Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh Original cung cấp cho các bạn kiến thức về sinh học đề tài:Phenotypic plasticity of body pigmentation in Drosophila: Models to estimate maternal effects for juvenile body weight in broiler chickens. | Genet Sei Evol 1997 29 225-249 Elsevier Inra 225 Original article Models to estimate maternal effects for juvenile body weight in broiler chickens ANM Koerhuisx 2 R Thompson3 1 Ross Breeders Ltd Newbridge Midlothian EH28 8SZ UK 2 Institute of Cell Animal and Population Biology University of Edinburgh EH9 3JT UK 3 Roslin Institute Edinburgh Roslin Midlothian EH25 9PS UK Received 21 May 1996 accepted 7 March 1997 Summary The estimation of genetic and environmental maternal effects by restricted maximum likelihood was considered for juvenile body weight JBWT data on 139 534 and 174 668 broiler chickens from two populations. Of the biometrical models usually assumed in the estimation of maternal effects reduced Willham models a genetic model allowing for direct and maternal genetic effects with a covariance between them and a permanent environmental maternal effect provided the best fit. The maternal heritabilities and were low compared to the direct heritabilities and the direct-maternal genetic correlations fam were negative and identical for both strains - and environmental maternal effects of full sibs and were approximately a factor of two greater than maternal half sibs and . A possible environmental dam-offspring covariance was accounted for in the mixed model by 1 estimation of the covariance between the environmental maternal and the environmental residual effects cEC and 2 a maternal phenotypic effect through regression on the mother s phenotype Fm Falconer model . Whilst increasing the likelihoods considerably these extended models resulted in somewhat more negative FAM values owing to positive estimates of cEC and and Fm and . A more detailed fixed effects model accounting for environmental effects due to individual parental flocks reduced estimates of FAM - to - . Results suggested a limited importance of maternal genetic effects exerting a non-Mendelian .
