With the aid of the radioimmunoassay technique, the progesterone profile of 32 cows and their reproductive performance were studied. It was estimated that the base line between folicular and luteal phase was 1,12 ng (P4)/ml of skim milk. The first ovulation in postpartum occured within 36.83 ± 18.92 days. The authors suggested that there is no difference in time required to restart the ovarian function in the postpartum of animals in tropical or temperate climate.
ovarian activity; postpartum; dairy cow; progesterone; skim-milk