Change of Expected Response to Multitrait Selection in A Synthetic Population of Perennial Ryegrass Through Recurrent Selection I. Prediction of the Bulmer Effect.

The in parameters, variances, covariances and heritabilities, caused by the Bulmer effect have been predicted for an artificial breeding population of perennial ryegrass using recursion formulae. This enabled anticipation of the decrease in the expected response to multitrait index selection, using two different sets of economic weights. This theoretical decrease in selection efficiency was found to be quite substantial; it is approximately halved after 4 cycles of individual recurrent selection with a fairly high selection intensity of 5 %. However the synthetic population is improved for 4 out of 5 agronomic traits and could theoretically reach quite a high level of performance after 5 cycles. The choice of economic weights has relatively little influence on the expected genetic progress of each trait. [ABSTRACT FROM AUTHOR]