Performance selection for Thoroughbreds racing in Hong Kong.
BACKGROUND
Different indicators of racing performance are commonly used in the racing industry to assess the genetic superiority of racing Thoroughbreds. However, how well these indicators predict the performance of future progeny or siblings varies depending on the population and circumstances in which the indicators were recorded or achieved.


OBJECTIVE
To identify heritable indicators of racing performance for horses racing in Hong Kong.


METHODS
Heritability analysis of racing performance traits.


METHODS
Performance data on the population of Thoroughbreds racing in Hong Kong between 3 September 2000 and 12 March 2011 (n = 4947) were acquired and used to estimate the heritabilities and probability values of fixed effects and covariates for a range of racing performance traits. Heritabilities for all performance traits were estimated using a single trait animal model. Each model included, as a minimum, the effects of sex, region of origin and trainer.


RESULTS
Heritability estimates for traits relating to finish position ranged from 0.01 to 0.06. Average handicap weight had a heritability of 0.07 ± 0.03. The effects of sex (fixed) and trainer (random) were significant (P<0.05) for all performance traits relating to earnings measures, handicap weights and finish positions. The heritability of win time at 1600 m was 0.52 ± 0.06 and was the only significant estimate of heritability for win time in the current study.


CONCLUSIONS
Although significantly affected by multiple environmental factors, certain indicators of Hong Kong racing performance can be reliably used to predict the performance of the individual's progeny or siblings. However, despite Hong Kong's controlled racing environment, these indicators appear to be no more heritable than in other less controlled racing environments.
Faculty of Veterinary Science, University of Sydney, New South Wales, Australia.
B D
BD
Velie
N A
NA
Hamilton
C M
CM
Wade
D000818:Animals; D005260:Female; D006723:Hong Kong; D006736:Horses / Q000235:genetics* / Q000502:physiology*; D008297:Male; D010805:Physical Conditioning, Animal / Q000502:physiology; D012420:Running; D013177:Sports
genetic; heritability; horse; performance; racehorse