The present investigation was conducted in conjunction with the European Union baseline study for the estimation of Salmonella prevalence in laying-hen flocks. It aimed at evaluating eggshell contamination in farms positive for Salmonella, characterizing the genetic patterns of Salmonella strains and identifying the factors associated with Salmonella contamination of eggshells. For this purpose, a total of 4,200 eggs were collected from 28 positive flocks and analyzed according to draft Annex D of International Organization for Standardization Method 6579. Molecular characterization of the Salmonella strains was obtained by the pulsed-field gel electrophoresis method with two restriction enzymes, XbaI and BlnI. The relationship between the presence of Salmonella on eggshells and rearing practices was studied by using multiple correspondence analysis. Results showed that 39.3% of the positive flocks had at least one positive eggshell, with a total of 1.05% of eggshells testing positive for Salmonella. We detected the same serovars on samples taken from the farm and from eggshells within a given flock, with isolates sharing the same genetic pattern in 7 of 11 flocks. Eggshells tested positive for Salmonella in flocks (i) located where delivery trucks pass near air entrances of the poultry house, (ii) with high holding capacity (>30,000 laying hens), and (iii) with more than five positive samples coming from the farm environment, as well as in cases of flocks with a maximum egg-laying rate of >96% and in cases where farmers worked in other animal production. This study provided valuable information that could be used for risk management and risk assessment studies.
Few studies have previously investigated how poor animal welfare might be associated with infection of zoonotic pathogens in humans. This paper assesses the predictive value of the presence of Campylobacter spp. in broiler chicken flocks when animal-based measures related to footpad dermatitis, hock burns, body lesions and arthritis are identified under commercial conditions (high density). The study population included 32 flocks analysed on farm and at slaughter, slaughtered between April and August 2008 in six different slaughter plants in Brittany, France. Welfare and health indicators are those indicated by the European legislation and sampling was carried out in the framework of the European baseline survey on the prevalence of Campylobacter in broiler chicken. Caecal contents, sampled both on farm and at slaughter, and carcass skin samples from the neck and breast at slaughter, were investigated for the presence of Campylobacter spp. Logistic models/classification trees were used to estimate the probability of the presence (or absence) of a specific foodborne pathogen in a flock based on specific animal-based measures (or combinations of measures) in order to study the potential relationship between welfare indicators and foodborne pathogen prevalence/incidence levels. On farm, flocks with more than 25% animals with severe lesions on between 25 and 50% of the footpad are predicted to be Campylobacter-positive whereas flocks where less than 13 individuals have arthritis are predicted to be Campylobacter-negative. The error rate on farm and at slaughter was 10 and 4% respectively indicating good predicting abilities. A poor welfare environment may result in stress, which reduces chicken immunocompetence making them more susceptible to Campylobacter spp. An infection with Campylobacter spp may lead to impaired defence and susceptibility to other pathogens which may result in greater intestinal excretion. Poor welfare and high growing rate lead to digestive troubles that lead to litter humidity. Litter humidity that, among other things, causes footpad dermatitis may also influence the horizontal transmission of the Campylobacter spp. infection due to the normal coprophagic behaviour of poultry. Reducing welfare problems by a better management of rearing conditions would not only improve broiler welfare, but it would also decrease the risks of Campylobacter contamination, of carcass condemnations and of economic loss for the poultry industry.
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