Prediction of breeding values with additive animal models for crosses from 2 populations

International audienc

Will models of genetic evaluation and genomic selection ‘converge’?

Fil: Cantet, Rodolfo Juan Carlos. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Reduced animal model for marker assisted selection using best linear unbiased prediction

International audienc

Bayesian conjugate analysis using a generalized inverted Wishart distribution accounts for differential uncertainty among the genetic parameters - an application to the maternal animal model

Consider the estimation of genetic (co)variance components from a maternal animal model (MAM) using a conjugated Bayesian approach. Usually, more uncertainty is expected a priori on the value of the maternal additive variance than on the value of the direct additive variance. However, it is not possible to model such differential uncertainty when assuming an inverted Wishart (IW) distribution for the genetic covariance matrix. Instead, consider the use of a generalized inverted Wishart (GIW) distribution. The GIW is essentially an extension of the IW distribution with a larger set of distinct parameters. In this study, the GIW distribution in its full generality is introduced and theoretical results regarding its use as the prior distribution for the genetic covariance matrix of the MAM are derived. In particular, we prove that the conditional conjugacy property holds so that parameter estimation can be accomplished via the Gibbs sampler. A sampling algorithm is also sketched. Furthermore, we describe how to specify the hyperparameters to account for differential prior opinion on the (co)variance components. A recursive strategy to elicit these parameters is then presented and tested using field records and simulated data. The procedure returned accurate estimates and reduced standard errors when compared with non-informative prior settings while improving the convergence rates. In general, faster convergence was always observed when a stronger weight was placed on the prior distributions. However, analyses based on the IW distribution have also produced biased estimates when the prior means were set to over-dispersed values.Fil: Munilla, S.. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal; ArgentinaFil: Cantet, Rodolfo Juan Carlos. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Isle-Jourdain (L’)

Date de l'opération : 1988 (SU) Inventeur(s) : Cantet Jean-Pierre Le creusement d'un fossé de drainage a entraîné la découverte de deux sépultures alignées, enfouies à une profondeur de 1,50 m. Les corps étaient inhumés l'un tête à l'est, l'autre à l'ouest, sans aucune structure d'accompagnement. La fouille de l'une d'entre elles a livré une épingle et une alliance en laiton. La position hétérodoxe des membres supérieurs (main repliée sur la base du cou ou derrière la tête), leur situation à..

Bayesian inference about dispersion parameters of univariate mixed models with maternal effects: theoretical considerations

International audienc

Pertinence d'une méthode de prédétermination des crues basée sur la simulation stochastique de pluies horaires.

International audienceExtreme events are rarely observed, so their analysis is generally based on observations of more frequent values. The relevance of flood frequency analysis (FFA) method depends on its capability to estimate the frequency of extreme values with reasonable accuracy using extrapolation. A FFA method based on stochastic simulation of flood event is assessed based on its reliability and stability. For such an assessment, different training/testing decompositions are performed for a set of data from more than 1,000 gauging stations. We showed that the method enables relevant "predictive" estimates, e.g. by assigning correct return periods to the record values that are systematically absent in calibration data sets. The model is also highly stable vis-a-vis the sampling. This characteristic is linked to the use of regional statistical rainfall data and a simple rainfall-runoff model that requires calibrating only one parameterLes événements extrêmes sont par nature rarement observés, c'est pourquoi leur estimation est généralement basée sur l'observation de valeurs plus courantes. La pertinence d'une méthode de prédétermination des événements extrêmes dépend donc de sa capacité à raisonnablement extrapoler les distributions de fréquences vers les valeurs extrêmes. Dans cette étude, une méthode de prédétermination de crues basée sur la simulation de scénarios de pluies horaires, est évaluée sur sa capacité à produire des estimations justes et stables. Cette évaluation s'appuie sur différents tests d'échantillonnage sur les périodes de calage et de validation, appliqués sur un jeu de données conséquent (plus de 1000 stations). Nous montrons que la méthode est capable de fournir une estimation pertinente sur les événements extrêmes bien que ceux-ci soit systématiquement ôtés de la période de calage. La méthode montre aussi une grande stabilité face à l'échantillonnage. Cette caractéristique est liée à l'utilisation d'une information statistique régionale sur la pluie et à la simplicité de la modélisation hydrologique paramétrée par un seul paramètre

Bayesian estimation in maternally ancestral animal models for weaning weight of beef cattle

