Genetic Parameter Estimates for Egg Production in Dwarf Broiler Breeders

Abstract

The objectives of this study were to estimate genetic and phenotypic correlations among and heritability estimates for hen-day rate (HDRT), egg weight (EWT), egg shape (ESHP), and age at first egg (AFE) in a fast-feathering female line of dwarf broiler breeders. Data were collected in 1993 from 58 sires and 1354 daughters. All phenotypic correlations except HDRT with ESHP were significant (P< .01). The negative phenotypic correlation of HDRT with AFE indicates an increase in egg production as AFE decreases. Similarly, negative phenotypic correlations between HDRT and EWT indicate that as HDRT increased EWT decreased, suggesting that increased egg production resulted in decreased EWT. The positive correlation of EWT with AFE and ESHP indicated that later maturing birds lay heavier eggs and that rounder eggs are heavier eggs. Genetic correlations were similar (in both sign and magnitude) to the phenotypic correlations, suggesting that genetic gains in HDRT or egg production are accompanied by decreases in EWT and AFE and that genetic reduction of AFE results in reduced EWT.