Genetic background of temperament traits in standardbred trotters
The genetic background of temperament traits in horses has been subject for research for many years to obtain understanding of domestication, breed differences and welfare. Previous studies have found heritabilities ranging from low to moderate for temperament. There are also a few studies who have...
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| Formato: | Second cycle, A2E |
| Lenguaje: | sueco Inglés |
| Publicado: |
2021
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| Acceso en línea: | https://stud.epsilon.slu.se/17151/ |
| _version_ | 1855572854799597568 |
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| author | Berglund, Paulina |
| author_browse | Berglund, Paulina |
| author_facet | Berglund, Paulina |
| author_sort | Berglund, Paulina |
| collection | Epsilon Archive for Student Projects |
| description | The genetic background of temperament traits in horses has been subject for research for many years to obtain understanding of domestication, breed differences and welfare. Previous studies have found heritabilities ranging from low to moderate for temperament. There are also a few studies who have found genetic regions or genes correlated to temperament in horses, but also genes found important for performance that possibly are linked to temperament. There are various methods used in research to assess temperament. Previous studies have for example used objective methods to assess temperament such as novel object tests. Subjective temperament assessment is also a widespread method used at e.g., young horse-riding tests, but also in the form of surveys aimed at trainers or caretakers of horses. Positive attributes of using a survey are that information about temperament traits that are not expressed at test stations/field tests can be obtained, for example traits related to learning and stress.
In this thesis, temperament assessments of Standardbred trotters were performed by collection of survey responses and DNA, to investigate the genetic background of 13 traits related to temperament at competition and to stress. Factor analysis was applied to find underlying variables explaining the temperament of Standardbreds. By using different statistical models, trait data obtained from a survey including 376 horses were analysed. Variance components for the temperament traits were estimated using linear animal models. In addition, the aim was to, as far as possible, prepare and sequence DNA obtained from the horses in the study. And if possible, perform an association analysis for one of the temperament traits.
Three factors were extracted from the factor analysis: anxiousness, tractability, and excitability. The factor anxiousness included mainly low self-control, memory of unpleasant events and fearfulness. Having a high score for this factor was significantly correlated with performing a stereotypic behaviour. The second factor named tractability, described cooperative horses that easily learned the task of competing and had a high will to win. The third factor, excitability, was dominated by nervousness and excitability. A similar factor has previously been found in Coldblooded trotters; a breed also bred for harness racing. This gave indications of that this temperament characteristic might be favourable when competing in trotting races.
Heritability estimates ranged from 0 to 0.42, where learning and cooperation were the traits with the highest heritability (h2=0.42 for both). In total, 288 samples were prepared for sequencing whereof 96 samples were sequenced. Based on the heritability estimations and trait score distributions, the trait excitability was chosen to be included in an association analysis. Significant differences between the case and control groups were found at a few loci.
In conclusion, despite the small data material, genetic variation in several of the temperament traits was found and significant heritabilities could be estimated. The next step would be to correlate the traits in this thesis to performance data and to look at the genetic correlation between these traits. The heritability estimations also gave a preliminary indication on which traits could be worth studying further on a molecular genetic level. The preliminary analysis of the whole genome sequencing data showed interesting results worth further investigation with data from more horses included. |
| format | Second cycle, A2E |
| id | RepoSLU17151 |
| institution | Swedish University of Agricultural Sciences |
| language | Swedish Inglés |
| publishDate | 2021 |
| publishDateSort | 2021 |
| record_format | eprints |
| spelling | RepoSLU171512021-09-09T01:09:06Z https://stud.epsilon.slu.se/17151/ Genetic background of temperament traits in standardbred trotters Berglund, Paulina Animal genetics and breeding The genetic background of temperament traits in horses has been subject for research for many years to obtain understanding of domestication, breed differences and welfare. Previous studies have found heritabilities ranging from low to moderate for temperament. There are also a few studies who have found genetic regions or genes correlated to temperament in horses, but also genes found important for performance that possibly are linked to temperament. There are various methods used in research to assess temperament. Previous studies have for example used objective methods to assess temperament such as novel object tests. Subjective temperament assessment is also a widespread method used at e.g., young horse-riding tests, but also in the form of surveys aimed at trainers or caretakers of horses. Positive attributes of using a survey are that information about temperament traits that are not expressed at test stations/field tests can be obtained, for example traits related to learning and stress. In this thesis, temperament assessments of Standardbred trotters were performed by collection of survey responses and DNA, to investigate the genetic background of 13 traits related to temperament at competition and to stress. Factor analysis was applied to find underlying variables explaining the temperament of Standardbreds. By using different statistical models, trait data obtained from a survey including 376 horses were analysed. Variance components for the temperament traits were estimated using linear animal models. In addition, the aim was to, as far as possible, prepare and sequence DNA obtained from the