Abstract

The aim of the study was to analyze the polymorphism of cytochrome P450 aromatase gene (CYP19) and the search for the association between the genotypes of two polymorphic sites (CYP19/Cyfr13I and CYP19/PvuII) in the P1.1 promoter region of the CYP19 gene and the age at first calving and calving interval length in Polish Holstein-Friesian cattle. The study used a data set of 909 Polish Holstein-Friesian cows born in the years 1991-1998 and kept in five farms. The analysis of the CYP19 gene polymorphism showed that homozygous AA genotype was most common in both CYP19/Cyfr13I and CYP19/PvuII loci while the least common, also in both loci was the BB genotype. The frequency of the A allele at both loci significantly exceeded the frequency of the B allele. The earliest age at first calving for both CYP19/Cyfr13I and CYP19/PvuII loci demonstrated BB homozygous cows and the latest was found for AA homozygotes. The longest first calving interval was characteristic of cows that were homozygous for the A allele at the CYP19/Cyfr13I locus whereas with respect to the CYP19/PvuII locus, heterozygotes had the longest first calving interval. The shortest first calving interval showed BB homozygotes at both investigated loci. Heterozygotes at the CYP19/Cyfr13I locus had the shortest second calving interval whereas regarding the CYP19/PvuII locus, the shortest second calving interval was found for AA homozygotes.