The occurrence of abomasal displacement in dairy cows modified by the weather situation

For abomasal displacement of dairy cows the empirical indication was investigated if a specific weather situation is correlated with its occurrence. Therefore the hypothe-sis was tested if the weather situation, which is characterised by specific meteoro-logical parameters or the temporal change of the weather situation, has an influence on the observed prevalence of abomasal displacements. The empirical data were collected for the years 2000 and 2001 in the area around Lisbon at 26 farms all with about 6500 Holstein-Friesian milk cows and with 326 cases of abomasal displace-ments in total. The weather situation was characterised by following meteorological parameters on daily basis: Atmospheric pressure, relative humidity, precipitation, daily insolation, maximum air temperature, minimum air temperature, average wind velocity (km/h). These original parameters were modified for the statistical analyses: atmospheric pressure, water vapour pressure, relative humidity, temperature, tem-perature range, precipitation, insolation, wind speed. The change of the weather situation was described by the mean absolute deviation (deviation of the meteoro-logical parameters from the running mean over a period of 5 and 10 days) and by a method which was based on the principal component analyses of the entire data set. For the weather situation only a weak influence on the occurrence of abomasal dis-placements could be found by a linear correlation- and regression analysis for follow-ing parameters: water vapour pressure, relative humidity, temperature, temperature range, precipitation, and insolation. Even if a high cross-correlation between these parameters could be found, a higher (lower) probability of abomasal displacement can be expected for following parameters: low (high) water vapour pressure, high (low) relative humidity, low (high) air temperature, low (high) temperature range, high (low) precipitation, low (high) insolation. For wind velocity and atmospheric pressure no statistically significant linear regression could be found. A time series analysis showed, a higher prevalence for abomasal displacement due to the change from sunny, warm and dry days to cool, overcast and humid days. From the present work it can be concluded that the meteorological situation has an influence on the occur-rence of abomasal displacement. Therefore the weather situation should be included among the predisposing causes of the occurrence of abomasal displacements.