1932

Abstract

Thoroughbred horses have been selected for racing performance for more than 400 years. Despite continued selection, race times have not improved significantly during the past 60 years, raising the question of whether genetic variation for racing performance still exists. Studies using phenotypes such as race time, money earned, and handicapping, however, demonstrate that there is extensive variation within these traits and that they are heritable. Even so, these are poor measures of racing success since Thoroughbreds race at different ages and distances and on different types of tracks, and some may not race at all. With the advent of genomic tools, DNA variants are being identified that contribute to racing success. Aside from strong associations for myostatin variants with best racing distance, weak to modest associations with racing phenotypes are reported for other genomic regions. These data suggest that diverse genetic strategies have contributed to producing a successful racehorse, and genetic variation contributing to athleticism remains important.

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2022-02-15
2024-06-17
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Literature Cited

  1. 1. 
    Willett P. 1970. The Thoroughbred New York: G.P. Putnams's Sons
    [Google Scholar]
  2. 2. 
    Binns M, Morris T. 2010. Thoroughbred Breeding: Pedigree Theories and the Science of Genetics Pomfret, VT: J.A. Allen
    [Google Scholar]
  3. 3. 
    Cunningham EP, Dooley JJ, Splan RK, Bradley DG. 2001. Microsatellite diversity, pedigree relatedness and the contributions of founder lineages to thoroughbred horses. Anim. Genet. 32:360–64
    [Google Scholar]
  4. 4. 
    Wallner B, Palmieri N, Vogl C, Rigler D, Bozlak E et al. 2017. Y chromosome uncovers the recent oriental origin of modern stallions. Curr. Biol. 27:2029–35.e5
    [Google Scholar]
  5. 5. 
    Felkel S, Vogl C, Rigler D, Dobretsberger V, Chowdhary BP et al. 2019. The horse Y chromosome as an informative marker for tracing sire lines. Sci. Rep. 9:6095
    [Google Scholar]
  6. 6. 
    Bower MA, Campana MG, Whitten M, Edwards CJ, Jones H et al. 2011. The cosmopolitan maternal heritage of the Thoroughbred racehorse breed shows a significant contribution from British and Irish native mares. Biol. Lett. 7:316–20
    [Google Scholar]
  7. 7. 
    Cosgrove EJ, Sadeghi R, Schlamp F, Holl HM, Moradi-Shahrbabak M et al. 2020. Genome diversity and the origin of the Arabian horse. Sci. Rep. 10:9702
    [Google Scholar]
  8. 8. 
    Petersen JL, Mickelson JR, Rendahl AK, Valberg SJ, Andersson LS et al. 2013. Genome-wide analysis reveals selection for important traits in domestic horse breeds. PLOS Genet 9:e1003211
    [Google Scholar]
  9. 9. 
    Estes JA. 1958. Pedigrees. Stud Managers’ Handbook82–101 Lexington: Univ. Ky article reprinted from 1952 column from The Blood Horse )
    [Google Scholar]
  10. 10. 
    Gaffney B, Cunningham EP. 1988. Estimation of genetic trend in racing performance of thoroughbred horses. Nature 332:722–24
    [Google Scholar]
  11. 11. 
    Eckhardt RB, Eckhardt DA, Eckhardt JT. 1988. Are racehorses becoming faster?. Nature 335:773
    [Google Scholar]
  12. 12. 
    Gardner DS. 2006. Historical progression of racing performance in the Thoroughbred horse and man. Equine Vet. J. 38:581–83
    [Google Scholar]
  13. 13. 
    Denny MW. 2008. Limits to running speed in dogs, horses and humans. J. Exp. Biol. 211:3836–49
    [Google Scholar]
  14. 14. 
    Hámori D, Halász G. 1959. Der Einfluß der Selektion auf die Entwicklung der Schnelligkeit des Pferdes. Z. Tierzüchtung Züchtungsbiol. 73:47–59
    [Google Scholar]
  15. 15. 
    Cunningham EP. 1990. The Genetics of Performance in Thoroughbreds Hobart, Aust: World Congr. Bloodhorse Breed.
    [Google Scholar]
  16. 16. 
