Genetic parameters and alternatives for evaluation and ranking of Nellore young bulls in pasture performance tests

• Main Authors: Breno de Oliveira Fragomeni, Daiane Cristina Becker Scalez, Fábio Luiz Buranelo Toral, José Aurélio Garcia Bergmann, Idalmo Garcia Pereira, Paula Souza Teixeira da Costa
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Zootecnia 2013-08-01
• Series: Revista Brasileira de Zootecnia
• Subjects: breeding value; heritability; least square; mixed models; selection
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982013000800004&lng=en&tlng=en

The objective of this study was to estimate (co)variance components for weight at 550 days, average daily gain and an index with both traits, and to compare alternatives for evaluation and ranking of Nellore young bulls in pasture performance tests. The heritability estimates were 0.73, 0.31 and 0.44 for weight at 550 days, average daily gain and index, respectively. Animals were ranked according to their predicted breeding values or the phenotypic deviations in relation to the mean of the test. Although the correlations between breeding values and phenotypic deviations were high, there were differences in the number of animals selected in common when the selection criteria were the predicted breeding values or the phenotypic deviations. Mixed models are more appropriate than the least squares method and should be utilized in the evaluation of young bulls in performance tests.