Synchronization of oestus and timed insemination of mares.

This study examines the impact of two reproductive hormones on the timing of estrus and subsequent artificial insemination in mares, finding that oestrus can be effectively synchronized using these methods, with no significant differences in pregnancy rates between groups.

Objective

The primary aim of this study was to determine whether the synchronization of estrus in mares could be achieved through the administration of specific hormones, and if this synchronization would result in successful pregnancies after artificial insemination.

Methodology

• The research involved 116 mares that were injected with two hormones, prostaglandin F-2 alpha (on Day 0) and fluprostenol (on Day 16) to synchronize their oestrus (sexual heat) cycles.
• These mares were then divided into three random groups. Group A (30 mares) were given an injection of hormone hCG on Day 20 and artificially inseminated on Day 21 without detection of oestrus. Group B (32 mares) were given the same treatment, but inseminated on both Days 21 and 23.
• Group C (54 mares) were observed for signs of oestrus on multiple days and inseminated while they were in oestrus.
• Semen for insemination was collected from three stallions using an artificial vagina. Each mare in the groups was randomly assigned to one of the stallions and inseminated with an equal ratio of semen within an hour of collection.

Results

• The study found that 80% of mares experienced a synchronized oestrus within 48 hours after treatment with fluprostenol.
• Pregnancy rates at approximately 60 days gestation were not significantly different between the experimental groups, suggesting that the procedures used to induce and synchronize estrus did not adversely impact the likelihood of successful pregnancy following artificial insemination.

Implications

• This research contributes to the understanding of equine reproductive physiology and the mechanisms with which breeders and veterinarians can control the breeding cycle.
• The efficient synchronization of oestrus in mares can help streamline the artificial insemination process, potentially leading to more predictable breeding programs.