    Langlois B. 1980. Heritability of racing ability in thoroughbreds—a review. Livest. Prod. Sci. 7:591–605
    [Google Scholar]
  17. 17. 
    Ricard A 1998. Developments in the genetic evaluation of performance traits in horses. Presented at 6th World Congress on Genetics Applied to Livestock Production Jan. 11–16 Univ. New Engl. NSW, Aust.:
    [Google Scholar]
  18. 18. 
    Langlois B, Blouin C. 2007. Annual, career or single race records for breeding value estimation in race horses. Livest. Sci. 107:132–41
    [Google Scholar]
  19. 19. 
    Oki H, Sasaki Y, Willham RL. 1994. Genetics of racing performance in the Japanese Thoroughbred horse: II. Environmental variation of racing time on turf and dirt tracks and the influence of sex, age, and weight carried on racing time. J. Anim. Breed. Genet. 111:128–37
    [Google Scholar]
  20. 20. 
    Oki H, Sasaki Y, Lin CY, Willham RL. 1995. Influence of jockeys on racing time in Thoroughbred horses. J. Anim. Breed. Genet. 112:171–75
    [Google Scholar]
  21. 21. 
    Langlois B. 1996. A consideration of the genetic aspects of some current practices in Thoroughbred horse breeding. Ann. Zootech. 45:41–51
    [Google Scholar]
  22. 22. 
    Tolley E. 1985. A review of the inheritance of racing performance in horses. Anim. Breed. Abstr. 53:163–85
    [Google Scholar]
  23. 23. 
    Ricard A, Bruns E, Cunningham EP 2000. Genetics of performance traits. The Genetics of the Horse AT Bowling, A Ruvinsky 411–38 Wallingford, UK: CAB Int.
    [Google Scholar]
  24. 24. 
    Thiruvenkadan AK, Kandasamy N, Panneerselvam S. 2009. Inheritance of racing performance of Thoroughbred horses. Livest. Sci. 121:308–26
    [Google Scholar]
  25. 25. 
    Velie BD, Hamilton NA, Wade CM 2015. Heritability of racing performance in the Australian Thoroughbred racing population. Anim. Genet. 46:23–29
    [Google Scholar]
  26. 26. 
    Oki H, Sasaki Y, Willham RL. 1997. Estimation of genetic correlations between racing times recorded at different racing distances by restricted maximum likelihood in Thoroughbred racehorses. J. Anim. Breed. Genet. 114:185–89
    [Google Scholar]
  27. 27. 
    Moritsu Y, Funakoshi H, Ichikawa S. 1994. Genetic evaluation of sires and environmental factors influencing best racing times of Thoroughbred horses in Japan. J. Equine Sci. 5:53–58
    [Google Scholar]
  28. 28. 
    Oki H, Sasaki Y, Willham RL. 1995. Genetic parameter estimates for racing time by restricted maximum likelihood in the Thoroughbred horse of Japan. J. Anim. Breed. Genet. 112:146–50
    [Google Scholar]
  29. 29. 
    Mota MD, Abrahão AR, Oliveira HN. 2005. Genetic and environmental parameters for racing time at different distances in Brazilian Thoroughbreds. J. Anim. Breed. Genet. 122:393–99
    [Google Scholar]
  30. 30. 
    Ekız B, Koçak Ö. 2007. Estimates of genetic parameters for racing times of Thoroughbred horses. Turk. J. Vet. Anim. Sci. 31:1–5
    [Google Scholar]
  31. 31. 
    Estes JA. 1948. More notes on ranking of sires in proportion to opportunity. Blood Horse 52:650–51
    [Google Scholar]
  32. 32. 
    Estes JA. 1948. Statistics on prominent sires, adjusted for changing dollar. Blood Horse 52:470–71
    [Google Scholar]
  33. 33. 
    Estes JA, Baumohl A. 1960. Racing class and sire success. Blood Horse 60:48–53
    [Google Scholar]
  34. 34. 
    Estes JA, Baumohl A. 1960. Dams of stakes winners. Blood Horse 60:99–105
    [Google Scholar]
  35. 35. 
    Burns EM, Enns RM, Garrick DJ. 2006. The effect of simulated censored data on estimates of heritability of longevity in the Thoroughbred racing industry. Genet. Mol. Res. 5:7–15
    [Google Scholar]
  36. 36. 
