L. Balaine

Factors associated with mortality of broilers during transport to slaughterhouse

In recent years, broiler mortality during transport to the slaughterhouse has become a cause for concern because of animal welfare considerations and associated economic losses. A descriptive and analytical epidemiological study was carried out to estimate the extent of DoA in poultry broiler production in the main producing regions of France and to determine factors influencing the DoA rate. Data regarding animal characteristics and rearing, catching, transport and lairage conditions were collected on farm and at the slaughterhouse for 404 chicken broiler flocks processed during 2005. The average DoA rate was 0.18% (from 0% to 1.4%). Variables found to be associated (P < 0.05) with the DoA rate in a multivariable negative binomial model were flock cumulative mortality on farm, the catching system (mechanical being more at risk than manual), the density in crates (more space allowance being associated with less mortality) and climatic conditions (rain and wind being associated with more DoA). Mortality during transport is thus related to all production steps from the farm to the slaughterhouse. Efforts have therefore to be made by all professionals to contain mortality on farm and during catching and transportation.

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.

Postmortem condemnations of processed broiler chickens in western France

A total of 404 broiler chicken flocks processed in 15 slaughterhouses in western France were studied to estimate the condemnation prevalence and describe the official reasons for condemnation and the main macroscopic lesions observed in a sample of the condemned carcases. The condemnation rate was 87 per 10,000 birds slaughtered (95 per cent confidence interval 79 to 95 per 10,000) but differed significantly according to the type of poultry produced (standard, light, heavy or certified). The main reasons for condemnation were emaciation and congestion, with rates of 30 and 22 per 10,000 birds slaughtered, respectively. Congestion was significantly associated with arthritis and ascites, whereas infected skin lesions were associated with bruises and abnormalities of colour, odour or conformation.

Risk and indicators of condemnation of male turkey broilers in western France, February–July 2006

A field study was conducted to estimate the sanitary condemnation proportion in male turkey broiler flocks, to describe the reasons for condemnation and the related macroscopic lesions, and to investigate whether primary production information would predict the risk of condemnation. Male turkey standard broiler flocks (117) were randomly selected in the 13 slaughterhouses located in Western France, from February to July 2006. The flocks were monitored from their arrival at the slaughterhouse until the results of the post mortem sanitary inspection. Information about rearing conditions, health history, catching and loading conditions, transportation to the slaughterhouse and slaughtering was also collected. Sampling design was considered in the calculations and the condemnation proportion was modelled using a negative binomial regression, accounting for clustering within slaughterhouse. The within-flock weighted average condemnation proportion was 1.8% (95% confidence interval, 1.3-2.3%). Emaciation, arthritis-polyarthritis and congestion were the main reported official reasons for condemnation, representing 76% of the condemned carcases. Three variables were significantly associated with increased risk of condemnation: observed locomotor disorders on the farm, high cumulative mortality 2 weeks before slaughter, and clinical signs observed by the Veterinary Services during the ante mortem inspection at the slaughterhouse. The final model explained 35% of the total variation in condemnation risk. Half of this explained variation could be attributed to locomotor disorders observed during rearing. The sensitivity and specificity of the model to predict a high flock condemnation risk were 80% and 74%, respectively, when using an optimum threshold of 0.95% to define high risk. The results of this study suggested that the variables found to be associated with condemnation proportion were markers of increased risk and could be used as indicators. These risk indicators can easily be retrieved from the pre-existing regulatory document transmitted before flock arrival at the slaughterhouse and could be used to screen flocks before slaughter, according to their expected risk of condemnation.

Feasibility of screening broiler chicken flocks for risk markers as an aid for meat inspection.

The feasibility of using risk markers to screen broiler chicken flocks and anticipate their risk of condemnation at meat inspection was examined in 404 randomly selected flocks in 15 French slaughterhouses in 2005. Condemnation rate and information about rearing conditions, health history, catching and loading, transport and slaughtering were collected. The Poisson regression model of the condemnation rate consisted of six simple and biologically relevant predictors: production type, frequency of farmers visits during the starting period, health disorders during rearing, on-farm mortality, mortality during transport, and slaughter-line speed. Although accurate prediction of the condemnation rate for a given flock was not feasible, flocks with low or high risk of condemnation could be distinguished. These findings could be useful at various stages of chicken production, to monitor and improve farm husbandry practices, minimize the impact of transport conditions, and optimize meat inspection procedures.

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.

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.

Risk factors for sanitary condemnation in broiler chickens and their relative impact: application of an original multiblock approach.

An innovative and well-adapted statistical method, called multiblock redundancy analysis, is proposed for a complex health-event analysis to account for the thematic block organization of variables. The outcome block contained the condemnation rates of 404 broiler chicken flocks, distinguishing infectious and traumatic condemnation categories. Explanatory variables were organized in blocks related to the different production stages (farm structure and routine husbandry practices; on-farm flock history and characteristics; catching, transport and lairage conditions; slaughterhouse and inspection features). The aim was to determine risk factors for both condemnation categories, and the relative impact of the different production stages on the whole condemnation rate. Results showed that significant factors were either specific to one condemnation category or related to both categories, and each of the explanatory blocks was involved in the explanation of infectious and traumatic condemnation rates. On-farm flock information explained 40% of the overall condemnation process whereas the other explanatory blocks had similar relative impacts.

Investigation of a type C/D botulism outbreak in free-range laying hens in France

ABSTRACT In 2014, a botulism outbreak in a flock of laying hens was investigated in France. In the flock of 5020 hens, clinical signs of botulism occurred at 46 weeks of age. A type C/D botulism outbreak was confirmed using the mouse lethality assay for detection of botulinum toxin in serum and a real-time PCR test to detect Clostridium botulinum in intestinal contents. The disease lasted one week with a mortality rate of 2.6% without recurrence. Botulism in laying hens has rarely been reported. Five monthly visits were made to the farm between December 2014 and May 2015 for a longitudinal study of the persistence of C. botulinum in the poultry house after the outbreak, and to assess egg contamination by C. botulinum. Several samples were collected on each visit: in the house (from the ventilation circuit, the egg circuit, water and feed, droppings) and the surrounding area. Thirty clean and 30 dirty eggs were also swabbed at each visit. In addition, 12 dirty and 12 clean eggs were collected to analyse eggshell and egg content. The samples were analysed using real-time PCR to detect type C/D C. botulinum. The bacterium was still detected in the house more than 5 months after the outbreak, mostly on the walls and in the egg circuit. Regarding egg contamination, the bacteria were detected only on the shell but not in the content of the eggs. Control measures should therefore be implemented throughout the egg production period to avoid dissemination of the bacteria, particularly during egg collection.

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.