tailieunhanh - Báo cáo sinh học: " Should genetic groups be fitted in BLUP evaluation? Practical answer for the French AI beef sire evaluation"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học thế giới đề tài: Should genetic groups be fitted in BLUP evaluation? Practical answer for the French AI beef sire evaluation | Genet. Sel. Evol. 36 2004 325-345 INRA EDP Sciences 2004 DOI gse 2004004 325 Original article Should genetic groups be fitted in BLUP evaluation Practical answer for the French AI beef sire evaluation Florence Phocas Denis Laloe Station de génétique quantitative et appliquée Institut national de la recherche agronomique 78352 Jouy-en-Josas Cedex France Received 27 February 2003 accepted 29 December 2003 Abstract - Some analytical and simulated criteria were used to determine whether a priori genetic differences among groups which are not accounted for by the relationship matrix ought to be fitted in models for genetic evaluation depending on the data structure and the accuracy of the evaluation. These criteria were the mean square error of some extreme contrasts between animals the true genetic superiority of animals selected across groups . the selection response and the magnitude of selection bias difference between true and predicted selection responses . The different statistical models studied considered either fixed or random genetic groups based on six different years of birth versus ignoring the genetic group effects in a sire model. Including fixed genetic groups led to an overestimation of selection response under BLUP selection across groups despite the unbiasedness of the estimation . despite the correct estimation of differences between genetic groups. This overestimation was extremely important in numerical applications which considered two kinds of within-station progeny test designs for French purebred beef cattle AI sire evaluation across years the reference sire design and the repeater sire design. When assuming a priori genetic differences due to the existence of a genetic trend of around 20 of genetic standard deviation for a trait with h2 in a repeater sire design the overestimation of the genetic superiority of bulls selected across groups varied from about 10 for an across-year selection rate p 1 6 and an accurate selection

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