Genetic-Economic Value in Selecting for Egg Production Rate, Body Weight and Egg Weight

INTRODUCTION THE genetic-economic value of a breeding flock is a function of rate of lay, egg size, body weight and other traits only partially independent. Top ranking entries in random sample tests, where income over feed costs is the criteria of ranking, are frequently characterized by high rate of lay, intermediate egg size and rather small body size. Economically it would seem sound to select for the smallest bird which lays the largest eggs most rapidly, but biologically this course of action is questionable. Lerner (1951) suggested that highest reproductive fitness was associated with genotypes for intermediate egg size. Since the breeder, of necessity, must consider many traits in a selection program, the question of negative genetic correlations must be considered. If negative genetic correlations are important, intense selection on one trait may cause depression in another. In Part 1 of this study several methods were used to estimate phenotypic . . .