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Home / Equine Research Bank / J Anim Breed Genet / Factor analysis of evaluated and linearly scored traits in S...
Journal of animal breeding and genetics = Zeitschrift fur Tierzuchtung und Zuchtungsbiologie2023; 140(4); 366-375; doi: 10.1111/jbg.12764

Factor analysis of evaluated and linearly scored traits in Swedish Warmblood horses.

Abstract: Assessment protocols to describe the various aspects of conformation, gait and jumping traits on a linear scale were introduced at young horse tests for Swedish Warmblood horses in 2013. The traits scored on a linear scale are assumed to be less subjective and more easily compared across populations than the traditional evaluated traits that are scored relative to the breeding goal. However, the resulting number of traits is considerable, and several of the traits are correlated. The aim of this study was to investigate the interrelationship between the different evaluated and linearly scored traits in Swedish Warmbloods using factor analysis. In total, 20,935 horses born 1996-2017 had information on evaluated traits, and 5450 of these also had linearly scored trait records assessed since 2014 when the protocol was updated. A factor analysis with varimax rotation was performed separately for evaluated and linearly scored traits using the Psych package in R. Height at withers was included in both analyses. A total of four factors for evaluated traits and 14 factors for linearly scored traits were kept for further analysis. Missing values for individual traits in horses with linearly scored trait records were imputed based on correlated traits before factor scores were calculated using factor loadings. Genetic parameters for, and correlations between, the resulting underlying factors were estimated using multiple-trait animal models in the BLUPF90 package. Heritability estimates were on a similar level as for the traits currently used in the genetic evaluation, ranging from 0.05 for the factor for linearly scored traits named L.behaviour (dominated by traits related to behaviour) to 0.59 for the factor for evaluated traits named E.size (dominated by height at withers and conformation). For both types of traits, separate factors were formed for jumping and gait traits, as well as for body size. High genetic correlations were estimated between such corresponding factors for evaluated traits and factors for linearly scored traits. In conclusion, factor analysis could be used to reduce the number of traits to be included in multiple-trait genetic evaluation or in genomic analysis for warmblood horses. It can also contribute to a better understanding of the interrelationships among the assessed traits and be useful to decide on subgroups of traits to be used in several multiple-trait evaluations on groups of original traits.
© 2023 The Authors. Journal of Animal Breeding and Genetics published by John Wiley & Sons Ltd.
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Publication Date: 2023-02-27 PubMed ID: 36852464DOI: 10.1111/jbg.12764Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The researchers conducted a study to understand the relationship between different traditionally evaluated and linearly scored traits in Swedish Warmblood horses. The results suggested that factor analysis could simplify the traits for detailed genetic evaluation or genomic analysis of horses.

Overview of the Study

  • The researchers used factor analysis to study the correlation between different traits in Swedish Warmblood horses. The traits were traditionally scored qualitatively and on a linear scale, which would be less subjective and more comparative across different populations.
  • The study was conducted on about 20,935 horses born between 1996 to 2017, out of which 5450 horses also had linearly scored traits since a new protocol was introduced in 2014.
  • The factor analysis was done separately for evaluated and linearly scored traits using a statistical computing tool called the Psych package in R-language. All the evaluated and linearly scored traits were considered, including the height of the horse.

Results of the Study

  • The study named four factors for evaluated traits and 14 factors for linearly scored traits for further analysis.
  • For missing values, the researchers used data from correlated traits to fill the gaps before calculating factor scores.
  • They estimated the genetic parameters and correlations using the calculated factors through multiple-trait animal models.
  • The estimated heritability ranged from 0.05 for behaviors relating to linearly scored traits to 0.59 for anatomical aspects related to traditionally evaluated traits.
  • The separate factors were formed for jumping and gait traits, and body size.
  • They discovered high genetic correlations between evaluated traits and linearly scored traits for similar aspects.

Applications of the Research Findings

  • The use of factor analysis could reduce the number of traits to be included multiple-trait genetic evaluations or genomic analysis in horses thereby making the analyses simpler and more efficient.
  • In addition, the factor analysis results could provide better insight into the relationships among the assessed traits and help in deciding subgroups of traits to be used in multiple-trait evaluations of different groups of original traits.

Cite This Article

APA
Nazari-Ghadikolaei A, Fikse F, Gelinder Viklund Å, Eriksson S. (2023). Factor analysis of evaluated and linearly scored traits in Swedish Warmblood horses. J Anim Breed Genet, 140(4), 366-375. https://doi.org/10.1111/jbg.12764

Publication

Journal of animal breeding and genetics = Zeitschrift fur Tierzuchtung und Zuchtungsbiologie
ISSN: 1439-0388
NlmUniqueID: 100955807
Country: Germany
Language: English
Volume: 140
Issue: 4
Pages: 366-375

Researcher Affiliations

Nazari-Ghadikolaei, Anahit
  • Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Fikse, Freddy
  • Växa, Uppsala, Sweden.
Gelinder Viklund, Åsa
  • Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Eriksson, Susanne
  • Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.

MeSH Terms

  • Horses / genetics
  • Animals
  • Sweden
  • Gait / genetics
  • Phenotype
  • Body Size
  • Factor Analysis, Statistical

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