Association analyses of forehead hair whorls, behaviour, and chromosome regions in Standardbred Trotters
Introduction: In horse breeding, athletic skills have been in focus and certain behaviour types have been found to be important for competition. Behaviour is heritable but is also affected by the environment. Just like humans, animals have their own personality and behaviour-traits. The hair whor...
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| Formato: | H3 |
| Lenguaje: | Inglés sueco |
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SLU/Dept. of Animal Breeding and Genetics (until 231231)
2022
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| Sumario: | Introduction: In horse breeding, athletic skills have been in focus and certain behaviour types have
been found to be important for competition. Behaviour is heritable but is also affected by the
environment. Just like humans, animals have their own personality and behaviour-traits.
The hair whorls in the equine forehead and their potential meaning have been discussed by people
practising horsemanship. They are believed to tell us things about the horse’s behaviour and
personality. The hair whorls are thought to take form when the skin on the foetus expands during
growth in the uterus. At a certain timepoint during development, the hair follicles get set in their
angle that gives the hair its direction to grow. But exactly how the hair whorls get their specific
appearance and what position they get is unclear. Since both brain and skin cells originate from the
ectoderm, there are theories that the brain can be mirrored by the overlying skin.
The aim of this study was to investigate if there is an association between facial hair whorls and
behaviour as well as finding regions of interest for the hair whorl types in the horses’ DNA.
Material and method: The behaviour data to be analysed in this study had already been collected
through a survey in another project about genetics and behaviour. The behaviour traits analysed
were nervosity, excitability, fearfulness, concentration, learning, memory, cooperation, will to win,
stubbornness, self-control, recovery, appetite and stereotypic behaviour. In that survey the trainer
gave the horses scores between 1-7 depending on how often they saw the behaviour during
competition. Hair samples from the horses’ tails had also been collected.
This study analysed the association between the thirteen different behaviour traits from the survey
and nineteen different hair whorl types in 175 Standardbred trotters. Their DNA were extracted, and
their genome low pass sequenced and analysed. Their genomic information was run in a computer
program that compared the individuals in the different hair whorl groups.
The hair whorls were inspected live or from a photo, a protocol was filled out and a photo was taken
on the horses’ forehead. The horses were then divided into groups as low (1 and 1-2) and high (7
and 6-7) scores from the survey, and hair whorl groups that were classified as contraries. Statistical
association analyses were then performed between individuals that had extreme scores (1 against 7
and 1-2 against 6-7) in the behaviour traits according to the survey, and the differing hair whorl
groups. The association were analysed using two by two contingency tables.
The results of this study can indicate the following; if a facial hair whorl is located to the right (to
the left from a frontal view), the chance is bigger that it becomes nervous during competition in
comparison to a horse with a facial hair whorl to the left (p-value: 0,025). If a horse has more than
one facial hair whorl, it more often took longer for it to learn the task of competing (p-value: 0,03).
Comparing the horses that had a facial hair whorl looking like a feather, there was a greater chance
of the trotter to be focused and concentrated during competition if the feather went in a vertical
direction, compared to if it had a horizontal or diagonal direction (p-value: 0,05). If the feather was
vertical, they also had a higher chance of having good appetite after competition (p-value: 0,03).
On five chromosome regions, but one especially, there was found a highly significant difference
between horses with one hair whorl and horses with two hair whorls in the forehead. For future
investigations in this subject, these results can serve as an interesting basis about associations
between facial hair whorls, behaviour, and genetics of Standardbred trotters. |
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