Estimates of covariance functions for growth from birth to 630 days of age in Nelore cattle

Title
Estimates of covariance functions for growth from birth to 630 days of age in Nelore cattle
Publication Date
2001
Author(s)
Albuquerque, L Galvao
Meyer, Karin
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
American Society of Animal Science
Place of publication
United States of America
UNE publication id
une:11446
Abstract
Weight records of Brazilian Nelore cattle, from birth to 630 d of age, recorded every 3 mo, were analyzed using random regression models. Independent variables were Legendre polynomials of age at recording. The model of analysis included contemporary groups as fixed effects and age of dam as a linear and quadratic covariable. Mean trends were modeled through a cubic regression on orthogonal polynomials of age. Up to four sets of random regression coefficients were fitted for animals' direct and maternal, additive genetic, and permanent environmental effects. Changes in measurement error variances with age were modeled through a variance function. Orders of polynomial fit from three to six were considered, resulting in up to 77 parameters to be estimated. Models fitting random regressions modeled the pattern of variances in the data adequately, with estimates similar to those from corresponding univariate analysis. Direct heritability estimates decreased after birth and tended to be lowest at ages at which maternal effect estimates tended to be highest. Maternal heritability estimates increased after birth to a peak around 110 to 120 d of age and decreased thereafter. Additive genetic direct correlation estimates between weights at standard ages (birth, weaning, yearling, and final weight) were moderate to high and maternal genetic and environmental correlations were consistently high.
Link
Citation
Journal of Animal Science, 79(11), p. 2776-2789
ISSN
1525-3163
0021-8812
Start page
2776
End page
2789

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