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A comparison was done of the ultrasound scanning of ovaries and examination of the hormonal profile of progesterone and 17β estradiol, through the control of the dynamic changes of the cyclic formations of the ovary during the reproductive cycle and early pregnancy of dairy cows. Total of 45 dairy cows were examined - 15 primiparous, 30 multiparous and 12 heifers of Holstein-Friesian breed on 3 dairy farms. The scanning of the ovaries was done with B-mode “real time” ultrasound scanners Aloka 210DX and SSD 500 Micrus (Japan) equipped with 5MHz rectal linear probes. The ultrasound observation was done every 2-3 days. On the same day immediately after the examination blood was collected from the examined cows into heparinized tubes. The blood plasma was separated by centrifugation at 3000rpm for 15 minutes and freezed afterwards on -30oC. The quantitative measurement of the progesterone (P4) and 17b estradiol (E2) concentration was done by the EIA method - “Progesterone and Estradiol serozyme” (Serono Diagnostic SA - Switzerland). In 4 separated experiments total of 54 complete reproductive cycles of the nonpregnant animals (4 heifers and 50 cows) and 21 pregnancies (0 to 27 - 44 days) in 8 heifers and 13 cows (3 primiparous and 10 pluriparous) were examined and analyzed. The results analysis has shown a high correlation rate between the ultrasound measurements of the Corpora Lutea diameters and the levels of progesterone in the peripheral blood. The exception was the onset of the cycle day 3-4 and the period of the regression of the CL both with low correlation due to the discrepancies in the morphological occurrence and the functional abilities of the CL. In the pregnant animals the size of the CL (>25 mm) viewed as a echogenic tissue was more or less constant after day 15 of the insemination. The level of progesterone reached its maximum about day 20 and followed by a slight decline and than stabilizing of its production. The follicle growth during the reproductive cycle was remarkably regular in 2 or 3 waves with more frequently occurrence of the first (65%). The duration of one wave was in average 11 days with significant differences between the cycles with 2 and 3 waves (p,0.003). Inside the wave phases could be separated on: phase of follicle occurrence, phase of dominant follicle selection and phase of its dominance. The level of 17b estradiol in the peripheral blood was significantly higher (p< 0.05) in the phase of the follicular growth, unovulatory and ovulatory waves than in the phase of the plateau and stagnation of the follicles. The correlation of E2 and the diameter of the follicles during the cycle was low (r<0.2), with exception of the onset of growth of the first wave of follicle population during the proestrus. In the pregnant animals the model of waves of follicular growth as well as the development of the dominant follicle occurred identically as in the unovulatory waves of the non pregnant animals.

Faculty of Veterinary Medicine

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