Estimation of Genetic Parameters for Racing Time and Ranking in Thoroughbred Horses.

This research is about analyzing the correlation between genetics and racing performance in thoroughbred horses, aiming to improve horse breeding strategies for increased performance.

Objective and Methodology

• The primary objective of this study was to identify and estimate the influence of genetic factors on two key racing performance metrics: race time and final ranking. Equally important was the analysis of the genetic trends concerning race time.
• To fulfill this objective, the study made use of a considerable dataset from the São Paulo Jockey Club, which comprised 23,290 records of race times and final ranks from 6,213 thoroughbred horses. The races covered a range of distances, specifically 1,000m, 1,600m, and 2,000m.
• The analytical model used in the study considered various factors as fixed covariates. These included the year of the run, the sex of the horse, the class of the race, track conditions, and the linear effect of the horse’s weight and age. The model also took into account the quadratic effect of age.
• On the random effects side, the model included direct additive genetic effects, permanent environmental effects related to the individual animal, and residual effects.

Findings

• Heritability estimates for race time varied from 0.01±0.03 to 0.17±0.04, while for final ranking, the estimates ranged from 0.04±0.03 to 0.09±0.04. This means the traits, race time and final ranking, were found to be at least partially inheritable.
• The study also computed repeatability estimates. These ranged from 0.19±0.02 to 0.37±0.02 for race time and 0.15±0.02 to 0.23±0.04 for final ranking, indicating potential for a consistent performance by individual horses.
• The correlations of estimated breeding values between race time and ranking were calculated using Pearson’s correlation method. The correlations ranged from -0,027±0.16 to 0.84±0.01, suggesting a possible relationship between these two parameters.
• An analysis of genetic trends for the shortest race distance (1,000m) showed a reduction in race time over the years. However, for races of 1,600 and 2,000 meters, there wasn’t a clear trend of decreasing racing times. This suggests different genetic factors may come to play at different race lengths.

Conclusion and Recommendations

• The study found that race time was likely to give a more favorable response to selection, primarily for shorter races. If breeders select for race time, they could expect a greater indirect impact on final ranking.
• However, genetic trends indicated only limited genetic progress over time. Hence, the research concluded that a reevaluation of the current selection process may be necessary to achieve desired improvements in racing performance.