Caged Flocks Research Articles

Risk Factors for Salmonella Detection in Commercial Layer Flocks in Spain.

Trends in Salmonella human infections are assumed to be related to the distribution of the pathogen in the animal reservoir/food products, and cases in humans are most often linked to poultry and poultry products (eggs, meat). Therefore, ongoing Salmonella national control programs (NCPs) in European Union Member States have the objective of monitoring and reducing its prevalence in commercial poultry flocks. Results from NCPs have shown certain factors (housing systems, season of sampling and if sampling is conducted by food business operators (FBOps) or competent authorities (CAs), among others) can influence detection rates, but associations are often not consistent. Here, we analyzed data from the Spanish NCP on 7216 laying hen flocks subjected to 36,193 sampling events over a six-year period to characterize its performance and identify variables influencing detection rates. Overall, 1205 sampling events were positive for Salmonella spp. (any serovar) and 132 for S. Enteritidis-S. Typhimurium/monophasic. Bayesian multivariable models adjusting for multiple covariates concluded that sampling events later in the year, in caged flocks with older animals and conducted by CAs had increased odds of positivity for Salmonella spp., revealing aspects linked with a differential estimation of Salmonella levels in laying hen flocks.

Housing and Management Practices on 33 Pullet Farms in Canada.

Simple SummaryThe rearing period of pullets plays an important role in the successful transition to furnished cages or non-cage housing systems for laying hens. Changes in the laying hen sector often occur without accompanying changes in the pullet rearing sector, which could pose a risk to the success of the housing system transition. However, little is known about the housing and management practices of pullets worldwide. Recently, a new Code of Practice was released (March 2017) in Canada which provides one of the first guidelines on pullet rearing. This study aimed to describe current housing and management practices applied on pullet farms in Canada, where farmers are in the process of transitioning to this new Code of Practice. Thirty-three pullet farmers were surveyed to understand commonly used management practices in cage (14), single-tier (11) and multi-tier (8) flocks. In general, non-cage farmers met the new requirements set out in the Code of Practice for space, perches and litter provision during pullet rearing. Flocks in conventional cages did not have opportunities for perching and foraging. Further research is needed to develop methods to provide pullets with opportunities to perch and forage in these systems. Additionally, clear litter management recommendations for farmers to ensure good litter quality are needed for non-cage housing systems.Although Canada is one of the first to provide guidelines on pullet rearing in a new Code of Practice which came into effect in March 2017, little information is available about the housing and management of pullets on Canadian farms. We surveyed 99 pullet farmers and received useable responses from 33 pullet farmers (33.3% response rate) who took part in the Start Clean-Stay Clean™ program through their provincial egg boards across Canada during October–December 2017 as part of a larger study. Most flocks were housed in conventional cage systems (42.4%), followed by single-tier (33.3%) and multi-tier systems (24.2%). Flocks ranged from 1–19 weeks of age (average: 10.5 weeks of age) and were white- (58.1%) or brown-feathered (41.9%). In general, non-cage farmers met the new requirements set out in the Code of Practice for space, perches and litter provision during pullet rearing during this transitional period. Conventional caged flocks did not have opportunities for perching and foraging, but developing new methods to provide pullets with opportunities to perch and forage will become more important as the laying hen housing system transition from conventional cages to furnished cage and non-cage housing systems in Canada progresses. Additionally, clear litter management recommendations for farmers to ensure good litter quality are needed for non-cage housing systems.

Analysis of antibody levels in egg yolk for detection of exposure to Ascaridia galli parasites in commercial laying hens

Ascaridia galli is one of the most abundant nematode parasites in poultry. A. galli infections can significantly impact the profitability of egg farms and have negative implications for bird health and welfare. The main objectives of this study were to determine whether A. galli specific antibodies in egg yolks can be used to detect prior or current exposure to A. galli in laying hens, and to distinguish between eggs obtained from caged and free-range hens. Twenty-two laying hen flocks from different production systems (10 free-range, 2 barn-housed, and 9 caged flocks) were enrolled in the study. An in-house enzyme-linked immunosorbent assay was used to analyze levels of A. galli specific antibodies in yolk. The numbers of A. galli eggs in hen excreta were also determined in a subset of farms. Free-range flocks had higher and also more variable levels of anti-A. galli antibodies in the egg yolk compared to those of the cage flocks (0.50 ± 0.39 vs. 0.16 ± 0.13 OD units) (P < 0.001). Results also confirmed that excreta from free-range and barn-housed flocks contained higher numbers of A. galli eggs than did excreta from caged flocks in which no A. galli eggs were detected. In conclusion, analysis of anti-A. galli antibodies in the egg yolk can be used to detect worm exposure in commercial layer flocks. However, the method used in this study cannot be used in isolation to distinguish between eggs from cage and free-range production systems as anti-A galli antibodies were detected in egg yolk samples from all production systems, and the range of antibody levels overlapped between production systems.

