tailieunhanh - Báo cáo sinh học: "Genetic parameters for somatic cell score according to udder infection status in Valle del Belice dairy sheep and impact of imperfect diagnosis of infection"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học quốc tế đề tài: Genetic parameters for somatic cell score according to udder infection status in Valle del Belice dairy sheep and impact of imperfect diagnosis of infection | Riggio et al. Genetics Selection Evolution 2010 42 30 http content 42 1 30 Ge n et i cs Selection Evolution RESEARCH Open Access Genetic parameters for somatic cell score according to udder infection status in Valle del Belice dairy sheep and impact of imperfect diagnosis of infection Valentina Riggio1 2 Baldassare Portolano1 Henk Bovenhuis2 Stephen C Bishop3 Abstract Background Somatic cell score SCS has been promoted as a selection criterion to improve mastitis resistance. However SCS from healthy and infected animals may be considered as separate traits. Moreover imperfect sensitivity and specificity could influence animals classification and impact on estimated variance components. This study was aimed at 1 estimating the heritability of bacteria negative SCS bacteria positive SCS and infection status 2 estimating phenotypic and genetic correlations between bacteria negative and bacteria positive SCS and the genetic correlation between bacteria negative SCS and infection status and 3 evaluating the impact of imperfect diagnosis of infection on variance component estimates. Methods Data on SCS and udder infection status for 1 120 ewes were collected from four Valle del Belice flocks. The pedigree file included 1 603 animals. The SCS dataset was split according to whether animals were infected or not at the time of sampling. A repeatability test-day animal model was used to estimate genetic parameters for SCS traits and the heritability of infection status. The genetic correlation between bacteria negative SCS and infection status was estimated using an MCMC threshold model implemented by Gibbs Sampling. Results The heritability was for bacteria negative SCS for bacteria positive SCS and for infection status on the liability scale. The genetic correlation between bacteria negative and bacteria positive SCS was suggesting that they may be genetically different traits. The genetic correlation between bacteria negative SCS and