Traditional battery cages for laying hens will soon be banned in the EU but the increased risk of feather pecking (FP) hampers the adoption of alternative housing systems. FP can cause injury and lead to cannibalism and the painful death of target birds. Current management practices (beak trimming, low light) have associated problems. In a joint European project we sought alternative solutions. In our study of associated traits, birds from a line showing low (LFP) rather than high feather pecking (HFP) exhibited greater sociality (motivation to be near companions) and a passive ‘coping’ style. High sociality and passivity were also negatively associated with FP in adults. These findings may guide future breeding programs. Trimming hens’ feathers to mimic the results of FP elicited pecking and some cannibalism, even by birds that had previously shown no FP. Social transmission of gentle but not severe FP occurred when LFP and HFP birds were housed together. Gentle pecking could conceivably lead to severe FP. We then examined chickens’ pecking preferences to guide environmental enrichment strategies. Bunches of string elicited substantially greater interest than other stimuli, including feathers, and white or yellow string was the most attractive. The birds’ manipulation of the string resembled preening. Incorporating silver beads or moving the devices reduced pecking. String sustained lengthy interest, reduced FP in HFP birds, and decreased feather damage in caged layers on a commercial farm. String offers effective, affordable and practicable environmental enrichment. The integrated application of appropriate environmental and genetic strategies is likely to attenuate the expression of FP and its harmful consequences.

Frequent diet change has been identified as a risk factor for feather pecking in commercial flocks but the mechanism underlying this association is not known. In this experiment we simulated a commercial change of diet between high quality (HQ) 19% protein, and low quality (LQ) 15% protein, diets. Twelve pairs of birds were fed both diets simultaneously for 38 days to determine whether clear preferences for the diets existed. A further 12 triplets of birds were fed either HQ or LQ diets for 38 days to examine any absolute effects of quality on behaviour. The remaining triplets received, on day 29, either a LQ to HQ diet change (n = 12 groups) or an HQ to LQ diet change (n = 12 groups). Half of the groups in these diet change treatments received oregano oil as a potential ‘masking’ agent to disguise the diet change. No dietary preferences were detected and there were no absolute effects of diet on behaviour. Diet change provoked significant increases in beak-related activity. Specifically, affiliative pecking (allopreening directed towards comb or beak) was increased after diet change. Masking the diet reduced the effects of diet change. Injurious pecking remained at low levels throughout the experiment and was not affected by diet change, but the relationship between affiliative pecking and subsequent injurious pecking requires further investigation.

Although genetic selection for certain characteristics has compromised the well-being of domestic animals, selective breeding could and probably should be used to improve welfare. Three of the major behavioural problems facing the poultry industry are fear, feather pecking and social stress. However, these and many other behavioural traits respond readily to genetic selection. The present paper reports the results of selective breeding studies in which underlying fearfulness, sociality, feather pecking, adrenocortical responsiveness, and growth rate were manipulated in Japanese quail, Coturnix japonica, or in chickens, Gallus gallus domesticus. The apparent benefits of selection for appropriate levels of these characteristics are discussed, as are the ethical issues involved. The ultimate aims of the selection programmes and the studies described here are to improve the birds ‘ welfare and productivity by increasing their ability to interact successfully with their physical environment, with one another, and with human beings.

Standard techniques for assessing plumage damage to hens from feather pecking typically require capture and handling. Handling of individual birds for plumage assessment is relatively easy in experimental studies; however, close inspection of individual birds in commercial flocks is less feasible because catching birds is difficult, may compromise bird welfare and affect egg production. The aim of this study was to assess a non-intrusive method for scoring plumage damage in a commercial free-ranging flock of laying hens. Plumage damage was scored within a 2 m distance of the birds, without capture or handling, using a 5-point scale for 5 body regions. The feather scores, recorded at a distance, by two independent scorers were compared (distance scores), and were then compared with feather scores recorded by a scorer who caught and handled the birds to examine the plumage damage closely (capture scores). There was a significant and positive correlation between the distance scores and the capture scores, and the mean correlation coefficient for all plumage score traits was 0.89. There was also a significant and positive correlation between scorers, and the mean correlation coefficient for all plumage score traits was 0.84. The standard deviation of the residual mean difference between scorers and between methods was less than 1 point for individual body regions and less than 1.5 points for the total body score. Large variation in feather damage within a flock and small sample size increased the standard error of the mean total feather score. When feather damage variation within flocks is low (ie little observed feather damage), the current industry standard of scoring a sample of 100 birds is likely to provide a reliable estimate of flock feather damage; however, when there is large variation within birds of a flock (ie considerable observed feather damage) ≥200 birds should be inspected to accurately monitor changes in plumage condition. The non-intrusive method of feather scoring described in this paper may be useful for commercial-scale feather pecking studies or for farmers who need to assess the plumage damage of their flocks reliably, quickly and with minimal disturbance or stress to the birds.

