Genetic evaluation of European quails by random regression models

Abstract

-The objective of this study was to compare different random regression models, defined from different classes of heterogeneity of variance combined with different Legendre polynomial orders for the estimate of (co)variance of quails. The data came from 28,076 observations of 4,507 female meat quails of the LF1 lineage. Quail body weights were determined at birth and 1, 14, 21, 28, 35 and 42 days of age. Six different classes of residual variance were fitted to Legendre polynomial functions (orders ranging from 2 to 6) to determine which model had the best fit to describe the (co)variance structures as a function of time. According to the evaluated criteria (AIC, BIC and LRT), the model with six classes of residual variances and of sixth-order Legendre polynomial was the best fit. The estimated additive genetic variance increased from birth to 28 days of age, and dropped slightly from 35 to 42 days. The heritability estimates decreased along the growth curve and changed from 0.51 (1 day) to 0.16 (42 days). Animal genetic and permanent environmental correlation estimates between weights and age classes were always high and positive, except for birth weight. The sixth order Legendre polynomial, along with the residual variance divided into six classes was the best fit for the growth rate curve of meat quails; therefore, they should be considered for breeding evaluation processes by random regression models.

Sensitivity of breeding values of meat quail as a result of tryptophan: lysine ratios in the diet

“…Saúde Prod. Anim., Salvador, v.19, n.4, p.403-414 Our results corroborate with the literature, which suggests the need to use residual variance heterogeneity, in terms that it promotes a better fit of residual variance while compared to the homogeneous variance (FARIA et al, 2017;TEIXEIRA et al, 2012;GONÇALVES et al 2012;BONAFE et al, 2011). Evaluating carcass traits of meat quails, Miranda et al (2016) also observed that the random regression models considering residual variance heterogeneity promoted better adjustment than the models that used homogeneous residual variance, as observed in this study.…”

Genotype and protein level interaction in growth traits of meat-type quail through reaction norm models

“…An additional source of body weight variation in advanced ages (e.g., 35 days) is the physiological difference between animals as sexual maturity for female and competitive behaviour for male. The increment of body weight variances over ages has already been reported in meat-type quail by Akbas et al (2004) and Gonçalves et al (2012). The increase of the genetic variance over PL suggests the presence of G×E for BW 28 in UFV1 line and BW 35 in both lines.…”

Sensitivity of breeding values for carcass traits of meat‐type quail to changes in dietary (methionine + cystine):lysine ratio using reaction norm models

“…Other authors (Lewis & Brotherstone ; Gonçalves et al . ) also reported the need to consider the heterogeneity of residual variance in models. These authors concluded that the residual variance with six heterogeneous classes provided the best adjustment, compared with the homogeneous residual variance.…”