Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Use of relationship matrix in the evaluation of natural service Limousin bulls | Genet Sei Evol 1992 24 137-145 Elsevier INRA 137 Original article Use of relationship matrix in the evaluation of natural service Limousin bulls D Laloê G Renand J Sapa F Ménissier Institut National de la Recherche Agronomique Station de Génétique Quantitative et Appliquée Centre de Recherches de Jouy-en-Josas 78352 Jouy-en-Josas Cedex France Received 8 April 1991 accepted 12 December 1991 Summary - In France natural service bulls of beef breeds are progeny tested using reference sires and planned matings. The evaluation is made with a single-trait best linear unbiased prediction BLUE procedure applied to a sire model on pre-weaning calf performance where sires are considered as unrelated. The purpose of this investigation was to examine the impact of using relationships between sires on breeding value estimates their accuracies and the connectedness between sires. Two mixed models with or without sire interrelations were used. Weaning weights of 5 207 Limousin calves from 219 sires were analysed. A total of 53 sires were related by a Malecot relationship coefficient . The correlation between breeding value estimates obtained with the 2 models was . The gain in accuracy was characterized by the reduction of prediction error variances and expressed by the ratio of these variances obtained with the 2 models. This gain averaged 4 reached 26 and was related to the sire relationship coefficient means correlation of . Overall connectedness indexes were computed and their interpretation discussed. The practical interest of using the relationship matrix in these evaluation programmes was examined in the light of French beef cattle breeding. relationship matrix I connectedness I accuracy sire model beef cattle Resume Prise en compte des parentés pour 1 évaluation des taureaux Limousins de monte naturelie. En France les taureaux de races à viande de monte naturelie sont évalués sur descendance en utilisant des taureaux de reference et des accouplements .
