Genetic Polymorphisms in New Zealand Sheep Breeds

Animal production is a booming industry with the improvement of economically desirable traits as its primary concern. Markerassisted selection utilizes genetic variations within candidate genes that influence production traits as a means of guiding animal breeding and improving the traits of interest. Growth hormone (GH) plays a crucial role in pre-natal muscular and bone growth and development. GH brings about various physiological functions either directly by binding its receptor or indirectly by stimulating the release of insulin growth factor 1 (IGF1). Insulin growth factor 1 receptor (IGF1R) mediates its function on metabolism, homeostasis and development upon the binding of IGF1. The POU-domain class 1 transcription factor 1 (POU1F1) regulates the pre-natal development of cells of the anterior pituitary, including somatotrophs that produce GH. Reports have demonstrated associations between polymorphisms in these genes and animal production traits. This novel study examined the polymorphisms in the coding regions of candidate genes, GH2Z, IGF1R and POU1F1, in New Zealand (NZ) sheep. The sheep breeds investigated were NZ Romney and Merino, two commercially sought-after breeds. The results revealed two variants, AA and AB, for the exon 3 of POU1F1. The AA and AB genotypes had frequencies of 78% and 22% for Romney sheep, and 64% and 36% for Merino sheep respectively. All frequencies were in accordance with the Hardy-Weinberg Equilibrium (P > 0.05). The exon 2 of GH2Z revealed multiple variations while no variation was detected for the exon 15 of IGF1R.

Keywords: Marker-assisted selection; Polymorphism; Sheep; Gene