Feather Pecking Behavior Research Articles

Variation in neighbouring genes of the dopaminergic and serotonergic systems affects feather pecking behaviour of laying hens

Feather pecking is a behavioural disorder of laying hens and has serious animal welfare and economic implications. One of the several aetiological hypotheses proposes that the disorder results from redirected exploratory behaviour. Variation in the gene encoding the dopamine D4 receptor (DRD4) has been shown to be associated with exploratory behaviour in several species, including in a passerine bird species. We therefore considered DRD4 as a candidate gene for feather pecking. We have annotated DRD4 in the chicken genome and have re-sequenced it in 140 animals belonging to: experimental layer lines divergently selected for high and low propensity to feather pecking; the unselected founder population; and two commercial lines with low and high propensity to feather pecking. We have identified two sub-haplotypes of DRD4 that are highly significantly associated with feather pecking behaviour in the experimental (P = 7.30 x 10(-7)) as well as in the commercial lines (P = 2.78 x 10(-6)). Linkage disequilibrium (LD) extends into a neighbouring gene encoding deformed epidermal autoregulatory factor 1 (DEAF1). The product of DEAF1 regulates the transcription of the gene encoding the serotonin (5-hydroxytryptamine) 1A receptor. Thus, DEAF1 represents another candidate gene for feather pecking. Re-sequencing of five animals homozygous for the 'low-pecking' sub-haplotype and of six animals homozygous for the 'high-pecking' sub-haplotype delineated an LD block of 14 833 bases spanning the two genes. None of the variants in the LD block is obviously functional. However, the haplotype information will be useful to select against the propensity to feather pecking in chicken and to elucidate the functional implications of the variants.

Does enhancement of specific immune responses predispose laying hens for feather pecking?

To mimic airborne immune challenges, layer hens were intratracheally and concurrently challenged with various doses of the protein antigen human serum albumin (HuSA) and the pathogen-associated molecular pattern lipopolysaccharide (LPS) at 7 and 13 wk of age. All groups received 1 similar dose of HuSA plus LPS at 11 mo of age. Evaluation of plumage and body condition at 12 mo of age revealed that birds that had undergone intratracheal immunization with a high dosage of HuSA, irrespective of the concurrent dose of LPS, had significantly more feather damage but less wounds to the vent region, as opposed to birds not receiving HuSA. On the other hand, a high dosage of LPS was related to comb damage. These results suggest that stimulation of specific (humoral) immune responses (to HuSA) rather than innate responses (to LPS) at a young age may predispose layers for feather pecking (FP) behavior at later ages. Involvement of immune mechanisms in FP or vent damage may differ. Predisposal for FP behavior by specific immunity can have consequences for health and vaccine management.

Adrenal reactivity in lines of domestic fowl selected on feather pecking behavior

Domestic chicken lines of the White Leghorn layer type differing in their level of feather pecking have been developed by divergent selection specifically on feather pecking behavior. This paper describes an investigation of basal level, reactivity to manual restraint and maximal adrenal response to 1–24 ACTH in breeder birds of the sixth generation of selection (S6) and their control line. Birds from the three lines had comparable basal levels of corticosterone (1.6 ng/ml, anova F 2,101 = 0.62, ns), whereas males had higher basal levels than females, lsmean 1.9 vs. 1.5 ng/ml (anova F 1,103 = 6.03, P < 0.05). Reactivity to handling and restraint for 10 min differed with HFP birds showing higher reactivity than LFP birds, lsmean 11.0 vs. 7.9 ng/ml ( t = − 2.00, P < 0.05), while control birds showed intermediate levels (10.2 ng/ml). Males had higher reactivity than females, lsmean 11.2 vs. 8.2 ng/ml (anova F 1,103 = 3.96, P < 0.05). Maximal response did not differ between lines (average 35.7 ng/ml, anova F 2,101 = 1.38, P > 0.05). Males had higher maximal response than females, lsmean 41.3 vs. 33.6 ng/ml (anova F 1,103 = 5.77, P < 0.05). The present study shows that selection against feather pecking behavior have resulted in lower levels of feather pecking as well as lower sensitivity to human handling and restraint in White Leghorn laying hen lines. From an animal welfare point of view this is a positive relationship.

