Genetic Polymorphism of Three Genes (PRL9 K-CN and PIT-1) Associated with Milk Traits in Egyptian Buffalo

摘要

In dairy farm animals, the principal goal of selection is the improvement of milk yield and composition. The genes encoding milk protein and hormones are excellent candidate genes for linkage analysis with quantitative trait loci (QTLs) because of their biological significance on the quantitative traits of interest. Prolactin (PRL), a polypeptide hormone with multiple functions, secreted mainly by the anterior pituitary gland, shows many biological activities and plays essential roles in reproduction, lactation and immune functions. Casein proteins and their genetic variants have been reported as important factors associated with lactation performance, milk composition and the efficiency of cheese yield. Genetic variants of the bovine kappa-casein (K-CN) gene are associated with milk protein content and have a significant influence on rennet clotting time, firmness and cheese yield of milk. The pituitary-specific transcription factor (PIT-1) gene is responsible for pituitary development and hormone-secreting gene expression in mammals. PIT-1 was studied as a candidate genetic marker for growth, carcass and also for milk yields traits. Genomic DNA extracted from 100 healthy buffaloes was amplified using primers that were designed for the cattle PRL, K-CN and PIT-1 gene sequences. The amplified fragments of PRL (294-bp), K-CN (530-bp) and PIT-1 (451-bp) were digested with Rsal, Hindlll and Hinfl restriction enzymes, respectively. All tested buffaloes were genotyped as GG for PRL, BB for K-CN and for PIT-1.