Effect of manipulating feathers of laying hens on the incidence of feather pecking and cannibalism

Feather pecking is a problem in commercial laying hens, particularly in loose-housing systems, where many hens can be affected by only a few feather peckers. In addition, feather pecking can become an even larger problem if it spreads throughout the flock. There are several possible ways that feather pecking may spread. The simplest way is that one hen may damage the feathers of a hen, and another hen may find the damaged feathers an attractive pecking target. The aim of this experiment was to determine if damaged feathers were feather-pecked more than undamaged feathers on the same body area, and to determine whether some types of feather-body area manipulations were preferred over others as pecking stimuli. Manipulations involved damaging the feathers on the rump, tail or belly of different hens, with two or three levels of severity of manipulation at each body area. Sixteen groups of 11 Lohmann Brown hens between 26 and 28 weeks were observed with the recipient, the feather pecker and the body area that was pecked all being recorded. The feather pecks were classified separately as either gentle or severe. Damaged feathers received significantly more severe feather pecks than undamaged feathers. There were also more gentle feather pecks to damaged feathers, although this did not reach statistical significance. The feather-body area manipulations that received the greatest number of severe feather pecks were the tail feathers when they were cut very short, the rump feathers when they were trimmed, and the rump when feathers were removed. These results support the suggestion that feather pecking does indeed spread through flocks by damaged feathers becoming an attractive target for feather-pecking behaviour. An unexpected result of performing the feather manipulations was an outbreak of cannibalism in half of the experimental groups. Even though there was no visible damage to the skin of the hens after having the feathers manipulated, 13 of the 16 attacked hens were wounded on the part of the body where the feathers had been damaged in some way.     

Feather eating in individually caged hens which differ in their propensity to feather peck

Two experiments examined the responses of 16 individually caged laying hens to the presentation of feathers plucked from dead birds of the same genetic line. In the first experiment, hens known from a previous experiment to be either feather 'peckers' or 'non-peckers' (8 of each) were tested for their propensity to eat feathers in four 10min trials, in which they were offered fresh semiplumes measuring 4-6cm (length), one at a time, in front of their cage. Wide variation between birds was observed in numbers of feathers eaten, pecked, picked-up and manipulated. Fourteen out of 16 birds readily ate presented feathers on one or more occasion and both birds that ate no feathers were non-peckers. Peckers ate, picked-up and manipulated feathers significantly more often than did non-peckers (P<0.05, P<0.01 and P<0.01, respectively). A second experiment investigated the possibility that presence of preen (uropygial) oil might contribute to the attractiveness of feathers to eat. The same group of 16 pecker and non-pecker hens were offered a choice between 20 washed and 20 unwashed semiplumes, presented simultaneously in separate containers, in two 10min trials. Unwashed feathers were eaten, pecked and picked-up in preference to washed feathers by both peckers and non-peckers (P<0.05, P<0.01, and P<0.01, respectively), indicating an attraction towards unwashed feathers, or an avoidance of washed feathers for some reason. Peckers and non-peckers did not differ significantly in their preferences. These results provide evidence of a relationship between feather eating and feather pecking at an individual level. The finding that hens could distinguish between normal feathers and those treated in such a way as to alter their olfactory (but not visual) properties suggests olfactory cues may be of importance in determining the attractiveness of conspecific feathers.     

Feather eating and its associations with plumage damage and feathers on the floor in commercial farms of laying hens

