Parallel Sequencing Reveals Campylobacter spp. in Commercial Meat Chickens Less than 8 Days Old.

Campylobacter from contaminated poultry meat is a major source of human gastroenteritis worldwide. To date, attempts to control this zoonotic infection with on-farm biosecurity measures have been inconsistent in outcome. A cornerstone of these efforts has been the detection of chicken infection with microbiological culture, where Campylobacter is generally not detectable until birds are at least 21 days old. Using parallel sequence-based bacterial 16S profiling analysis and targeted sequencing of the porA gene, Campylobacter was identified at very low levels in all commercial flocks at less than 8 days old that were tested from the United Kingdom, Switzerland, and France. These young chicks exhibited a much greater diversity of porA types than older birds testing positive for Campylobacter by culture or quantitative PCR (qPCR). This suggests that as the bacteria multiply sufficiently to be detected by culture methods, one or two variants, as indicated by porA type, dominate the infection. The findings that (i) most young chicks carry some Campylobacter and (ii) not all flocks become Campylobacter positive by culture suggest that efforts to control infection, and therefore avoid contamination of poultry meat, should concentrate on how to limit Campylobacter to low levels by the prevention of the overgrowth of single strains. IMPORTANCE Our results demonstrate the presence of Campylobacter DNA among fecal samples from a range of commercially reared meat chicks that are less than 8 days of age, consistent across 3 European countries. The recently developed, sensitive detection method indicates that infection occurs on commercial farms much earlier and more widely than previously thought, which opens up new opportunities to control Campylobacter contamination at the start of the food chain and reduce the unacceptably high levels of human disease.

Early warning of footpad dermatitis and hockburn in broiler chicken flocks using optical flow, bodyweight and water consumption.

Footpad dermatitis and hockburn are serious welfare and economic issues for the production of broiler (meat) chickens. The authors here describe the use of an inexpensive camera system that monitors the movements of broiler flocks throughout their lives and suggest that it is possible to predict, even in young birds, the cross-sectional prevalence at slaughter of footpad dermatitis and hockburn before external signs are visible. The skew and kurtosis calculated from the authors' camera-based optical flow system had considerably more power to predict these outcomes in the 50 flocks reported here than water consumption, bodyweight or mortality and therefore have the potential to inform improved flock management through giving farmers early warning of welfare issues. Further trials are underway to establish the generality of the results.

Effect of environment on Pekin duck behaviour and its correlation with body condition on commercial farms in the UK.

1. Forty-six flocks of commercially-reared Pekin ducks were studied to determine the effects of housing system and environment on the behaviour of farmed ducks and its correlation with physical condition. Houses differed predominantly in their ventilation, drinking, feeding and brooding systems, and were indicative of systems currently in use in the UK. 2. At 41 d of age ducks spent 15% of the time feeding, 67% drinking, 42% rooting and 155% dry preening. They spent large amounts of time relatively inactive, 435%, or performing comfort behaviours, 17%. On average 46% of their time was spent walking and only 18% wet preening. 3. A greater proportion of the maximum number of ducks able to use the drinker at any one time used the trough; nipple use was least and Plasson use intermediate. The proportion of ducks wet preening was not affected by drinker type but increased with increasing drinker space (mm/bird). 4. Duck behaviour was little affected by commercial production system and was influenced more by environment, age and physical condition. Activity at an older age incorporated more of the behaviours associated with thermal comfort (panting) and maintenance of plumage condition (dry and wet preening). These behaviours increased with increasing temperature, relative humidity and atmospheric ammonia. Poor walking ability was correlated to increased frequency of panting, reduced activity at the drinker, and longer resting bouts.

Environment and management factors affecting Pekin duck production and welfare on commercial farms in the UK.

