出的结论是，存在精浆的 LC 浓度与精液参数相关，并且将 LC 添加到基于脱脂牛奶的补充剂中可以保持在 5°C 下储存长达 48 小时的马精子的活力。