Feather eating has been associated with feather pecking, which continues to pose economic and welfare problems in egg production. Knowledge on feather eating is limited and studies of feather eating in commercial flocks of laying hens have not been performed previously. Therefore, the main objective was to investigate feather eating and its association with plumage damage and floor feather characteristics in commercial flocks of layers in barn and organic production systems. The study was performed in 13 flocks of barn layers and 17 flocks of organic layers. Each flock was visited at around 32 and 62 weeks of age. During both visits, the plumage condition was assessed and the density of floor feathers recorded. In week 62, droppings and floor feathers were collected. Droppings were examined for presence of feather content, whereas length, downiness and pecking damage were recorded for each floor feather. In week 62, a higher prevalence of hens with poor plumage condition was found in barn (22.2%) compared with organic production systems (7.4%; P<0.001), but the prevalence of droppings with feather content did not differ between the two production systems (8.5% in barn v. 4.3% in organic; P=0.99). Our hypothesis about a positive correlation between feather eating and plumage damage was not supported as no correlation was found between the prevalence of poor plumage condition and the prevalence of droppings with feather content. However, the prevalence of pecking damaged floor feathers was positively correlated both with prevalence of droppings with feather content (P<0.05) and poor plumage condition (P<0.01), indicating a possible association between feather eating and feather pecking. In conclusion, it was confirmed that feather eating occurs on-farm, but feather eating was only found to be positively correlated to the number of floor feathers with pecking damage and not as expected to the prevalence of plumage damage. More research is needed into the sources from where feathers are selected for ingestion, that is, whether they are picked from the floor litter, plucked directly from other hens or dislodged during preening of own feathers.     

Keratinization and lipogenesis in epidermal derivatives of the zebrafinch, Taeniopygia guttata castanotis (Aves, Passeriformes, Ploecidae) during embryonic development

Little is known of the lipid content of beta-keratin-producing cells such as those of feathers, scutate scales, and beak. The sequence of epidermal layers in some apteria and in interfollicular epidermis in the zebrafinch embryo (Taeniopygia guttata castanotis) was studied. Also, the production of beta-keratin in natal down feathers and beak was ultrastructurally analyzed in embryos from 3-4 to 17-18 days postdeposition, before hatching. Two layers of periderm initially cover the embryo, but there are eventually 6-8 over the epidermis of the beak. In the beak and sheath cells of feathers, peridermal granules are numerous at 12-14 days postdeposition but they are less frequent in apteria. These granules swell and disappear during sheath or peridermal degeneration at 15-17 days postdeposition. A thin beta-keratin layer forms under the periderm among feather germs of pterylous areas but is discontinuous or disappears in apteria. In differentiating cells of barbs, barbules, and calamus cells of natal down, electron-dense beta-keratin filaments form bundles oriented along the main axis of these cells. Cells of the pulp epidermis and collar, at the base of the follicle, contain lipids and bundles of alpha-keratin filaments. Degenerating pulp cells show vacuolization and nuclear pycnosis. During beta-keratin packing, keratin bundles turn electron-pale, perhaps due to the addition of lipids to produce the final, homogenous beta-keratin matrix. In contrast to the situation in feathers, in the cells of beak beta-keratin packets are irregularly oriented. In both feather and beak epidermal cells the Golgi apparatus and smooth endoplasmic reticulum produce vesicles containing lipid-like material which is also found among forming beta-keratin. The contribution of lipids or lipoprotein to the initial aggregation of beta-keratin molecules is discussed.     

The Evolution of Feathers*

Existing hypotheses on the evolution of feathers are reviewed with the assumptions that feather evolved from reptilian scales and that pennaceous feathers evolved before downy feathers. Observations with a scanning electron microscope demonstrate that basic to the structure of pennaceous feathers is the lamelliform structure of barbules, the planes of which are oriented at right angles to the plane of the feather vane. Thus the structure of the vane is more open than generally realized. The airtight vane of flight feathers is assumed a later specialization. Most of the existing hypotheses assume that the feather acts as a relatively solid barrier between the skin of the bird and the exterior and they are therefore not in agreement with the actual structure of feathers. A hypothesis is needed which explains the adaptive value of a pennaceous feather being porous. The hypothesis is put foward that feathers evolved due to selection for a water-repellent integument. For purely physical reasons a porous surface repels water drops more strongly than does a solid surface of the same material. Physicists have pointed out that the structure of feathers conforms closely with the theoretical requirements for water-repellency. Possibly feathers started to evolve on reptiles living at the seashore, where the main advantage of increased water-repellency was to reduce cooling from evaporation of water off a wet integument.     

