With the increase in egg production rate and the coming of peak laying period, some metabolic disorders usually emerge in layers. The current study was conducted to compare the physiological difference between the early laying stage (around 30% laying rate) and peak laying stage (more than 95% laying rate) of laying hens based on hepatic transcriptome, serum metabolomics and caecal microbiota. The results showed that the egg weight and yolk weight were significantly higher in peak laying hens. Further, serum malondialdehyde and total bile acid concentrations were higher, but total anti-oxidant capacity, total bilirubin and low-density lipoprotein cholesterol (LDL-c) concentrations were significantly lower in peak laying hens. Hepatic transcriptome analysis identified 540 up-regulated and 269 down-regulated genes. Consistently, fatty acid biosynthesis, PPAR and insulin signalling pathways were significantly enriched. Subsequently, the result of serum metabolomics identified 74 up- and 77 down-regulated metabolites. Among down-regulated metabolites, hesperetin, apigenin and betaine related to anti-oxidant function were down-regulated. In addition, western blotting result showed BCL2 and p53 proteins expressions were decreased in the peak laying period, whereas hepatic CEBPα protein level was increased. On the other hand, gut microbiota analysis revealed that Chao index was decreased in peak laying hens. And the LEfSe analysis showed the dominant microflora including Ruminococcus, Oxalobacter, Paracoccus and so on was found in peak laying hens. These findings indicated that the hepatic lipid metabolism of peak laying hens is enhanced and the decline in anti-oxidant performance of hens also implies its importance during the early stage of egg production.

From the year 2012, conventional battery cages for laying hens will be banned under the European Union Council Directive 1999/74/EC. Enriched cages, which include a perch, a nest area, and a pecking and scratching area will not be banned, and have certain advantages over other systems of egg production. Previous studies have shown that even when a pecking and scratching area is provided, most dustbathing occurs on the wire floor as sham dustbathing. This study investigated whether novel cage floor types could stimulate full expression of dustbathing behaviour, similar to that seen on loose litter. One hundred and forty four hens were housed in pairs in non-commercial enriched cages that differed only in that they contained one of four randomly allocated floor types. Floor types were conventional wire ('wire'), wood shavings ('litter'), conventional wire wrapped with garden twine ('string') and perforated rubber matting ('rubber'). Birds on litter or rubber performed fewer bouts of dustbathing than those on wire and string. However, bouts on litter were longer than those on the three other floor types. Overall, birds on litter or string showed a greater total duration of dustbathing than those on rubber, and birds on litter had a richer repertoire of dustbathing elements. Birds on litter performed significantly more pecking and scratching than those on string or rubber, which did not differ from those on wire. Birds on rubber and litter had poorer foot and feather condition than those on wire or string. Altering the cage floor produced minor changes in behaviour, and further novel floor types should be evaluated.

From 2012 onwards, all laying hens in Europe will need to be housed either in furnished cages or non-cage systems (aviaries or floor-housing systems). In terms of animal welfare, furnished cages and non-cage systems both have advantages and disadvantages. Data on direct comparisons between the two, however, are limited. The aim of this study was to carry out an on-farm comparison of laying hens’ welfare in furnished cages and non-cage systems. To meet this aim, six flocks of laying hens in furnished cages and seven flocks in non-cage systems (all without an outdoor run) were visited when hens were around 60 weeks of age and a number of measures were collected: behavioural observations, fearfulness, plumage and body condition, incidence of bone breaks, bone strength, TGI-score (or Animal Needs Index), dust levels and mortality. In non-cage systems, birds were found to be more active and made greater use of resources (scratching area, perches) than in furnished cages. These birds also had stronger bones and were less fearful than birds in furnished cages. On the other hand, birds in furnished cages had lower mortality rates, lower incidence of bone fractures and lower airborne dust concentrations. When all the welfare indicators were integrated into an overall welfare score, there were no significant differences between systems. These results indicate that furnished cages and non-cage systems have both strong and weak points in terms of their impact on animal welfare.

