EFFECT OF BAROMETRIC PRESSURE ON GESTATION LENGTH IN COWS

Abstract

In an effort to determine the effects of barometric pressure on the length of gestation in cattle, two sets of data on calving dates with their corresponding barometric pressure readings were evaluated statistically. The first set of data were from three herds (367 calves), and were collected for two different periods - fall of 1979 and spring of 1980. Chi-square was used to test for significance. Result indicated that there was no significant difference between the rate of parturition in cattle and changes in barometric pressure (X² = 7.331, df = 2, P 0.05). The second set of data were on the length of gestation for two herds (94 calves) of different breeds. The cows were artificially inseminated. Multiple regression was performed between (Y variables) the deviation of each gestation length from 283 days i.e. the average gestation length of cattle and X Variables, the average barometric pressures during four six - hour periods on days of parturition and for three days prepartum (1:00 - 6:00 a.m. day of birth; 6:00 – 12:00 p.m. DB; 12:00 6:00 p.m. DB; 6:00 - 12:00 a.m. DB; 6:00 – 12:00 a.m. D₃).