LH PROFILE AND ADVANCEMENT OF OVULATION AFTER TRANSCERVICAL INFUSION OF SEMINAL PLASMA AT DIFFERENT STAGES OF ESTRUS IN GILTS

The influence of a transcervical infusion of seminal plasma on preovul atory LH profiles and the advancement of ovulation after seminal plasm a infusion for different times during oestrus were investigated using the single uterine horn infusion technique (Mariensee model), in combi nation with transcutaneous sonographic monitoring of the ovaries. Prep arative surgery in 23 German Landrace gilts comprised the detachment o f the left uterine horn from the corpus, leaving the caudal end open t o the peritoneal cavity but sealing the corpus wound. In six gilts fit ted with a permanent jugular vein catheter the patent hems were admini stered a transcervical infusion of seminal plasma (n = 5 cycles) or PB S (n = 4 cycles) immediately after the detection of oestrus by a tease r boar. In addition, 17 non-catheterized gilts received infusions of s eminal plasma either 0 h (n = 3 gilts), 16 h (n = 7 gilts) or 24 h (n = 7 gilts) after the detection of oestrus. Seminal plasma infusion at the onset of oestrus provoked ovulation in the ipsilateral ovary of th e treated horn 8.5 +/- 0.9 h earlier than in the contralateral (contro l) ovary. Seminal plasma did not influence the LH profile compared wit h PBS (P > 0.05), but shortened the interval between the LH peak and i psilateral ovulation to 23.4 +/- 4.0 h compared with 31.8 +/- 3.4 h in the contralateral ovulation (P less than or equal to 0.01). Infusion 16 h after the onset of oestrus reduced the effect to 4.6 +/- 3.8 h wi th a wide range of 0-8 h (P < 0.01). The effect was more pronounced in gilts with long intervals between the onset of oestrus and contralate ral ovulation compared with earlier ovulation on the control ovary. Se minal plasma infusion less than 16 h before contralateral ovulation an d 24 h after the detection of oestrus had no effect. It is concluded t hat transcervical infusion of seminal plasma early in oestrus synchron izes the variable intervals between the onset of oestrus and ovulation in sows by a locally active mechanism.