    Moritsu Y, Terai A, Tashiro T 1998. Relationship between sire breeding values for the rating score on turf and dirt racing tracks in Thoroughbred racehorses. J. Equine Sci. 9:89–92
    [Google Scholar]
  37. 37. 
    Wade CM, Giulotto E, Sigurdsson S, Zoli M, Gnerre S et al. 2009. Genome sequence, comparative analysis, and population genetics of the domestic horse. Science 326:865–67
    [Google Scholar]
  38. 38. 
    Kalbfleisch TS, Rice ES, DePriest MS Jr., Walenz BP, Hestand MS et al. 2018. Improved reference genome for the domestic horse increases assembly contiguity and composition. Commun. Biol. 1:197
    [Google Scholar]
  39. 39. 
    Burns EN, Bordbari MH, Mienaltowski MJ, Affolter VK, Barro MV et al. 2018. Generation of an equine biobank to be used for Functional Annotation of Animal Genomes project. Anim. Genet. 49:564–70
    [Google Scholar]
  40. 40. 
    Donnelly CG, Bellone RR, Hales EN, Nguyen A, Katzman SA et al. 2021. Generation of a biobank from two adult Thoroughbred stallions for the Functional Annotation of Animal Genomes initiative. Front. Genet 12:650305
    [Google Scholar]
  41. 41. 
    Kingsley NB, Kern C, Creppe C, Hales EN, Zhou H et al. 2019. Functionally annotating regulatory elements in the equine genome using histone Mark ChIP-Seq. Genes 11:3
    [Google Scholar]
  42. 42. 
    Schaefer RJ, Schubert MK, Bailey EK, Bannasch DL, Barrey EP et al. 2017. Developing a 670k genotyping array to tag similar to 2M SNPs across 24 horse breeds. BMC Genom. 18:565
    [Google Scholar]
  43. 43. 
    McCue ME, Bannasch DL, Petersen JL, Gurr J, Bailey E et al. 2012. A high density SNP array for the domestic horse and extant Perissodactyla: utility for association mapping, genetic diversity, and phylogeny studies. PLOS Genet 8:e1002451
    [Google Scholar]
  44. 44. 
    Bray MS, Hagberg JM, Pérusse L, Rankinen T, Roth SM et al. 2009. The human gene map for performance and health-related fitness phenotypes: the 2006–2007 update. Med. Sci. Sports Exerc. 41:35–73
    [Google Scholar]
  45. 45. 
    Mosher DS, Quignon P, Bustamante CD, Sutter NB, Mellersh CS et al. 2007. A mutation in the myostatin gene increases muscle mass and enhances racing performance in heterozygote dogs. PLOS Genet 3:e79
    [Google Scholar]
  46. 46. 
    McPherron AC, Lee SJ. 1997. Double muscling in cattle due to mutations in the myostatin gene. PNAS 94:12457–61
    [Google Scholar]
  47. 47. 
    Schröder W, Klostermann A, Distl O. 2011. Candidate genes for physical performance in the horse. Vet. J. 190:39–48
    [Google Scholar]
  48. 48. 
    Gu J, Orr N, Park SD, Katz LM, Sulimova G et al. 2009. A genome scan for positive selection in Thoroughbred horses. PLOS ONE 4:e5767
    [Google Scholar]
  49. 49. 
    Hill EW, Gu J, Eivers SS, Fonseca RG, McGivney BA et al. 2010. A sequence polymorphism in MSTN predicts sprinting ability and racing stamina in Thoroughbred horses. PLOS ONE 5:e8645
    [Google Scholar]
  50. 50. 
    Binns MM, Boehler DA, Lambert DH. 2010. Identification of the myostatin locus (MSTN) as having a major effect on optimum racing distance in the Thoroughbred horse in the USA. Anim. Genet. 41:Suppl. 2154–58
    [Google Scholar]
  51. 51. 
    Tozaki T, Miyake T, Kakoi H, Gawahara H, Sugita S et al. 2010. A genome-wide association study for racing performances in Thoroughbreds clarifies a candidate region near the MSTN gene. Anim. Genet. 41:Suppl. 228–35
    [Google Scholar]
  52. 52. 