Research into the responses of hens on perches is important in order to assess the welfare impact of alternative systems for egg production which incorporate perches in their design. Previous studies suggest that many flight and landing accidents occur in such systems as birds attempt to move between perches and facilities, resulting in a high incidence of bone breakage. In this study three horizontal perches were set with a gradient between them of 0, 30, 45 or 60 degrees according to treatment. Four groups of 15 ISABrown laying hens were individually exposed to each treatment, being placed on the uppermost perch (Perch 1) with a food reward available at the lowest perch (Perch 3). Behaviours performed before reaching Perch 3 were recorded over time. More birds failed to move to Perch 3 in 10 minutes when perches were separated by 45 or 60 degrees. In birds which stayed on the perches for the full 10 minutes, without reaching Perch 3, downward head movements, calling, intended jump behaviours, side-stepping and wing-flapping decreased significantly with time spent on the perches. Motivation to complete the task, in order to gain the food reward, was high in all treatments. However, when birds found perches difficult to negotiate, behaviours indicating intention to move to the food decreased with time and the incidence of behaviours indicating frustration and thwarting increased. In non-cage systems such frustration could reduce bird welfare.

It is extremely difficult to carry out an assessment of welfare in an entirely objective manner. The choice of welfare indicators, as well as the assignment of relative weightings to these indicators, both involve a certain degree of subjectivity. The aim of this study was to create a possible method of dealing with this subjectivity, using the opinions of groups of experts to increase the consensus for a protocol for the on-farm assessment of laying-hen welfare. The selection of the 17 separate welfare indicators was based both on a questionnaire submitted to 18 international poultry welfare experts and on the practical feasibility of collecting the respective data during a one-day farm visit. Subsequently, a second group of 13 experts was asked to assign relative weightings to the welfare indicators in this protocol. This assessment was carried out twice, once with and once without provision of detailed information on the welfare indicators. When detailed information was provided, the weightings assigned to the welfare indicators were generally lower than when no detailed information was provided. In conclusion, subjectivity regarding the choice of welfare indicators and the assignment of their relative weightings, can be dealt with and made transparent by seeking consensus among experts. Although the choice of experts, the methodology for extracting consensus data, and the nature and amount of information on the welfare indicators that should be provided, are likely to benefit from further refinement, the data presented in this study should be valuable for the development and application of formalised protocols for an integrated assessment of the welfare of laying hens, on-farm.

Non-cage systems for housing laying hens often incorporate a framework of perches, allowing birds to move in three dimensions. Wood is predominantly used for perch construction, because it is relatively cheap and easy to work with. However, wooden perches are difficult to clean and disinfect, which could lead to disease and discomfort for the birds using them. The objectives of this study were to identify which characteristics of perch design are preferred by laying hens; and to test whether birds would use perches of alternative materials for a comparable amount of time as they use wooden perches. Six laying hens were housed individually in litter-floored pens and were offered a choice of three pairs of contrasting perch types (experiments 1-3): a rectangular, wooden perch (‘control’) versus two, thin, parallel, rectangular wooden perches; ‘control’ versus a similar perch covered with foam and fabric; and ‘control’ versus a round, wooden perch. Birds were given each pair of perches twice, controlling for perch position in the pen. Time spent on each perch in a 48h period was determined from video records. Preferences were then tested in consecutive trials (experiments 4-5) between perches of the following materials: wood versus plastic versus steel; and wood versus textured aluminium. There were no significant differences in time spent on different perches, suggesting that birds had no preferences between perch types. The implications of these results could be important for the design of alternative systems for laying hens. Birds may be content to perch on artificial materials which could be more hygienic than wood and easier to maintain in a commercial system.

Conventional cages for laying hens have many disadvantages for welfare and there have been widespread calls for them to be banned. However, they also have advantages: in particular, they house the birds in small groups. Modified designs intended to reduce the disadvantages while retaining the advantages have included the get-away cage (providing perches and other facilities for up to 60 birds), but these designs have not yet had much success. The Edinburgh project on modified cages has adopted a stage-by-stage, systematic approach to cage design. Recommendations include increased area and height compared to conventional cages, and inclusion of a perch, a nest box and a dust bath. Current trials combine all these features in designs with commercial potential One remaining welfare problem is restriction of locomotion, with associated effects on bone strength However, alternative, non-cage husbandry systems for laying hens also have welfare problems, including those associated with large group sizes, and these problems may be worse than those in modified cages. Probably most important is the risk of cannibalism - or the practice of beak trimming to prevent it. Rather than banning cages, it might be more appropriate for legislation to specify the facilities which should be provided for laying hens.

