Abstract :
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.