Fatty liver haemorrhagic syndrome occurrence in laying hens: impact of production system

ABSTRACTSurveys were conducted with cage and alternative layer production systems to assess the prevalence of fatty liver haemorrhagic syndrome (FLHS). Commercial caged laying hens of different ages from three farms in Queensland were monitored for three months. The mortality rate of flocks ranged from 0.8% (the youngest flock) to 11.6% (the oldest flock). Six hundred and fifty-one birds were necropsied, and approximately 40% of hens died due to FLHS. Hens kept in cages in a controlled environment shed, were at a similar risk of developing FLHS to hens kept in naturally controlled sheds, however, the heavier birds in a flock were more likely to have the condition than lighter birds. In another study, layer flocks kept in cage, barn and free-range housing systems at the University of Queensland facility, were monitored for 50 weeks. Data from necropsies and performance records showed no significant differences in mortality rates between the housing systems (6.1%, 6.4% and 5.8%, for cages, barns and free-range, respectively), but the cause of mortality was different. In cages, 74% of necropsied hens died due to FLHS. In the other systems, only 0–5% of dead hens were diagnosed with the condition. These results are in agreement with previous Australian and overseas findings which have shown that FLHS is one of the main causes of hen death in caged flocks. Factors associated with husbandry practices in different production systems, such as restricted movement, increased production and temperature variations, influence hepatic lipid metabolism and predispose hens to FLHS.

Ascarid infections in laying hens kept in different housing systems

The present study was undertaken to investigate the prevalence of ascarid infections in Swedish commercial laying hens in 2004 and 2008 following a recent nationwide change to alternative housing systems but before anthelmintics became available. Also, the influence on prevalence of farm and flock characteristics and management was studied in 2004. The results showed that the overall prevalence was significantly higher in 2008 (38%; n = 64/169) compared with 2004 (24%; n = 44/186) (P = 0.001). Ascarid infections were rare in caged flocks, including furnished (enriched) cages, both years (2.4 to 4.3%), and were significantly more common in non-cage systems in both years (16.7 to 48.6% in 2004, and 28.6 to 77.1% in 2008 depending on the housing system). There was no significant difference in prevalence between hens kept on litter indoors and free-range/organic hens. The absence of a hygiene barrier at the entrance of the house or unit increased the risk of infection (P < 0.001), which suggests that parasite eggs were introduced horizontally to the farms. The risk of infection also increased with the age of equipment used in the barn; for example, the risk increased with an odds ratio of 7.5 (95% confidence interval = 2.3 to 25) when comparing equipment 1 year old with equipment ≥7 years old. The results of this study show that ascarid infections may re-emerge following a change to alternative housing. With the impending ban on conventional battery cages in the member states of the European Union, ascarid infections are likely to increase in importance and efficient control options such as hygiene barriers should be implemented on all farms.

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.

Causes of mortality in laying hens in different housing systems in 2001 to 2004

BackgroundThe husbandry systems for laying hens were changed in Sweden during the years 2001 – 2004, and an increase in the number of submissions for necropsy from laying hen farms was noted. Hence, this study was initiated to compare causes of mortality in different housing systems for commercial laying hens during this change.MethodsBased on results from routine necropsies of 914 laying hens performed at the National Veterinary Institute (SVA) in Uppsala, Sweden between 2001 and 2004, a retrospective study on the occurrence of diseases and cannibalism, i.e., pecking leading to mortality, in different housing systems was carried out. Using the number of disease outbreaks in caged flocks as the baseline, the expected number of flocks with a certain category of disease in the other housing systems was estimated having regard to the total number of birds in the population. Whether the actual number of flocks significantly exceeded the expected number was determined using a Poisson distribution for the variance of the baseline number, a continuity correction and the exact value for the Poisson distribution function in Excel 2000.ResultsCommon causes of mortality in necropsied laying hens included colibacillosis, erysipelas, coccidiosis, red mite infestation, lymphoid leukosis and cannibalism. Less common diagnoses were Newcastle Disease, pasteurellosis and botulism. Considering the size of the populations in the different housing systems, a larger proportion of laying hens than expected was submitted for necropsy from litter-based systems and free range production compared to hens in cages (P < 0.001). The study showed a significantly higher occurrence of bacterial and parasitic diseases and cannibalism in laying hens kept in litter-based housing systems and free-range systems than in hens kept in cages (P < 0.001). The occurrence of viral diseases was significantly higher in indoor litter-based housing systems than in cages (P < 0.001).ConclusionThe results of the present study indicated that during 2001–2004 laying hens housed in litter-based housing systems, with or without access to outdoor areas, were at higher risk of infectious diseases and cannibalistic behaviour compared to laying hens in cages. Future research should focus on finding suitable prophylactic measures, including efficient biosecurity routines, to reduce the risk of infectious diseases and cannibalism in litter-based housing systems for laying hens.

