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Estimates of genetic changes in 365d-weight in a Brazilian nellore herd

E.C. Pimenta Filho^I; R.B. Lôbo^{II, IV}; F.A.M. Duarte^II; A. Zancaner^III; C J. Wilcox^IV

^IDepartamento de Zootecnia, Universidade Federal da Paraiba, Campus de Areia, 38397 Areia, Paraiba, Brazil
^IIDepartamento de Genética, Faculdade de Medicina, Universidade de São Paulo, 14049 Ribeirão Preto, SP, Brazil. Send correspondence to R.B.L.
^IIIFazenda Bonsucesso, Caixa Postal 298, 16700 Guararapes, SP, Brazil. Deceased.
^IVDairy Science Department, University of Florida, Gainesville, Florida 32611 USA.
The surviving authors dedicate this paper in memory of our colleague Arnaldo Zancaner

ABSTRACT

Data for 1,753 calves born from 1975 to 1984 were used to estimate genetic change in weight at 365 days of age in a Nellore herd in northeastern Brazil. Three estimation procedures were used; two were based on repeated use of sires over successive years, and the third on comparison of mean yearly genetic gains. Mathematical model included sire effects (random), and a set of fixed effects (sex, age of dam at parturition, season, and year of birth). The overall mean weight and standard error were 190 ± 5 kg (CV = 15%). Heritability estimate from correlation among paternal half-sibs was .27 ± .08. Estimates of genetic gain obtained by the three procedures agreed well, 1.38, 1.98 and 1.44 kg/year. Expected genetic gain was 1.68 kg/year. Results were very similar to larger studies done in temperate areas.

Keywords: Brazilian nellore.

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