Parâmetros genéticos para desempenho em corridas de cavalos puro sangue inglês utilizando procedimentos Bayesiano e Thurstoniano
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Data
2012-05-25
Autores
Gama, Manuela Pires Monteiro da [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O objetivo desse trabalho foi estimar parâmetros genéticos para o caráter tempo e colocação final em corridas de cavalos Puro Sangue Inglês (PSI) com procedimentos Bayesiano e Thurstoniano, a fim de fornecer subsídios para a seleção de reprodutores e consequente melhoramento genético da raça no Brasil. A partir de dados fornecidos pela empresa Turf Total Ltda foram consideradas 251.754 informações de tempo e 272.277 informações de colocações finais em 34.316 corridas de cavalos PSI ocorridas entre 1992 e 2011 em 6 hipódromos do país, para as distâncias de 1.000, 1.300, 1.600 e 2.000 metros. Os efeitos considerados fixos foram idade, sexo, posição de largada e páreo para as análises de tempo, e sexo, idade, posição de largada, páreo e nível de dificuldade da corrida para as análises de colocações finais. As herdabilidades e correlações genéticas para tempo foram estimadas utilizando inferências bayesianas, ao passo que para as estimativas de herdabilidade de colocação final utilizou-se o modelo Thurstoniano. As estimativas de herdabilidade para tempo em análises unicaraterísticas. foram semelhantes às encontradas na literatura, e variaram entre 0,31 e 0,04 e as repetibilidades encontradas variaram de 0,61 a 0,22, respectivamente com o aumento das distâncias. As estimadas para colocação final variaram de 0,57 a 0,21, apresentando a mesma tendência que as herdabilidades para tempo. As estimativas de herdabilidade para tempo na análise multicaracterística variaram entre 0,34 e 0,15 com repetibilidade entre 0,63 e 0,36. Nessa análise, a seleção para tempo também mostrou-se mais eficiente em distâncias menores, onde as herdabilidades foram maiores. As estimativas de correlações genéticas foram positivas e variaram de 0,47 a 0,97. Conclui-se que, em distâncias mais curtas, a seleção tanto para tempo...
The objective of this study was to estimate genetic paremeters for racing time and final rank in Thoroughbred horses using Bayesian and Thurstonian procedures, in order to provide data that contribute for selection and the consequent genetic improvement of the breed in Brazil. Data were provided by the company Turf Total Ltda. and consisted of 251,754 racing time records and 272,277 final rank records obtained from 34,316 Thoroughbred races (distances of 1,000, 1,300, 1,600 and 2,000 m) that occurred between 1992 and 2011 on six race tracks. Fixed effects included age, sex, post-position and race for the analysis of racing time, and sex, age, post-position, race and level of difficulty for final rank analysis. The heritabilities for racing time and final rank and the genetic correlations between racing times were estimated by Bayesian inference. In addition, a Thurstonian model was used to estimate the heritability for final rank. The heritability estimates for racing time in one-trait analysis were similar to those reported in the literature and ranged from 0.31 to 0.04. Repeatability estimates tended to decrease with increasing race distance (0.61 to 0.22) .The heritabilities estimates for final rank ranged from 0.57 to 0.21 and showed the same trend as the heritabilities for time. The heritability estimates for racing time obtained by multi-trait analysis ranged form 0.34 to 0.15, with repeatabilities of 0.63 to 0.36 at the distances studied. Multi-trait analysis also showed that selection for racing time was more efficient at shorter distances when heritabilities were higher. The genetic correlations were all positive and ranged from 0.47 to 0.97. In conclusion, selection for both racing time and final rank is more efficient at shorter distances... (Complete abstract click electronic access below)
The objective of this study was to estimate genetic paremeters for racing time and final rank in Thoroughbred horses using Bayesian and Thurstonian procedures, in order to provide data that contribute for selection and the consequent genetic improvement of the breed in Brazil. Data were provided by the company Turf Total Ltda. and consisted of 251,754 racing time records and 272,277 final rank records obtained from 34,316 Thoroughbred races (distances of 1,000, 1,300, 1,600 and 2,000 m) that occurred between 1992 and 2011 on six race tracks. Fixed effects included age, sex, post-position and race for the analysis of racing time, and sex, age, post-position, race and level of difficulty for final rank analysis. The heritabilities for racing time and final rank and the genetic correlations between racing times were estimated by Bayesian inference. In addition, a Thurstonian model was used to estimate the heritability for final rank. The heritability estimates for racing time in one-trait analysis were similar to those reported in the literature and ranged from 0.31 to 0.04. Repeatability estimates tended to decrease with increasing race distance (0.61 to 0.22) .The heritabilities estimates for final rank ranged from 0.57 to 0.21 and showed the same trend as the heritabilities for time. The heritability estimates for racing time obtained by multi-trait analysis ranged form 0.34 to 0.15, with repeatabilities of 0.63 to 0.36 at the distances studied. Multi-trait analysis also showed that selection for racing time was more efficient at shorter distances when heritabilities were higher. The genetic correlations were all positive and ranged from 0.47 to 0.97. In conclusion, selection for both racing time and final rank is more efficient at shorter distances... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Equino - Desempenho, Equine - Genetic paremeters, Gibbs sample
Como citar
GAMA, Manuela Pires Monteiro da. Parâmetros genéticos para desempenho em corridas de cavalos puro sangue inglês utilizando procedimentos Bayesiano e Thurstoniano. 2012. v, 44 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências Agrárias e Veterinárias, 2012.