[Factors affecting pregnancy rates in the German Thoroughbred Breed].

This research paper investigates how certain factors, such as age and season, influence pregnancy rates in the German Thoroughbred Breed, specifically aiming to enhance fertility rates in older breeding stallions.

Methods

• The researchers used data from the studbooks of the German Thoroughbred Breeding Association, spanning between 1996 and 2009.
• The data included the records of 319 stallions and 6622 brood mares, with a total of 21,372 pregnancies at the end of the breeding season.

Findings

• The study found that pregnancy rates were significantly influenced by the age of the stallion and mare along with the season (which was identified by the month in the breeding season when mating took place).
• They observed crucial interactions between the age of the stallion and book (defined as the number of mares covered per stallion), as well as between stallion age and season.
• Both the age of the stallion and mare and the progression of the breeding season contributed to a decrease in pregnancy rates.
• However, it was noted that stallions older than 16 years exhibited higher pregnancy rates when they covered more than 12 brood mares per season.
• For the older stallions, pregnancy rates were most notably reduced in the later months of the breeding season.

Conclusions

• The findings suggest that to maximize the chances of successful breeding with older stallions, the mares should be bred as early as possible in the breeding season.
• In addition, it is recommended that a sufficiently large number of mares be covered by the older stallions.