Intégration de données pour la qualité de la viande chez le porc : Méta-analyse et analyse multidimensionnelle

Abstract : Meat quality includes criteria of different importance depending on the animal species. Meat quality is a significant economic factor in pork production, and numerous publications have shown that it is strongly influenced by the interaction between genetic type (especially the halothane gene (Hal) and Napole yield gene (RN)), breeding conditions, and pre-slaughter and slaughter conditions of animals. The European Union, longtime leader of the globalmarket of pork and pork products, now faces increasing competition from other countries,including Brazil, the United States and China. This thesis project is part of a multidisciplinary European project on improving the quality of pork and pork products for the consumer. One of the modules of this project is dedicated to the integration of existing and upcoming data to produce a model for predicting technological and sensory pork quality, based on animal,production, and slaughter information. The objective of this thesis is to synthesize existing knowledge derived from bibliographic and experimental data relating to the main factors influencing meat quality within a meta-analysis, which is a statistical approach combining the results of a series of independent studies on a given problem. The results of this work have confirmed the effect of the halothane gene, as well as fasting, transport and lairage times on most of the analyzed parameters of technological pork meat quality. Indeed, our meta-analysis confirmed the significant effect of the halothane gene on all the analyzed meat quality attributes. However, the halothane gene effect was associated with the breed effect only for the following variables: L*-value (reflectance), b*-value (yellowness) and DL (drip loss). Slaughter weight contributed significantly only to the explanation of differences in ultimate pH between homozygous genotypes: NN and nn. Regarding the preslaughter conditions, the results of our meta-analysis showed that fasting time had a significant effect on pHu and DL measured in longissimus muscle. While, lairage affected only the pHu in semimembranosusmuscle. Interestingly, we found that DL was the lonely attribute significantly affected by transport time and its interaction with fasting time. The significant effect of the vitamin E supplementation on lipid oxidation process in pork and, therefore, affect the technological meat quality, was demonstrated by using a non linear meta-analytic regression model. Statistically, the comparison between the Bayesian and frequentist meta-analytic approaches has highlighted the ability of the hierarchical Bayesian model to reduce uncertainty in parameter estimates, especially when the number of studies included in the meta-analysis is relatively limited. In addition to the meta-analytic approach, an exploratory study by multivariate analyses was performed to identify the correlations among a large number of variables structured into separate groups. Our results showed that the variables which discriminated the five classes of breed (Large White and Basque pigs) x rearing system (conventional, alternative and extensive) were the same as those discriminating individuals. Indeed, a first group composed of transcriptomic, chemical and technological variables discriminated breeds. Slaughter reactivity variables discriminated rearing systems, especially the Basque pigs reared in the extensive system.
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Btissam Salmi-Boukhari. Intégration de données pour la qualité de la viande chez le porc : Méta-analyse et analyse multidimensionnelle. Alimentation et Nutrition. AgroParisTech, 2011. Français. ⟨NNT : 2011AGPT0060⟩. ⟨tel-01124045⟩

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