02088naa a2200289 a 450000100080000000500110000800800410001902200140006002400410007410000220011524501420013726000090027952011800028865000180146865000250148665000220151165300170153365300230155065300180157370000250159170000170161670000220163370000220165570000250167770000220170277300740172421234352020-12-11       2020    bl uuuu     u00u1 u    #d  a1679-03597 a10.5433/1679-0359.2020v41n2p5452DOI1 aCAVALCANTE, D. H.  aFitting of fixed regression curves with different residual variance structures for Nellore cattle growth modeling.h[electronic resource]  c2020  aDifferent polynomial functions were tested for mean trajectory modeling with different residual variance structures. A total of 15,148 weight records of 3,115 Nellore Mocho cattle with ages between 1 and 660 days, raised in northern Brazil. First, the mean trajectory of cattle growth curve was fitted by a fixed regression using orthogonal polynomials with orders ranging from two to seven. Analyses were performed using the least-squares method, disregarding animal and/ or maternal random effects. Then, the best model was evaluated using different residual variance structures and homogeneous and heterogeneous classes. We considered as fixed effects those of groups of contemporary and of dam age at birth (as linear and quadratic covariate). The random model part included animal and maternal effects (direct genetic and permanent environments). We concluded that the estimates of variance components and genetic parameters were affected by both fixed regression curve polynomial order and residual variance structure. Moreover, random regression model considering an order-four polynomial function with a fixed curve and six-class residual variance showed better fits.  aLinear models  aParâmetro Genético  aRegressão Linear  aCurva média  aModelagem residual  aModelo linear1 aSOUSA JÚNIOR, S. C.1 aSILVA, L. P.1 aMALHADO, C. H. M.1 aMARTINS FILHO, R.1 aAZEVEDO, D. M. M. R.1 aCAMPELO, J. E. G.  tSemina: Ciências Agráriasgv. 41, n. 2, p. 545-558, mar./abr. 2020.