Feather Pecking Behaviour and associated Welfare issues in Laying Hens

Feather pecking, the pecking at or removal of feathers from one bird by another, is a problem in the poultry industry. Elimination of damaging feather pecking from flocks is made especially difficult by the numerous factors that appear to influence its prevalence. This review outlines the various contributors to feather pecking organised around Tinbergen's four questions on causation, ontogeny, phylogeny and function. There is growing evidence that feather pecking (especially severe feather pecking) is related to foraging motivation and gut function. However, other factors, such as improper early experiences, strain and individual differences and perseveration of the behaviour help explain its continued occurrence, even if the birds are kept in enriched environments. To date, methods of dealing with feather pecking are inadequate and involve welfare concerns of their own and alternate solutions, such as provision of forages, are not usually successful in abolishing feather pecking behaviour. The problems of excessive pelage/plummage removal or redirected oral/foraging related behaviour are not unique to poultry and seem to occur in other species in which foraging and forage intake is important. Between species comparisons of related behaviour patterns may improve our understanding of feather pecking and help to design effective solutions. In order to solve the problem of feather pecking, the factors discussed in this review need to be accounted for or we risk applying ‘band-aid’ solutions, which may appear outwardly to be solving the problem. However, the underlying cause(s) may still be present and the animal's welfare may still be compromised.

Laying Hens Learn to Avoid Feathers

Previous work demonstrated an association between feather pecking and feather eating in laying hens. This raised the question if digestive feedback affects feather eating or feather pecking in laying hens. We hypothesized that feathers enriched with sugar form a positive feedback and feathers enriched with quinine sulfate form a negative feedback. Forty-eight laying hens were kept in individual cages and fed a pelleted diet ad libitum. Twenty-four birds were offered feathers on a daily basis; 12 of these birds were offered feathers soaked in 4% quinine sulfate solution (Q), and the other 12 were offered feathers soaked in 4% sucrose solution (S). The other 24 birds were kept as a control (C) without access to feathers. After a 10-d feather feeding period, 3 groups of 4 S and 4 C birds each and 3 groups of 4 Q and 4 C birds each were assembled. Feather-pecking behavior was recorded over a period of 8 d. The number of Q feathers eaten was significantly lower than the number of S feathers. Birds that were offered Q feathers in the feather feeding phase showed significantly less severe feather pecking than S and C birds. The results clearly show that Q as an unpalatable substance was the signal the animal used to avoid damaging the feather cover in laying hens.

Mixed housing of different genetic lines of laying hens negatively affects feather pecking and fear related behaviour

Adult laying hens from Rhode Island Red (RIR) origin both express lower levels of feather pecking and lower fear responses towards a novel object than laying hens from White Leghorn (WL) origin. The present study investigated whether mixed housing of RIR and WL laying hens would affect their behaviour in both an open field (at 17–18 weeks of age) and manual restraint test (at 24 weeks of age) and their feather damage due to severe feather pecking. In experiment A, ‘pure’ groups contained birds from one line only throughout the rearing and laying period. ‘Mixed’ groups contained an equal number of RIR and WL birds. Pure and mixed groups contained four birds, which were housed in battery cages. It was found that RIR birds were more active in the open field and manual restraint test than WL birds, although RIR birds from mixed groups became less active in the open field test than RIR birds from pure groups. This would indicate that RIR birds were less fearful than WL birds, but that they became more fearful in presence of these WL birds. In experiment B, RIR and WL birds were only housed together during the laying period, in varying ratios. It was found that WL birds from mixed groups had more feather damage due to severe feather pecking than WL birds from pure groups, whereas no effect of mixing was found in RIR birds. RIR birds from mixed groups therefore appeared to have developed relatively high levels of feather pecking, targeted at WL birds. This would indicate that, together with results from experiment A, fearful RIR birds from mixed groups were at higher risk to develop feather pecking than less fearful RIR birds from pure groups. This study clearly demonstrates that social factors have a strong influence on the development of feather pecking and related behavioural characteristics.

