Breeding behaviour of a stallion at pasture with 20 mares in synchronized oestrus.

The research article details a study monitoring the mating habits of a stallion in an open pasture with 20 mares experiencing synchronized oestrus. The study investigated the frequency and intervals of mating across several days, resulting in a high conception rate, suggesting more frequent mating in pasture conditions than expected.

Methodology

• The researchers placed a 6-year-old stallion in a pasture with 20 mares for nine days.
• The oestrus of the mares was synchronized using two treatments of PGF-2 alpha applied 15 days apart.
• Observation and breeding began three days following the second PGF-2 alpha treatment, and the activities were monitored during daylight hours.

Findings

• During the study, 18 out of 20 mares showed oestrus, meaning they were in their reproductive phase. Each of these mares mated an average of 4.56 times, with a range between 1 and 12 times.
• There were 1.74 mounts by the stallion per mating. The maximum number of matings completed by the stallion in one day was 16, which occurred on day two of the study.
• The average interval between matings was approximately 72.8 minutes, though there was significant variability, with the range between 34.5 minutes (on Day 1) to 128.7 minutes (on Day 6). Mating intervals were irregular across the oestrus period.
• Most mares (88.9%) mated at least once in the three days leading up to the last day of their oestrus, whereas only five mares mated on the final day of oestrus.

Conclusions

• From the 20 mares, 17 (85%) were found to be pregnant when examined 38 days following the conclusion of the experiment. This high first oestrus conception rate indicates a high level of reproductive success.
• The results imply that the stallion exhibited more mating activity in a pasture setting than predicted in hand mating scenarios, suggesting the potential for higher conception rates in natural, less controlled conditions.