In the current state of development of alternative systems, modifying cages for laying hens could on balance be more beneficial to welfare than banning them.

The aim of this study was to investigate whether there were differences in fearfulness between laying hens (Gallus gallus domesticus) housed in aviaries and in cages. The tonic immobility (TI) test was used to assess the fearfulness. Norwegian light hybrid White Leghorn hens were housed in battery cages and in three types of aviaries: the Marielund, the Laco-Volétage and the Tiered Wire Floor. Each system housed about 1,500 birds. Tests were performed on 50 birds per housing system at 70 weeks of age in one laying flock and at 30 and 70 weeks of age in the next.

At 30 weeks of age in the second laying flock, the duration of the tonic immobility response was unaffected by type of system. At 70 weeks, however, hens in cages showed tonic immobility of longer duration than hens in aviaries, in the first as well as in the second laying flock No differences in TI between hens from the three types of aviaries were found. The duration of TI did not correlate with plumage condition or body-weight, except for a longer duration of TI with poorer plumage condition in aviaries at 30 weeks. These results indicate that the fearfulness of hens in cages, as measured by the TI test, increased considerably with time. The lower fearfulness shown by hens in aviaries suggests that this important aspect of welfare is more secured in aviaries than in cages.

The welfare of caged laying hens could be improved by placing objects in the feed trough. Such objects might (a) simulate general ground-litter thus promoting more normal foraging activity and (b) give hens the opportunity to work ‘for feed - a behaviour usually thwarted in conventional cages. Spherical objects with various characteristics were placed in the feed trough of a tier of caged laying hens (n = 16). The hens pecked frequently at the objects, moving them to the trough space of adjacent cages. The mean proportion of hen heads over the trough containing these objects was significantly greater than before the objects were present (35.3 cf 32.9%) and significantly greater than the proportion of heads over a similar trough containing no objects (33.6%). Thirty days later, the mean proportions were still significantly different (33.5 cf 31.0%) showing that there was little habituation. Daily manual scattering of the objects increased the distance they were subsequently moved by the hens (23.0 cf 19.3 cm/day) indicating increased pecking activity. In a second study 12 hens were given a choice of feeding from troughs containing 0, 12 or 36 spherical objects. There was no overall preference to feed from any of the troughs. All the hens fed from troughs containing the objects, possibly indicating that the opportunity to move the objects and forage or work for feed was desired on occasions. Brightly coloured spherical objects are considered to be a promising method of successful environmental enrichment for caged laying hens. Their use to improve the welfare of caged laying hens appears to be practical and reasonably inexpensive.

A Delphi technique was used to gather the opinions of animal welfare experts on the most appropriate measures for welfare assessment of farm animals. The experts were asked to consider measures that were directed towards the animal (animal-based), rather than measurement of their environment. This systematic approach was designed to achieve a degree of consensus of opinion between a large number of experts. Two rounds of postal questionnaires were targeted at people with expertise in one or more of the species of interest. The respondents suggested measures based upon observations of health status, behaviour, and examination of records. These measures reflect the animal's welfare state — in other words, how the animal is coping within the environment and husbandry system in which it lives. The measures for cattle, pigs and laying hens were categorised into 22, 23 and 28 aspects, respectively, with the highest ranking of importance being given to observation of lameness in dairy cattle and pigs and to observation of feather condition in laying hens. This Delphi study was the basis for the development of a series of protocols to assess the welfare state of dairy cattle, pigs and laying hens.

To evaluate agreement between flock-based fear tests used in welfare assessments of laying hens in commercial organic farms, three tests were applied in 27 flocks of layers. Tests were performed at 35 and 55 weeks of age and were based on the concepts of ‘novel object’, ‘sudden sound’ and two different measures of ‘approaching human’. In general, agreements between tests were poor. The two measures based on ‘approaching human’ had the highest agreement, while the agreement between all other flock-based tests were lower. There was low agreement between testing at age 35 and 55 weeks.

