Advances in genomic strategies to improve growth and meat production traits in sheep: An overview

Growth and meat production traits (body weight at birth, 3-months and 6-months, eye muscle area, fat thickness, pre-weaning and post-weaning gains, average daily weight gain, chest girth, height at withers and shin circumference) are reviewed to know the relationship with the loci which are controlled by specific genes that are associated with these traits. Quantitative trait loci (QTL) for different body and carcass weight traits are identified. Chromosomes 1, 2, 3, 4, 5, 6, 16, 18 and 20 are considered as candidate genomic regions for body weight and some major gene effects like transferrin gene on chromosome 1, Belgium Texel double muscling and myostatin (MSTN) gene on chromosome 2, growth effect around insulin-like growth factor 1 (IGF-1) on chromosome 3, calpastatin gene on chromosome 5, leptin gene on chromosome 4, Booroola fecundity gene on chromosome 6, growth hormone receptor (GHR) gene in chromosome 16, callipyge effect and carawell muscle hypertrophy on chromosome 18 and MHC complex on chromosome 20 have been identified. High-throughput genotyping and next-generation sequencing technologies are the advanced techniques for the creation of the high-density SNP array as a tool for the genomic analysis of domestic animals. Genome-wide association studies (GWAS) and genomic selection are the ultimate use of SNP array for the improvement of economically important traits. Hence, genome-wide sequencing is an advanced tool which may help in better selection of animal genetic resources. It may be used for applying molecular breeding strategies in genetic improvement programmes oflivestock.