Genomewide association study of body weight traits in Baluchi sheep.

Abstract

The body weight is an economically important trait in sheep. We performed a genomewide association study using Ovine 50 K SNP chip to identify the genes and chromosome regions associated with body weight in Baluchi sheep. A total of 96 blood samples from two herds along with data on weight at birth (BW), weaning (WW), six month (SMW) and yearling (YW) were collected. Markers were tested for association based on linear regression using the PLINK software. Thirteen different SNP markers reached 5% Bonferroni chromosome-wide significance levels. In this study we detected one SNP with genomewide significance effect on yearling weight on chromosome 8. All significant SNPs at chromosome-wide significance level were within or close to known ovine genes. The SNP at genomewide significance level was within gene SYNE1. Thus, we suggest more investigation to prove these genes as candidate genes for body weight traits in sheep. Growth traits are economically important traits for sheep. Mapping of quantitative trait loci (QTL) is an appropriate approach and provides useful information for marker assisted selection (MAS) and gene-based selection in sheep breeding strategies. Relatively few number of QTLs have been reported in sheep. The current release (February 2014) of the Sheep QTLdb (http://www.animalgenome.org/cgi-bin/ QTLdb) contains 129 QTLs for growth traits reported from a genomic study based on marker-QTL linkage analysis. QTL mapping using linkage map QTLs to large confidence intervals on the genome. As a result, use of QTL in MAS is complicated. It would be possible to exploit linkage disequilibrium (LD) to map QTL if dense markers were available. With the advent of next-generation sequencing