In order to evaluate the degree to which the flock-based fear tests reflect individual hens' underlying fearfulness; tonic immobility (TI) tests were also applied on individual hens in eight flocks. There was large individual variation in the duration of tonic immobility, but also significant difference between flocks regarding mean duration of immobilisation. However there was no statistically significant association between TI-tests and flock-based tests. These results emphasise the need for careful consideration of choice of test stimuli for flock-based fear tests, and indicate that the investigated flock-based fear tests do not reflect the individual hens' underlying fearfulness.

Twelve Isa Brown hens (Gallus gallus domesticus) were trained to open a locked door for access to a pen containing an enclosed nest box (‘nest test’) and to return to a home pen containing food, water, litter and a perch (‘home test’). The door was connected to a computer-controlled load cell, which recorded work exerted on the door and unlocked the door when the hen had exceeded a predetermined workload. Following training, the workload was set at 10 Ns, and hens received one nest test per day at 80, 60, 40 or 20 min prior to oviposition, and then one home test per day after 1, 2, 3 or 4 h confinement in the nest pen. As oviposition approached, hens showed a higher work-rate for access to the nest pen, showed a shorter latency to use the nest box and spent a greater proportion of their visit time in the nest box. Hens also worked harder for the home pen, showed a lower latency to feed and spent more time feeding after their return as period of confinement increased. The hens’ work-rate for the nest pen at 40 min prior to oviposition was comparable with their work-rate for the home pen after 4 h confinement, while their work-rate was at its highest in nest tests at 20 min prior to oviposition. The technique appears to be a valid means of assessing the importance of environmental resources, the values of which vary with time. The results suggest that hens place a higher value on gaining access to a discrete nest-site prior to oviposition than they do on gaining access to food following 4 h food deprivation.

When thwarted in a behaviour, laying hens show an increase in stereotyped pacing, displacement preening and a specific vocalisation known as the ‘gakel-call’. How these behaviours, which might serve as indicators of welfare, are influenced by social factors is not yet known. In this study, we investigated the effect of an audience (another bird or a human) on the expression of the gakel-call and other behaviours indicating frustration. Twenty-four Lohman Brown hens were trained to gain free access to food in a test cage. Sixteen hens were used as test birds and eight as non-test audience birds. The food-deprived test hens were tested for 15 min in a non-thwarting situation (food freely available) and for 15 min in a thwarting situation (food covered but visible). For both situations we investigated four different treatments: no audience in the adjacent cage; a non-thwarted audience bird in the adjacent cage; a thwarted audience bird in the adjacent cage; and finally a human audience. The durations of stereotyped pacing and displacement preening were significantly higher in test birds during thwarting than during non-thwarting; thwarted birds also gave significantly more gakel-calls compared to non-thwarted birds. The test birds, and also the audience birds, gave more gakel-calls when thwarted in the presence of a thwarted conspecific than when in the presence of a non-thwarted bird, but there were no significant differences in stereotyped pacing or displacement preening, which are usually associated with frustration. In conclusion, this study supports the view that the gakel-call signals frustration in laying hens. Furthermore, the state of the audience influences the occurrence of gakel-calls in thwarted hens. Thus, when using the gakel-call as a welfare-indicator, the social aspects of the vocal expression of frustration in laying hens should not be overlooked.

Recently, several farm assurance schemes in the United Kingdom have been adopting innovative approaches, such as welfare outcome assessment, into their routine procedures. In this paper, we present the findings of four consultation exercises, undertaken as part of a review process that examined farmer perspectives on planned or implemented changes to their current certification visits as members of UK-based dairy and laying hen schemes. The changes included the introduction of welfare outcome assessment by assessors, joint-scoring of welfare-outcome measures by farmers and assessors and self-assessment of welfare outcome measures by farmers between assessor visits. This study also explores the challenges that arise when schemes are aiming to adopt a scheme-level continuous improvement approach to promote welfare improvement on participating farms. The key challenges fall under three themes: the purpose and value for the farmer of the assessment of welfare outcomes as part of a farm assurance assessment process; the potential conflict rather than concordance with the role of the farmer in caring for their animals; and finally the technicalities of the assessment process, such as sample sizes for assessment being calibrated for gauging welfare prevalence at a scheme rather than farm level and the role of the farm assurance assessors both to assess impartially compliance against the standards and to provide welfare advice to support improvement. This study highlights that the involvement of farmers at all stages in the development and in the evaluation of outcome assessment initiatives is likely to be beneficial for welfare improvement on-farm.

