Theriogenology Department, Faculty of Veterinary Medicine, Cairo University, Giza Square, Egypt.
Reprod Domest Anim. 2024 Aug;59(8):e14709. doi: 10.1111/rda.14709.
Heat stress (HS) disrupts testicular homeostasis because of oxidative stress. N-acetylcysteine (NAC) is a thiol compound with antioxidants, anti-inflammatory and anti-apoptotic properties. As a sequel, this research aimed to assess the ameliorative effects of NAC supplementation on the reproductive performance of goat bucks kept under environmental HS. Primarily, Doppler examination as well as semen collection and evaluation were conducted on 12 mature bucks for 2 weeks (W) as pre-heat stress control (W1 and W2) during winter (February 2023). The temperature-humidity index (THI) was 63.4-64.3 (winter season). Then during summer HS conditions (from the beginning of July till the end of August 2023) bucks were assessed before NAC supplementation (W0), afterwards they were arbitrarily assigned into two groups. The control group (CON; n = 6) received the basal diet while the NAC group (n = 6) received the basal diet in addition to oral NAC daily for 7 weeks (W1-W7). The THI was 78.1-81.6 (summer season). Testicular blood flow parameters, serum concentration of nitric oxide (NO) and testosterone were measured. Additionally, total antioxidant capacity (TAC) and malondialdehyde (MDA) content in seminal plasma and semen quality parameters were evaluated. There were marked reductions (p < 0.05) in the resistive index (RI; W1, W4 and W5), pulsatility index (PI; W2 and W4-W7), and systolic/diastolic ratio (S/D; W4-W7) in the NAC group compared to the CON group. Furthermore, testosterone and NO levels were higher (p < 0.01 and p < 0.05, respectively) in the NAC group (W2, W3, W5 and W3-W5, respectively). Seminal plasma TAC increased (p < 0.05) and MDA decreased (p < 0.05) in the NAC group (W2, W4 and W5) compared to the CON group. Moreover, there were marked improvements (p < 0.05) in semen quality parameters (mass motility, total motility, viability and normal morphology) in the NAC group. In conclusion, oral NAC supplementation could be used to enhance the reproductive performance of goat bucks during HS conditions which is supported by remarkable enhancement in testicular haemodynamics, NO, testosterone levels and semen quality parameters.
热应激（HS）会破坏睾丸内环境稳态，原因是氧化应激。N-乙酰半胱氨酸（NAC）是一种含巯基的化合物，具有抗氧化、抗炎和抗凋亡作用。因此，本研究旨在评估 NAC 补充对在环境 HS 下饲养的公山羊繁殖性能的改善作用。首先，对 12 只成熟公山羊进行了多普勒检查以及精液采集和评估，持续 2 周（W）作为热应激前对照（W1 和 W2），时间为冬季（2023 年 2 月）。温湿度指数（THI）为 63.4-64.3（冬季）。然后，在夏季 HS 条件下（从 2023 年 7 月初到 8 月底），在 NAC 补充前（W0）对公山羊进行评估，之后它们被随机分为两组。对照组（CON；n=6）接受基础日粮，而 NAC 组（n=6）除了基础日粮外，每天还接受口服 NAC 补充 7 周（W1-W7）。THI 为 78.1-81.6（夏季）。测量了睾丸血流参数、血清一氧化氮（NO）和睾酮浓度。此外，评估了精液中总抗氧化能力（TAC）和丙二醛（MDA）含量以及精液质量参数。与 CON 组相比，NAC 组的阻力指数（RI；W1、W4 和 W5）、搏动指数（PI；W2 和 W4-W7）和收缩期/舒张期比值（S/D；W4-W7）均显著降低（p<0.05）。此外，NAC 组的睾酮和 NO 水平更高（p<0.01 和 p<0.05，分别为 W2、W3、W5 和 W3-W5）。与 CON 组相比，NAC 组的精液血浆 TAC 增加（p<0.05），MDA 减少（p<0.05）（W2、W4 和 W5）。此外，NAC 组的精液质量参数（精子活力、总活力、活力和正常形态）显著改善（p<0.05）。总之，口服 NAC 补充可以提高公山羊在 HS 条件下的繁殖性能，这得益于睾丸血液动力学、NO、睾酮水平和精液质量参数的显著提高。
