Association between Insulin–Like Growth Factor I Polymorphism and Early Growth Traits in Iranian Zandi Sheep, Found Polymerase Chain Reaction Restriction Fragment Length Polymorphism (PCR-RFLP)

Early growth traits in sheep are economically important. Breeding for these traits has been shown to be problematic using quantitative genetic methods, particularly in native sheep herds. Molecular genetics is useful for sheep breeding. The gene for insulin-like growth factor 1 (IGF1) is one of the important candidate genes known for ovine early growth traits. The aim of this study was to investigate IGF1 polymorphism in exon 1 and its association with some early growth traits in Iranian Zandi sheep. For this purpose, 120 male and female lambs were selected randomly at up to 5 months old and blood samples were taken individually. Also, phenotypic records were collected from related farms. Genomic DNA was extracted by a salting-out method. A 265 bp region in exon 1 of IGF1 was amplified by polymerase chain reaction (PCR), then genotyped using the restriction endonuclease HaeII. Two alleles, here called A and B, were found. Examination using PopGene32 showed allele frequencies of 0.47 A and 0.53 B. Genotype % frequencies were 28.33 AA, 37.50 AB and 34.17 BB. Chi-squared and G-squared tests showed that the population was not at Hardy-Weinberg equilibrium (P