Alternative models for QTL detection in livestock. I. General introduction

In a series of papers, alternative models for QTL detection in livestock ar e proposed and their properties evaluated using simulations. This first pap er describes the basic model used, applied to independent half-sib families , with marker phenotypes measured for a two or three generation pedigree an d quantitative trait phenotypes measured only for the last generation. Hypo theses are given and the formulae for calculating the likelihood are fully described. Different alternatives to this basic model were studied, includi ng variation in the performance modelling and consideration of full-sib fam ilies. Their main features are discussed here and their influence on the re sult illustrated by means of a numerical example. (C) Inra/Elsevier, Paris.