Estimation of genetic parameters for racing time and ranking in Thoroughbred horses.
Authors: de Oliveira Padilha Denyus Augusto, Padilha Suelen Fernandes, Martins Rafaela, Scheffer Bruna Elisa Machado, Miliorini Mayumi Regina, Dias Laila Talarico, Teixeira Rodrigo de Almeida
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Genetic Parameters for Racing Performance in Thoroughbreds Researchers analysed over 23,000 racing records from 6,213 São Paulo Thoroughbreds to quantify the heritability of race time and finishing position across sprint (1,000 m), intermediate (1,600 m), and distance (2,000 m) races. Heritability for race time ranged considerably from 0.01 to 0.17 depending on distance, whilst final ranking showed lower heritability (0.04–0.09), though repeatability estimates were notably higher (0.19–0.37 for time; 0.15–0.23 for ranking), suggesting that non-genetic, individual factors—such as fitness, training, and environmental conditions—account for substantial variation between runs. A weak to moderate genetic correlation existed between breeding values for speed and ranking across distances, indicating these traits are partially independent; selection for faster race times at shorter distances demonstrated genetic progress over the study period, yet longer distance races showed minimal improvement. For breeding programmes, the findings suggest that race time represents a more responsive selection criterion than ranking alone, with particular promise in sprint racing, though the authors flag concerning stagnation in genetic gains for middle and long distances—warranting reassessment of selection strategies and breeding objectives to avoid plateauing in performance.
Read the full abstract on PubMed
Practical Takeaways
- •Breeders should prioritize selection for race time as a breeding criterion over final ranking, as it shows better heritability and stronger genetic response, especially for shorter distance races
- •The limited genetic progress observed suggests current selection practices need reevaluation to improve the effectiveness of breeding programs
- •Race distance matters: genetic improvements are more apparent in sprint races (1,000 m) than middle-distance races, so consider distance-specific selection strategies
Key Findings
- •Heritability for race time ranged from 0.01±0.03 to 0.17±0.04 across different race distances (1,000-2,000 m)
- •Heritability for final ranking was lower, ranging from 0.04±0.03 to 0.09±0.04
- •Genetic trends showed race time improvement over time at 1,000 m distance, but no clear pattern at longer distances (1,600-2,000 m)
- •Race time demonstrates greater response to selection than ranking, particularly for shorter races, suggesting it is a more effective breeding criterion