Wilsher cervical forceps for artificial insemination technique in jennies

Abstract

The pregnancy rate after artificial insemination (AI) with fresh semen between jennies and mares seems to be similar. However, the jenny's cervix differs from the mare, it's longer and tortuous, being difficult the passage through the cervix to perform different reproductive procedures such as AI or embryo transfer. This retrospective study aimed to compare the pregnancy rate in jennies using two different methods of fresh semen AI. Eight native Argentinian jennies were used, characterized by a small body mass index, between 150 and 250 kg of body weight, and an average height of 1.20 m. Nineteen AI cycles performed between the 2019-2020 breeding season in Argentina were analyzed. Ovulation was induced during estrus using 1500 IU of hCG (Human Chorionic Gonadotropin, Ovusyn®, Zoetis) at the evidence of a preovulatory follicle ≥ 35 mm. They were inseminated with semen from two donkeys of proven fertility. An ultrasound was performed every 24h until ovulation and the interval between AI and ovulation was 12 to 48h. The jennies were evaluated by ultrasound, 15 days post ovulation for pregnancy diagnosis. For AI, two techniques were used: 1) conventional artificial insemination (n=11), where the AI catheter was inserted by hand through the vaginaand the fingers guided it through the cervix to the uterus, and 2) the Wilsher technique (n=8) which has been originally described for equine embryo transfer. The Polansky speculum was introduced in the vagina, the cervix was visualized with the aid of a flashlight and taken from the ventral segment with the Wilsher forceps. The pointed upper jaw of the opened forceps was inserted into the external os of the cervix and forceps jaws were closed grasping firmly the ventral segment of the cervix. To straighten the cervix and cervical canal the Wilsher forceps were pulled backward, and an AI catheter was inserted through the cervix to the uterus. A Fisher's exact test was performed to evaluate the pregnancy rate 15 days post ovulation. For statistical analysis, p<0.05 was considered statically significant. Pregnancy rates per cycle using conventional (54.5% (6/11)) or Wilsher forceps technique (75.0% (6/8)) were not statistically different (p=0.63). Our preliminary results suggest that both AI techniques are suitable to achieve high pregnancy rates per cycle although the application of Wilsher technique can be a specially useful tool in AI of small donkey breeds. In general, this technique is easier and faster than conventional jenny's AI due to her long and tortuous cervix. More experimental data are needed to confirm these results.