Size scaling and stiffness of avian primary feathers: implications for the flight of Mesozoic birds

The primary feathers of birds are subject to cyclical forces in flight causing their shafts (rachises) to bend. The amount the feathers deflect during flight is dependent upon the flexural stiffness of the rachises. By quantifying scaling relationships between body mass and feather linear dimensions in a large data set of living birds, we show that both feather length and feather diameter scale much closer to predictions for geometric similarity than they do to elastic similarity. Scaling allometry also indicates that the primary feathers of larger birds are relatively shorter and their rachises relatively narrower, compared to those of smaller birds. Two-point bending tests indicated that larger birds have more flexible feathers than smaller species. Discriminant functional analyses (DFA) showed that body mass, primary feather length and rachis diameter can be used to differentiate between different magnitudes of feather bending stiffness, with primary feather length explaining 63% of variance in rachis stiffness. Adding fossil measurement data to our DFA showed that Archaeopteryx and Confuciusornis do not overlap with extant birds. This strongly suggests that the bending stiffness of their primary feathers was different to extant birds and provides further evidence for distinctive flight styles and likely limited flight ability in Archaeopteryx and Confuciusornis.     

Developmental integration of feather growth and pigmentation and its implications for the evolution of diet-derived coloration

Variation in avian coloration is produced by coordinated pigmentation of thousands of growing feathers that vary in shape and size. Although the functional consequences of avian coloration are frequently studied, little is known about its developmental basis, and, specifically, the rules that link feather growth to pigment uptake and synthesis. Here, we combine biochemical, modeling, and morphometric techniques to examine the developmental basis of feather pigmentation in house finches (Carpodacus mexicanus)--a species with extensive variation in both growth dynamics of ornamental feathers and their carotenoid pigmentation. We found that the rate of carotenoid uptake was constant across a wide range of feather sizes and shapes, and the relative pigmented area of feathers was independent of the total amount of deposited carotenoids. Analysis of the developmental linkage of feather growth and pigment uptake showed that the mechanisms behind partitioning the feather into pigmented and nonpigmented parts and the mechanisms regulating carotenoid uptake into growing feathers are partially independent. Carotenoid uptake strongly covaried with early elements of feather differentiation (the barb addition rate and diameter), whereas the pigmented area was most closely associated with the rate of feather growth. We suggest that strong effects of carotenoid uptake on genetically integrated mechanisms of feather growth and differentiation provide a likely route for genetic assimilation of diet-dependent coloration.     

Population differences in the structure and coloration of great tit contour feathers

Contour feathers cover most of the avian body and play critical roles in insulation, social communication, aerodynamics, and water repellency. Feather production is costly and the development of the optimum characteristics for each function may be constrained by limited resources or time, and possibly also lead to trade‐offs among the different characteristics. Populations exposed to different environmental conditions may face different selective pressures, resulting in differences in feather structure and coloration, particularly in species with large geographical distributions. Three resident populations of great tit Parus major L. from different latitudes differed in feather structure and coloration. Individuals from the central population exhibited less dense and longer contour feathers, with a higher proportion of plumulaceous barbs than either northern or southern birds, which did not differ in their feather structure. Ultraviolet reflectance and brightness of the yellow of the contour feathers of the breast was higher for the southern than for the northern population. Birds with greener plumage (higher hue) had less dense but longer feathers, independently of the population of origin. Differences in feather structure across populations appear to be unrelated to the contour feather colour characteristics except for hue. Nutritional and time constraints during molt might explain the pattern of feather structure, whereas varying sexual selection pressure might underlie the coloration patterns observed. Our results suggest that different selective pressures or constraints shape contour feather traits in populations exposed to varying environmental conditions. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114 , 82–91.     

