Gamete and Embryology (GAME) Laboratory, College of Public Health, Medical & Veterinary Sciences, James Cook University, Townsville, Queensland, Australia.
Discipline of Veterinary Science, College of Public Health, Medical & Veterinary Sciences, James Cook University, Townsville, Queensland, Australia.
PLoS One. 2019 Apr 30;14(4):e0216143. doi: 10.1371/journal.pone.0216143. eCollection 2019.
Heat stress-induced sperm DNA damage has recently been demonstrated in boars during tropical summer; which could negatively impact early embryo survival and litter size in sows. Given the boar's inefficient capacity to sweat, non-pendulous scrotum and low antioxidant activity in seminal plasma, elevated endogenous levels of antioxidants are needed to combat reactive oxygen species induced during periods of heat stress. This should prevent the build-up of pathological levels of DNA damage in boar spermatozoa. Our aim was to investigate whether a combined antioxidant supplement could mitigate sperm DNA damage in boars exposed to tropical summer conditions. Terminal deoxynucleotidyl transferase dUTP nick end labelling and flow cytometry of 20,000 spermatozoa/boar/treatment revealed that boar diets supplemented with 100 g/day custom-mixed antioxidant during peak wet summer effectively reduced sperm DNA damage by as much as 55% after 42 and 84 days treatment respectively (16.1 ± 4.9 peak wet control vs. 9.9 ± 4.5 42 day vs. 7.2 ± 1.6% 84 day treatments; P ≤ 0.05). Supplementation did not improve sperm concentration beyond control levels for either season (P > 0.05); nor alter total motility, progressive motility or several other motion parameters measured by computer assisted sperm analysis of 20 x 106 sperm/mL at 38°C (P > 0.05). Antioxidant supplementation during tropical summer appears to mitigate the negative impact of heat stress on DNA integrity but not concentration nor motility of boar spermatozoa; which may provide one solution to the problem of summer infertility in the pig.
热应激导致的精子 DNA 损伤最近在热带夏季的公猪中得到证实；这可能会对母猪的早期胚胎存活率和产仔数产生负面影响。鉴于公猪的出汗效率低下、阴囊不下垂和精液中抗氧化剂活性低，需要提高内源性抗氧化剂水平来对抗热应激期间产生的活性氧。这应该可以防止公猪精子中 DNA 损伤的病理性积累。我们的目的是研究在热带夏季条件下，联合抗氧化补充剂是否可以减轻公猪的精子 DNA 损伤。对 20,000 个精子/头/处理进行末端脱氧核苷酸转移酶 dUTP 缺口末端标记和流式细胞术分析表明，在潮湿的夏季高峰期，每天补充 100 克定制混合抗氧化剂的公猪日粮可有效降低精子 DNA 损伤，分别在 42 天和 84 天治疗后降低多达 55%（16.1 ± 4.9 峰值湿对照组与 9.9 ± 4.5 42 天治疗组相比，7.2 ± 1.6% 84 天治疗组；P ≤ 0.05）。补充剂并没有提高两个季节的精子浓度超过对照水平（P > 0.05）；也没有改变总活力、前向运动活力或在 38°C 下通过计算机辅助精子分析测量的 20 x 106 个精子/mL 的其他几个运动参数（P > 0.05）。在热带夏季补充抗氧化剂似乎可以减轻热应激对 DNA 完整性的负面影响，但不能提高公猪精子的浓度或活力；这可能是解决猪夏季不育问题的方法之一。