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.

Severe feather pecking, a potentially stereotypic behaviour in chickens (Gallus gallus), can be reduced by providing enrichment. However, there is little comparative information available on the effectiveness of different types of enrichment. Providing forages to birds is likely to decrease feather-pecking behaviour the most, as it is generally thought that feather pecking stems from re-directed foraging motivation. Yet, other types of enrichment, such as dustbaths and novel objects, have also been shown to reduce feather pecking. In order to develop a practical and effective enrichment, these different possibilities must be examined. Using a Latin Square Design, 14-week old birds were given each of four treatments: i) forages; ii) novel objects; iii) dustbaths; or iv) no enrichment. The amount of feather-pecking behaviour and the number of pecks to the enrichments were recorded. Results showed feather pecking to be highest when no enrichment was present and lowest when the forages were present, with the other two enrichments intermediate. This was despite the fact that the numbers of pecks birds gave to the forages and dustbaths were not significantly different, suggesting that they were similarly used. Thus, we suggest here that forage enrichments are most effective at alleviating feather pecking at least in the short term and attempts should be made to develop poultry housing that allows for natural foraging behaviour. Following this, providing any kind of enrichment will increase bird welfare and is therefore still beneficial.

In The Netherlands, laying hen chicks are often reared without litter on the raised slatted area of a barn system or confined in the aviary system during the first two to five weeks after hatching, with chick paper or chicken wire on the floor. In the absence of a suitable pecking substrate, chicks may redirect their pecking behaviour to other birds, which possibly increases the risk of developing feather-pecking behaviour. The aim of this study was to determine whether housing on wood-shavings (WS treatment; n = 15 groups) as compared to housing on chicken wire (CW treatment; n = 15 groups) between day 1-20 could reduce feather pecking in adult birds. After day 20, all chickens were allowed wood-shavings as litter. Behavioural observations showed that CW chicks performed significantly less ground-pecking behaviour compared with WS chicks up to day 20. More CW chicks showed gentle feather pecking at day 7 and 14 as compared to WS chicks, and more CW chicks pecked at the feeder or drinker than WS chicks up to day 20. CW chicks showed rebound behaviour: the day after they were introduced to wood-shavings they displayed more ground-pecking behaviour compared to the WS chicks. Later on in the rearing period no noticeable differences between treatments were found in frequency of gentle and severe feather-pecking bouts. During laying, more gentle feather-pecking bouts were observed in CW than in WS groups but no differences in severe feather-pecking bouts were observed, nor in feather damage at the end of the trial. The results indicate that hens can display substantial flexibility in their pecking behaviour and that, despite more gentle feather pecking in CW hens in laying, the absence of substrate in early rearing does not increase the risk of developing severe feather-pecking behaviour when adult.

Feather pecking is a serious economic and welfare problem in laying hens. Feather damage occurs mainly through severe feather pecking (SFP). Selection experiments have proved that this behavior is heritable and lines have been divergently selected for high (HFP) and low feather pecking (LFP). The number of bouts of SFP per hen follows a Poisson distribution with a maximum nearby 0. A few studies indicate that the distribution within flocks is not homogenous but contains sub-groups of birds showing extremely high levels of feather pecking (EFP). It was the aim of the current study to re-analyze data on SFP of lines selected for HFP/LFP and their F2 cross so as to uncover hidden sub-populations of EFP birds. Data of seven selection generations of HFP and LFP selection lines as well as their F2 cross have been used. We fitted a two-component mixture of Poisson distributions in order to separate the sub-group of EFP from the remaining birds. HFP and LFP lines differed mainly in mean bouts per bird. The proportion of EFP was only marginal in the LFP as compared with the HFP and the F2 population. Selection for LFP did not result in total elimination of EFP. The presence of even small proportions of EFP may play an important role in initiating outbreaks of feather pecking in large flocks. Further studies on feather pecking should pay special attention to the occurrence of EFP sub-groups.