Production of feather protein hydrolysate by keratinolytic bacterium Vibrio sp. kr2

A feather protein hydrolysate was produced using the keratinolytic bacterium Vibrio sp. strain kr2. Complete feather degradation was observed in medium containing up to 60 g L(-1) raw feathers. Cultivation on 40, 60 or 80 g L(-1) feathers for five days resulted in similar amounts of soluble protein, reaching maximum values around 2.5 g L(-1). Maximum yields of soluble protein were achieved at 30 degrees C and initial pH ranging from 6.0 to 8.0. Strain kr2 was effective in producing keratin hydrolysate from chicken feathers. Bacterial feather hydrolysate has the potential for utilization as an ingredient in animal feed or as organic fertilizer, thereby reducing the environmental impact of feather waste from the poultry industry.     

Variation in the mechanical properties of flight feathers of the blackcap Sylvia atricapilla in relation to migration

Migration causes temporal and energetic constraints during plumage development, which can compromise feather structure and function. In turn, given the importance of a good quality of flight feathers in migratory movements, selection may have favoured the synthesis of feathers with better mechanical properties than expected from a feather production constrained by migration necessities. However, no study has assessed whether migratory behaviour affects the relationship between the mechanical properties of feathers and their structural characteristics. We analysed bending stiffness (a feather mechanical property which is relevant to birds’ flight), rachis width and mass (two main determinants of variation in bending stiffness) of wing and tail feathers in migratory and sedentary blackcaps Sylvia atricapilla. Migratory blackcaps produced feathers with a narrower rachis in both wing and tail, but their feathers were not significantly lighter; in addition, bending stiffness was higher in migratory blackcaps than in sedentary blackcaps. Such unexpected result for bending stiffness remained when we statistically controlled for individual variation in rachis width and feather mass, which suggests the existence of specific mechanisms that help migratory blackcaps to improve the mechanical behaviour of their feathers under migration constraints.     

Production of feather hydrolysate by <Emphasis Type="Italic">Elizabethkingia meningoseptica</Emphasis> KB042 (MTCC 8360) in submerged fermentation

A keratinolytic bacterium Elizabethkingia meningoseptica KB042 was isolated from dropped off feathers. The bacterium showed 82.50 ± 0.3% feather degradation when grown on medium containing 10 g/l chicken feathers with initial pH 7.0 at 37°C, 150 rpm in 6 days. The pH of the medium was increased up to 10.02 ± 0.10 during 6 days of incubation. Soluble protein and amino acids concentration in the culture fluid was also found increased until the end of incubation. During the cultivation of strain KB042 on feather as sole source of carbon and nitrogen, the maximum cysteine release was noted on the 3rd day. Varying feather concentration 1.0–2.0% in basal medium resulted in soluble protein release between 1814.42 and 1954.61 μg/ml. The amino acid concentration was found to be maximum, i.e. 937.85 ± 11.9 μg/ml in the cultures grown with 2% feather. The hydrolysate was also found rich in essential amino acids valine, tryptophan, threonine, leucine and cysteine and contains minor amount of methionine and arginine. These data indicate a potential biotechnology for biotransformation and utilization of feather keratin as a source of protein which can be used as animal feed after successful animal trials.     

Male barn swallows use different signalling rules to produce ornamental tail feathers

