Age at first egg and egg production--their inheritance and expected response to different methods of selection.

Abstract

Synopsis Data pertaining to a closed White Leghorn flock maintained at the Punjab Agricultural University were used for estimating genetic and phenotypic parameters for age at first egg and 70‐d egg production and also to evaluate the expected response to different methods of selection. Records of 2377 pullets, a progeny of 1001 dams and 155 sires over a period of two years, were used. The birds in this flock attained sexual maturity on an average at the age of 176.6 d and produced on an average 33.6 eggs in first 70 d of egg production. Heritability for age at first egg and 70‐d egg production was obtained from different observational components. Age at first egg was found to have a medium heritability, the estimates being 0.370 ±0.003, 0.080 ±0.016 and 0.224 + 0.040 from sire, dam and full sib components, respectively. The heritabilities for 70‐d egg production were low. The estimates were 0.132±0.004, 0.214±0.011 and 0.173±0.06 from sire, dam and full sib components, respectively. Phenotypic, genetic a...