03171naa a2200229 a 450000100080000000500110000800800410001902200140006002400380007410000190011224501940013126000090032550001460033452022090048065300210268965300240271065300250273465300170275970000170277670000190279377301290281210615232020-11-27       2020    bl uuuu     u00u1 u    #d  a0304-40177 a10.1016/j.vetpar.2020.1092722DOI1 aMARQUES, C. B.  aGenetic parameters for production traits, resistance and resilience to Nematode parasites under different worm burden challenges in Corriedale sheep. (Research paper)h[electronic resource]  c2020  aArticle history: Received 24 June 2020; Received in revised form 11 October 2020; Accepted 11 October 2020; Available online 15 October 2020.  aABSTRACT. Characterized as the most important gastrointestinal parasite (GIP) in the world, Haemonchus contortus is also the most predominant and pathogenic genus in Uruguay, causing high morbidity and mortality rates in sheep flocks. For approximately 26 years resistance to GIP has been included in the National Genetic Evaluation (NGE) of Corriedale and Merino breeds, using Faecal Egg Count (FEC) as the selection criterion. The aim of the present study was to estimate genetic parameters for FEC, post-weaning Body Weight (BW), Packed Cell Volume (PCV), FAMACHA© and Body Condition Score (BCS), to determine the possibility to include these traits in the NGE of GIP resistance and resilience, as complementary selection criteria and to investigate the sensitivity of breeding values to different environmental worm burden challenges. Data were collected on 19,510 lambs from 2000 to 2009 in 24 Corriedale studs that participated in the NGE of sheep in Uruguay. (Co)variances components were estimated using a multi-trait animal model performing a Bayesian analysis. Posterior means estimated for heritability (h2) were of low to moderate magnitude (between 0.10 and 0.33) for the traits analysed. Genetic correlations (rg) were not significantly different from zero for BW- Loge (FEC + 100), BW-FAMACHA©, BW-PCV, Loge (FEC + 100)-PCV, BCS-FAMACHA©, moderate favourable rg for Loge (FEC + 100)-FAMACHA and PCV-BCS (0.55, 0.41) and high favourable rg for BW-BCS (0.66). These results indicate the possibility to complement selection programs incorporating BW, Loge (FEC + 100), FAMACHA©, PCV and BCS in order to select resistant and resilient animal to GIP. Furthermore, genetic parameters for BW and Loge (FEC + 100) to different environmental worm burden challenge was investigated. Two contemporary groups of low worm environment (Loge (FEC + 100) below 6.40) and a high worm environment (Loge (FEC + 100) above 6.75) were considered. In this model, h2 estimated for BW and Loge (FEC + 100) were found to be not statistically different between low and high environmental worm burden, furthermore, high correlations between traits at both environments were also presented.  © 2020 Elsevier B.V.  aFaecal egg count  aGenetic correlation  aHaemonchus contortus  aHeritability1 aGOLDBERG, V.1 aCIAPPESONI, G.  tVeterinary Parasitology, November 2020, Volume 287, Article number 109272. Doi: https://doi.org/10.1016/j.vetpar.2020.109272