The evolution of secondary sexual characters is the subject of controversial debate between those defending their role as ‘viability indicators’ and those arguing that ornaments are purely ‘attractive traits’ selected by females. Recent theoretical studies suggest that these hypotheses are not mutually exclusive, as both viability and attractiveness can contribute to improve the reproductive success of progeny and could thus simultaneously underlie female choices. If that is the case, strategies of cheaper advertisement, allowing the expression of larger ornaments for the same cost, could proliferate even in species in which honest signalling of viability prevails. Under this scenario, different males could invest a different amount of resources per ornament unit of expression, thus using different signalling rules. We studied the relationship between tail feather length (a trait that is the subject of a female mate preference) and feather mass (a measure of investment in feather production) in a barn swallow Hirundo rustica population. Different males used different and consistent signalling rules when developing ornamental feathers. That is, to produce a feather of a given length, each male used a constant amount of resources across different years, but this amount varied between males. Although the amount of material invested in feathers (feather mass) is a condition-dependent trait, the organization of this material in ornamental feathers (i.e. the signalling rules) was not. Neither survival nor risk of feather breakage was related to the signalling rules. Thus, these results suggest that both ‘viability’ and ‘runaway’ mechanisms are independent determinants of the evolution of ornamental sexual feathers in the barn swallow. A preference for long tails will ensure that females either obtain a sire with high viability, or one transferring the capability to produce longer and more attractive tails at a lower cost of production to its offspring.     

Theory of the development of curved barbs and their effects on feather morphology

Feathers exhibit an extraordinary diversity of shapes, which are used by birds to accomplish a diverse set of functions. Pennaceous feathers have a double branched morphology that develops from a tube of epidermis, and variation in branch geometry determines feather shape. Feather development is both complex (i.e., a simple developmental modification can have multiple effects on mature feather shape), and redundant (i.e., different developmental modifications can create the same shape). Due to this, it is not readily apparent how different feather shapes develop. In many feathers, barbs are not straight, but instead curve in toward, or away, from the feather tip. Barb curvature can affect the shape of mature feathers but the development of curved barbs is unknown. Previous research has hypothesized that barb curvature could develop either during the helical growth of barb ridges in the tubular feather germ, or during barb angle expansion as the feather unfurls from the sheath. To better understand the development of curved barbs and their effects on mature feathers we present a theoretical model of curved barb development and test the model with empirical investigations of feathers. We find that curved barbs affect many aspects of feather morphology including vane width, barb length, and barb spacing. In real feathers, curved barbs can develop both during helical barb ridge growth and during barb angle expansion, with most of the observed curvature due to barb angle expansion. Our results demonstrate that barb angle expansion as a feather unfurls from the sheath is a complex and dynamic process that plays an important role in determining the shape and structure of mature feathers. Curved barbs create heterogeneity in barb geometry within the feather vane, which could have important implications for aerodynamic function and the development of within feather pigmentation patterns. J. Morphol. 277:995–1013, 2016. © 2016 Wiley Periodicals, Inc.     

The colour of fossil feathers

Feathers are complex integumentary appendages of birds and some other theropod dinosaurs. They are frequently coloured and function in camouflage and display. Previous investigations have concluded that fossil feathers are preserved as carbonized traces composed of feather-degrading bacteria. Here, an investigation of a colour-banded feather from the Lower Cretaceous Crato Formation of Brazil revealed that the dark bands are preserved as elongate, oblate carbonaceous bodies 1-2mum long, whereas the light bands retain only relief traces on the rock matrix. Energy dispersive X-ray analysis showed that the dark bands preserve a substantial amount of carbon, whereas the light bands show no carbon residue. Comparison of these oblate fossil bodies with the structure of black feathers from a living bird indicates that they are the eumelanin-containing melanosomes. We conclude that most fossil feathers are preserved as melanosomes, and that the distribution of these structures in fossil feathers can preserve the colour pattern in the original feather. The discovery of preserved melanosomes opens up the possibility of interpreting the colour of extinct birds and other dinosaurs.     