    Shin DH, Lee JW, Park JE, Choi IY, Oh HS et al. 2015. Multiple genes related to muscle identified through a joint analysis of a two-stage genome-wide association study for racing performance of 1,156 Thoroughbreds. Asian-Aust. . J. Anim. Sci. 28:771–81
    [Google Scholar]
  53. 53. 
    Farries G, McGettigan PA, Gough KF, McGivney BA, MacHugh DE et al. 2018. Genetic contributions to precocity traits in racing Thoroughbreds. Anim. Genet. 49:193–204
    [Google Scholar]
  54. 54. 
    Farries G, Gough KF, Parnell AC, McGivney BA, McGivney CL et al. 2019. Analysis of genetic variation contributing to measured speed in Thoroughbreds identifies genomic regions involved in the transcriptional response to exercise. Anim. Genet. 50:670–85
    [Google Scholar]
  55. 55. 
    McGivney BA, Hernandez B, Katz LM, MacHugh DE, McGovern SP et al. 2019. A genomic prediction model for racecourse starts in the Thoroughbred horse. Anim. Genet. 50:347–57
    [Google Scholar]
  56. 56. 
    Velie BD, Hamilton NA, Wade CM 2016. Heritability of racing durability traits in the Australian and Hong Kong Thoroughbred racing populations. Equine Vet. J. 48:275–79
    [Google Scholar]
  57. 57. 
    Han H, McGivney BA, Farries G, Katz LM, MacHugh DE et al. 2020. Selection in Australian Thoroughbred horses acts on a locus associated with early two-year old speed. PLOS ONE 15:e0227212
    [Google Scholar]
  58. 58. 
    Hill EW, McGivney BA, Gu J, Whiston R, MacHugh DE 2010. A genome-wide SNP-association study confirms a sequence variant (g.66493737C>T) in the equine myostatin (MSTN) gene as the most powerful predictor of optimum racing distance for Thoroughbred racehorses. BMC Genom 11:552
    [Google Scholar]
  59. 59. 
    Petersen JL, Valberg SJ, Mickelson JR, McCue ME. 2014. Haplotype diversity in the equine myostatin gene with focus on variants associated with race distance propensity and muscle fiber type proportions. Anim. Genet. 45:827–35
    [Google Scholar]
  60. 60. 
    Santagostino M, Khoriauli L, Gamba R, Bonuglia M, Klipstein O et al. 2015. Genome-wide evolutionary and functional analysis of the Equine Repetitive Element 1: An insertion in the myostatin promoter affects gene expression. BMC Genet 16:126
    [Google Scholar]
  61. 61. 
    Rooney MF, Hill EW, Kelly VP, Porter RK 2018. The “speed gene” effect of myostatin arises in Thoroughbred horses due to a promoter proximal SINE insertion. PLOS ONE 13:e0205664
    [Google Scholar]
  62. 62. 
    Bower MA, McGivney BA, Campana MG, Gu J, Andersson LS et al. 2012. The genetic origin and history of speed in the Thoroughbred racehorse. Nat. Commun. 3:643
    [Google Scholar]
  63. 63. 
    Gu J, MacHugh DE, McGivney BA, Park SD, Katz LM, Hill EW. 2010. Association of sequence variants in CKM (creatine kinase, muscle) and COX4I2 (cytochrome c oxidase, subunit 4, isoform 2) genes with racing performance in Thoroughbred horses. Equine Vet. J. Suppl569–75
    [Google Scholar]
  64. 64. 
    Hill EW, Gu J, McGivney BA, MacHugh DE. 2010. Targets of selection in the Thoroughbred genome contain exercise-relevant gene SNPs associated with elite racecourse performance. Anim. Genet. 41:Suppl. 256–63
    [Google Scholar]
  65. 65. 
    Harrison SP, Turrion-Gomez JL 2006. Mitochondrial DNA: an important female contribution to thoroughbred racehorse performance. Mitochondrion 6:53–63
    [Google Scholar]
  66. 66. 
    Lin X, Zheng HX, Davie A, Zhou S, Wen L et al. 2018. Association of low race performance with mtDNA haplogroup L3b of Australian thoroughbred horses. Mitochondrial DNA A 29:323–30
    [Google Scholar]
  67. 67. 
