Association between polymorphism in the JAK2 gene (JAK2/e20/RsaI) and selected performance parameters in beef cattle

The aim of the present study was to analyse the polymorphism in the JAK2 gene in three beef cattle breeds (Angus, Hereford, and Limousin) in relation to performance traits. A total of 465 individuals were genotyped. The PCR-RFI,P method was used to identify a silent mutation in exon 20 (dbSNP ID: rs110298451). Three genotypes (AA, AG, GG) were identified in all the tested breeds, with the A allele being the most frequent. In the Limousin breed, the most favourable traits were recorded for individuals with the AA genotype, i.e. higher birth weight (+ 2.1 kg), average daily gains (+68g) and weight at 210 days (+12.3 kg) compared to individuals with the GG genotype. Different results were obtained for the Hereford breed, where the GG genotype determined the highest birth weight (+1.3 kg), daily gains (+50 g) and body weight at weaning (+ 10.6 kg) in comparison with individuals of the AA genotype. In Angus cows, heterozygotes were characterized by the highest beefing abilities. There was no significant association between the JAK2/e20/Rsal polymorphism and age at first calving. The results obtained in the present study did not indicate whether the analysed JAK2/e20/Rsal polymorphism could be used in cattle selection. Therefore, it would be reasonable to perform additional association studies on larger numbers of recorded and genotyped animals