Single-Nucleotide Polymorphisms of Insulin-Like Growth Factor-1 (IGF1) Gene in Goat and Their Association with Growth Traits

Goat farming plays a vital role in sustaining the livelihoods of smallholder farmers worldwide, with improved growth performance being a primary objective of numerous breeding programs. The insulin-like growth factor-1 (IGF1) gene has been extensively studied as a key candidate gene due to its crucial involvement in regulating cell growth, differentiation, and metabolism, which underpin developmental processes. This systematic review synthesizes findings from 11 studies conducted between 2008 and 2024 across Asia and Africa, focusing on single nucleotide polymorphisms (SNPs) within the IGF1 gene and their associations with growth traits in various goat populations. A range of genotyping techniques, including PCR-RFLP, sequencing, real-time PCR, and T-ARMS-PCR, were applied to both indigenous and crossbred goats. Multiple SNPs were identified, with the g.5752 locus consistently reported in three independent studies, indicating its potential utility as a marker-assisted selection (MAS). Genotypic frequencies varied from 0.00 to 0.91, and allelic frequencies ranged from 0.08 to 0.94, reflecting substantial genetic diversity among goat breeds. Although 79.9% of observations did not show statistically significant associations, 20.1% revealed notable links, particularly with body weight, body length, and body height. These findings suggest that while IGF1 polymorphisms hold promise as molecular markers for growth traits, the phenotypic expression of growth in goats is likely influenced by complex polygenic inheritance and gene–environment interactions. Future research should focus on genome-wide association studies and breed-specific validation to enhance the application of IGF1 SNPs in genetic improvement strategies for sustainable goat production.