    Denham J, McCluskey M, Denham MM, Sellami M, Davie AJ. 2020. Epigenetic control of exercise adaptations in the equine athlete: Current evidence and future directions. Equine Vet. J. 53:431–50
    [Google Scholar]
  68. 68. 
    Farries G, Bryan K, McGivney CL, McGettigan PA, Gough KF et al. 2019. Expression quantitative trait loci in equine skeletal muscle reveals heritable variation in metabolism and the training responsive transcriptome. Front. Genet. 10:1215
    [Google Scholar]
  69. 69. 
    Bryan K, McGivney BA, Farries G, McGettigan PA, McGivney CL et al. 2017. Equine skeletal muscle adaptations to exercise and training: evidence of differential regulation of autophagosomal and mitochondrial components. BMC Genom 18:595
    [Google Scholar]
  70. 70. 
    Love S, Wyse CA, Stirk AJ, Stear MJ, Calver P, Voute LC, Mellor DJ. 2006. Prevalence, heritability and significance of musculoskeletal conformational traits in Thoroughbred yearlings. Equine Vet. J. 38:597–603
    [Google Scholar]
  71. 71. 
    Santschi EM, White BJ, Peterson ES, Gotchey MH, Morgan JM, Leibsle SR 2017. Forelimb conformation, sales results, and lifetime racing performance of 2-year-old Thoroughbred racing prospects sold at auction. J. Equine Vet. Sci. 53:74–80
    [Google Scholar]
  72. 72. 
    Jeffcott LB, Rossdale PD, Freestone J, Frank CJ, Towers-Clark PF. 1982. An assessment of wastage in Thoroughbred racing from conception to 4 years of age. Equine Vet. J. 14:185–98
    [Google Scholar]
  73. 73. 
    Wilsher S, Allen WR, Wood JL 2006. Factors associated with failure of Thoroughbred horses to train and race. Equine Vet. J. 38:113–18
    [Google Scholar]
  74. 74. 
    Oki H, Miyake T, Kasashima Y, Sasaki Y. 2008. Estimation of heritability for superficial digital flexor tendon injury by Gibbs sampling in the Thoroughbred racehorse. J. Anim. Breed. Genet. 125:413–16
    [Google Scholar]
  75. 75. 
    Welsh CE, Lewis TW, Blott SC, Mellor DJ, Stirk AJ, Parkin TD. 2014. Estimates of genetic parameters of distal limb fracture and superficial digital flexor tendon injury in UK Thoroughbred racehorses. Vet. J. 200:253–56
    [Google Scholar]
  76. 76. 
    Blott SC, Swinburne JE, Sibbons C, Fox-Clipsham LY, Helwegen M et al. 2014. A genome-wide association study demonstrates significant genetic variation for fracture risk in Thoroughbred racehorses. BMC Genom 15:147
    [Google Scholar]
  77. 77. 
    Tozaki T, Kusano K, Ishikawa Y, Kushiro A, Nomura M et al. 2020. A candidate-SNP retrospective cohort study for fracture risk in Japanese Thoroughbred racehorses. Anim. Genet. 51:43–50
    [Google Scholar]
  78. 78. 
    Dupuis MC, Zhang Z, Druet T, Denoix JM, Charlier C et al. 2011. Results of a haplotype-based GWAS for recurrent laryngeal neuropathy in the horse. Mamm. Genome 22:613–20
    [Google Scholar]
  79. 79. 
    Boyko AR, Brooks SA, Behan-Braman A, Castelhano M, Corey E et al. 2014. Genomic analysis establishes correlation between growth and laryngeal neuropathy in Thoroughbreds. BMC Genom 15:259
    [Google Scholar]
  80. 80. 
    Morley PS, Bromberek JL, Saulez MN, Hinchcliff KW, Guthrie AJ. 2015. Exercise-induced pulmonary haemorrhage impairs racing performance in Thoroughbred racehorses. Equine Vet. J. 47:358–65
    [Google Scholar]
  81. 81. 
    Velie BD, Raadsma HW, Wade CM, Knight PK, Hamilton NA. 2014. Heritability of epistaxis in the Australian Thoroughbred racehorse population. Vet. J. 202:274–78
    [Google Scholar]
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