Genetic and phenotypic relationships in Japanese quail. 1. Body weight, carcass, and organ measurements.

Live BW, carcass data, and organ data taken at 34 days of age on approximately 1,000 quail of both sexes from 110 sires and 290 dams were utilized to estimate genetic parameters from the initial generation of a selection study. The birds represented a sample of a line selected for high 4-wk BW. Data were analyzed using Henderson's Method 3 (MM3) and restricted maximum likelihood (REML) with and without a relationship matrix. The paternal half-sib heritabilities for body, carcass, and organ weights in Japanese quail were moderate to high for most traits studied, suggesting that selection to increase or decrease these traits should be successful. With the exception of BW, abdominal fat (AF), and heart weights, maternal half-sib heritability estimates were smaller than paternal half-sib estimates. Heritability estimates of traits adjusted for BW tended to be lower than counterparts not adjusted for BW. The genetic correlations of BW with the other carcass measurements were positive, and tended to be moderate to high. The correlation of BW with AF was .34, suggesting that selection for increased BW alone will lead to a bird with more abdominal fat. The correlations of AF with the other traits tended to be low to moderate in magnitude, with three of the correlations being negative, suggesting correlated responses with other traits when selecting for increased or decreased AF would be small. Genetic correlations among various muscle measurements were all positive and most were high in magnitude, indicating that traits easiest to measure and collect can be used in a selection process. The genetic correlations among the organ measurements were positive and moderate as were the correlations of organ weights with muscle weights. Negative genetic correlation estimates between AF and muscle measures were obtained from analysis when BW was a covariate. The REML heritability estimates were higher than MM3 estimates and REML genetic correlation estimates were less extreme than MM3.