A. Huneau-Salaün

Risk factors for Salmonella enterica subsp. enterica contamination in 519 French laying hen flocks at the end of the laying period.

A cross-sectional study was carried out to identify risk factors for Salmonella spp. contamination in French laying hen flocks at the end of the laying period. Five hundred and nineteen flocks were studied between October 2004 and September 2005. The Salmonella status of the flocks was assessed from 5 faeces samples (pooled faeces samples from cage flocks and foot swabs from flocks kept on the floor, i.e. in a barn, outdoors and on organic farms) and 2 dust samples analysed using a classical bacteriological method. At least one contaminated sample was found in 93 flocks and the apparent prevalence of Salmonella was 17.9% (CI 95%=14.5, 21.3). Prevalence was significantly higher in caged flocks than in on-floor flocks and logistic-regression models were built for each subpopulation. Associations between farm characteristics, managerial practices and the presence of one or more Salmonella-positive samples in a flock were assessed using a mixed logistic-regression model with a flock-specific random effect. In caged flocks (n=227) the risk of Salmonella contamination increased with flock size and when delivery trucks passed near poultry-house entrances. The risk of detecting a positive sample was lower with pooled faeces samples than with dust samples. In on-floor flocks (n=292), a higher risk of contamination was associated with multistage management (presence of hens of different ages on the farm) and contamination by Salmonella Enteritidis of a previous flock kept on the farm. However, the use of a container for dead bird disposal was a protective factor.

Factors influencing bacterial eggshell contamination in conventional cages, furnished cages and free-range systems for laying hens under commercial conditions.

1. The aim was to assess eggshell contamination in various laying hen-housing systems and to identify factors influencing this contamination. 2. Fifty-eight laying hen farms in France were studied, including 21 flocks housed in conventional cages, 7 in furnished cages and 30 kept on-floor. 3. Sixty eggs per flock were analysed to obtain counts of the total mesophilic flora. Data on equipment and hen management were collected. 4. Mean bacterial count on eggshells tended to be higher in on-floor systems (4·82 ± 0·51 log CFU/eggshell) than in cage systems (4·57 ± 0·58 log CFU/eggshell, P = 0·09). 5. Contamination increased with age of the hens, airborne dust concentration, manual packing of the eggs, and packing in plastic rather than in recycled-pulp egg-flats. 6. The effect of the housing system on eggshell contamination, previously described in experimental assays, was confirmed under production conditions.

Isolation of Salmonella enterica in Laying-Hen Flocks and Assessment of Eggshell Contamination in France

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.

Risk factors for Listeria monocytogenes contamination in French laying hens and broiler flocks

The objective of this study was to identify potential risk factors for Listeria monocytogenes contamination in French poultry production. Eighty-four flocks of layer hens kept in cages and 142 broiler flocks were included in this study. For each production type, a questionnaire was submitted to farmers and fecal samples were taken to assess the L. monocytogenes status of the flocks during a single visit to the farm. Two logistic regression models (specific to each production) were used to assess the association between management practices and the risk of L. monocytogenes contamination of the flock. The prevalence of L. monocytogenes-positive flocks was 30.9% (95% CI: 21.0; 40.9) and 31.7% (95% CI: 24.0; 39.4) for cage-layers and broiler flocks, respectively. For layer flocks, the risk of L. monocytogenes contamination was increased when pets were present on the production site. When droppings were evacuated by conveyor belt with deep pit storage, the risk of L. monocytogenes contamination decreased significantly. Feed meal was found to be associated with a higher risk of L. monocytogenes contamination than feed crumb. For broiler flocks, the risk of L. monocytogenes contamination was increased when farmers did not respect the principle of two areas (clean and dirty) at the poultry house entrance. A first disinfection by thermal fogging and the absence of pest control of the poultry house before the arrival of the next flock was found to increase the risk of contamination. When litter was not protected during storage and when farm staff also took care of other broiler chicken houses, the risk of L. monocytogenes contamination increased significantly. In the case of the watering system, nipples with cups were found to decrease the risk of contamination.

Aerial dust concentration in cage-housed, floor-housed, and aviary facilities for laying hens

Agricultural workers, and pig and poultry farmers in particular, are exposed to airborne contaminants including organic dusts, gases, fungi, bacteria, and endotoxins that can have adverse effects on their respiratory health. To date, data comparing the aerial dust concentrations in the different hen-housing systems used by commercial poultry farmers are scarce. An epidemiological study was conducted in commercial housing facilities for laying hens, half of which were housed in a cage system without litter and the remaining half on an on-floor system with litter. The aims were to measure and compare the ambient dust concentrations in the different housing systems and identify any factors in building design and hen management that could influence the dust burden. An average concentration of respirable ambient dusts (≤4 μm) of 0.37 mg/m(3) (95% CI [0.31-0.42]) was measured in the on-floor system, and this value was higher than average values in the cage system {0.13 mg/m(3) (95% CI [0.11-0.14]) P = 0.01}. The highest dust concentration was observed in aviaries (1.19 mg/m(3) [0.80-1.59]). The type of housing and the presence of litter therefore had a preponderant effect on air quality. Dust concentrations in caged buildings were influenced by cage design and rearing practices, whereas litter management, the age of hens, and temperature control were determining factors for dust levels in on-floor houses. This study underlines the need for information and preventive measures to reduce the exposure of poultry workers to bioaerosols, particularly in alternative systems where high levels of ambient dust were observed.

