Comparison of single timed artificial insemination (AI) in gilts using OvuGel-ELANCO (triptorelin acetate) or PG600-MERCK (eCG/pLH) to synchronize ovulation
Project 16-003 - Lead Researcher: Bob Friendship
Research Summary – Project 16/03
Funding approved in 2016 and project completed in 2017
Lead Researcher: Bob Friendship
Graduated student: Lima Rodrigues completed her MSc in December 2017 at the University of Guelph
Optimal sow fertility is during the 24-hour period before ovulation. Among sows and gilts there is great variation in duration of estrus and in the estrus-to-ovulation interval which makes timing AI challenging. The variation can result in inseminations that are too soon or too late relative to ovulation and the result is reduced conception rates. Control of estrus and ovulation are important tools to help reduce the reliance on estrus detection for successful timing of insemination. Previous research from the University of Guelph has demonstrated success with fixed time single dose insemination of sows when using a protocol of an injection of equine chorionic gonadotropin (eCG) to induce estrus followed by an injection of porcine luteinizing hormone (pLH) to induce ovulation (protocol #1). The research group has now completed a study using a second protocol for inducing a predictable ovulation in weaned sows using an intravaginal gel (OvuGel, ELANCO)(protocol #2). The treatment is applied 96 h after weaning and the resulting predictable ovulation allows for an application of a single fixed-time insemination.
While proven in sows, the research had not been tested on gilts. With the annual gilt replacement rate approaching 50%, overall improvement in herd reproductive efficiency must include improved gilt performance. In addition, with the increasing popularity of batch farrowing the research group saw the need for techniques to ensure a predictable number of service-ready gilts for each breeding period. The researchers compared the results of 3 groups of gilts. All groups received daily oral doses of Regu-Mate to stop cycling after their first heat. Group 1 received the ovulation synchronization treatment protocol #1 (3 days after removal from Regu-Mate) and group 2 received the treatment protocol #2 (6 days after removal from Regu-Mate) previously tested by the researchers in sows. The control group gilts were inseminated based on detection of estrus after withdrawal from Regu-Mate.
Gilts in the control group all came into heat and were bred between 5-10 days after withdrawal of Regu-mate. Ultrasound showed all gilts in Group 1 and 2 had ovulated within 24 hours after breeding, whereas at least half the gilts in the control group had not ovulated 24 hours after the first breeding. There were no statistically significant differences in farrowing rate or litter size between the three groups, but average weaning weight was higher in the ovulation synchronization groups. While there is a cost to the hormones used in either protocol it can be balanced with the savings of a reduced cost for semen (only 1 dose required) and the time saved through successfully breeding the entire group once and all at the same time.
Use of the ovulation synchronization protocols may be a good tool for producers looking for options to improve overall herd reproductive performance or reduce their time in the breeding barn. Producers interested in in trying these protocols should contact their veterinarian.