Throughout the world, male chicks from layer breeds are killed just after hatching, as they are not profitable as regards the production of meat. The Dutch and European parliaments have insisted on research into possible alternatives to the killing of day-old chicks. In the present study we have investigated Dutch public opinion on the acceptability of these alternatives by means of discussions in so-called focus groups and via a public survey through computer-aided personal interviews (CAPI). To inform the participants about the subject, a film was made to explain the current practice and introduce a number of technological alternatives that would prevent development of male embryos, as well as the possibility of creating a ‘dual-purpose chicken’ that would allow male chicks to be used for meat production. The topics addressed in the study included the willingness of participants to pay a premium for eggs and chicken meat, were it necessary to prevent killing of male chicks. Focus-group discussions showed that many participants were unaware of the current practice of killing male chicks, and were shocked by this practice. However, once informed, the participants seemed able to take various considerations into account and rank the alternatives. The alternatives ‘looking into the fresh egg (to determine sex of the egg and not incubate male eggs)’, and ‘dual-purpose chickens’ scored best out of all the possible alternatives, and higher than maintaining the current practice. ‘Influencing the laying hens such that they produce fewer male eggs’ scored the same as maintaining the current practice. The use of ‘genetic modification to facilitate looking into the fresh egg’ scored only slightly lower than maintaining the current practice. Alternatives whereby developing male embryos die, or are killed, scored lower than maintaining the current practice.

Research synthesis, using techniques such as meta-analysis to combine the results of a number of studies, is a particularly useful technique when there are multiple studies with conflicting results, or where there may be conflicting interests, and can serve to extract the maximum information from animal experiments. The effect of conventional cages and alternative housing systems on measures of production, behaviour, physical and physiological condition in laying hens is an important question that would benefit from research synthesis. We found that statistical constraints did not allow the usual methods of meta-analysis, so as a first step towards quantitative comparison, we used a simple vote-counting approach based on the treatment means. We counted the number of papers in which conventional cages or alternative systems had a higher weighted mean for various response variables. Egg production was higher in conventional cages than in alternative systems, though this effect was probably mostly confined to the comparison with multi-level indoor systems. Bones were stronger from hens kept in alternative systems than those kept in conventional cages. We confirmed previous reviews that birds show more comfort behaviour and possibly dustbathing (or vacuum dustbathing) behaviour in alternative systems, but aggressive pecking did not differ between systems. Perhaps surprisingly, mortality, feather pecking and body wounds were not found to differ between systems. The latter findings suggest that the chance of a mortality or cannibalism outbreak may be no greater in alternative systems than in cage systems, but it should be noted that our analysis did not consider the magnitude of the difference in mortality. In conclusion, the meta-comparison undertaken here supports some but contradicts other conclusions reached in qualitative reviews.

Farmers’ recognition of health and welfare problems, and their responses to related intervention programmes, such as those to reduce injurious pecking in hens, directly influence the welfare of animals in their care. Changing those responses can be achieved through a re-positioning of social drivers as well as from individual behaviour. This study begins by considering how certain levels of plumage damage become normalised while others might be considered unacceptable. Drawing upon in-depth farmer interviews, the study investigates how management practices for addressing the issue of injurious pecking are developed and enacted, looking at the relative influence of intrinsic and extrinsic individual behavioural factors. Twelve farmers with varied uptake of evidence-based management strategies designed to reduce levels of injurious pecking were interviewed. Although farmers ranked images of flocks with various levels of plumage damage in a similar order to scientists, their perception of levels of injurious pecking in their own flocks varied, and was not consistently associated with the actual levels measured. Most farmers recognised both financial and welfare implications of injurious pecking and expressed pride in having a good-looking flock. The popular management strategies were those designed to redirect pecking to other objects, whereas a substantial barrier to uptake was the perception of creating other problems: for example, mislaid eggs if early access to litter and range were adopted. To achieve uptake of knowledge that improves animal welfare on-farm, it may be necessary both to shift the norms perceived as acceptable, and to overcome barriers to change that include lack of time and understanding, by providing impartial advice and facilitation of ownership of the issues.

