The objective ofthis paper was to compare different random regression models adjusted throughLegendre polynomial functions of different orders to evaluate the one best adjustedto the genetic study of the meat quail growth curve. The data used in this studywere from 26,835 and 27,447 observations from 3,909 and 4,040 meat quails ofthe UFV-1 and UFV-2 strain, respectively. The body weight of the two strainwas evaluated on 1, 7, 14, 21, 28, 35 and 42 days of age. The orders of adjustmentof the continuous functions were gradually increased (orders varying from 3to 6), to determine the least necessary order to describe structure of covariancein function of time in the random regression models. Legendre polynomial functionsof the 6th order for direct additive genetic effect and 5thorder for permanent effect, for strain UFV-1 and 6 for both random effects forstrain UFV-2 should be used in the genetic evaluation of the quail meat growthcurve in study. The estimated heritability indicates which genetic traits canbe obtained as a response to the physical body weight selection in two strain.
