OVARIAN ACTIVITY IN ULTRASOUND IMAGE AND MILK PROGESTERONE CONCENTRATION IN POSTPARTUM DAIRY-COWS

Eighteen pluriparous dairy cows were ultrasonographically observed twi ce a week from day 9-10 post partum to the 2nd ovulation. Milk samples were taken three times a week and progesterone was assayed by RIA. Be fore the 1st postpartum ovulation and during the 1st sexual cycle, 1.0 9 +/- 1.09 and 1.8 +/- 1.11, respectively, subordinate follicles and 1 .5 +/- 0.52 and 2.4 +/- 0.72, respectively, follicular waves were foun d. The 1st ovulation occurred 17.9 +/- 5.04 days after parturition, th e length of the 1st sexual cycle was 19.4 +/- 4.66 days and clinical i nvolution of the uterus was completed 22.6 +/- 4.34 days after parturi tion. The period from parturition to the time of the 1st postpartum ov ulation and the length of the lst sexual cycle were positively correla ted with the number of follicular waves during the periods. About 81% of the first postpartum follicular waves and 88% of the lst ovulations occurred in the ovary contralateral to the previous pregnant uterine horn. The differences disappeared after the 1st postpartum ovulation. Average values of milk progesterone were discovered during the 1st and 2nd sexual cycles at day 5-7 (5.9 +/- 4.78 and 6.3 +/- 5.16 ng/ml) an d at day 10-12 (5.6 +/- 5.83 and 11.4 +/- 7.74 ng/ml).