Composition of Eggs from Dwarf and Normal Chickens in Lines Selected for 56-Day Body Weight

Egg weight and egg components were measured at two ages in random samples of 30 nondwarf and 30 dwarf chickens from lines selected for high and low body weight at 56 days of age. Egg, dry shell, dry albumen, total moisture, relative moisture, and dry albumen weights as well as albumen and yolk percentage dry matter were similar at 300 and 360 days of age. Absolute and relative dry yolk weights increased with age, whereas relative shell weight and wet and dry albumen to yolk (A:Y) ratios decreased. Pullets from the high weight line laid larger eggs with more dry yolk, but less relative dry yolk and shell dry matter than those from the low weight line. Nondwarf pullets produced larger eggs with more absolute and relative dry yolk and shell dry matter than dwarf pullets. Line × genotype interactions were present for egg traits other than absolute and relative dry yolk and shell dry matter, providing evidence of differential effects of the dwarfing allele in different genotypic backgrounds.