TAILIEUCHUNG - Báo cáo khoa hoc:" Connectedness in the French Holstein cattle population Eric"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học thế giới đề tài: Connectedness in the French Holstein cattle population Eric | Genet. Sei. Evol. 31 1999 163-176 Inra Elsevier Paris 163 Original article Connectedness in the French Holstein cattle population Eric Hanocq Didier Boichard Station de génétique quantitative et appliquée Institut national de la recherche agronomique 78352 Jouy-en-Josas cedex France Received 24 December 1998 accepted 12 February 1999 Abstract - An analysis of connectedness in the French Holstein cattle population was carried out. This study was motivated by the fact that artificial insemination Al bulls are evaluated at the national level whereas they are usually progeny tested only in the region of their Al stud. Connectedness among Al studs was measured by the generalised coefficient of determination CD of contrasts between mean breeding values of bulls from the different Al studs. Four connectedness components were distinguished. The relative influence of each component was assessed through the increase in prediction error variance PEV of the contrasts after this information was discarded. CDs of contrasts were always higher than . Therefore connectedness level among Al studs was high and provided an accurate national genetic evaluation. Out of the different components of connectedness withdrawing of proven bull connection data caused the greatest increase in PEV primarily due to the change in the connecting structure of the data. Genetic relationships among bulls were the next important source of information. In contrast contributions from the planned use of the bulls progeny tested were quantitatively limited 8 increase in PEV and foreign semen had a minor contribution 2 increase in PEV . However in spite of its limited quantitative impact compared to the other components planned sampling bull connectedness is recommended because it provides high quality data for model validation and bias investigations. Inra Elsevier Paris connectedness accuracy progeny test genetic evaluation dairy cattle Resume Analyse de la connexion en population bovine Holstein

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