Injurious feather pecking in non-cage systems is a serious economic and welfare concern for the egg-producing industry. Here, we describe the first results from an ongoing collaborative project to improve range environment and welfare of laying hens (Gallus gallus domesticus) within the McDonald's Restaurants Ltd, UK supply base. The objective of this study was to investigate, in a commercial situation, the correlation between: i) proportion of range cover and ii) proportion of canopy cover, with plumage damage of end-of-lay hens. The assessment of plumage damage due to injurious feather pecking is a key animal-based welfare indicator for laying hens in non-cage systems. In 2007 and 2008, all laying-hen producers within the McDonald's Restaurants Ltd egg-supply base, were required to plant (if not present already), 5% of the total range area with blocks of trees ether side, and between 20-25 m from the laying hen house. Plumage damage at end of lay was positively correlated with mortality and flocks depleted in summer had less plumage damage at end of lay than flocks depleted in autumn or winter, possibly because of weather conditions at the time of placement. There was no correlation between the proportion (5-90%) of range cover and plumage damage at the end of lay, however, plumage damage was negatively correlated with percent of canopy cover within tree-planted areas. Providing a minimum of 5% tree cover, planted close to the house but with good canopy coverage, may be a feasible and practical method enabling producers to reduce plumage damage due to injurious feather pecking in their laying-hen flocks. Tree cover provision may also provide environmental benefits, such as soil stabilisation, reduced nutrient leaching and carbon sequestration.

The aim of this study was to investigate the effect of group size and stocking density on the welfare and performance of hens housed in furnished cage systems during summer. A total of 924 Hy-Line Brown hens were assigned to three housing systems: a standard battery cage system (control, 4 hens per cage and 398 cm2 per hen), two furnished systems (including perches and nest); one with a small (SFC, 21 hens per cage; 586 cm2 per hen) and one with a large group size (LFC, 48 hens per cage; 543 cm2 per hen). The results showed that hens housed in SFC and LFC had a higher feed intake and a poorer feed efficiency compared to control hens. Laying rate and egg weight were not significantly affected by housing systems. Hens housed in LFC and SFC systems showed less sitting and more walking behaviours than control hens. SFC hens showed more nesting and less perching behaviours than LFC hens. Hens kept in SFC systems showed fewer signs of heat stress during summer, with less panting activity than LFC or control hens, and a relatively lower rectal temperature than controls. The rectal temperature of LFC hens did not differ from the SFC hens and controls. Blood concentrations of luteinising hormone, follicle-stimulating hormone and oestradiol were not significantly influenced. In conclusion, group size and stocking density in furnished cages have an effect on behaviour and performance of hens. The furnished cage systems with small group sizes were favourable for hen welfare without markedly affecting performance. Group size should be considered in the development of furnished cage systems.

The aim of the present study was to investigate the effects of selection on low mortality in combination with brooding by a mother hen on open-field response at 5-6 weeks of age and on plumage and body condition at 42 weeks of age. Birds in the experiment were either selected for low mortality in group housing (low mortality line) or randomly selected (control line) for two generations. These lines originated from the same population. Twenty groups of 10 female birds from each line were used. Within each line, ten groups were brooded by a foster mother and ten groups were non-brooded. At 5-6 weeks of age, the chicks were tested in an open-field test for five minutes. At 42 weeks of age, plumage condition and incidence of comb lesions and toe wounds of all birds was recorded. It was found that both brooded chicks and chicks from the low mortality line were more active in the open-field test at 5-6 weeks of age, indicating that they were less fearful or had a stronger exploratory motivation. No interactions were found between selection on low mortality and brooding. Birds from the low mortality line also had a lower incidence of comb and toe wounds compared with the control line at 42 weeks of age. No effect of brooding on plumage condition or incidence of wounds was found. This study indicates that selection on low mortality is a promising way forward to reduce maladaptive behaviour in laying hens, especially if such an approach is combined with improved rearing conditions.