Detection of mortality clusters associated with highly pathogenic avian influenza in poultry: a theoretical analysis

Rapid detection of infectious disease outbreaks is often crucial for their effective control. One example is highly pathogenic avian influenza (HPAI) such as H5N1 in commercial poultry flocks. There are no quantitative data, however, on how quickly the effects of HPAI infection in poultry flocks can be detected. Here, we study, using an individual-based mathematical model, time to detection in chicken flocks. Detection is triggered when mortality, food or water intake or egg production in layers pass recommended thresholds suggested from the experience of past HPAI outbreaks. We suggest a new threshold for caged flocks--the cage mortality detection threshold--as a more sensitive threshold than current ones. Time to detection is shown to depend nonlinearly on R0 and is particularly sensitive for R0<10. It also depends logarithmically on flock size and number of birds per cage. We also examine how many false alarms occur in uninfected flocks when we vary detection thresholds owing to background mortality. The false alarm rate is shown to be sensitive to detection thresholds, dependent on flock size and background mortality and independent of the length of the production cycle. We suggest that current detection thresholds appear sufficient to rapidly detect the effects of a high R0 HPAI strain such as H7N7 over a wide range of flock sizes. Time to detection of the effects of a low R0 HPAI strain such as H5N1 can be significantly improved, particularly for large flocks, by lowering detection thresholds, and this can be accomplished without causing excessive false alarms in uninfected flocks. The results are discussed in terms of optimizing the design of disease surveillance programmes in general.

Reaction of laying hens to humans in the home or a novel environment

Tests assessing the fear of humans by measuring avoidance or approach reactions of the test animals towards humans can be useful tools in welfare assessment schemes. In this study, we wanted to compare tests assessing the reactions of laying hens towards humans in the home environment to a test performed in a novel environment. As well we investigated inter-test correlations in the home environment. We performed several tests to assess the hens’ approach and avoidance reactions towards an unfamiliar human inside the home environment of laying hens in 14 caged flocks and 10 free-range flocks. We measured the reactions of hens to a stationary person and a moving person approaching individual hens in both systems, as well as reactions to a stationary person trying to touch individual hens in non-cage systems and reactions of caged hens to a person passing by. Additionally, a standardised arena test was performed outside the home environment to compare the birds’ avoidance reactions towards an approaching human in a novel environment. In caged hens no significant correlations of tests performed inside the home environment with the arena test could be found, but there were moderate to high correlations ( r s > 0.6) with one parameter of the arena test in non-caged hens. The different tests applied inside the home environment correlated significantly and moderately to highly with each other, supporting the validity of these tests to measure fear of humans. The caged laying hens in our study reacted differently in the novel environment from the non-caged birds, indicating that the birds’ reactions towards humans in an unfamiliar environment depend on the housing system. In summary, a comparison of the level of fear of humans between flocks in different housing systems by using an arena test outside the home environment seems difficult and was not possible in the present study.

Risk factors associated with colibacillosis outbreaks in caged layer flocks

Colibacillosis appears to be of increasing significance in layer flocks, but there have been no studies of the risk factors associated with outbreaks. This study aimed to investigate the possible associations between risk factors of non-infectious nature and outbreaks of mortality due to colibacillosis in flocks of caged layer hens. Information on management, biosecurity measures and housing conditions was collected in 20 flocks suffering from the disease and in 20 clinically healthy control flocks. The data were processed using multiple logistic regression. The statistical analysis demonstrated that an increase in the distance to the nearest poultry farm by 1 km was associated with a six-fold decreased risk of an outbreak of colibacillosis (odds ratio=0.16). Furthermore, a 1 l increase in cage volume per hen was associated with a 33% decrease in the risk of an outbreak (odds ratio=0.75). It was concluded that the distance between poultry farms and the hen density in the cages are important risk factors for outbreaks of colibacillosis in flocks of layer hens.