What's in a peck? Using fixed action pattern morphology to identify the motivational basis of abnormal feather-pecking behaviour

Like many captive animals, hens, Gallus gallus, used for agricultural production perform abnormal behaviours. They are particularly prone to feather pecking, the severest form of which involves the pecking at and removal of feathers, which can cause bleeding and even stimulate cannibalism. The two main hypothesized explanations for feather pecking concern frustrated motivations to forage or, alternatively, to dustbathe, leading to redirected behaviour in the form of pecks at plumage. Previous work on pigeons has shown that the detailed morphology of pecks involved in drinking and feeding, or in working for food or water, involves motivationally distinct ‘fixed action patterns’. We therefore used methods similar to these fixed action pattern studies to quantify the motor patterns involved in foraging and in dustbathing pecks, for comparison to feather pecking. We videoed 60 chickens pecking at a variety of forages and dustbaths, along with novel objects, water and bird models that could be feather pecked. We recorded the durations of the head fixation before the peck, between the head fixation to beak contact with each stimulus and of the whole peck sequence. We used mixed models to assess whether the motivation underlying a peck affected its morphology and whether severe feather pecks resembled or differed from either dustbath or foraging pecks (or even novel-object pecking or drinking). The motor patterns involved in pecks at forages, dustbaths, novel objects and water all varied significantly; importantly, the motor patterns involved in pecking during dustbathing and foraging differed (P 0.95) but different from all other pecks, including dustbathing (P < 0.0001 for all measures). These results indicate that severe feather pecking derives from frustrated motivations to forage, not to dustbathe. More broadly, they suggest that finely analysing fixed action pattern morphology can help elucidate the motivational bases of puzzling abnormal behaviours in captive animals.

Role of loose feathers on the development of feather pecking in laying hens

1. The effect of the presence of loose feathers (on the floor) on the behaviour and plumage condition of laying hens (Lohmann Silver, LS) was studied during the rearing and laying periods. 2. From one day old, 60 birds in each of 4 straw-bedded pens (n = 240 in total) with 6·5 birds/m2 were either kept under conventional rearing and management conditions (CT: control group with feathers on the floor; n = 120) or in pens from which the feathers were collected from the floor 4 times/week (FR: feathers removed; n = 120). Fifty birds from each of these 4 groups (n = 200 in total) were randomly selected at the age of 16 weeks and allocated to 4 identical pens in a poultry layer house (PH; with perches and 1/3 slatted floor) with access to an outside area (winter garden, WG) at a stocking density of 6 birds/m2 in both PH and WG. 3. Observations on feather pecking and other behaviours (feeding, drinking, preening, standing, sitting, foraging, moving and dust bathing) were carried out at 8 ages: 6, 10, 15 (rearing period), 20, 25, 30, 35 and 40 weeks (laying period). Feather scoring was carried out at 15, 32 and 39 weeks of age. 4. There were no differences in feather pecking rates, forms (gentle, severe and aggressive pecks) as well as in the plumage condition between groups at the end of the rearing period. 5. Birds in the FR group exhibited lower rates and less severe feather pecking during the laying period. Accordingly, birds in the control group had worse feather condition at 32 and 39 weeks of age. Feather pecking rates within groups were, in general, greater in the afternoon compared to the morning periods. Birds in the control group were more active in walking. 6. Wings, rump, tail and back were the main targets for feather pecking. The majority of feather pecking occurred on the floor (66%) followed by feeding area (26%), perches (4%) and slats (4%). 7. Our results suggest that loose feathers on the floor may play an important role in the development and severity of feather pecking behaviour in laying hens and support the hypothesis (McKeegan and Savory, 1999) that feather pecking can be viewed as redirected foraging behaviour.

