Heritability of the egg production characteristics in purebred and crossbred pullets

Abstract

Heritability of the characteristics such as the age of the females at the first egg-laying day, egg yield of the first year, intensity and average cycle of egg-laying was studied in Australorps, White Leghorns and in the crossbreds of Barred Plymouthrock X Australorp, Australorp X White Leghorn and White Leghorn X Australorp. Coefficient of heritability was calculated as the ratio of genotypic dispersion to the phenotypic one (ƞm). The highest heritability coefficients of the maternal lines were found for the intensity and average cycle of the egg-laying (0.6—0.7), and in the paternal lines for the age of the females at the first egg-laying day (0.8). There were no significant differences in heritability coefficients between purebreds and crossbreds. It seems that calculation of heritability coefficients in small groups can be done better by using dispersion analysis method than by correlation and regression method. According to the author, the coefficient of heritability appears as one of the criteria for the determination of relation between the qualities of pure-line parents and their crossbred offsprings, and therefore he suggests the use of characters with high heritability in the industrial breeding.