A Study on Genetic Improvement of New Hampshire Chickens

Abstract

This experiment was designed to obtain information needed for investigating the most efficient selection method to improve both the body weight at nine weeks of age and egg production in New Hampshire chickens.The heritability estimates for body weight at various early ages were generally high, ranging from 0.658 to 0.452 for males. In females, the estimates from sire components were similar to those of the male, and those from dam components were considerably higher yet. This suggestes that maternal effects and/or gene interaction affect body weight at these various early ages.The heritability estimate for egg numbers during the first 60 days from first egg was moderate.The genetic correlation of body weight at nine weeks of age with egg number was moderately negative.Selection by a single trait at a time may cause the largest genetic change in the body weight or egg number. The largest genetic gain in total economic value may be attained by using a index selection for the total score. Selection on independent culling levels for each trait increases the body weight and egg number at any given time, but is less efficient than index selection, in total economic value.