The Role of the IGF1 Gene in Regulating Growth and Productivity of Sheep: Implications for Sustainable Breeding Khadija Salka1,2, VM Ani Nurgiartiningsih3, Suyadi Suyadi3* , Sohaib Akram2
1Pir Mehar Ali Shah Arid Agriculture University, Rawalpindi, 43490, Pakistan
2Student of Master^s Degree in Animal Science, Universitas Brawijaya, Malang, 65145, Indonesia
3Department of Animal Reproduction and Breeding, Faculty of Animal Science, Universitas Brawijaya, Malang, 65145, Indonesia
*Corresponding Author: suyadi[at]ub.ac.id
Abstract
A primary focus of efforts to promote sustainable production systems among small ruminants lies in enhancing early growth and carcass efficiency in sheep, where faster and healthier growth leads to more productivity and less resource input per kg of meat produced. Insulin-like growth factor 1 (IGF1) is an essential mediator of growth hormone action, regulating its effects on myogenesis, protein synthesis, and energy partitioning. This review summarizes evidence from genomic and expression studies covering different breeds, showing that IGF1 sequence variation (SNPs, haplotypes) and IGF1 expression (along with its receptor IGF1R) are both associated with traits that directly affect sheep growth before weaning, body size, carcass weight, and carcass composition. Within New Zealand Romney and other populations, IGF1 exon-linked polymorphisms correlated with growth to weaning and carcass fatness, while studies in Santa Ines, Makooei, and Hulun Buir sheep have found a diversity of IGF1 or IGF1R SNPs or haplotypes statistically associated with ADG, body measurements, and various carcass traits, thus indicating potential for marker-assisted selection. IGF1 expression is also shown to be developmentally regulated in Hu sheep muscle, correlating with carcass and muscle quality traits. The overall implication is that IGF1 axis markers can, upon validation in the breed context and when combined with functional expression data, impact breeding strategies in ways that enhance productivity, animal welfare, and environmental efficiency (better feed conversion). We discuss the opportunities and limitations for the incorporation of IGF1 markers into a sustainable breeding program in sheep and recommend targeted validation and harmonized phenotyping to ensure their practical application.