Development and evolutionary origin of feathers

Avian feathers are a complex evolutionary novelty characterized by structural diversity and hierarchical development. Here, I propose a functionally neutral model of the origin and evolutionary diversification of bird feathers based on the hierarchical details of feather development. I propose that feathers originated with the evolution of the first feather follicle-a cylindrical epidermal invagination around the base of a dermal papilla. A transition series of follicle and feather morphologies is hypothesized to have evolved through a series of stages of increasing complexity in follicle structure and follicular developmental mechanisms. Follicular evolution proceeded with the origin of the undifferentiated collar (stage I), barb ridges (stage II), helical displacement of barb ridges, barbule plates, and the new barb locus (stage III), differentiation of pennulae of distal and proximal barbules (stage IV), and diversification of barbule structure and the new barb locus position (stage V). The model predicts that the first feather was an undifferentiated cylinder (stage I), which was followed by a tuft of unbranched barbs (stage II). Subsequently, with the origin of the rachis and barbules, the bipinnate feather evolved (stage III), followed then by the pennaceous feather with a closed vane (stage IV) and other structural diversity (stages Va-f). The model is used to evaluate the developmental plausibility of proposed functional theories of the origin of feathers. Early feathers (stages I, II) could have functioned in communication, defense, thermal insulation, or water repellency. Feathers could not have had an aerodynamic function until after bipinnate, closed pennaceous feathers (stage IV) had evolved. The morphology of the integumental structures of the coelurisaurian theropod dinosaurs Sinosauropteryx and Beipiaosaurus are congruent with the model's predictions of the form of early feathers (stage I or II). Additional research is required to examine whether these fossil integumental structures developed from follicles and are homologous with avian feathers. J. Exp. Zool. (Mol. Dev. Evol.) 285:291-306, 1999.Copyright 1999 Wiley-Liss, Inc.     

Different scales of spatial segregation of two species of feather mites on the wings of a passerine bird

The "condition-specific competition hypothesis" proposes that coexistence of 2 species is possible when spatial or temporal variations in environmental conditions exist and each species responds differently to those conditions. The distribution of different species of feather mites on their hosts is known to be affected by intrinsic host factors such as structure of feathers and friction among feathers during flight, but there is also evidence that external factors such as humidity and temperature can affect mite distribution. Some feather mites have the capacity to move through the plumage rather rapidly, and within-host variation in intensity of sunlight could be one of the cues involved in these active displacements. We analyzed both the within- and between-feather spatial distribution of 2 mite species, Trouessartia bifurcata and Dolichodectes edwardsi , that coexist in flight feathers of the moustached warbler Acrocephalus melanopogon. A complex spatial segregation between the 2 species was observed at 3 spatial levels, i.e., "feather surfaces," "between feathers," and "within feathers." Despite certain overlapping distribution among feathers, T. bifurcata dominated proximal and medial regions on dorsal faces, while D. edwardsi preferred disto-ventral feather areas. An experiment to check the behavioral response of T. bifurcata to sunlight showed that mites responded to light exposure by approaching the feather bases and even leaving its dorsal face. Spatial heterogeneity across the 3 analyzed levels, together with response to light and other particular species adaptations, may have played a role in the coexistence and segregation of feather mites competing for space and food in passerine birds.     

Epidermal-dermal tissue interactions between mutant and normal embryonic back skin: site of mutant gene activity determining abnormal feathering is in the epidermis.

The site of the scaleless gene's activity in the development of abnormal feathers was determined by reciprocally recombining epidermis and dermis between normal and scaleless chick embryos and culturing the recombinants for seven days on the chorioallantoic membrane. When recombined with a common dermal source, feather development is enhanced by scaleless high line as compared to scaleless low line epidermis. Against a common responding tissue, 7-day normal back epidermis, significant differences were not found in feather inducing ability between normal, scaleless high line and scaleless low line dermis. It was concluded that, in relation to abnormal feathering, these tissue interactions reveal that the site of the scaleless gene's activity is the epidermis. A model of tissue interaction in the development of normal and abnormal feathers is presented. According to the model, the focus of the scaleless mutation and the genes accumulated by selection for high or low feather numbers is the epidermis, the effect being that the reactivity of the epidermis to dermal stimuli is altered. Subsequently, the epidermis controls the morphogenetic organization of the dermis. The scaleless dermis is presumed to contain normal positional information for the determination of feather structure and pattern.     

