Department of Animal and Grassland Sciences, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan.
Center for Animal Disease Control, University of Miyazaki, Miyazaki, Japan.
PLoS One. 2019 Jul 23;14(7):e0220255. doi: 10.1371/journal.pone.0220255. eCollection 2019.
Several external factors including lunar cycle and weather conditions might be associated with calving conditions. Our objective here was to determine the effects of lunar cycle and weather conditions on calving frequency and the occurrence of preterm calving in Japanese Black cows. Calving records were obtained from 905 farms in Miyazaki Prefecture, Japan. Data were collected from 41,116 calvings. We conducted two studies: Study 1 investigated the effects of lunar cycle and weather conditions on daily calving frequency (DCF) with the observational unit of each day and Study 2 investigated those effects on the occurrence of preterm calving with the observational unit for each calving. Preterm calving was defined by whether or not a cow calving before 280 days of gestation, lower 10th percentile of gestation length of the collected data, and by whether or not a cow calving before 289 days of gestation, median of the gestation length. For Study 1, lunar cycle was not associated with DCF in all cows, in only primiparous cows and in only multiparous cows. As well as lunar cycle, weather conditions such as temperature, diurnal temperature variation, the temperature-humidity index, precipitation amount, barometric pressure, relative humidity and solar radiation, were also not associated with DCF. For Study 2, lunar cycle phases were not associated with the occurrence of preterm calving. However, preterm calving was associated with all of the weather conditions (P < 0.05) except for precipitation amounts and solar radiation. Temperature, the temperature-humidity index and relative humidity were positively associated with the occurrence of preterm calving. In contrast, diurnal temperature variations and barometric pressure were negatively associated with the occurrence of preterm calving. In conclusion, the lunar cycle was not associated with DCF and preterm calving, but the weather conditions were associated with preterm calving.
一些外部因素，包括月相和天气条件，可能与分娩条件有关。我们的目的是确定月相和天气条件对日本黑牛分娩频率和早产分娩发生率的影响。分娩记录来自日本宫崎县的 905 个农场。数据收集自 41116 次分娩。我们进行了两项研究：研究 1 调查了月相和天气条件对每日分娩频率（DCF）的影响，以每天为观察单位；研究 2 以每次分娩为观察单位，调查了这些因素对早产分娩发生率的影响。早产分娩的定义是牛是否在妊娠 280 天之前分娩，所收集数据的妊娠长度第 10 个百分位数以下，或牛是否在妊娠 289 天之前分娩，妊娠长度中位数以下。对于研究 1，在所有牛、初产牛和经产牛中，月相均与 DCF 无关。除了月相，温度、日温差、温湿度指数、降水量、气压、相对湿度和太阳辐射等天气条件也与 DCF 无关。对于研究 2，月相阶段与早产分娩的发生无关。然而，除了降水量和太阳辐射外，所有天气条件（P < 0.05）都与早产分娩有关。温度、温湿度指数和相对湿度与早产分娩的发生呈正相关。相反，日温差和气压与早产分娩的发生呈负相关。总之，月相与 DCF 和早产分娩无关，但天气条件与早产分娩有关。