Factors Which May Affect the Precision of Experiments Employing Chickens

Reported in this paper are factors which can increase differences between experimental group means and/or reduce variation with groups. Factors which affected the precision of research results included sex and body weight distribution with experimental caged flocks; comb type and beak trimming which influenced social rank; dose of chemicals and infectious agents and antigens; and chicken-human relationships. Experimental precision was especially affected when these factors influenced some but not all experimental groups. Increased precision of experimental procedures allows for reducing the numbers of animals and/or observations needed for experiments.

Chickens, Evaluation of Standard Acaricides for Control Of Northern Fowl Mites, 1979

Abstract Five field tests were conducted in Missouri using commercial caged layer flocks. Mite populations were assessed prior to and regularly after treatment via visual inspection of 10 to 25 hens selected at random from each replicate. We used the following 0-6 index system: 0 = no mites, 1 = 1-5 mites, 2 = 6-15 mites, 3 = 16-50 mites, 4 = 51-100 mites, 5 = 101-500 mites, and 6 = more than 500 mites. In all cases, acaricide treatment was assigned at random and untreated control replicates incorporated into the experimental design.

Epidemiology of western encephalitis in Alberta: response of natural populations of mosquitoes to avian host.

The response of natural populations of mosquitoes to avian host was determined under field conditions in dryland and irrigated areas in Alberta. Caged flocks of chickens were used as avian host. Females of Culex tarsalis, Culiseta inornata, Aedes flavescens, Aedes dorsalis, Aedes spencerii, Aedes vexaus, Aedes campestris, Aedes cataphylla , and Aedes nigromaculis were attracted to and readily fed on the chickens although other hosts were available in the areas studied. Bird-biting mosquitoes, which are in continuous supply throughout the spring and summer, were observed to feed on nestlings of Franklin gulls, red-winged blackbirds, Brewer's blackbirds, yellow-headed blackbirds, and ringed-neck pheasants. The interrelations of mosquito and bird populations are believed to be essential factors in the epidemiology of Western Encephalitis virus in the study area.

Influence of Hunger on Aggressive Behavior in Certain Buntings of the Genus Emberiza

TheIs paper is based on studies of hand-reared yellowhammers (EmTheIs beriza citrinella), corn buntings (E. calandra), and reed buntings (E. schoeniclus) and on observations of these birds made in the field near Cambridge, England. Previous field observations (Hinde, 1952) suggest that passerines fight more frequently when hungry. The main part of this paper describes a series of experiments investigating the possible effects of hunger on aggressive responses. The hierarchical organization of caged flocks is also discussed. Andrew (1957a) describes the head-forward threat postures of buntings and the displays that the males use when at territorial boundaries (reproductive fighting displays).

The Social Hierarchy in Ring Doves. II. The Effect of Treatment with Testosterone Propionate

Social organization has been described in flocks of many species of birds both wild and caged. Schjelderup-Ebbe ('24, '31) reported in more than fifty species a type of hierarchy which he designated as a peck-order. Subsequent investigation by others has confirmed his observations with relation to the domestic chicken (Masure and Allee, '34a; Murchison, '35). In the case of pigeons and shell parrakeets, Masure and Allee ('34b) reported a social order based upon rather than peck-right, that is, upon a dominance established after many conflicts rather than upon an initial combat. Shoemaker ('39a) and Bennett ('39), in flocks of canaries and of ring doves respectively, likewise found peckdominance to be characteristic of the social organization in caged flocks of these birds. Others who have observed hierarchies in bird flocks, based upon dominance in some form, are Lorenz ('35) in jackdaws, geese, and certain other birds, both in wild and artificial associations, and Noble, Wurm, and Schmidt ('38) in American black crowned night herons. The question arises as to what factors underly the social organization in a flock of birds. Schjelderup-Ebbe ('35) directed attention to a number of conditions which he believed to be of some importance in this matter. Among them were health, season, sex, age, relative strength and fatigue. Certain of these same conditions have been recognized by other investigators. Allee, referring to the do-