Heritability and factors associated with number of harness race starts in the Spanish Trotter horse population.

The research investigates the genetic factors and other influencers impacting the number of harness race starts and therefore, the race longevity/durability of the Spanish Trotter Horse breed. It concludes that genetic selection can potentially help improve these factors.

Objective and Method

• The aim of the study was to perform a genetic analysis and identify factors that influence the number of harness race starts, a measure of race longevity or durability, in Spanish Trotter Horses (STH).
• Performance data of STHs from national level harness racing between 1990 and 2014 was used. The sample size was extensive, including 331,970 instances.
• A grouped data model was used to analyze the relationship of different factors to the risk of ending a horse’s racing career. This also helped estimate the heritability and breeding values for total number of harness race starts.

Parameters and Factors

• The research considered a multitude of factors, both time-independent and time-dependent.
• Time-independent effects included the horses’ sex, their age at the first race, and their earnings from the first start.
• Time-dependent effects factored in the calendar year of racing, the particular driver, the trainer, the category of the racetrack, and the racing season.
• Each of these elements could have potentially influenced the total number of harness race starts, horse longevity, and durability.

Results and Heritability

• The average number of harness races a STH horse achieved in Spain was found to be 54.7, which varied based on factors like age at first race, earnings from first start, and season of competition.
• Notably, the estimated heritability for the number of harness race starts was found to be 0.17 ± 0.01, suggesting a meaningful correlation between genetic factors and the number of harness race starts.
• This figure implies that a positive response to direct genetic selection can be expected, potentially improving the racing career longevity and durability of the horses.

Conclusion and Implication

• Despite health status data of the horses being unavailable, the researchers concluded that the total number of harness race starts could be a useful tool for analyzing genetic factors and evaluating racing longevity and durability.
• It was also suggested that the estimated heritability supports the application of genetic selection to increase the total career number of races, thus improving the longevity/durability of Spanish Trotter Horses.