Genetic parameter estimates of weekly body weight and Richard's growth curve in Japanese quail

This study was conducted to estimate heritabilities and genetic correlations for growth traits in a randomly mated and non-selected Japanese quail population. To this end, a total of 1108 pedigree recorded quail were used. To obtain the estimates of individual growth curve parameters of Richards function, all quail were weighed weekly from hatching to 6 weeks of age. In estimation of heritabilities and genetic correlations for all the traits in this study, a restricted maximum likelihood estimator (REML) was applied under a multiple trait animal model. Mean values of body weights from hatching to 6 weeks of age were determined as 7.83, 22.9, 51.1, 82.2, 119, 155 and 176 g, respectively. Estimates of heritability for weekly body weights were found to be 0.63, 0.42, 0.40, 0.46, 0.45, 0.52 and 0.36. Mean values and estimates of heritability for beta(0), beta(1), beta(2) parameters of Richards function were 258 g, 1.43, 0.087 and 0.35, 0.32, 0.31, respectively. All of the genetic correlations between weekly body weights were high, except for hatching weight. The mean values and estimates of heritability for weight and age at the point of inflection were found to be 96.1 g and 23.3 day, 0.21 and 0.41, respectively. Consequently, because of the advantages compared to other growth characteristics, the age at point of inflection is suggested as a selection criterion in for the genetic improvement of meat yield.