Agritrop
Home

Estimation des paramètres génétiques des petits ruminants en milieu d'élevage traditionnel au Sénégal. Importance de la structure des données et du choix du modèle d'analyse

Clément Virginie. 1999. Estimation des paramètres génétiques des petits ruminants en milieu d'élevage traditionnel au Sénégal. Importance de la structure des données et du choix du modèle d'analyse. Paris : INA-PG, 220 p. Thèse de doctorat : Biologie des populations, génétique et éco-éthologie

Thesis
[img]
Preview
Published version - Français
Use under authorization by the author or CIRAD.
ID300689.pdf

Télécharger (90MB) | Preview

Encadrement : Bibé, Bernard

Abstract : As part of the ongoing PPR (Pathology and productivity of small ruminants) program by CIRAD-EMVT (Montpellier, France) and ISRA (Dakar, Senegal) a genetic analysis was carried out based on data collected during individual monitoring in the Senegalese traditional husbandry system. The study concerned three different areas and two species, sheep and goats. The aim was to estimate genetic parameters of reproductive traits: prolificity, lambing interval and age at first lambing. As the individual monitoring was conducted in the traditional husbandry system, environmentai variability was high and the animals were subjected to harsh environmental constraints. The first step was to identify and test environmental factors affecting the reproductive performance. The fixed factors - village where the animals came from, season and year of lambing (traits of prolificity and lambing interval) and season and year of birth (trait of age at first lambing) - were highly significant. With regard to prolificity, the parity and lambing interval fixed factors were significant, with a litter size increasing with parity and longer lambing intervais. The step of estimating heritability and repeatability was performed according to an "animal model" by estimating the variance components through restricted maximum likelihood. In sheep heritability was 0.12 ± 0.02 for prolificity; it varied from 0.07 ± 0.02 to 0.16 ± 0.01 for lambing interval and from 0.07 ± 0.07 to 0.28 ± 0.12 for age at first lambing, In goats, heritability varied from 0 to 0.08 ± 0.02 for proiificity, from 0.02 ± 0.03 to 0.10 ± 0.01 for lambing interval and from 0.12 ± 0,06 and 0.17 ± 0.08 for age at first lambing. The results were not as high as those in the references. This could be explained by the fact that the reproductive traits, even if they were corrected for the significant fixed factors, could be influenced by not controlled environmental factors. There may also be a conflict between a large offspring production and the ability to adapt to prevalent environmental conditions in Senegal. (Résumé d'auteur)

Mots-clés Agrovoc : Paramètre génétique, Méthode d'élevage, Contrôle de performance, Race (animal), Reproduction, Résistance aux maladies, Modèle, Simulation, Mouton, Chèvre

Mots-clés géographiques Agrovoc : Sénégal

Classification Agris : L10 - Animal genetics and breeding
U10 - Mathematical and statistical methods

Auteurs et affiliations

  • Clément Virginie

Autres liens de la publication

Source : Cirad - Agritrop (https://agritrop.cirad.fr/300689/)

View Item (staff only) View Item (staff only)

[ Page générée et mise en cache le 2020-07-20 ]