The aim of this study was the detection of polymorphism in the bovine growth hormone and leptin genes using the PCR-RFLP method. A
polymorphic site of the growth hormone gene (Alul loci) that results in amino acid change at position 127 of the protein chain (leucine, L to
valine, V) has been linked to differences in circulating metabolites, metabolic hormones and to milk yield. The polymorphism in bovine leptin
gene is situated in the intron between two exons, which results in an amino acid change at position 2059 of the protein chain (cytosine, C to
thymine, T). The polymorphisms were studied in a group of 58 bulls of the Slovak spotted breed. A strategy employing PCR was used to amplify 428 bp (GH gene) and 422 bp (LEP gene) products from blood samples. Digestion of PCR products with restriction enzymes AluI and Sau3AI revealed alleles: L and V; A and B for GH gene and LEP gene, respectively. The growth hormone gene is a candidate gene for body weight gain in cattle, since it plays a fundamental role in growth regulation. Leptin plays an important role in the regulation of feed intake, energy metabolism, growth and reproduction of cattle; therefore, animals with higher leptin gene expression will probably have lower daily weight gain than others with similar forage offer and nutritional condition and will also likely have longer calving intervals.