1. Forty-six flocks of commercially-reared Pekin ducks were studied in 23 houses differing in their ventilation and brooding systems, and water and feed resources, in order to identify factors affecting duck welfare in commercial practice. 2. A wide range of environmental variables were measured, together with the physical and plumage condition of the ducks at two ages, whilst companies supplied mortality and growth rate data. 3. At 23 d, more than 98% of ducks had clean eyes, nostrils and feathers and an upright posture, and 86% had no gait abnormalities. By 41 d, body condition had deteriorated slightly with 84% of ducks having clean eyes, 67% clean feathers and 79% no gait abnormalities. 4. Gait worsened with increasing temperature and litter moisture, and atmospheric ammonia concentrations. The incidence of foot pad lesions was 10% (moderate) and 3% (severe) and was positively correlated with increasing humidity and ammonia. 5. Average mortality rates were 52% for ducks reared to 335 kg at 48 d with average growth rates of 603 to 813 g/d. High temperatures correlated with high mortality and reduced growth rate; growth rate was not related to poor gait. 6. Controlling the ducks' environment, particularly temperature, humidity, litter moisture and ammonia is crucial to duck welfare. Effective ventilation systems, high quality straw and access to some form of open water were considered important for duck welfare.

Pattern recognition and active vision in chickens.

Recognition of objects or environmental landmarks is problematic because appearance can vary widely depending on illumination, viewing distance, angle of view and so on. Storing a separate image or 'template' for every possible view requires vast numbers to be stored and scanned, has a high probability of recognition error and appears not to be the solution adopted by primates. However, some invertebrate template matching systems can achieve recognition by 'active vision' in which the animal's own behaviour is used to achieve a fit between template and object, for example by repeatedly following a set path. Recognition is thus limited to views from the set path but achieved with a minimal number of templates. Here we report the first evidence of similar active vision in a bird, in the form of locomotion and individually distinct head movements that give the eyes a similar series of views on different occasions. The hens' ability to recognize objects is also found to decrease when their normal paths are altered.

Evolution and animal welfare.

Animal welfare is a topic often thought to reside outside mainstream biology. The complexity of the methods used to assess welfare (such as health, physiology, immunological state, and behavior) require an understanding of a wide range of biological phenomena. Furthermore, the "welfare" of an animal provides a framework in which a diversity of its responses can be understood as fitness-enhancing mechanisms. Different methods for assessing animal welfare are discussed, with particular emphasis on the role of an animal's own choices and reinforcement mechanisms. No part of biology is as yet able to explain consciousness, but by confronting the possibility that nonhuman animals have conscious experienced of suffering, animal welfare studies force a consideration of even this hardest problem of all biological phenomena in a particularly direct and evolutionary way.

Peck orders and group size in laying hens: `futures contracts' for non-aggression.

We analyse a simple model of the establishment and maintenance of dominance hierarchies in hens. To be beneficial, dominance relationships require that the probability of meeting the same individual repeatedly is high, otherwise costs of establishing the dominance relation are never recouped. Winners and losers benefit from dominance relationships, not necessarily from changing the rate at which they acquire resources but by avoiding costly contests over them in future encounters. We show that so-called `loser effects', in which animals base their strategies for contesting resources solely upon their past experiences of winning or losing dominance fights and not upon who their opponent is, cannot work - these strategies (`pragmatists') must additionally involve either individual or status category recognition. As alternatives to dominance relationships, we show that signals of status or fighting ability that determine access to contested resources are expected to evolve in species with typically large groups because in such conditions the costs of establishing dominance relations are not recouped. Such signals do not depend upon recognizing others individually, but rather upon general category recognition. Status signals are not expected in small groups because dominance relationships are likely to be cheaper and just as effective. The results of the model have implications for the welfare of hens kept in large groups.

Discrimination and recognition of photographs of places by homing pigeons.

Operant studies on pigeons using slide-projected images suggest that photographs of geographical locations might be used as a research tool to study the importance of visual landmarks in homing. Before using this method, however, it is necessary to show that pigeons do see photographic slides as representing real world locations. After reviewing the evidence for picture-to-object correspondence for geographical locations in pigeons, we report the results of an experiment designed to test whether outdoor experience at a location affected homing pigeons' ability to categorise slides of that versus another location displayed in an operant set-up. Four birds visited one location immediately before each experimental session; four birds visited an irrelevant location. No effect of outdoor experience was found on acquisition, or transfer to novel stimuli. The possible reasons for limitations on picture-to-object correspondence are discussed.

An exaggerated preference for simple neural network models of signal evolution?

