Variabilidade na expressão da reatividade de potros brasileiro de hipismo não associada à polimorfismo do gene DBH
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Data
2017-05-22
Autores
Lima, Bruno Nogueira de Oliveira [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Em todos os esportes equestres é comum que os animais sejam testados com grande variação de obstáculos, percursos e ambientes. Essas dificuldades impostas nas provas equestres justificam o foco em um dos aspectos mais importantes do temperamento dos cavalos: sua reatividade ou comportamento de fuga ("flightness"). A reatividade dos potro pode ser caracterizada pela aproximação ou fuga de determinado estímulo. Este estudo teve como objetivo verificar a existência da variabilidade na expressão do comportamento de um grupo de potros Brasileiro de Hipismo (BH) frente à novo objeto e se existe alguma associação entre a reatividade dos animais durante o teste do novo objeto e a presença do polimorfismo de nucleotídeo único (SNP - Single Nucleotide Polymorphism) A758T do gene DBH. O teste do novo objeto (feito com a utilização de um guarda-chuva aberto) foi realizado em 260 potros Brasileiro de Hipismo (BH) sem nenhum treinamento montado. A avaliação da reatividade e rapidez de habituação foi feita por avaliação qualitativa do comportamento (QBA - Qualitative Behavior Analysis) durante o teste de novo objeto. Foi possível observar grande variabilidade fenotípica entre os potros, sendo que os animais foram divididos em um grupo com altos valores para as variáveis RELAXADO, FOCADO, CONFIANTE e POSITIVAMENTE CURIOSO e outro grupo de animais com altos valores para PRECAVIDO, AGITADO, CONFUSO e DESESPERADO. Também foi observado que os criatórios diferiram entre si quanto à adoção de seleção direcional ou não para a reatividade dos animais. Apesar disso, a presença de animais que podem ser caracterizados como "patologicamente ansiosos", evidencia a necessidade de maior atenção por parte dos criatórios nacionais na seleção de animais com menor reatividade. O nosso estudo evidenciou também que a SNP A758T no gene DBH não estava presente no subgrupo de 20 animais genotipados dentro da população estudada. Esse subgrupo de 20 animais genotipados era não aparentado e possuía fenótipo representativo da população, portanto, desestimula pesquisas futuras com a SNP A758T na raça BH.
In all the equestrian sports it is common that the animals are tested with a great variation of obstacles, courses and environments. These difficulties imposed in the equestrian sports justify the focus in one of the aspects of a horse's temperament: his reactivity or flight behavior (“flightiness”). The horse's reactivity can be characterized by his approach or escape of determined stimulus. This study aimed to verify the existence of behavior variability in Brazilian Sport Horse fillies and colts and if there is any association between that behavior and the presence of the DBH SNP A758T. In order to accomplish this, we tested 260 Brazilian Sport Horse fillies and colts, without any mounted training, in a novel object test using an umbrella. The horse’s reactivity and habituation speed was analyzed through a QBA- Qualitative Behavior Analysis during the novel object test. It was possible to observe a great phenotypic variability between the animals and divide them in a group with high values for the variables RELAXED, FOCUSED, CONFIDENT and POSITIVELY CURIOUS and another group of animals with high values for CAUTIOUS, AGITATED, CONFUSED and DESPAIRED. We also observed that the breeders differed with respect to the adoption of a directional selection or not for the animals' reactivity. In spite of this, the presence of animals that can be characterized as "pathologically anxious", shows the need for a greater attention on the part of national breeders in the selection of animals with less reactivity. Moreover, our study also showed that SNP A758T in the DBH gene was not present in a subgroup of 20 animals within the study population. This subgroup of 20 genotyped animals were unrelated and had a phenotype representative of the population, therefore discourages future research with SNP A758T in Brazilian Sport Horses.
In all the equestrian sports it is common that the animals are tested with a great variation of obstacles, courses and environments. These difficulties imposed in the equestrian sports justify the focus in one of the aspects of a horse's temperament: his reactivity or flight behavior (“flightiness”). The horse's reactivity can be characterized by his approach or escape of determined stimulus. This study aimed to verify the existence of behavior variability in Brazilian Sport Horse fillies and colts and if there is any association between that behavior and the presence of the DBH SNP A758T. In order to accomplish this, we tested 260 Brazilian Sport Horse fillies and colts, without any mounted training, in a novel object test using an umbrella. The horse’s reactivity and habituation speed was analyzed through a QBA- Qualitative Behavior Analysis during the novel object test. It was possible to observe a great phenotypic variability between the animals and divide them in a group with high values for the variables RELAXED, FOCUSED, CONFIDENT and POSITIVELY CURIOUS and another group of animals with high values for CAUTIOUS, AGITATED, CONFUSED and DESPAIRED. We also observed that the breeders differed with respect to the adoption of a directional selection or not for the animals' reactivity. In spite of this, the presence of animals that can be characterized as "pathologically anxious", shows the need for a greater attention on the part of national breeders in the selection of animals with less reactivity. Moreover, our study also showed that SNP A758T in the DBH gene was not present in a subgroup of 20 animals within the study population. This subgroup of 20 genotyped animals were unrelated and had a phenotype representative of the population, therefore discourages future research with SNP A758T in Brazilian Sport Horses.
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Palavras-chave
Cavalos, Reatividade, Variabilidade, Horses, Reactivity, Variability