Serotonergic Mediation of Aggression in High and Low Aggressive Chicken Strains

Serotonin (5-HT) regulates aggressive behavior via binding to its receptors, such as 5-HT1A and 1B, in humans and rodents. Here we investigate the heritable components of 5-HT regulation of aggressiveness in chickens, utilizing 3 distinct genetic strains. In this study, we used 2 divergently selected strains (high and low group productivity and survivability, respectively; HGPS and LGPS) and a third strain, Dekalb XL (DXL), an aggressive out-group. Hens were paired within the same strain. At 24 wk of age, the subordinate of each pair received a daily i.p. injection of NAN-190 (0.5 mg/kg, a 5-HT1A antagonist), GR-127935 (0.5 mg/kg, a 5-HT1B antagonist), or saline (control) for 5 consecutive days. Frequency of aggressive behaviors was increased in the hens of DXL and LGPS treated with 5-HT1A antagonist and in the HGPS hens treated with 5-HT1B antagonist. The 5-HT1B antagonist-treated HGPS hens and 5-HT1A antagonist-treated LGPS hens also displayed increased feather pecking, but neither antagonist had an effect on feather pecking of DXL hens. This may suggest that multiple mediating factors alter feather pecking behaviors. Among the controls, LGPS hens have higher epinephrine levels than HGPS or DXL hens, indicative of the inferior stress-coping ability of LGPS hens. Treatment with 5-HT1B antagonist reduced epinephrine in LGPS hens but not in DXL or HGPS hens, suggesting a role of 5-HT1B in stress regulation in LGPS hens. The results provide evidence for different heritable serotonergic mediation of aggressive behaviors and stress coping in chickens.

Low Dietary Energy Concentration, High Nonstarch Polysaccharide Concentration, and Coarse Particle Sizes of Nonstarch Polysaccharides Affect the Behavior of Feather-Pecking-Prone Laying Hens

An experiment was conducted with 504 non-cage-housed ISA Brown laying hens from 18 to 40 wk of age to investigate the separate effects of dietary energy concentration, nonstarch polysaccharide (NSP) concentration, and particle sizes of added NSP source on the eating behavior, feather-pecking behavior, and hen performance of laying hens. Hens were allotted to 1 of 6 dietary treatments according to a 2 × 3 factorial arrangement, with 7 replicates per treatment. The factors were control and low energy concentration (2,825 vs. 2,540 kcal/kg), control and high NSP concentration (133 vs. 195 g/kg), and fine vs. coarse particle size of the added NSP source in the high-NSP diets. We hypothesized that eating time would be increased by feeding low-energy diets or coarsely ground, high-NSP diets, or both, resulting in reduced feather-pecking behavior, without negatively affecting hen performance. Energy reduction, NSP addition, and coarse grinding of NSP increased eating time by 14.2% (P= 0.001), 17.2% (P< 0.001), and 7.9% (P= 0.075), respectively, compared with the control level of these factors. Addition of NSP decreased eating rate (g/min) by 21.0% (P= 0.010). Layers already performed gentle feather-pecking behavior during the fifth week of the rearing period. Dietary treatments did not affect the maximal level of feather condition scores, but arise of feather damage was delayed by 10 wk in hens fed low-energy, coarsely ground, NSP-rich diets compared with hens fed control diets. Hens fed the control NSP diets showed reduced culling rates, because of less cannibalistic pecking, when energy concentration was decreased (44.1 vs. 13.1%), whereas in the high-NSP diets, culling rate decreased slightly when hens were fed the low-energy diets (31.6 vs. 28.6%; P= 0.071). Hens that were fed the low-energy diets compensated for the 10% reduction in energy concentration by a 9.3% higher maximal feed intake (143.0 vs. 130.8 g/d). Hen performance and BW gain of the hens were not affected by dietary treatments. We concluded that hens that were fed low-energy or high (coarsely ground)-NSP diets spend more time on feed intake, compared with hens that were fed the control diets. As a result, hens in some treatments showed less feather-pecking behavior.

Effect of feeding silages or carrots as supplements to laying hens on production performance, nutrient digestibility, gut structure, gut microflora and feather pecking behaviour

