Alternative models for QTL detection in livestock. III. Heteroskedastic model and models corresponding to several distributions of the QTL effect

This paper describes two kinds of alternative models for QTL detection in l ivestock: an heteroskedastic model, and models corresponding to several hyp otheses concerning the distribution of the QTL substitution effect among th e sires: a fixed and limited number of alleles or an infinite number of all eles. The power of different tests built with these hypotheses were compute d under different situations. The genetic variance associated with the QTL was shown in some situations. The results showed small power differences be tween the different models, but important differences in the quality of the estimations. In addition, a model was built in a simplified situation to i nvestigate the gain in using possible linkage disequilibrium. (C) Inra/Else vier, Paris.