Studies on the prevalence of feather pecking in different commercial laying hen systems and its welfare and economic impacts are reviewed in the following paper. Current methods for controlling feather pecking include beak-trimming and alterations to light regimes, but these methods have significant disadvantages from the perspective of bird welfare. A substantial body of research has now identified risk factors for feather pecking during both the rearing and laying periods. It is argued that these findings can be translated into optimised management practices that can prevent and control feather pecking whilst simultaneously conferring welfare benefits. The genetic basis of feather pecking is considered, and studies that suggest group selection techniques could produce birds with a reduced tendency to feather peck in commercial flocks are highlighted.

Injurious pecking is a serious concern for commercial turkey production and welfare. The behaviour is thought to represent re-directed ground foraging, but the development and causes are poorly understood with little supporting literature. In the initial development of the behaviour, early lighting regimes and social facilitation may play contributing roles. Other factors such as the availability of foraging material, diet composition, stocking densities, and group dynamics may also affect levels of injurious pecking. Given that commercial turkeys are group-housed, alternative breeding techniques, like group selection based on social effects, might successfully reduce moralities from pecking without detracting selection pressure from economic traits. However, to better suit their behavioural needs, any genetic attempts to adapt turkeys to perform less injurious pecking should be done in combination with environmental and dietary improvements.

Feather pecking (FP) in laying hens remains an important economic and welfare issue. This paper reviews the literature on causes of FP in laying hens. With the ban on conventional cages in the EU from 2012 and the expected future ban on beak trimming in many European countries, addressing this welfare issue has become more pressing than ever. The aim of this review paper is to provide a detailed overview of underlying principles of FP. FP is affected by many different factors and any approach to prevent or reduce FP in commercial flocks should acknowledge that fact and use a multifactorial approach to address this issue. Two forms of FP can be distinguished: gentle FP and severe FP. Severe FP causes the most welfare issues in commercial flocks. Severe FP is clearly related to feeding and foraging behaviour and its development seems to be enhanced in conditions where birds have difficulty in coping with environmental stressors. Stimulating feeding and foraging behaviour by providing high-fibre diets and suitable litter from an early age onwards, and controlling fear and stress levels through genetic selection, reducing maternal stress and improving the stockmanship skills of the farmer, together offer the best prospect for preventing or controlling FP.

Feather pecking is a major welfare problem in egg production. It may be caused by endogenous (genetic and physiological) and environmental (feeding, density and housing conditions) factors. Despite the number and variety of experiments performed over past years, it is still not possible to define a genetic background for this trait. A possible reason is the complex nature of feather pecking, but also the lack of a homogenous approach in the studies conducted. The present paper summarizes recent findings regarding genetic and physiological components of feather pecking. Furthermore, it emphasizes the need for complex study combining a selection experiment together with the power of molecular biology and bioinformatics.

Layer breeding companies apply selection criteria to improve over 30 traits important for commercial egg production. Intensive selection for egg production over the decades has resulted in a significant reduction in genetic and phenotypic variations in egg production, however the decrease in genetic variation observed in commercial lines are not yet critical. Peak production now approaches the biological limit of one egg a day, but in early production (at sexual maturity) and late production (persistency) genetic variation is still high. Including these traits in the selection criteria will improve the egg production in commercial birds. Due to high heritability and the absence of any significant negative effects on production parameters, residual feed consumption is used as selection criteria to improve the feed efficiency. Considerable research has been carried out on egg weight, eggshell strength and internal quality of the eggs and improvements have been made as a result of selection. With the reintroduction of floor system and increased consumer interest in processed eggs, in future more emphases have to be given to the eggshell strength and internal quality of the eggs. Poultry production in the unfavourable environmental conditions of the tropics is hindered by direct and indirect heat stress leading to a general depression in performance. Results on the utilisation of naked-neck and frizzle gene in high-ambient temperatures is encouraging, and, in future, will play an important role in production of layer lines suitable for overcoming such genotype-environment interaction. Feather pecking is an undesirable behaviour, which causes major problems in non-cage systems. Several authors have identified a hereditary basis of feather pecking behaviour, which is suggested by strain differences. Hence, selection of birds with no or very low tendency to perform feather pecking should reduce the incidence. Recent molecular genetic studies resulted in identification of QTL affecting different economic traits and identification of candidate genes causing variation in performance among birds. In future these findings will play a major role in further genetic improvement of layers without any negative effect.