Cage hygiene, laying location, and egg quality: The effects of linings and litter provision in furnished cages for laying hens

This study investigates the influence of litter provision and linings used for nests and pecking and scratching areas on cage hygiene, laying location, and egg quality. Research was carried out in furnished cages, each housing 60 beak-trimmed ISA Brown hens. Four different treatments were compared in a factorial arrangement, including 2 different nest linings (artificial turf vs. plastic mesh), either used alone or combined with the use of litter (wheat bran) spread over the rubber mat in the pecking and scratching area (PSA). An additional treatment, using artificial turf mat in the PSA and nests (as commonly used in commercial flocks), was used to compare the effect of PSA lining in the other treatments. We observed laying location, the number of dirty and broken eggs, the microbiological contamination of eggshells according to laying location, and general cage hygiene. The use of nests for laying decreased when they were lined with plastic mesh. Eggs laid outside the nest were of lower quality than those laid inside it, and this was particularly true for eggs laid in the PSA. Although hygiene was low on artificial turf mats, eggs laid on PSA covered with a rubber mat were dirtier and had a higher count of mesophilic bacteria on the eggshell than those laid on PSA covered with an artificial turf mat. Rubber mats in PSA were rapidly destroyed and proved to be unsuitable. The provision of litter had no effect on cage hygiene but substantially increased wear on mats. This study shows nest lining and litter provision methods to be key factors that need to be taken into account to encourage the use of nest boxes for laying, and hence, to ensure good egg quality. Further research into new linings for PSA is needed for the future improvement of egg-laying conditions.

Endotoxin concentration in poultry houses for laying hens kept in cages or in alternative housing systems

1. Endotoxins as components of organic dust may have adverse effects on the respiratory health of workers in poultry buildings. The move towards more welfare-friendly housing systems for layers may increase worker exposure to air contaminants due to the use of litter. 2. The endotoxin concentrations in the inhalable fraction of airborne dust (below 100 µm) from cage and alternative system houses (on-floor, free range and aviaries) were compared under both experimental and commercial conditions. 3. The endotoxin concentration was higher in experimental aviaries (median: 565 EU/m3, range: 362-1491 EU/m3) than in cage housing (98 EU/m3 (51-470)). 4. In field conditions, the endotoxin concentration in the air of 13 alternative houses was higher (35 to 3156 EU/m3) than in cage system buildings (n = 8, 78-576 EU/m3). It was correlated to the respirable dust concentration (fraction below 5 µm) and to the temperature inside the hen house but no seasonal variation was observed. 5. The present study emphasises that considerable worker exposure to endotoxins may occur in laying houses, especially in alternative systems.

Plumage condition, body weight, mortality, and zootechnical performances: The effects of linings and litter provision in furnished cages for laying hens

This experiment was designed to determine the effect of litter provision and lining in nests and pecking and scratching areas on health and zootechnical performances. Research was carried out in furnished cages, each housing 60 beak-trimmed ISA Brown hens. Four different treatments were compared in a factorial arrangement, including 2 different nest linings (artificial turf versus plastic mesh), either used alone or combined with the use of litter (wheat bran) spread over the rubber mat in the pecking and scratching area (PSA). An additional treatment using artificial turf mat in the PSA and nests (as commonly used in commercial flocks) was used to compare the effect of PSA lining in the other treatments. Zootechnical performances (laying rate, egg weight, and feed intake) were unaffected by PSA lining or by nest lining. The use of artificial turf mats in the PSA resulted in less feather loss than rubber mats, especially on breast and cloaca/vent areas. No consequences were observed on BW or mortality. However, the use of plastic mesh in nests was seen to increase mortality in comparison with artificial turf mats, without affecting plumage condition and BW. Although wheat bran provision did not influence feed intake and laying rate, litter provision did result in slightly higher mean egg weight. Moreover, BW tended to be lower when litter was distributed in cages, and neck and breast plumage condition improved. The distribution of litter was not seen to have any effect on mortality. The provision of litter and the lining of the PSA and nests to improve the welfare of caged laying hens have an effect on mortality, plumage quality, and some zootechnical performances. These results show the importance of choosing the most suitable linings and litter to obtain the best possible compromise between the ethological needs of laying hens, zootechnical performance, and animal health.

Contribution of Meat Inspection to the surveillance of poultry health and welfare in the European Union

In the European Union, Meat Inspection (MI) aims to protect public health by ensuring that minimal hazardous material enters in the food chain. It also contributes to the detection and monitoring of animal diseases and welfare problems but its utility for animal surveillance has been assessed partially for some diseases only. Using the example of poultry production, we propose a complete assessment of MI as a health surveillance system. MI allows a long-term syndromic surveillance of poultry health but its contribution is lowered by a lack of data standardization, analysis and reporting. In addition, the probability of case detection for 20 diseases and welfare conditions was quantified using a scenario tree modelling approach, with input data based on literature and expert opinion. The sensitivity of MI appeared to be very high to detect most of the conditions studied because MI is performed at batch level and applied to a high number of birds per batch.

Evaluation of common cleaning and disinfection programmes in battery cage and on-floor layer houses in France

1. The aim in this study was to evaluate cleaning and disinfection programmes in battery cage and on-floor layer houses in France. 2. Cleaning and disinfection efficiency was assessed by a visual evaluation of cleaning and a bacteriological monitoring of surface contamination from counts of thermotolerant streptococci on contact agar plates. 3. In battery cage houses, dropping belts, manure conveyors, and house floors remained highly contaminated due to poor cleaning in half of the buildings examined. 4. In on-floor houses, a high standard of cleaning was achieved but errors in the planning of cleaning and disinfection operations sometimes led to a high residual contamination of nest boxes and egg sorting tables.