Inheritance of Body Weight in Japanese Quail

Two generations of Japanese quail were weighed in order to estimate genetic parameters of body weight throughout the growth phase of the life cycle. Sexual dimorphism became evident at the age of sexual maturity. This was due to an acceleration of weight gains by females just prior to laying their first egg. Body weight at 1 day of age reflected a large maternal influence which rapidly declined with age. Unrealistic estimates of the heritability of female body weight were obtained at the time of sexual maturity. At other ages heritability estimates of body weight were generally moderate to high. All phenotypic correlations between weights at various ages were positive, with the magnitude generally decreasing as the interval between weighings increased. Genotypic correlations were larger and followed the same general trends as phenotypic correlations with certain exception, namely when one of the ages was day 1 and when the ages involved maturity of females.