In dairy farm animals, the principal goal of the selection is the improvement of milk yield and composition. The genes of milk proteins and hormones are excellent candidate genes for linkage analysis with quantitative trait loci (QTL) because of their biological significance on the quantitative traits of interest.Prolactin (PRL) is a polypeptide hormone with multiple functions, secreted mainly by the anterior pituitary gland. Prolactin's biological activity consists of various roles in the reproduction, lactation and a number of homeostatic biological functions including immune functions.Casein proteins and their genetic variants have been reported as important factors associated with lactation performance, milk composition and cheese yield efficiency. Genetic variants of 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 is studied as a candidate genetic marker for growth, carcass and also for milk yield traits.Genomic DNA extracted from 100 healthy buffaloes was amplified using primers that were designed from 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 RsaI, HindIII and HinfI restriction enzymes, respectively. The results showed that all tested buffaloes are genotyped as GG for PRL, BB for K-CN and BB for PIT-1.

Leptin and l-calpain have been considered as two candidate genes for carcass performance and meat quality traits in the farm animals. The micromolar calcium-activated neutral protease (CAPN1) gene encodes l-calpain that degrades myofibril proteins under the postmortem conditions which appears to be the primary enzyme in the postmortem tenderization process. Leptin is the hormone product of the obese (LEP) gene. The role of leptin as a lipostatic signal regulating whole-body energy metabolism makes it one of the best physiological markers of body weight, food intake, reproduction and immune system functions.Genomic DNA extracted from 100 healthy buffaloes was amplified using primers that were designed from the cattle CAPN1 and LEP gene sequences. The amplified fragments of CAPN1 obtained from all tested buffalo DNA at 670-bp were digested with FokI endonuclease. The result showed that all tested buffaloes are genotyped as CC for CAPN1. For LEP gene, the amplified fragments obtained from all tested buffalo DNA at 400-bp were digested with Sau3AI endonuclease. All buffalo animals investigated in the present study are genotyped as AA for LEP gene.