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Genetic analysis for mastitis resistance and milk somatic cell score in French Lacaune dairy sheep

  • Francis BarilletEmail author
  • Rachel Rupp
  • Sandrine Mignon-Grasteau
  • Jean-Michel Astruc
  • Michèle Jacquin
Open Access
Research

Abstract

Genetic analysis for mastitis resistance was studied from two data sets. Firstly, risk factors for different mastitis traits, i.e. culling due to clinical or chronic mastitis and subclinical mastitis predicted from somatic cell count (SCC), were explored using data from 957 first lactation Lacaune ewes of an experimental INRA flock composed of two divergent lines for milk yield. Secondly, genetic parameters for SCC were estimated from 5 272 first lactation Lacaune ewes recorded among 38 flocks, using an animal model. In the experimental flock, the frequency of culling due to clinical mastitis (5%) was lower than that of subclinical mastitis (10%) predicted from SCC. Predicted subclinical mastitis was unfavourably associated with the milk yield level. Such an antagonism was not detected for clinical mastitis, which could result, to some extent, from its low frequency or from the limited amount of data. In practice, however, selection for mastitis resistance could be limited in a first approach to selection against subclinical mastitis using SCC. The heritability estimate of SCC was 0.15 for the lactation mean trait and varied from 0.04 to 0.12 from the first to the fifth test-day. The genetic correlation between lactation SCC and milk yield was slightly positive (0.15) but showed a strong evolution during lactation, i.e. from favourable (-0.48) to antagonistic (0.27). On a lactation basis, our results suggest that selection for mastitis resistance based on SCC is feasible. Patterns for genetic parameters within first lactation, however, require further confirmation and investigation.

Keywords

dairy sheep somatic cell count mastitis genetic parameters risk factors 

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Copyright information

© INRA, EDP Sciences 2001

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors and Affiliations

  • Francis Barillet
    • 1
    Email author
  • Rachel Rupp
    • 2
  • Sandrine Mignon-Grasteau
    • 1
    • 3
  • Jean-Michel Astruc
    • 4
  • Michèle Jacquin
    • 1
  1. 1.Station d'amélioration des animauxInstitut national de la recherche agronomiqueCastanet-Tolosan CedexFrance
  2. 2.Station de génétique quantitative et appliquéeInstitut national de la recherche agronomiqueJouy-en-Josas CedexFrance
  3. 3.Station de recherches avicolesInstitut national de la recherche agronomiqueNouzillyFrance
  4. 4.Institut de l'élevageCastanet-Tolosan CedexFrance

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