Ultrasonographic examination of ovarian structure dynamics in superovulated ewes

In this study, ultrasonography was used to monitor the superovulation progr ess in ewes in order to exclude animals with low or pathological ovarian re sponse. Ovaries of 17 mixed-breed ewes, superovulated with pregnant mare's serum gonadotropin (PMSG), were scanned daily by transrectal ultrasonograph y over a period of 10 days around oestrus. Plasma progesterone concentratio ns were measured daily. On the last day of the examination period, a laparo scopic examination of the ovaries was performed. The dynamics of the follic les and corpora lutea (CL) could be followed clearly. Animals with follicle s >8 mm at the day of insemination (Day 0) showed a progression of this sta tus until Day 5. No prediction of the ovulation rate was possible at this t ime. At Day 5 the number of CL was detected with an acceptable accuracy. It is recommended that a routine scanning of the ovaries prior to inseminatio n, selecting donors with follicles between 4 and 8 mm diameter and no folli cles larger than 8 mm for insemination. An ultrasonographic examination pri or to embryo recovery (Day 5) allows the exclusion of donors with low ovula tion rates (1-2 CL), avoiding unnecessary interventions.