1. An experiment was carried out to examine the suitability of using maize silage, barley–pea silage and carrots as foraging materials for egg-laying hens. Production performance, nutrient digestibility, gastrointestinal characteristics, including the composition of the intestinal microflora as well as feather pecking behaviour were the outcome variables. 2. The protein content of the foraging material (g/kg DM) was on average 69 g in carrots, 94 g in maize silage and 125 g in barley–pea silage. The starch content was highest in the maize silage (312 g/kg DM), and the content of non-starch polysaccharides (NSP) varied from 196 to 390 g/kg, being lowest in carrots. Sugars were just traceable in the silages, whereas carrots contained on average 496 g/kg DM. 3. Egg production was highest in hens fed either carrots or maize silage, whereas hens fed barley–pea silage produced less (219 vs. 208). Although the consumption of foraging material was high (33, 35 and 48% of the total feed intake on ‘as fed’ basis for maize silage, barley–pea silage and carrots, respectively) only a minor effect on nitrogen corrected apparent metabolisable energy (AMEn) and apparent digestibility was seen. At 53 weeks of age, hens fed maize silage had AMEn and apparent digestibility values close to the control group (12·61 and 12·82, respectively), whereas access to barley–pea silage and carrots resulted in slightly lower values (12·36 and 12·42, respectively). Mortality was reduced dramatically in the three groups given supplements (0·5 to 2·5%) compared to the control group (15·2%). 4. Hens receiving silage had greater relative gizzard weights than the control or carrot-fed groups. At 53 weeks of age, the gizzard-content pH of hens receiving silage was about 0·7 to 0·9 units lower than that of the control or carrot-fed hens. Hens fed both types of silage had higher concentrations of lactic acid (15·6 vs. 3·2 µmoles/g) and acetic acid (3·6 vs. 6·1 µmoles/g) in the gizzard contents than the other two groups. The dietary supplements had a minor effect on the composition of the intestinal microflora of the hens. 5. Access to all three types of supplements decreased damaging pecking in general (to feathers as well as skin/cloaca), reduced severe feather pecking behaviour and improved the quality of the plumage at 54 weeks of age. 6. In conclusion, access to different types of foraging material such as silages and carrots improved animal welfare.

Effect of nutrient dilution on feed intake, eating time and performance of hens in early lay

1. An experiment with 480 ISA Brown layers was conducted to measure the effect of dietary energy (11·8, 11·2 and 10·6 MJ/kg) and non-starch polysaccharides (NSP) (128, 146 and 207 g/kg) concentration, soluble NSP content (64 and 85 g/kg), particle size distribution of the NSP fraction (fine and coarse) and feed form (mash and crumble) on feed intake, eating time and egg performance of laying hens in early lay (from 18 to 26 weeks of age). Twelve experimental diets were tested, each replicated 4 times. 2. Laying hens in early lay that were fed low- or high-NSP diets were able to compensate for 10% dietary dilution by 9·5 and 4·9% higher feed intakes, respectively. Feeding crumble or coarsely ground mash did not affect feed intake. 3. Eating time of the hens fed the undiluted diets increased over the experimental period from 16·4 to 24·6% of the observation period, but was not affected by sand or grit addition, particle size distribution or feed form. Feeding high-NSP diets increased eating time by 22%. 4. Egg performance and body weight gain of the hens that were fed low-NSP or high-NSP diets were similar or better compared to the undiluted diets, whereas coarse grinding of the diets showed 7 to 10% lower egg performance and weight gain. Egg performance and weight gain were not affected by feed form. 5. It is concluded that hens in early lay, fed energy-diluted diets, by adding sand or grit (low-NSP) or NSP-rich raw materials (high-NSP) to the control diet, were able to increase their feed intake, resulting in energy intake and egg performance comparable to the control group. Supplementing diets with insoluble NSP also decreased eating rate. Prolonged eating time using insoluble NSP could be useful in reducing feather pecking behaviour.

Plumage colour and feather pecking in laying hens, a chicken perspective?

