[The forecasting of the time of calving using a rapid progesterone test]

The rectal temperature and any alterations in eight different external signs of parturition were investigated twice daily in 22 "Deutsche Schwarzbunte" cows during the last 10 days of gestation. There was great variation in the externally detectable signs of parturition during the preparatory stages and short before labour. During the same time period, plasma progesterone and total oestrogens were determined using radioimmunology. From 60 hours to 12 hours prior to calving the progesterone levels fell rapidly to 0.77 +/- 0.22 ng/ml. Additionally, the plasma progesterone was determined semi-quantitatively in 31 cows using a rapid progesterone assay in order to predict the commencement of parturition within 36 hours. This allowed a more objective and reliable assessment of calving time than the evaluation of external signs of labour.