On-line version ISSN 1678-992X
GIOLO, Suely Ruiz; HENDERSON, Robin and DEMETRIO, Clarice Garcia Borges. Mixed-effects growth curves in the valuation of Nellore sires. Sci. agric. (Piracicaba, Braz.) [online]. 2009, vol.66, n.1, pp. 84-89. ISSN 1678-992X. http://dx.doi.org/10.1590/S0103-90162009000100012.
Cattle breeding programmes need objective criteria in order to evaluate and subsequently improve production systems. This work uses a logistic growth curve model for evaluating sires based on their progeny weight measured repeatedly over time. The parameters of the curve are described as a linear function of fixed and random effects. A Bayesian approach is used for the estimation. Analysis of the weights recorded on animals of the Nellore breed shows that growth curve models with fixed and random effects can be useful to evaluate and selecting sires.
Keywords : beef cattle; logistic model; longitudinal data; random effects.