A study of ovarian activity in the ewe using chronic catheterization of the utero-ovarian vein

Eighty-six adult, cyclic, anestrous and postpartum Ile-de-France ewes were placed under general anaesthesia. A catheter was inserted in the utero-ovarian vein (u.o.v.) of one or both ovaries in each ewe. The animals were kept unrestrained in pens and allowed to experience normal maternal behaviour, including suckling. Oestrus was detected with rams. Out of 167 catheters inserted, 70.7% allowed repetitive blood collection, 24.0% were obstructed for short periods and 5.4% remained completly blocked. Oestradiol- 17beta was assayed without extraction from the u.o.v. plasma samples. From these results, we conclude that this technique is suitable for investigating the mechanisms involved in the recovery of cyclical ovarian activity after parturition, particularly because the follicular response to endogenous gonadotropins can be assessed. This is not possible when plasma samples are obtained from a jugular vein.