Variations in the morphology,distribution, and arrangement of feathers in domesticated birds

Domesticated birds exhibit a greater diversity in the morphology of their integument and its appendages than their wild ancestors. Many of these variations affect the appearance of a bird significantly and have been bred selectively by poultry and pigeon fanciers and aviculturists for the sake of visual appeal. Variations in feather distribution (e.g., feathering of legs and feet, featherless areas in normally feather-bearing skin) are widespread in chickens and pigeons. Variations in the number of feathers (e.g., increased number of tail feathers, lack of tail feathers) occur in certain pigeon and poultry breeds. Variations in feather length can affect certain body regions or the entire plumage. Variations in feather structure (e.g., silkiness, frilled feathering) can be found in exhibition poultry as well as in pet birds. Variations in feather arrangement (e.g., feather crests and vortices) occur in many domesticated bird species as a results of mutation and intense selective breeding. The causes of variations in the structure, distribution, length and arrangement of feathers is often unknown and opens a wide field for scientific research under various points of view (e.g., morphogenesis, pathogenesis, ethology, etc.). To that extent, variations in the morphology, distribution and arrangement of feathers in domesticated birds require also a concern for animal welfare because certain alleles responsible for integumentary variations in domesticated birds have pleiotropic effects, which often affect normal behaviour and viability.     

Is the denser contour feather structure in pale grey than in pheomelanic brown tawny owls Strix aluco an adaptation to cold environments?

In colour polymorphic species morphs are considered to be adaptations to different environments, where they have evolved and are maintained because of their differential sensitivity to the environment. In cold environments the plumage insulation capacity is essential for survival and it has been proposed that plumage colour is associated with feather structure and thereby the insulation capacity of the plumage. We studied the structure of contour feathers in the colour polymorphic tawny owl Strix aluco. A previous study of tawny owls in the same population has found strong selection against the brown morph in cold and snowy winters whereas this selection pressure is absent in mild winters. We predicted that grey morphs have a denser and more insulative plumage, enabling them to survive better in cold climate compared to brown ones. The insulative plumulaceous part of the dorsal contour feathers was larger and the fine structure of the plumulaceous part of the feather was denser in grey tawny owls than in brown ones. In the ventral contour feathers the plumulaceous part of the feather was denser in females than in males and in older birds without any differences between morphs. Our study suggests that insulative microscopical feather structures differ between colour morphs and we propose that feather structure may be a trait associated with morph‐specific survival in cold environments.     

Reducing feather pecking when raising laying hen chicks in aviary systems

Aviary systems for laying hens offer several advantages over battery cages. However, pecking the feathers of conspecifics remains a serious problem that negatively affects the welfare of the birds as well as the economy of a farm. From experimental studies with small groups, it has been shown that feather pecking and foraging behaviour are related and that both behaviour are influenced by early access to litter substrate. We, therefore, hypothesised, that feather pecking in aviaries can be reduced with an adequate management in the first 2 weeks of life.Each of seven pens on six commercial poultry farms, was divided into two identical compartments (matched pair design). In one of the compartments (experimental compartment) chicks were reared for the first 2 weeks of life with access to litter (wood shavings, in one case with additional straw), while the chicks in the other compartment (control) were kept on a plastic grid. Thereafter, all chicks had unrestricted access to litter and there were no differences between the two compartments neither in housing conditions nor in management procedures.Chicks in the experimental compartments spent significantly more time foraging (week 5), showed significantly less feather pecking (weeks 5 and 14) and significantly fewer birds had damaged tail feathers (weeks 5 and 14).The study demonstrates that in aviaries, under commercial conditions, early access to litter substrate has a significant effect on the development of feather pecking. In order to reduce feather pecking and to increase foraging behaviour, it is recommended that laying hen chicks raised in aviary systems do get access to litter from day 1 on.