Efficiency of bovine IGF-i gene in the improvement of milk productivity using marker-assisted selection (MAS)

Because of insulin-like growth factor-I (IGF-I) gene plays an important regulatory function in milk secretion in cattle, IGF1 gene is potential quantitative trait locus and genetic marker (i.e, SNP) associated with milk production trait in cattle. Consequently, marker-assisted selection (MAS) will be useful to increase and accelerate the rate of genetic improvement on milk productivity. In this study, 48 female Holstein cattle reared under Egyptian conditions were selected based on their milk productivity and DNA from blood was extracted to amplify 249-bp of the gene encoding IGF-I. According to the breeding value, PCR products of IGF-I gene (249-bp) were sequenced only in the 15 highest and lowest milk productivity animals (GenBank accession numbers from gb|HQ183710| to gb|HQ183724|, sequentially). The result indicated that two single nucleotide polymorphisms (SNP's) at two different positions were observed in one of the highest milk productivity animals. Where, all 15 animals have adenine (A) and cytosine (C) bases at the positions 33 and 63, respectively, except, one animal (GenBank Acc. No. gb|HQ183711|) has thymine (T) and guanine (G) bases at the same positions (33 and 63, respectively). Thus, this finding can be used as marker-assisted selection (MAS) for high milk productivity in Holstein cattle.