Estimates of variances due to parent of origin for weights of Australian beef cattle pdfsubject

1 Estimates of variances due to differential expression of paternally and maternally 2 derived genes can be obtained from animal model type analyses by fitting appropriate 3 gametic effects. This is feasible for large scale analyses, as the inverse of the gametic 4 relationship matrix can be set up directly from a list of pedigrees. 5 We present a series of analyses applying such model for large sets of records for birth, 6 weaning, yearling and final weights of Australian Angus and Hereford cattle. Results 7 show that maternal genetic effects on these traits are largely confounded with maternal 8 parent of origin effects, so that it is difficult to reliably separate the respective variance 9 components. On the other hand, paternal parent of origin effects tend to act similarly 10 to sire × herd effects so that estimates of their variance are inflated by any effects not 11 modelled and contributing to such apparent interaction. 12 Fitting an animal model with both parent of offspring effects, maternal genetic and 13 permanent environmental effects as well as sire × herd and maternal grand-sire × herd of 14 origin of dam interactions as additional random effects yielded estimates of the variance 15 due to paternal parent of origin effects of 5 to 7% of the phenotypic variation for birth and 16 weaning weights and of 0 to 1% for yearling and final weights. Corresponding estimates 17 for maternal parent of origin effects were 0 to 11% for birth and weaning weights and 7 to 18 8% for yearling and final weights, while sire and maternal grand-sire interaction effects 19 explained from 0 to 4% of the phenotypic variance. 20