Restricted Selection Indexes in Poultry Breeding Programs

Abstract

Practical uses of restricted selection indexes were discussed and a simple method for computing selection indexes with varying degrees of restriction was developed. This method has the advantage of simplicity, and the genetic cost of the restriction can be readily calculated. It gives a suitable artificial economic weighting needed to stabilize any trait under selection with original index. The range of possible intermediate restrictions was plotted to choose a particular degree of restriction. When strains have already reached optimum level for certain traits selection indexes are designed to achieve maximum income, assuming that there should be no (or only minor) changes in specified traits. Restricted selection indexes at various degrees of restriction on two traits in a White Leghorn flock are described. The traits to which restriction was applied were sexual maturity and egg weight.