Insulin-Like Growth Factor 1 Gene and Growth Traits Correlations in Sheep: A Systematic Review

Abstract

Insulin-like Growth Factor 1 (IGF1) is a growth factor gene of the endocrine that is known for involvement in growth, as well as fetal development and metabolism. The IGF1 is majorly embedded in the animal growth processes and as a result, contributes to the improved output of meat and regulation of somatic cell growth with regards to the dietary conditions. There have been studies that investigated the effect of IGF1 on growth traits. However, as far as we know, there is no study that systematically reviewed the relationship between IGF1 and growth traits in sheep. Therefore, this systematic review aimed to systematically review the Single Nucleotide Polymorphisms (SNPs) of the IGF1 gene and their relationship with growth traits in sheep. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) were used for identification, screening, eligibility and inclusion and 14 studies were found to be eligible. This systematic review used four search engines (PubMed, web of science, google scholar and science direct) and components of the research question identification of the Population, Exposure and Outcomes (PEO) to gather eligible studies. The results showed that 26 different SNPs were identified with no similar SNPs identified by the included articles. The results indicated that the identified SNPs (G855C, G857A, C271T and A91C) had a relationship with Birth Weight (BWt), Weaning Weight (WW), Body Weight (BW), Average Daily Gain (ADG), Body Length (BL), Withers Height (WH), Heart Girth (HG), Rump Length (RL), Rump Height (RH) and Paunch Girth (PG) in sheep. The IGF1 gene influences growth traits of sheep and as such G855C, G857A, C271T and A91C SNPs might be used as potentially viable genetic indicators for the betterment of performance traits in sheep during breeding programs. Further studies have to confirm the validity of the identified SNPs of the IGF1 gene.