Research

Mapping quantitative trait loci (QTL) in sheep. I. A new male framework linkage map and QTL for growth rate and body weight

Herman W Raadsma¹ , Peter C Thomson¹ , Kyall R Zenger¹ , Colin Cavanagh^1,2 , Mary K Lam¹ , Elisabeth Jonas¹ , Marilyn Jones¹ , Gina Attard¹ , David Palmer¹ and Frank W Nicholas¹

¹  ReproGen – Advanced Technologies in Animal Genetics and Reproduction, Faculty of Veterinary Science, University of Sydney, 425 Werombi Road, Camden NSW 2570, Australia

²  Commonwealth Scientific and Industrial Research Organisation Plant Industry, Black Mountain, ACT 2601, Australia

author email corresponding author email

Genetics Selection Evolution 2009, 41:34doi:10.1186/1297-9686-41-34

Published:	24 April 2009

Abstract

A male sheep linkage map comprising 191 microsatellites was generated from a single family of 510 Awassi-Merino backcross progeny. Except for ovine chromosomes 1, 2, 10 and 17, all other chromosomes yielded a LOD score difference greater than 3.0 between the best and second-best map order. The map is on average 11% longer than the Sheep Linkage Map v4.7 male-specific map. This map was employed in quantitative trait loci (QTL) analyses on body-weight and growth-rate traits between birth and 98 weeks of age. A custom maximum likelihood program was developed to map QTL in half-sib families for non-inbred strains (QTL-MLE) and is freely available on request. The new analysis package offers the advantage of enabling QTL × fixed effect interactions to be included in the model. Fifty-four putative QTL were identified on nine chromosomes. Significant QTL with sex-specific effects (i.e. QTL × sex interaction) in the range of 0.4 to 0.7 SD were found on ovine chromosomes 1, 3, 6, 11, 21, 23, 24 and 26.