Recently, simple neural network models have been used to explain the evolution of important phenomena in animal signalling, such as extravagant ornamentation and symmetrical signals, as responses to inevitable 'hidden preferences' of recognition systems. We argue that these very simple models may be misleading because they may not behave in important ways like the recognition systems of real animals and so cannot justify their claim to demonstrate general principles of perception in a signalling context. We show that the way in which these simple models respond to exaggerated signals may not be, as is claimed, a close parallel to the phenomena of peak shift or supernormal responses. We also argue that the preference for symmetrical patterns shown by the models is unlikely to reflect the way computationally that real animals solve problems of pattern invariance and may be an artefact of the particular way the models have been set up. Whereas more sophisticated neural net models do capture known properties of real visual systems and are consequently of great use in understanding perception, the same cannot be said of very simple one-dimensional models with small numbers of units and connections. Given the far reaching explanatory claims made of these simpler models their limitations should be more widely recognized.

Receiver psychology and the design of animal signals.

Animal communication is studied both by neurobiologists and by evolutionary biologists, but in very different ways. The purpose of this article is to show how both groups could benefit from a greater appreciation of each other's approach. Evolutionary biologists should take more account of the role played by the sensory systems and brains of receivers in constraining the design of animal signals. Neurobiologists should be more aware of recent advances in the understanding of signal-receiver co-evolution and the evolutionary origins of animal signals. A series of recent examples are cited that illustrate how pre-existing neurophysiological or psychological properties of receiver organisms are essential to our understanding of the design characteristics of animal signals and of their origins. Also discussed are a number of other areas of signalling in which the study of 'receiver psychology' is likely to be fruitful.

Are there general principles of signal design?

Explanations of signal design must meet three requirements: they must be logically coherent, they must explain the diversity in size of animal signals and they must explain the diversity in form of signals. Three selection pressures operating on animal signals are discussed: the degree of conflict or cooperation, the 'efficacy' of signals and how signalling costs are paid. A distinction is made between cases where costs of signalling are paid in the production of the signal and cases where costs are paid as a consequence of giving a signal on the grounds that differences in signal design result. This is illustrated by reference to the example of warning coloration. It is concluded that general principles still elude us because of the numbers of different selection pressures that operate on the design of animal signals.

Colour and pattern in relation to sexual and aggressive behaviour in the bluehead wrasse Thalassoma bifasciatum.

Terminal phase adult male bluehead wrasse show rapid and frequent changes of body colour from bright green to opalescent. Green body colour is associated with aggressive chases of other fish, opalescent with courting females and spawning and so the body colour gives an indication of the fish's 'intention' over the next few seconds. Pectoral fin spots appear during courtship and a hypothesis is suggested for their function.

Slides of conspecifics as representatives of real animals in laying hens (Gallus domesticus).

Four 18-week-old Ross Brown laying hens were trained to discriminate between slides of the heads of familiar or unfamiliar conspecifics. Those individuals trained to discriminate between slides of familiar conspecifics failed to show a better discrimination ability when presented with slides of novel views of these object birds, as compared with subjects trained to discriminate between slides of unfamiliar conspecifics and presented with similar corresponding novel views. There was also no evidence that subjects learnt to discriminate slides of familiar conspecifics more quickly than slides of unfamiliar conspecifics. It was concluded that there was no evidence that the hens perceived the slides presented as representations of their group members.

Cage height preference and use in battery-kept hens.

Caged hens are shown to have a strong preference for cages which have a large vertical space allowance. When filmed in cages of unrestricted head room, nearly 25 per cent of hens' head movements occurred above 40 cm, which is the proposed CEC recommendation.

Cage size and flooring preferences in litter-reared and cage-reared hens.

Pullets (Ross Rangers) reared commercially either in cages or on deep litter were tested for their responses to small (0.38 X 0.43 m) and large (0.76 X 0.86 m) cages with wire floors and to small and large cages with litter floors. When tested at 29 weeks of age, the birds' responses were significantly affected both by cage size (large preferred to small) and by flooring (litter preferred to wire). No difference in cage preference was apparent between cage-reared and litter-reared birds either when they were first tested at 17 weeks or when they were re-tested at 29 weeks. Birds do not have to be reared on litter in order to be attracted by it.