A genome scan for quantitative trait loci affecting average daily gain and Kleiber ratio in Baluchi Sheep

Genomewide association study (GWAS) is an efficient tool for the detection of SNPs and candidate genes in quantitative traits. Growth rate is an important trait for increasing the meat production in sheep. A total of 96 Baluchi sheep were genotyped using Illumina Ovine SNP50 BeadChip to run a GWAS for an average daily gain (ADG) and Kleiber ratio (KR) traits in different periods of age in sheep. Traits included were average daily gain from birth to three months (ADG_0-3), from three months to six months (ADG_3-6), from six months to nine months (ADG_6-9), from nine months to yearling (ADG_9-12), from birth to six months (ADG_0-6), from three months to nine months (ADG_3-9), from three months to yearling (ADG_3-12) and corresponding Kleiber ratios (KR_0-3, KR_3-6, KR_6-9, KR_9-12, KR_0-6, KR_3-9 and KR_3-12, respectively). A total of 42,243 SNPs passed the quality-control filters and were analysed by PLINK software in a linear mixed model. Two SNPs were identified on two chromosomes at the 5% genomewide significance level for KR(3-9) and KR(6-9). Two candidate genes, namely MAGI1 and ZNF770, were identified correspondingly harbouring and close to these QTL. Also, a total of 21 SNPs were found on chromosomes 2, 3, 5, 6, 7, 10, 17, 19, 20 and 25 at the 5% chromosomewide significance level for ADG and KR traits. Thus, we suggest more studies to discover the causative variants for growth traits in sheep.