Introduction

Abstract

Since the rediscovery of Mendel's “fundamental laws of inheritance” in 1900, our understanding of genetic basis of inheritance from qualitative to quantitative traits has been rapid. Very important was Fisher's work (1918), which first partitioned genetic variation into additive, dominant, and epistatic components. Further subdivision of the epistatic effects was provided by Cockerham (1954). Fisher, Wright, and Haldane's quantitative genetic and biometrical theories were evaluated and applied to animal breeding by J. L. Lush and his students, among others. Selection experiments have been the basis for testing theories, hypotheses, and predictions of quantitative genetic theory. In addition, selection experiments enable researchers to estimate genetic parameters, test alternate breeding schemes, and study the causes of selection limits and plateaus and develop means to overcome them. The design of any selection experiment depends upon its objectives.Application of quantitative genetic and biometrical methods to poultry breeding have resulted in unprecedented genetic improvement …