The objective of this study was to compare test-day (TD) models with autoregressive covariance structures for the estimation of genetic and environmental components of variance for milk, fat and protein yields, and somatic cell score (SCS) in Holstein cows. Four models were compared: model I (CS model) was a simple TD repeatability animal model with compound symmetry covariance structure for en...

Multivariate analyses of carcass traits for Angus cattle, consisting of six traits recorded on the carcass and eight auxiliary traits measured by ultrasound scanning of live animals, are reported. Analyses were carried out by restricted maximum likelihood, fitting a number of reduced rank and factor analytic models for the genetic covariance matrix. Estimates of eigenvalues and eigenvectors for...

Article history: Received 14 November 2009 Received in revised form 29 April 2010 Accepted 6 May 2010

There are many reasons for the popular use of the isotropic or geometrically anisotropic covariance function and variogram in spatial statistics. A less known reason demonstrated in this paper is that an isotropic or geometrically anisotropic model would be the only choice in certain circumstances, for instance, when the underlying random field is smooth enough.

This paper proposes a new covariance matching based technique for blurred image PSF (point spread function) estimation. A patch based image degradation model is proposed for the covariance matching estimation framework. A robust covariance metric which is based on Riemannian manifold is adapted to measure the distance between covariance matrices. The optimal PSF is computed by minimizing the di...

The antagonistic pleiotropy (AP) theory of ageing predicts genetically based trade-offs between investment in reproduction in early life and survival and performance in later life. Laboratory-based research has shown that such genetic trade-offs exist, but little is currently known about their prevalence in natural populations. We used random regression 'animal model' techniques to test the gen...

This study assessed the heritability of ambulatory heart period, respiratory sinus arrhythmia (RSA), and respiration rate and tested the hypothesis that the well-established correlation between these variables is determined by common genetic factors. In 780 healthy twins and siblings, 24-h ambulatory recordings of ECG and thorax impedance were made. Genetic analyses showed considerable heritabi...

Animal models typically require a known genetic pedigree to estimate quantitative genetic parameters. Here we test whether animal models can alternatively be based on estimates of relatedness derived entirely from molecular marker data. Our case study is the morphology of a wild bird population, for which we report estimates of the genetic variance-covariance matrices (G) of six morphological t...

20 Variational modules, sets of pleiotropically covarying traits, affect phenotypic evolution, and 21 therefore are predicted to reflect functional modules, such that traits within a variational 22 module also share a common function. Such an alignment of function and pleiotropy is 23 expected to facilitate adaptation by reducing the deleterious effects of mutations, and 24 allowing coordinated...