Postpartum ovarian activity in dairy cows: Correlation between behavioral estrus, pedometer measurements and ovulations.

The efficacy of pedometers as estrus detection aids was tested in a group of 47 Holstein cows during the postpartum period. Pedometers were strapped on the left front leg of each cow on the day of parturition and pedometer measurements were recorded twice daily for 60 days. The cows were also observed twice a day for behavioral signs of estrus. Daily blood samples were collected during Days 1-30, and thereafter once every two days from Days 30-60 after parturition for progesterone assay. Rectal palpations of the ovaries were carried out once every four days during the first month after parturition. Based on the progesterone profiles and rectal palpation findings, 91 ovulations were recorded in 42 cows and 5 cows remained acyclic during the observation period. Seventy-six percent (69 91 ) of the ovulations were associated with pedometer indications of estrus, while only 35% (32 91 ) of the ovulations were associated with observed estrus. Fifty-seven percent (24 42 ) of the first postpartum ovulations were associated with pedometer measurements, but only 19% (8 42 ) of the first postpartum ovulations were associated with behavioral signs of estrus. Similarly, pedometers were superior to observations as a method of detection of estrus associated with the second and third postpartum ovulations (91% vs 37%, 92% vs 78% respectively). It is concluded that pedometers are useful aids for estrus detection, particularly in the immediate postpartum.