Relações genéticas entre índices de biotipo animal e características de importância econômica em bovinos Nelore
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Data
2018-10-22
Autores
Tramonte, Nicole Colucci
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Universidade Estadual Paulista (Unesp)
Resumo
O objetivo do presente estudo foi reunir as características morfológicas de estrutura (ES), precocidade (PS) e musculosidade (MS) ao sobreano em características únicas indicadoras de biotipo animal, estimar seus parâmetros genéticos e para características de importância econômica como peso ajustado aos 450 dias de idade (P450), área de olho de lombo (AOL), espessura de gordura subcutânea na costela (EG), espessura de gordura subcutânea na garupa (EGP8), ES, PS, MS, perímetro escrotal ajustado aos 365 (PE365) e 450 (PE450) dias de idade, idade ao primeiro parto (IPP), probabilidade de parto precoce (PPP) e stayability(STAY), a fim de verificar a possibilidade da utilização das características indicadoras biotipo em programas de melhoramento genético de bovinos de corte da raça Nelore. Os dados analisados foram fornecidos pela Associação Nacional de Criadores e Pesquisadores (ANCP). O modelo utilizado para a estimativa de parâmetros genéticos incluiu o efeito aleatório genético aditivo direto e o efeito fixo de grupo de contemporâneos. Para as análises foi utilizada a metodologia ssGBLUP. Métodos multivariados foram empregados para análises de componentes principais pelo procedimento PROC PRINCOMP do software SAS. Foram utilizados dados de ES, PS, MS e P450. O primeiro e o segundo componentes da análise explicaram 82,08% da variabilidade dos dados de e foram utilizados como autovalores para obtenção dos índices de biotipo animal PCA1 e PCA2. A característica SAM foi formada pela combinação dos escores de ES, PS e MS, penalizando ou bonificando os animais tardios, ou precoces, respectivamente. Os índices de biotipo animal apresentaram alta variabilidade genética, com estimativas de herdabilidade de moderada a alta magnitude, iguais a 0,42, 0,40 e 0,39, para PCA1, PCA2 e SAM respectivamente, indicando rápida resposta à seleção direta e, podem ser recomendados como critérios de seleção em substituição à seleção praticada por meio dos escores visuais de E, P e M. As correlações genéticas entre as características indicadoras de biotipo e as de importância econômica indicam que a seleção direta para biotipo poderá contribuir para o aumento da produtividade e eficiência econômica. A característica indicadora de biotipo que apresentou correlações genéticas mais satisfatórias entre as de importância econômica foi a SAM. Assim, a seleção direta para esta poderá contribuir para a obtenção de ganhos em precocidade sexual e de terminação e desempenho ponderal, mantendo a estrutura corporal dos animais.
The aim of this study was to gather the morphological characteristics after yearling of body structure (BS), finishing precocity (FP) and muscling (MS) in unique traits indicative of animal biotype and estimate its genetic parameters and for the characteristics of economic importance of body weight at 450 days of age (W450), ribeye area (REA), backfat thickness (BF), rump fat thickness (RF), BS, FP, MS, scrotal circumference at 365 (SC365) and 450 (SC450) days of age, age at first calving (AFC), heifer pregnancy (HP) and stayability (STAY) in order to verify the possibility of using the animal biotype indicator characteristics in breeding programs for Nelore beef cattle. The data analyzed were provided by the National Association of Breeders and Researchers (ANCP). The model used for the estimation of genetic parameters included the additive genetic direct random effect and the fixed group effect of contemporaries. For the analyzes, the ssGBLUP methodology was used. Multivariate methods were used for principal component analyzes by the PROC PROCOMP procedure of the SAS software. Data from BS, FP, MS and W450 were used. The first and second components of the analysis explained 82.08% of the variability of the data and were used as eigenvalues to obtain the indices of animal biotype PCA1 and PCA2. The SAM characteristic was formed by the combination of BS, FP and MS scores, penalizing or subsidizing late or early animals, respectively. The animal biotype indexes presented high genetic variability, with heritability estimates of moderate to high magnitude, equal to 0.42, 0.40 and 0.39 for PCA1, PCA2 and SAM respectively, indicating a rapid response to direct selection and, can be recommended as selection criteria in place of the selection practiced through the visual scores of ES, PS and MS. The genetic correlations between the biotype and economic indicators indicate that direct selection for biotype may contribute to the increase productivity and economic efficiency. The biotype indicating trait that presented more satisfactory genetic correlations among those of economic importance was SAM. Thus, the direct selection for this can contribute to the achievement of gains in sexual precocity and of termination and ponderal performance, maintaining the body structure of the animals.
The aim of this study was to gather the morphological characteristics after yearling of body structure (BS), finishing precocity (FP) and muscling (MS) in unique traits indicative of animal biotype and estimate its genetic parameters and for the characteristics of economic importance of body weight at 450 days of age (W450), ribeye area (REA), backfat thickness (BF), rump fat thickness (RF), BS, FP, MS, scrotal circumference at 365 (SC365) and 450 (SC450) days of age, age at first calving (AFC), heifer pregnancy (HP) and stayability (STAY) in order to verify the possibility of using the animal biotype indicator characteristics in breeding programs for Nelore beef cattle. The data analyzed were provided by the National Association of Breeders and Researchers (ANCP). The model used for the estimation of genetic parameters included the additive genetic direct random effect and the fixed group effect of contemporaries. For the analyzes, the ssGBLUP methodology was used. Multivariate methods were used for principal component analyzes by the PROC PROCOMP procedure of the SAS software. Data from BS, FP, MS and W450 were used. The first and second components of the analysis explained 82.08% of the variability of the data and were used as eigenvalues to obtain the indices of animal biotype PCA1 and PCA2. The SAM characteristic was formed by the combination of BS, FP and MS scores, penalizing or subsidizing late or early animals, respectively. The animal biotype indexes presented high genetic variability, with heritability estimates of moderate to high magnitude, equal to 0.42, 0.40 and 0.39 for PCA1, PCA2 and SAM respectively, indicating a rapid response to direct selection and, can be recommended as selection criteria in place of the selection practiced through the visual scores of ES, PS and MS. The genetic correlations between the biotype and economic indicators indicate that direct selection for biotype may contribute to the increase productivity and economic efficiency. The biotype indicating trait that presented more satisfactory genetic correlations among those of economic importance was SAM. Thus, the direct selection for this can contribute to the achievement of gains in sexual precocity and of termination and ponderal performance, maintaining the body structure of the animals.
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Palavras-chave
Componentes principais, Correlação genética, Escores visuais, Herdabilidade, Genetic correlation, Heritability, Principal components, Visual scores