Influence of meteorological events on obstetrical data in cattle and swine.

In a interdisciplinary scientific cooperation involving human and veterinarian obstetricians and meteorologists, an attempt was made to correlate the obstetrical data of cows and pigs with meteorologically defined weather events. During the observation period of 10 years the parturitions of cattle (n = 645) showed no significant statistical connection to the weather on day of delivery, the day before parturition or the day after. The only significant result in cattle was a shortening of the gestation period by 4.9 days in a group of cows that went into labour on, or after, the sixth day of a constant weather situation. Significant variations in the duration of gestation in swine (n = 786) were related to the weather on the day of delivery; central high-gradient anticyclonic spring, summer and autumn weather was linked to an extension of the pregnancy by nearly 1 day, while cyclonic central low-gradient weather during autumn was related to a shortening of pregnancy by approximately 1 day. The weather on the day before parturition was also correlated with the duration of gestation in swine. In this respect, low-gradient cyclonic autumn weather coincided with gestation periods that were reduced by 0.95 days, while central anticyclonic winter and spring weather coincided with extensions of gestation of 0.98 and 1.12 days, respectively. Compared with labour during low-gradient anticyclonic weather, the course of labour in pigs was significantly protracted by approximately 1.5 h during low-gradient cyclonic weather. Weather fronts on the day before, the day after or on the day of labour had no influence on the gestation and parturition data collected in either species.