2009-Ibanez-Escriche_et_al

2009-Ibanez-Escriche_et_al - Bayesian threshold analysis of...

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N. Ibáñez-Escriche, L. Varona, J. Casellas, R. Quintanilla and J. L. Noguera mortality at farrowing in Large White, Landrace, and Pietrain populations Bayesian threshold analysis of direct and maternal genetic parameters for piglet doi: 10.2527/jas.2007-0670 originally published online Sep 12, 2008; 2009.87:80-87. J Anim Sci http://jas.fass.org/cgi/content/full/87/1/80 the World Wide Web at: The online version of this article, along with updated information and services, is located on www.asas.org by on October 22, 2010. jas.fass.org Downloaded from
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ABSTRACT: A Bayesian threshold model was fitted to analyze the genetic parameters for farrowing mortal- ity at the piglet level in Large White, Landrace, and Pietrain populations. Field data were collected between 1999 and 2006. They were provided by 3 pig selection nucleus farms of a commercial breeding company regis- tered in the Spanish Pig Data Bank (BDporc). Analyses were performed on 3 data sets of Large White (60,535 piglets born from 4,551 litters), Landrace (57,987 pig- lets from 5,008 litters), and Pietrain (42,707 piglets from 4,328 litters) populations. In the analysis, farrow- ing mortality was considered as a binary trait at the piglet level and scored as 1 (alive piglet) or 0 (dead piglet) at farrowing or within the first 12 h of life. Each breed was analyzed separately, and operational models included systematic effects (year-season, sex, litter size, and order of parity), direct and maternal additive ge- netic effects, and common litter effects. Analyses were performed by Bayesian methods using Gibbs sampling. The posterior means of direct heritability were 0.02, 0.06, and 0.10, and the posterior means of maternal heritability were 0.05, 0.13, and 0.06 for Large White, Landrace, and Pietrain populations, respectively. The posterior means of genetic correlation between the direct and maternal genetic effects for Landrace and Pietrain populations were −0.56 and −0.53, and the highest posterior intervals at 95% did not include zero. In contrast, the posterior mean of the genetic correla- tion between direct and maternal effects was 0.15 in the Large White population, with the null correlation included in the highest posterior interval at 95%. These results suggest that the genetic model of evaluation for the Landrace and Pietrain populations should include direct and maternal genetic effects, whereas farrow- ing mortality could be considered as a sow trait in the Large White population. Key words: Bayesian analysis, farrowing mortality, genetic parameter, piglet mortality, threshold model, variance component ©2009 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2009. 87:80–87 doi:10.2527/jas.2007-0670 INTRODUCTION Litter size at weaning is an important economic trait in prolific species (Tess et al., 1983). Even though heri- tability estimates of pig litter size are usually low, sev- eral studies have reported a successful response by di- rect selection (Bidanel et al., 1994; Johnson et al., 1999; Noguera et al., 2002). However, experimental evidence suggests that litter size selection could increase piglet mortality (Johnson et al., 1999; Sorensen et al., 2000).
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2009-Ibanez-Escriche_et_al - Bayesian threshold analysis of...

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