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National audience; La maîtrise du portage de Salmonella est une des préoccupations majeures de la filière porcine notamment depuis l'adoption de la directive européenne de 2004 sur les zoonoses. La prévalence d'animaux porteurs asymptomatiques en fin d'engraissement est un point critique pour la propagation de Salmonella dans la chaîne d'abattage et la contamination des produits porcins. L'objectif de cette étude est d'évaluer l'effet de conduites d'élevage et de la qualité du nettoyage-désinfection sur la prévalence de portage des porcs charcutiers au départ à l'abattoir. Nous avons développé un modèle mathématique pour simuler à la fois, la dynamique des populations de truies et de porcs dans un élevage naisseur-engraisseur, la gestion de la conduite en bandes par l'éleveur et la propagation des salmonelles. La transmission entre animaux dépend du niveau de contamination du sol des salles de l'élevage dans lesquelles les animaux se succèdent. Cette contamination est liée au nombre d'animaux infectés qui excrètent dans ces salles et à la qualité du nettoyage-désinfection. Plusieurs scénarios combinant différentes valeurs d'efficacité du nettoyage-désinfection avec deux types de conduites en bande, avec et sans mélange de bandes en fin d'engraissement, ont été testés. Dans nos résultats, la séroprévalence dans les lots de porcs charcutiers au départ à l'abattoir est significativement plus élevée avec une diminution de l'efficacité du nettoyage-désinfection. Les valeurs de séroprévalence dans les lots de porcs charcutiers sont proches pour des efficacités de décontamination situées entre 99,9 et 90% quelle que soit la conduite testée. Une efficacité de décontamination de 80% est associée à une séroprévalence très élevée. Ce niveau est plus fort dans le cas d'une conduite avec mélange de bandes en fin d'engraissement. Les résultats montrent que, une fois la bactérie installée dans le troupeau, le respect des pratiques d'hygiène permet de maintenir la prévalence de l'infection à un niveau faible

Health-control costs were described in 248 dairy farms in Pays de la Loire (France) in 1995/97. Total costs, excluding mandatory programs, averaged 85.70 /cow-year (61.2, 8.8, 9.2, 3.5 and 3.0 for cows, heifers, calves, general hygiene, and herd-level infectious disease control, respectively) and 1.14 /100 kg milk. Cow disorders associated with the highest costs (in /cow-year) were: udder (26.76), metabolic (6.63), reproductive (5.27), peripartum (4.89), locomotor (2.28) and digestive (2.21) disorders. In addition, 5.43, 4.15, and 3.38 /cow-year were spent on nutritional products, herd-health and fertility programs, and parasite control, respectively. In heifers and calves, respectively, major costs were for parasite control (7.05 /cow-year) and digestive disorders (6.70 /cow-year). For all costs, large variability existed between farms. One farm out of four had low costs for all disorders, among which only half had low incidences for all disorders. Variable health status occurred at all levels of costs. Proportion of preoccurrence costs was independent of total costs. A trend in increasing costs with dairy intensification was observed, assumed to result partly from different health management options. Costs/kg milk were significantly higher in non-Holstein than in Holstein farms. In all farming systems, large variability of health-control costs suggested that there was potential for improvement of health management.

International audience

International audience

International audience

International audience

In modern production systems, the most economically limiting diseases are multifactorial enzootic health disorders. Relevant decisions in health management have to be based on rational procedures. A first-level approach implies the use of quantitative information on the economic impact of the disease. A more relevant approach of decisions regarding health problems consists of evaluating the economic worth of the interventions in terms of cost-effectiveness. Decision analysis and decision support are of interest today, particularly for herd health control schemes regarding enzootic disorders.

International audience; Paratuberculosis control is a major concern in major dairy producing areas. In most European countries, no vaccine is available and control relies on reducing within-herd transmission through improved biosecurity for young calves, and on testing and culling infected animals. Effectiveness of control in dairy farms is highly variable, and farming system characteristics are a assumed to play an important role in the observed differences. A paratuberculosis transmission model and a herd simulation model were combined to investigate effects of calf housing, hygiene, and occurence of involuntary culling due to other disorders (mastitis and infertility) on the effectiveness and the efficiency of paratuberculosis control. The herd was managed under a quota constraint. Several surveillance systems and control actions for paratuberculosis were combined and compared. Effects of the control programmes can be compared in terms of prevalence of infectious animals, replacement rate, resulting herd size and quota achievement. The type of calf housing had a minor effect contrary to hygiene management and time-to-cull infectious animals. Whatever the surveillance in place to trigger a control programme (surveillance based on either clinical case, or on systematic testing with tests of limited sensitivity), hygiene and involuntary culling interacted to a large extent on the results of the control programme. Implementing systematic test-and-cull was more efficient than clinical surveillance or doing nothing after 7 to 13 years. Return on investment of systematic surveillance was higher and occurred earlier when hygiene was impaired. The differences between control scenarios were small when hygiene was improved. Modelling is a valuable tool to account for farm characteristics.

Limited data are available regarding animal-based biomarkers over time as outcomes of biosecurity in pig farms. The aim of this study was to gain an insight into the biosecurity implementation in a convenience sample of 15 swine herds, and to describe potential biomarkers of interest; inputs from a systematic evaluation of biosecurity implementation were used to develop tailor-made biosecurity protocols monitored over a 12-month period. The farms’ implementation was then described, and animal-based biomarkers were explored as output parameters. A significative biosecurity improvement was observed at the end of the study (p = 0.047), in particular in the professional zone (p = 0.012). Four clusters of farms were identified for their progress on biosecurity implementation by means of Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA): 4/15 farms improved their biosecurity only in the professional zone, 8/15 showed scarce/null improvement of total biosecurity, 2/15 worsened their biosecurity, and 1/15 greatly improved biosecurity. The farm biosecurity profiles showing an improvement included farms with a reduction in lung lesions and scars at slaughter at the end of the study. The results suggest that a systematic evaluation of biosecurity is a useful approach to formulate tailor-made biosecurity plans and monitor their implementation; biomarkers might bring insight into the outcomes of biosecurity.

Co-encadrant : Nathalie LE FLOC'H de l'UMR SENAH Diffusion du document : Confidentiel Diplôme : other