You can now test your racehorses for speed through Equinome. They have developed a genetic test for Thoroughbreds for the C:C (short), C:T (middle) and T:T (long) genes.
C:C -likely to be a fast, early maturing horse that performs well as a two-year-old. Average best distance – 6.5 f (1300 m)
C:T -mixture of speed and stamina and is the most versatile in terms of distance. A C:T horse can perform well as a two-year-old, but is best suited to races between 7 – 12 f (1400 – 2400 m).
T:T -best suited to races greater than 1 mile that require stamina. T:T horses are later maturing and do not perform optimally as two-year-olds. Average best distance – 11.1 f (2230 m)
The research is published in an open access journal:
A Sequence Polymorphism in MSTN Predicts Sprinting Ability and Racing Stamina in Thoroughbred Horses, Hill et al., PLos ONE, Vol 5.1, Jan 2010.
Variants of the MSTN gene encoding myostatin are associated with muscle hypertrophy phenotypes in a range of mammalian species, most notably cattle, dogs, mice, and humans. Using a sample of registered Thoroughbred horses (n = 148), we have identified a novel MSTN sequence polymorphism that is strongly associated (g.66493737C.T, P = 4.8561028) with best race distance among elite racehorses (n = 79). This observation was independently validated (P = 1.9161026) in a resampled group of Thoroughbreds (n = 62) and in a cohort of Thoroughbreds (n = 37, P = 0.0047) produced by the same trainer. We observed that C/C horses are suited to fast, short-distance races; C/T horses compete favorably in middle-distance races; and T/T horses have greater stamina. Evaluation of retrospective racecourse performance (n = 142) and stallion progeny performance predict that C/C and C/T horses are more likely to be successful two-year-old racehorses than T/T animals. Here we describe for the first time the identification of a gene variant in Thoroughbred racehorses that is predictive of genetic potential for an athletic phenotype.
Myostatin (GDF-8) is a member of the transforming growth factor beta superfamily and the encoding gene (MSTN) is thought to contribute to muscular hypertrophy in many species, including dogs (shown by speed in whippets) and cows (increased muscle mass for greater beef output). It was shown to be essential for proper regulation of skeletal muscle mass in mice. It seems to control the amount of muscle mass through hyperplasia, an increase in the amount of muscle fibers (versus an increase in the individual diameter of the fibers).