Relationship of embryonic development to egg weight, hatch weight, and growth in Japanese quail.

Relationships between egg, embryo, hatch, two-week and four-week body weights of three quail lines differing in growth rate were investigated. Two of the quail lines had previously undergone 29 generations of selection for increased four-week body weight, and the third line was a nonselected control. Selected lines produced heavier eggs, larger 10 to 11 day embryos, and larger chicks. Percent embryo weights were similar for all three lines indicating that correction for egg size eliminated differences in embryo weight. Percentages of hatch weights of selected lines were significantly (P less than .01) larger than comparable percentages in the control line. Correlations between egg and embryo weights were of low magnitude but correlations between egg and hatch weights were large (.7 to .8). Mean regression coefficients for four-week body weight on egg weight were 5.11 and 2.67 g. in trials 1 and 2, respectively. Relationships between egg, embryo, hatch, and body weights of Japanese quail appeared to be of the same general magnitude as those observed in the domestic fowl.