The influence of mare numbers, ejaculation frequency and month on the fertility of Thoroughbred stallions.

This research is about identifying influential factors that determine the fertility rates among Thoroughbred stallions. The primary factors examined were the number of mares, how frequently stallions ejaculate, and the time of year.

Research Methodology

• The investigators examined the daily breeding records of 31 Thoroughbred stallions.
• These 31 stallions collectively mated with 3034 mares on 4851 separate occasions throughout the 2010 season.
• The researchers associated the breeding results with the first scan pregnancy rates, attempting to find patterns and factors that influence fertility rates.
• The impact of mare book size (number of mares mated with), month of mating, number of matings per day, and mating frequency or abstinence were all examined in relation to per mating pregnancy rates.

Research Findings

• The overall pregnancy rate per mating instance for all stallions combined was 59.6%, though individual stallions had rates as low as 19.0% and as high as 80.1%.
• The researchers found that the mating pregnancies rates were significantly lower in the months of June and July.
• The number of mares each stallion mated with ranged from 15 to 161, with the average number of matings per 100 mares being 160 across the entire season.
• Researchers found that the pregnancy rate per mating was not directly related to book size (number of mares), the number of matings in the season, or the daily mating frequency.
• However, it was observed that some stallions showed variances in per mating pregnancy rates that were related to the month of mating or the number of ejaculations in the preceding three days.

Research Conclusions

• Most Thoroughbred stallions were capable of maintaining acceptable fertility levels despite mating with a large number of mares.
• Out of the 31 stallions initially examined, five of them had a per mating pregnancy rate of 50% or less.
• The study identified notable variations in per mating pregnancy rates among Thoroughbred stallions.
• More comprehensive research is required to identify the specific factors contributing to these differences and provide valuable information for mare and stallion owners.