Feather pecking in laying hens is an important issue in animal welfare. Four studies in laying hens were selected which investigated increased or reduced pecking behaviour using direct or indirect measures of feather pecking behaviour. Direct comparison of the selected experiments is difficult, as the selection criteria and even the selection procedures varied. Keeping these differences in mind, the results of the experiments showed that a) It is possible to change pecking behaviour in the desired direction using selection, b) Aggressive pecking is not related to feather pecking, c) There is no clear consensus as to the relation between selection on pecking behaviour and laying performance and egg quality, d) Plasma serotonin level in the blood was reduced in the lines selected against pecking behaviour in both the individual selected lines and the group selected lines and there were indications that dopamine also plays a role in the regulation of pecking behaviour, and finally e) There are differences between the selected lines and their control lines with regard to the immune parameters both in the individual selected lines as the group selected lines, indicating that direct as well as indirect selection for reduced pecking behaviour changes the immune response.

Feather pecking during rearing is difficult to identify and therefore often underestimated. However, as rearing conditions will affect the behaviour of adult hens, it is important or prevent feather pecking during rearing. This paper reviews the knowledge in the scientific literature on the effect of rearing conditions on injurious pecking. Factors such as stocking density and feeding strategies during rearing are known to influence feather pecking. Minimising the differences between the rearing and laying environment via a seamless transition is likely to make a flock less prone to injurious feather pecking. This can be achieved by providing perches and substrate for foraging and dust bathing during rearing, by providing facilities (e.g. litter trays) on perforated platforms during early lay and by focussing on early access to the range.

In the near future EU-legislation will ban the use of conventional battery cages, while national legislation in some countries in Western Europe will ban beak trimming as well. The ban on battery cages and beak trimming causes an increased risk of feather pecking and cannibalism in laying hens. Many factors influence feather pecking behaviour, but this paper focuses on nutritional factors. Nutritional factors can have positive and negative effects on feather pecking behaviour in laying hens. Severe feather pecking has been demonstrated in birds that were fed a too low mineral level in the diet, a too low protein level or a too low amino acid level (methionine, arginine). Sometimes somewhat more feather pecking was found when layers were fed diets with mainly vegetable protein sources as compared with diets with protein from animal origin. Also more feather pecking may occur when the diets were fed restrictedly, fed coarsely ground, or fed as pellets. Feeding high-fibre diets, low energy diets, or roughages reduced feather pecking. Providing additional grain or straw in the litter during rearing could result in lower levels of feather pecking behaviour in adult stages. Some of these positive effects on feather pecking seem to be related to the time birds spend on feed intake and foraging. This paper gives an overview of the relationships between the occurrence of feather pecking behaviour and nutritional factors, such as diet composition and feeding strategies in laying hens.

A review of QTL for production, behaviour and disease resistance traits published to the end of 2004 is presented. QTL were located randomly over the genome and there was little commonality between different studies for similar traits. However, there were several reports of QTL from different experiments in similar regions of chromosomes 1 (at 250 and 450 cM), 4 and 8 and for disease resistance on chromosome 5. Generally there were 6 to 8 QTL affecting the major production traits in experimental breed crosses and collectively they accounted for a substantial proportion of the line difference where this information was provided. The size of typical genome-wide significant effects for production traits was 0.3 to 1.0 phenotypic standard deviations. Genetic effects for growth traits were generally additive whereas about one-third of QTL for other production traits showed significant dominance effects. Variable reporting standards were noted and proposals for minimum published information are presented. Currently there are scientific opportunities for meta-analyses of results from experiments on body weight gain and considerable potential for combining data and results from different studies for other traits in the future.

Battery cages for laying birds were banned in Switzerland in 1981. Several new systems were developed in the years that followed, but to date only the deep litter and aviary systems have complied with both the regulations of the Swiss Animal Welfare Act and given satisfactory production results. The ways in which layer replacements are reared has been found to be crucial if they are to be able to cope optimally with the new aviary system. For this reason, the Federal Veterinary Office commissioned a survey to investigate how layer replacement pullets were reared in Switzerland. Sixty six out of a total of 155 farms that had facilities to rear 500 or more chicks at one time were visited between April and December 1997. Data were gathered on the type of housing system, management methods and the prevalence of feather pecking. The results of the survey are presented in a descriptive way and discussed in relation to the conditions during the laying period.