Classificação morfológica em bovinos leiteiros
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2020-01-22
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A classificação morfológica é uma mais-valia, porque através dela é possível melhorar a conformação do animal, aumentando, a produção de modo direto e indireto e a valorização do mesmo. O presente trabalho teve como principais objetivos 1) realizar um estudo sobre várias características morfológicas 2) a relação entre elas e 3) quais as de maior peso para a classificação morfológica. Na parte I elaborou-se uma revisão bibliográfica onde foi abordada a classificação morfológica e efetuado um breve resumo sobre as características lineares e a sua importância. Na parte II foi apresentada 1) uma parte prática, que resultou no acompanhamento de um dos classificadores, classificando um total de 511 animais, e 2) uma parte que resultou num estudo sobre as várias características morfológicas avaliadas em 141879 animais. A média da pontuação final observada neste trabalho foi de 81,87±2,11 pontos. Constatou-se que a maior percentagem dos valores fenotípicos das características lineares situa-se entre 5, 6 e 7 pontos. Verificou-se que todas as características em estudo, apresentam uma correlação altamente significativa (P<0,001), porém, entre o ângulo da garupa e a largura da garupa verificou-se uma correlação com grau de significância de P<0,05. As três correlações mais altas em estudo foram: entre a largura do peito e a profundidade corporal (0,69), entre a textura do úbere e a inserção do úbere anterior (0,59) e entre a colocação dos tetos anteriores e a colocação dos tetos posteriores (0,58). Observou-se ainda que para a região da força as variáveis de maior peso foram a estatura, a profundidade corporal e a largura do peito; para o sistema mamário a inserção do úbere anterior, o ligamento suspensor médio e a profundidade do úbere; para a região das pernas e pés a mobilidade e as pernas vistas de trás; e a angulosidade para o carácter leiteiro. Observou-se uma boa qualidade de ajustamento para todas as regiões, com um coeficiente de determinação superior a 0,8. Com recurso ao critério de Kaiser selecionamos as 7 primeiras componentes principais das 23 características, tendo uma representação de 63% de variância cumulativa. A característica mais importante na formação de cada uma das 7 primeiras componentes foi: 1) largura do úbere posterior, 2) textura do úbere, 3) pernas vistas de lado, 4) colocação dos tetos anteriores, 5) qualidade óssea, 6) ângulo da garupa e 7) profundidade do úbere.
Morphological classification is an asset, because through it, it is possible to improve the conformation of the animal, increasing the direct and indirect production and the valorization of the same. The main objectives of the present work were 1) to carry out an study on various morphological traits 2) the relationship between them and 3) which as greater weight for morphological classification. In part I a bibliographic review was elaborated where the morphological classification was approached and a brief summary about the linear traits and their importance was made. Part II presented 1) a practical part, which resulted in the followup of one of the classifiers, classifying a total of 511 animals, and 2) a part that resulted in a study of the various morphological traits evaluated in 141879 animals. The average final score observed in this study was 81.87 ± 2.11 points. The percentage of the phenotypic values of linear characteristics was found to be between 5, 6 and 7 points. It was found that all the traits under study present a highly significant correlation (P <0.001), however, between the rump angle and the rump width a correlation with a significance level of P <0.05. The three highest correlations under study were: between chest width and body depth (0.69), between udder texture and front udder insertion (0.59), and between front teat placement and rear teat placement (0.58). It was also observed that for the strength region, the variables with the highest weight were stature, body depth and chest width; for the mammary system, the front udder insertion, the central ligament and the udder depth; for the legs and feet region mobility and rear legs-rear view; and the angularity to the dairy character. However, a good adjustment quality was observed for all regions, with a coefficient of determination greater than 0.8. Using the Kaiser criterion, we selected the first 7 main components of the 23 traits, representing 63% cumulative variance. The most important feature in the formation of each of the first 7 components were: 1) rear udder width, 2) udder texture, 3) rear legs – side view, 4) front teat placement, 5) bone quality, 6) rump angle and 7) udder depth.
Morphological classification is an asset, because through it, it is possible to improve the conformation of the animal, increasing the direct and indirect production and the valorization of the same. The main objectives of the present work were 1) to carry out an study on various morphological traits 2) the relationship between them and 3) which as greater weight for morphological classification. In part I a bibliographic review was elaborated where the morphological classification was approached and a brief summary about the linear traits and their importance was made. Part II presented 1) a practical part, which resulted in the followup of one of the classifiers, classifying a total of 511 animals, and 2) a part that resulted in a study of the various morphological traits evaluated in 141879 animals. The average final score observed in this study was 81.87 ± 2.11 points. The percentage of the phenotypic values of linear characteristics was found to be between 5, 6 and 7 points. It was found that all the traits under study present a highly significant correlation (P <0.001), however, between the rump angle and the rump width a correlation with a significance level of P <0.05. The three highest correlations under study were: between chest width and body depth (0.69), between udder texture and front udder insertion (0.59), and between front teat placement and rear teat placement (0.58). It was also observed that for the strength region, the variables with the highest weight were stature, body depth and chest width; for the mammary system, the front udder insertion, the central ligament and the udder depth; for the legs and feet region mobility and rear legs-rear view; and the angularity to the dairy character. However, a good adjustment quality was observed for all regions, with a coefficient of determination greater than 0.8. Using the Kaiser criterion, we selected the first 7 main components of the 23 traits, representing 63% cumulative variance. The most important feature in the formation of each of the first 7 components were: 1) rear udder width, 2) udder texture, 3) rear legs – side view, 4) front teat placement, 5) bone quality, 6) rump angle and 7) udder depth.
Descrição
Esta dissertação foi elaborada com vista à obtenção do Grau de Mestre em Engenharia Zootécnica apresentada à Universidade de Trás-os-Montes e Alto Douro
Palavras-chave
classificação morfológica , características lineares