The Heritability of the Percent Gamma Globulin Level in the New Hampshire Chick

The percent gamma globulin levels obtained at hatch, 1, 3, 5 and 7 weeks of age were 12.4, 10.9, 11.5, 14.2 and 15.4 respectively. Only weeks 1 and 3 were not significantly different. The decrease from hatch to 1 week of age was attributed to a loss of maternal antibody and a low rate of synthesis by the chick. The greatest increment from 3 to 5 weeks of age was consistent with the reports in the literature. The within individuals, variance component, obtained from the analysis of each age group considerably increased from 1 to 7 weeks of age. The sire and dam variance components did not vary with time. A large maternal effect at hatch was suggested by the sire (hs2=0.17) and dam (hd2=1.21) estimates of heritability. The analysis of the data from 1 to 7 weeks of age gave a sire estimate of heritability of 0.26 and a dam estimate of 0.67.