The Bayesian approach was implemented for fitting several maternally ancestral models for weaning weight data of Angus calves. The goal was to evaluate to what extent genetic evaluation models with additive grand maternal effects (G), or with an ancestrally structured covariance matrix for maternal environmental effects (E), or with a sire × year interaction (ISY), or combinations thereof (GE, GSY, ESY, GESY), redistribute the additive variability and reduce the negative magnitude of the additive correlation between direct and maternal effects (rAoAm), when compared with the regular maternal animal model (I). All animals with records had known dams and maternal granddams. The sampling scheme induced low autocorrelations among all variables and tended to converge quickly. The signs of the estimates of rAoAm were consistently negative for all models fitted. The magnitudes of the estimates of rAoAm from models E, G, GE, ESY, and GESY were almost one-third of those from models I and ISY. Inclusion of the sire × year interaction had some effect in reducing the negative magnitude of rAoAm, but also reduced the size of the estimates of direct (ho 2) and maternal ( hm 2) heritabilities. In comparison, models E or G reduced the negative magnitude of rAoAm by 0.50 units and produced more favorable estimates of ho 2 and hm 2 than models I and ISY. The estimate of ho 2 from G was similar to the one from I; however, the estimated hm 2 was 0.04 units greater, whereas the estimate of rAoAm was much less negative (−0.21 vs. −0.71) than the respective estimates from I. The environmental correlation between the weaning weights of dams and their daughters (λ) was estimated to be −0.28 ± 0.03 in E and ESY, and −0.21 ± 0.03 in GE and GESY. Inclusion of the sire × year interaction effect by itself did not have much of an impact in the reduction of the estimated magnitude of rAoAm. Rank correlations among EBV for direct effects were larger than 0.94 and did not show any appreciable difference among models, whereas the rank correlation among maternal breeding values displayed differences in the ranking between I and the other models. Models E and ESY recovered the largest amount of total additive variability with maternal effects.Fil: Suárez, M. J.. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal. Cátedra de Mejoramiento Genético Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cantet, Rodolfo Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal. Cátedra de Mejoramiento Genético Animal; Argentin

Bayesian estimation of (co) variance components in Argentinian Brangus for carcass traits using the FCG algorithm

Se emplearon los datos de 2273 toritos y vaquillonas Brangus para estimar las heredabilidades (h2 ) y las correlaciones aditivas y ambientales de caracteres de calidad de carne medidos por ultrasonido. Los registros provenían del programa de evaluación genética de la Asociación Argentina de Brangus. Los caracteres medidos fueron el área del ojo del bife (AOB), el marmoreado (MB), la grasa dorsal (GD) y la grasa de cadera (GC). La edad media de los animales al momento de la medición fue 641 días en machos y 685 días en hembras. Los parámetros genéticos y ambientales fueron estimados mediante un algoritmo bayesiano conjugado. Los valores estimados de h2 fueron 0,22, 0,16, 0,12 y 0,21, para AOB, GD, CC y MB, respectivamente. En términos generales, las estimaciones de las correlaciones genéticas y ambientales se encontraron cercanas a la cifra media de la literatura. Si bien los valores estimados de h2 fueron inferiores al promedio de la investigación realizada en vacunos para carne, la variabilidad encontrada es suficiente como para que la respuesta a la selección por estos caracteres – empleando predicciones de los valores de cría calculadas con los parámetros estimados - sea moderadamente efectiva.Data on 2273 Brangus young bulls and heifers were used to estimate heritabilities (h2 ) and genetics and environmental correlations for ultrasound carcass measures. Records were from the genetic evaluation program of Asociación Argentina de Brangus. Traits measured were rib-eye area (AOB), marbling (MB), back-fat thickness (GD), and hip-fat thickness (GC). Average ages of measure were 641 days in males and 685 in females. The genetic and environmental dispersion parameters were estimated by a conjugate Bayesian algorithm (FCG). Estimates of h2 were 0,22, 0,16, 0,12, and 0,21, for AOB, GD, CC, and MB, respectively. In general, estimates of genetic and environmental correlations were close to the average published values. Even tough estimates of h2 were below the average of published estimates for beef cattle, the additive genetic variation found in the current study would lead to a moderate response to selection – using predictions of breeding value that are calculated with the estimate parameters.Fil: Cantet, Rodolfo Juan Carlos. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Birchmeier, A. N.. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal; Argentin

Peyriac-de-Mer – L'Îlette

Date de l'opération : 1992 (SD) Inventeur(s) : Cantet Jean-Pierre Le site de L'Îlette se trouve à un kilomètre au nord du village de Peyriac-de-Mer, sur le versant ouest de la colline calcaire du Doul qui culmine à 56 m d'altitude et qui s'intègre dans un ensemble de reliefs à profil dissymétrique entourant le petit étang salé du Doul. Ces reliefs constituent un promontoire rocheux en forme de presqu'île, qui domine les vastes étangs de Bages et de Sigean dans lesquels il sépare deux sous-ens..