Clinic of Farm Animals, School of Veterinary Medicine, Aristotle University of Thessaloniki, St. Voutyra 11, Thessaloniki, Greece.
Anim Reprod Sci. 2012 Dec;136(1-2):33-41. doi: 10.1016/j.anireprosci.2012.10.017. Epub 2012 Nov 1.
The objective of this study was to investigate the effect of microclimatic conditions on DNA integrity of bovine sperm. DNA fragmentation of frozen-thawed sperm was analyzed in monthly semen samples of nine AI bulls ejaculating in weekly routine for one year. The extent of DNA fragmentation was determined using the Sperm Chromatin Structure Assay (SCSA™) and quantified by the DNA fragmentation index (DFI) and the percentage of sperm showing high DFI values (%DFI) immediately (0h) and 3h (3h) after thawing. Microclimatic factors (ambient air temperature, relative humidity, dew point) were recorded in hourly intervals throughout the year. Their mean values were calculated for seven different time periods (up to day 56) preceding ejaculation (day 0). DFI (P<0.01) and its relative change between 0h and 3h (P<0.05) were related to the set of microclimatic parameters recorded the last 11 days and from day 49 to 43 prior to ejaculation, respectively. A significant relationship was detected between %DFI and microclimatic parameters of days 35-29 preceding ejaculation (P<0.05), while the degree of change of %DFI from 0h to 3h was related to microclimatic parameters recorded from day 28 to 22 before ejaculation (P<0.05). Dew point and relative humidity appeared to be the strongest and weakest predictors of DNA integrity, respectively. In conclusion, the results of the present study showed a lag effect of microclimate on DNA integrity of frozen-thawed bovine sperm. However, microclimatic parameters of a single time period before ejaculation could not be identified as the source of variation of different SCSA parameters.
本研究旨在探讨微气候条件对牛精子 DNA 完整性的影响。在为期一年的每周例行射精中，对 9 头人工授精公牛的每月精液样本进行冷冻解冻精子 DNA 碎片化分析。使用精子染色质结构分析（SCSA）测定 DNA 碎片化程度，通过 DNA 碎片化指数（DFI）和显示高 DFI 值的精子百分比（%DFI）进行量化，分别在解冻后即刻（0h）和 3h（3h）进行。全年以每小时间隔记录微气候因素（环境空气温度、相对湿度、露点）。在射精前（第 0 天）的七个不同时间段（最多至第 56 天）计算其平均值。DFI（P<0.01）及其在 0h 和 3h 之间的相对变化（P<0.05）分别与记录的最后 11 天和射精前第 49 天至第 43 天的微气候参数有关。在射精前第 35-29 天检测到 %DFI 与微气候参数之间存在显著相关性（P<0.05），而从 0h 到 3h 的 %DFI 变化程度与射精前第 28 天至第 22 天记录的微气候参数有关（P<0.05）。露点和相对湿度似乎是 DNA 完整性的最强和最弱预测因子。总之，本研究结果表明，微气候对冷冻解冻牛精子 DNA 完整性存在滞后效应。然而，射精前单一时间段的微气候参数不能确定为不同 SCSA 参数变化的来源。
