study of igf-1 gene polymorphism and its association with growth related traits in sistani cattle

insulin-like growth factor-i (igf-1) is a peptide hormone which is similar in molecular structure to insulin and it is located on chromosome 5 in cattle. since the igf-1 plays an important role in the growth and development of multiple tissues, the purpose of current study was to identify the igf-1 gene polymorphism in sistani beef cattle. a total of 53 sistani beef cattle (one year) were randomly selected and blood samples were drawn from the cervical vein. dna was extracted from the whole blood with modified salting-out method. a 249 bp length fragment in exon 1 of igf-1 gene was amplified by polymorphism chain reaction by using specific primer pairs. genotyping of each sample was performed by using restriction enzyme snabi and electrophoresed on 2% agarose gel. the results revealed the existence of two alleles a and b for the examined locus with the frequencies of 0.25 and 0.75, respectively. three different genotypic variants including aa, ab and bb were identified with genotypic frequencies of 0.057, 0.396 and 0.547, respectively. chi square test based on observed and expected frequencies of different genotypic variants of  the exon 1 of igf-1 gene in sistani cattle population showed that deviation from hardy-weinberg equilibrium was not significant. analysis associate of the studied genotypes and growth related traits showed significant effects between aa and ab genotypes (p