horses in the study. And if possible, perform an association analysis for one of the temperament traits. Three factors were extracted from the factor analysis: anxiousness, tractability, and excitability. The factor anxiousness included mainly low self-control, memory of unpleasant events and fearfulness. Having a high score for this factor was significantly correlated with performing a stereotypic behaviour. The second factor named tractability, described cooperative horses that easily learned the task of competing and had a high will to win. The third factor, excitability, was dominated by nervousness and excitability. A similar factor has previously been found in Coldblooded trotters; a breed also bred for harness racing. This gave indications of that this temperament characteristic might be favourable when competing in trotting races. Heritability estimates ranged from 0 to 0.42, where learning and cooperation were the traits with the highest heritability (h2=0.42 for both). In total, 288 samples were prepared for sequencing whereof 96 samples were sequenced. Based on the heritability estimations and trait score distributions, the trait excitability was chosen to be included in an association analysis. Significant differences between the case and control groups were found at a few loci. In conclusion, despite the small data material, genetic variation in several of the temperament traits was found and significant heritabilities could be estimated. The next step would be to correlate the traits in this thesis to performance data and to look at the genetic correlation between these traits. The heritability estimations also gave a preliminary indication on which traits could be worth studying further on a molecular genetic level. The preliminary analysis of the whole genome sequencing data showed interesting results worth further investigation with data from more horses included. Den genetiska bakgrunden förtemperamentsegenskaper hos hästar är ett ämne som studerats under många år för att få en djupare förståelse för hästars domesticering, rasskillnader och välfärd. De tidigare studier som finns inom området har skattat låga till medelhöga arvbarheter. Ett fåtal studier har hittat potentiella regioner eller gener korrelerade till temperamentsegenskaper, inklusive gener som visats vara viktiga för prestation och som eventuellt är kopplade till temperament. Det finns ett flertal metoder för att studera temperament inom forskning. Tidigare studier inom området har exempelvis använt objektiv bedömning så som reaktivitetstest (Novel object test). Subjektiv bedömning av temperamentsegenskaper hos hästar är en vanligt förekommande metod som används vid ridhästtestermen också i form av enkätundersökningarriktade mot tränare och skötare.Fördelen med en enkät är att den fångar temperament som inte alltid kan mätas i en testsituation, så som egenskaper relaterade till lärande och stress. I denna studie har temperamentsegenskaper hos den varmblodiga travhästen studerats genom insamling av enkätsvar samt DNA. Vidare så analyserades den genetiska bakgrunden till 13 egenskaper relaterade till temperament under tävlingsmomentet och stress. Faktoranalys användes för att undersöka underliggande faktorer som förklarar varmblodstravarens temperament. Med hjälp av olika statistiska modeller analyserades temperamentsegenskaper från totalt 376 individer. Varianskomponenter estimerades med linjära djurmodeller för temperamentsegenskaperna.Utöver detta så var målet att i möjligaste mån förbereda och sekvensera DNA från hästar med enkätsvar samt om möjligt, utföra en associationsanalysför en av temperamentsegenskaperna. Tre faktorer extraherades genom faktoranalys, dessa var ängslighet, medgörlighet och upphetsning. Den första faktorn ängslighet, inkluderade främst egenskaperna låg självkontroll, minne av otrevliga händelser samt rädsla. Höga poäng i denna faktor var signifikant korrelerat till att uppvisa en stereotypi. Faktor 2, medgörlighet, inkluderade främst egenskaperna vilja att vinna, läraktighet och samarbetsvilja. Den tredje faktorn, upphetsning, inkluderade främst nervositet och upphetsning. En liknande faktor har i en tidigare studie hittats hos kallblodstravare och skulle möjligtvis kunna vara en temperamentsegenskap som är fördelaktig i travtävlingar. Egenskapernas arvbarhet skattades vara mellan 0 till 0.42, där läraktighet och samarbetsvilja hade de högst skattade arvbarheterna (h 2=0.42 för båda).Totalt förbereddes 288 DNA-prover varav 96 inkluderades i sekvenseringen. Baserat på egenskapernas arvbarhet och poängfördelning så valdes egenskapen upphetsning ut till kommande associationsanalys. Signifikanta skillnader mellan fall- och kontrollgrupper återfanns vid ett flertal loci. Slutligen, trots ett litet datamaterial,sågs en genetisk variation hos ett flertal av de analyserade temperamentsegenskaperna och signifikanta arvbarheter kunde skattas. Nästa steg är att korrelera temperamentsegenskaperna till prestationsegenskaper och att skatta genetiska korrelationer mellan dessa. Arvbarhetsskattningarna i detta arbete gav en indikation på vilka egenskaper som kan vara intressanta att studera vidare på en molekylärgenetisk nivå. Den preliminära analysen av data från helgenomsekvenseringen visade intressanta resultat som bör analyseras vidare med fler hästar inkluderade 2021-08-18 Second cycle, A2E NonPeerReviewed application/pdf sv https://stud.epsilon.slu.se/17151/1/Berglund_P_210818.pdf Berglund, Paulina, 2021. Genetic background of temperament traits in standardbred trotters. Second cycle, A2E. Uppsala: (VH) > Dept. of Animal Breeding and Genetics (until 231231) <https://stud.epsilon.slu.se/view/divisions/OID-670.html> urn:nbn:se:slu:epsilon-s-17151 eng |
| spellingShingle | Animal genetics and breeding Berglund, Paulina Genetic background of temperament traits in standardbred trotters |
| title | Genetic background of temperament traits in standardbred trotters |
| title_full | Genetic background of temperament traits in standardbred trotters |
| title_fullStr | Genetic background of temperament traits in standardbred trotters |
| title_full_unstemmed | Genetic background of temperament traits in standardbred trotters |
| title_short | Genetic background of temperament traits in standardbred trotters |
| title_sort | genetic background of temperament traits in standardbred trotters |
| topic | Animal genetics and breeding |
| url | https://stud.epsilon.slu.se/17151/ https://stud.epsilon.slu.se/17151/ |