Ekipaj, C/ Valencia 3, 28223 Pozuelo de Alarcón, Madrid, Spain.
Theriogenology. 2010 Jul 1;74(1):60-6. doi: 10.1016/j.theriogenology.2009.12.019. Epub 2010 Mar 1.
The objective of this study was to analyze the relative roles of high temperature and photoperiod as environmental factors of seasonal infertility in swine. The results of five years (2003-2007) of ultrasound pregnancy diagnosis carried out in 266 indoor farms were analyzed. For all farms, the data covered the entire study period. The farms were situated in four French regions. The data of 22,773 batches and 610,117 sows were included. Seasonal infertility was defined as the relative difference between the fertility rate in 'summer' (inseminations in weeks 25-42) and 'winter' (inseminations in weeks 1-18 of the same year). In each region, two meteorological variables were defined, based on the data of a reference weather station: the number of hot days (maximum temperature >or= 25 degrees C) and tropical days (maximum temperature >or= 32 degrees C and minimum temperature >or= 18 degrees C). The mean fertility was 85%. The median seasonal infertility was 2.8% and more than 7.1% for a quarter of farms. Seasonal infertility did not vary with areas or baseline fertility (defined for each studied farm as the average winter fertility over five years). Seasonal infertility differed with the year (p<0.001). Seasonal infertility was significantly higher during 2003 than in the other four years, which did not differ among each other. In the four regions, 2003 was the year with the highest number of hot days and 2007 with the least. Our study strengthens the hypothesis of a prominent role of photoperiod in seasonal infertility and of an additional role of heat stress the hottest years.
本研究旨在分析高温和光周期作为猪季节性不孕的环境因素的相对作用。分析了在 266 个室内农场进行的为期五年（2003-2007 年）的超声妊娠诊断结果。对于所有农场，数据涵盖了整个研究期间。农场位于法国的四个地区。共包括 22773 批和 610117 头母猪的数据。季节性不孕定义为“夏季”（第 25-42 周授精）和“冬季”（同年第 1-18 周授精）之间的授精率的相对差异。在每个地区，根据参考气象站的数据，定义了两个气象变量：高温天数（最高温度≥25°C）和热带天数（最高温度≥32°C，最低温度≥18°C）。平均受孕率为 85%。季节性不孕的中位数为 2.8%，超过四分之一的农场的季节性不孕超过 7.1%。季节性不孕与地区或基础受孕率（定义为每个研究农场五年的冬季平均受孕率）无关。季节性不孕随年份而变化（p<0.001）。2003 年的季节性不孕明显高于其他四年，且这四年之间没有差异。在四个地区，2003 年是高温天数最多的一年，而 2007 年是高温天数最少的一年。我们的研究加强了光周期在季节性不孕中起主要作用的假设，以及热应激在最热年份中起额外作用的假设。