1. This study investigated whether feather damage due to feather pecking and bird behaviour were influenced by plumage colour in Oakham Blue laying hens (black, white, grey colour variants). The reflectance properties of feathers and spectral composition of light environments experienced by the hens were also examined. 2. Nine hundred and seventy-nine birds were inspected and scored for feather damage; 10·5 h of video recordings were examined to record feather pecking and bird behaviour. Feathers and light environments were measured using a USB-2000 spectrometer and DH-2000-CAL-DTH lamp. 3. Oakham Blue birds with white plumage had less feather damage due to feather pecking than black or grey birds. There was more severe feather pecking in the mornings than in the afternoon. White birds feather pecked severely more than black or grey birds, although there were no other behavioural differences between plumage colours. 4. White feathers reflected at a higher intensity than black or grey feathers. However, black and grey feather spectra were relatively flat and the contribution of UV wavelengths to plumage reflection was proportionally greater than that for white feathers. 5. Light intensity inside a poultry house was 100 × (UW/cm2/nm) less than on the range and there was low or no UV reflectance. Under the dim, artificial lights inside a poultry house, Oakham Blue hens with black and grey feathers may be less visible to conspecifics than white birds because their plumage reflects at a lower intensity. Furthermore, the lack of available UV light inside vs. outside and the higher contribution of UV reflectance to black and grey plumage may make black and grey birds appear more different inside the house than white birds. It is possible that this novel/unusual appearance may make black or grey Oakham Blue hens more susceptible to feather pecking.

Daytime behavioural patterns of slow-growing chickens in deep-litter pens with perches

1. Behavioural patterns of 4 slow-growing local breeds of chickens in Taiwan and China, Taiwan Country chickens, Beijing Fatty chickens, pure Silkies, and upgraded commercial Silkies, were studied from 5 to 16 weeks of age as a reference of management for commercial production. 2. Fifteen males and 15 females of the same breed were housed in a pen. Every breed had 6 pens and 24 pens were studied. 3. Taiwan Country chickens displayed more aggressive, sexual and feather pecking behaviours, had less resting time, the fastest feeding rate and used perches more often. The fast-growing and heavy commercial Silkies had more feeding activity and less preening activity. They were also similar to the crested and docile Beijing Fatty chickens and had less stand/walking and more resting time. The pure Silky bantams showed much more foraging activity than the other breeds. 4. When males started to display more aggression and sexual behaviour, after 8–12 weeks of age, resting time for all birds started to decline and stand/walking increased. 5. These results could imply that different local breeds need different housing systems for the bird's welfare.

Behaviour when young as a predictor of severe feather pecking in adult laying hens: The redirected foraging hypothesis revisited

It has been suggested that feather pecking in poultry results when foraging behaviour is redirected to feathers in the absence of adequate foraging incentives and that gentle feather pecking is a precursor of severe feather pecking. Associations have also been proposed between feather pecking and other behaviours including dust bathing and preening. Here, we present the results of a longitudinal study on the development of severe feather pecking in individual domestic fowl. We hypothesised that behaviour, and especially foraging and gentle feather pecking behaviour, of individual birds when young predicts severe feather pecking behaviour by the same birds when adult. To test this hypothesis, we used behavioural data collected from 192 individual White Leghorn hens (12 focal birds/group) housed continuously from hatch in 16 floor pens. Data on 34 behaviour variables recorded when the birds were young (3–15 weeks of age) were subjected to factor analysis. The resulting factors were entered as independent variables in a generalised linear model to determine their relationship with severe feather pecking by the same birds as adults (17–37 weeks of age). We found a positive association between a factor describing foraging when young and severe feather pecking when adult, and a negative association between a factor describing dust bathing when young and severe feather pecking when adult ( P < 0.05). Levels of severe feather pecking increased following the onset of lay and we found no significant association between factors describing feather pecking when young and severe feather pecking by the same individuals when adult. Most of the birds were observed to perform exploratory gentle feather pecks when young. No evidence was found that exploratory or stereotyped gentle feather pecks consistently became more severe over time but factor analysis indicated that severe feather pecking by young birds was more closely correlated with exploratory, than stereotyped, gentle feather pecking, signalling utility in distinguishing between exploratory and stereotyped gentle feather pecking in future studies. We conclude that severe feather pecking did not substitute for foraging behaviour but, rather, was more likely to emerge in adult hens that had performed relatively more foraging, and less resting and dust bathing, when young. However, none of the individual behaviour variables recorded when young could be used to identify precisely which individuals would exhibit severe feather pecking when adult.

