PrP GENE POLYMORPHISM AND ITS INFLUENCE ON SOME PRODUCTIVE TRAITS OF SHEEP BREEDS REARED IN BULGARIA

摘要

The rapid dissemination of scrapie over the past few decades led to development of a specific eradication programme, based on the polymorphisms within the prion protein gene (PRNP). Current approach encourages the selection of animals carrying the resistant ARR/ARR genotype, while other genotypes are considered less preferable. Although the strategy seems to be working quite well, farmers are concerned whether this will affect sheep productivity and subsequently decrease net profits. The current study was aimed to elucidate the linkage between the PrP gene polymorphism (based on codons 136, 154 and 171) and some productive traits (live weight, reproduction, milk and fleece yield) of three sheep breeds reared in Bulgaria – Assaf, Northeast Bulgarian Merino and Blackhead Pleven. The total number of detected genotypes was six – ARR/ARR, ARR/ARQ, ARR/ARH, ARQ/ARQ, AHQ/ARQ and ARR/VRQ, with different prevalence within each breed. The observed lack of significant differences in the studied performance traits between the PRNP genotypes suggests that PRNP polymorphisms did not influence the sheep productive performance. Therefore, selection of animals on the resistant genotype (ARR/ARR) would not worsen their productivity. The obtained results should help the better understanding of scrapie selection and the positive effect that it would have to both health care and industry.