A partial genome scan to identify quantitative trait loci affecting birthweight in Kermani sheep

The aim of this study was to map quantitative trait loci (QTL) underlying variation in birthweight (BWT) in a population of Kermani sheep, an indigenous fat-tailed sheep breed in southeast of Iran. Based on the combined results from QTL analyses in different livestock species, genome homology among mammalian species and functional and positional candidate gene studies, genomic intervals located on ovine chromosomes 1, 3, 6, 11 and 14 were considered as candidate genomic regions for BWT. Progeny (276 animals) from six half-sib families were genotyped for 25 informative microsatellite markers flanking the candidate intervals. QTL analysis in the candidate intervals was conducted using the least squares regression interval mapping approach. Linkage analysis indicated significant QTL for BWT on sheep chromosomes 1, 3, and 6 (chromosome-wide significance of P < 0.01). No QTL was detected on OAR11, and OAR14. QTL effect ranged from 1.0 to 1.6 in unit of residual standard deviation in different families. Although growth QTL have been mapped on sheep chromosomes 1, 3 and 6, this is the first report of QTL for BWT on these chromosomes.