ESTIMATION OF GENETIC PARAMETERS FOR SCRAPIE RESISTANCE IN LOCAL BREEDS OF SHEEP RAISED IN ROMANIA

In the European Union, animal breeding programs have been implemented to increase scrapie resistance in sheep. In addition to increasing animal resistance to an infectious disease, selection for pathogen resistance has the potential to lessen the transmission of the pathogen to offspring, particularly when the population under consideration may serve as the primary pathogen reservoir. Several sheep populations from Romania were used in this study: Tsurcana; Tsigae; Merinos; Cap Negru de Teleorman and some imported breeds: Suffolk; Ille de France and Awassi. Sanger sequencing method was used to identify PRNP genetic polymorphism, at 136, 154 and 171 codons. From the analyzed samples, a moderate share of the homozygous ARR allele, responsible for the highest resistance to scrapie, respectively (R1), was observed, and the heterozygous ARR/ARQ (R2) and homozygous ARQ/ARQ (R3) genotypes had an abundance of over 50% of the genotype panel. In practice, the use of phenotype as input to the model is given by numbers (risk classes from 1 to 5). To estimate the heritability of resistance to scrapie, the animal threshold model was used.