Genet. Sel. Evol. 37 (2005) 273-289
DOI: 10.1051/gse:2005002

A comparison of two methods for prediction of response and rates of inbreeding in selected populations with the results obtained in two selection experiments

Valérie Loywyck^a, Piter Bijma^b, Marie-Hélène Pinard-van der Laan^a, Johan van Arendonk^b and Etienne Verrier<sup>c

a</sup>  UMR Génétique et diversité animales, Institut national de la recherche agronomique / Institut national agronomique Paris-Grignon, 78352 Jouy-en-Josas Cedex, France
^b  Animal breeding and genetics group, Wageningen University, PO Box 338, 6700 AH Wageningen, The Netherlands
^c  UMR Institut national de la recherche agronomique / Institut national agronomique Paris-Grignon, 16 rue Claude Bernard, 75005 Paris, France

(Received 2 April 2004; accepted 10 November 2004)

Abstract - Selection programmes are mainly concerned with increasing genetic gain. However, short-term progress should not be obtained at the expense of the within-population genetic variability. Different prediction models for the evolution within a small population of the genetic mean of a selected trait, its genetic variance and its inbreeding have been developed but have mainly been validated through Monte Carlo simulation studies. The purpose of this study was to compare theoretical predictions to experimental results. Two deterministic methods were considered, both grounded on a polygenic additive model. Differences between theoretical predictions and experimental results arise from differences between the true and the assumed genetic model, and from mathematical simplifications applied in the prediction methods. Two sets of experimental lines of chickens were used in this study: the Dutch lines undergoing true truncation mass selection, the other lines (French) undergoing mass selection with a restriction on the representation of the different families. This study confirmed, on an experimental basis, that modelling is an efficient approach to make useful predictions of the evolution of selected populations although the basic assumptions considered in the models (polygenic additive model, normality of the distribution, base population at the equilibrium, etc.) are not met in reality. The two deterministic methods compared yielded results that were close to those observed in real data, especially when the selection scheme followed the rules of strict mass selection: for instance, both predictions overestimated the genetic gain in the French experiment, whereas both predictions were close to the observed values in the Dutch experiment.

Key words: selection experiments / poultry / inbreeding / genetic response / prediction methods

Correspondence and reprints: loywyck@inapg.fr

© INRA, EDP Sciences 2005