A COMPARISON OF ALTERNATIVE INDEX PROCEDURES FOR MULTIPLE GENERATION SELECTION ON NONLINEAR PROFIT

Alternative index procedures for selection on non-linear profit are qu adratic indices, desired gains indices, group or mate selection indice s, or direct optimization of responses over multiple generations. In t his study a multiple generation time horizon was considered and severa l linear, quadratic and desired gains indices were compared. Genetic a nd economic responses over multiple generations were calculated consid ering a quadratic profit function combining protein yield and days ope n. Directly optimizing reponse over multiple generations was found to yield slightly higher economic responses (+ <1.5%) than stepwise (each generation) adjustment of a linear index. A constant linear index usi ng base population averages and a quadratic index were found to be les s efficient. The quadratic index was less efficient than the linear in dex when considering multiple generations. Desired gains indices allow ed stabilization of base population average for days open, however, fo rcing considerable economic losses. Relative efficiencies of methods d epended on the degree of non-linearity of the profit function.