tailieunhanh - Báo cáo sinh học: " Predicting the consequences of selecting on PrP genotypes on PrP frequencies, performance and inbreeding in commercial meat sheep populations"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học thế giới đề tài: Predicting the consequences of selecting on PrP genotypes on PrP frequencies, performance and inbreeding in commercial meat sheep populations | Genet. Sel. Evol. 39 2007 711-729 INRA EDP Sciences 2007 DOI gse 2007027 Available online at Original article Predicting the consequences of selecting on PrP genotypes on PrP frequencies performance and inbreeding in commercial meat sheep populations Wing-Young N. MANa Ronald M. LEWISb Kay BOULTONc Beatriz VlLLANUEVAa a Scottish Agricultural College West Mains Road Edinburgh EH9 3JG UK b Department of Animal and Poultry Sciences 0306 Virginia Polytechnic Institute and State University Blacksburg Virginia 24061 USA c Meat Livestock Commission Snowdon Drive Milton Keynes MK6 1AX UK. Received 12 January 2007 accepted 6 June 2007 Abstract - Selection programmes based on prion protein PrP genotypes are being implemented for increasing resistance to scrapie. Commercial meat sheep populations participating in sire-referencing schemes were simulated to investigate the effect of selection on PrP genotypes on ARR and VRQ allele frequencies inbreeding and genetic gain in a performance trait under selection. PrP selection strategies modelled included selection against the VRQ allele and in favour of the ARR allele. Assuming realistic initial PrP frequencies selection against the VRQ allele had a minimal impact on performance and inbreeding. However when selection was also in favour of the ARR allele and the frequency of this allele was relatively low there was a loss of up to three to four years of genetic gain over the 15 years of selection. Most loss in gain occurred during the first five years. In general the rate of inbreeding was reduced when applying PrP selection. Since animals were first selected on their PrP genotype before being selected on the performance trait the intensity of selection on performance was weaker under PrP selection compared with no PrP selection . Eradication of the VRQ allele or fixation of the ARR allele within 15 years of selection was possible only with PrP selection targeting all breeding animals. sire referencing .

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