Altered Circulating Levels of Serotonin and Immunological Changes in Laying Hens Divergently Selected for Feather Pecking Behavior

The aim of this study was to investigate the changes in immunological parameters as well as changes with respect to plasma levels of serotonin and tryptophan in lines selected for and against feather pecking (FP) behavior [high FP (HP) line and low FP (LP) line] for 5 generations. The hens from the HP line had a higher plasma serotonin level than those from the LP line (0.059 vs. 0.037 micromol/L, F(2,27) = 0.031, P < 0.05). The plasma level of tryptophan was, on average, 67.30 micromol/L and did not differ between the lines (68.3 vs. 66.3 micromol/L, F(2,28) = 0.36, P < 0.05). The HP line had a higher response to infectious bursal disease virus vaccination after 1 wk post-vaccination compared with the control and LP lines. The number of white blood cells (P < 0.0001) and the expression of MHC class I molecules on CD4 (P < 0.02), CD8beta (P < 0.006) and on B cells (P < 0.03) were highest in the LP line compared with the control and HP lines. Selection for or against FP, therefore, changes the number of white blood cells and the expression of MHC class I molecules on T and B cells, which may influence the health status of the birds.

The behaviour of broiler chickens in different light sources and illuminances

Most broiler chickens are reared commercially in artificial light environments, which differ sharply from the natural light environment in which they evolved. It is not known how light affects the behaviour of broiler chickens, despite much research in the past. Here, we describe two experiments aimed at assessing how commercially available light sources at set illuminances influenced the behaviour of broiler chickens. In the first experiment, the preferences of four groups of six broiler chickens for four different light sources at two illuminances were assessed when the birds were 1 and 6 weeks of age. Broiler chickens of 6 weeks of age preferred to occupy biolux and warm-white fluorescent light sources over incandescent and spectral-sensitivity matched light, irrespective of the light intensity. In the second experiment, eight groups of 275 broiler chickens were reared semi-commercially in either of their two preferred light sources from Experiment 1 at either bright or dim illuminances (5 or 100 clx, adjusted to fowl perceived illuminance). Broilers showed a fairly resilient time-budget across light sources and intensities, whereas age and time-of-day affected most behaviours recorded. The birds spent 61% of their time resting in the litter at 6 weeks of age but resting was not significantly affected by light source or illuminance. However, the broilers showed less feather-pecking behaviour in warm-white rather than biolux light and more foraging behaviour in dim rather than bright light intensities. The two experiments combined different experimental designs to encompass potential intervening environmental variables and thereby strengthening the application of behavioural research to industry.

Divergent Selection on Feather Pecking Behavior in Laying Hens Has Caused Differences Between Lines in Egg Production, Egg Quality, and Feed Efficiency

The correlated changes in egg production, egg quality, and feed efficiency (FE) due to selection for feather pecking (FP) were investigated by analyzing the data from an experiment including 2 divergently selected lines and a control line. The experiment was conducted with hens from 42 to 46 wk (hatch 1) and 39 to 43 wk (hatch 2) of age in the fifth generation of selection. The number of FP bouts per hour in the low FP line (LFP) was lower than the high FP line (HFP; 0.38 vs. 2.01), and total plumage score in line LFP was better than in line HFP (16.9 vs. 11.6). During the 4 wk, egg number and egg mass in line LFP were higher than those in HFP (24.4 vs. 18.3 and 1,223 vs. 1,132 g, respectively). On the other hand, line HFP had greater egg weight (60.7 vs. 59.2 g), albumen height (73.0 vs. 64.9 in Haugh units), shell thickness (38.1 vs. 37.0 mm), and yolk percentage (30.6 vs. 29.5%) than the LFP line. The control line was intermediate for those traits. The residual feed consumption (RFC) was highest in line HFP, lowest in line LFP, and intermediate in line C. Partial regressions of feed consumption (FC) on BW gain and egg mass were not significantly different among the 3 lines, whereas a significant difference in regression on metabolic BW (32.6 g/d in line LFP, 38.0 g/d in control line, and 43.4 g/d in line HFP) was observed. In addition, there was a negative regression of FC per day on plumage score (×1.73 g). The adjustment for plumage score accounted for 60% of the difference between regressions on metabolic BW in lines LFP and HFP. These results indicated that selection for FP has led to a change in egg production, egg quality, and FE. The better FE in line LFP resulted from a lower requirement for maintenance energy. The later was partly accounted for by a better plumage cover.

Impact of feeding management on feather pecking in laying hens

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.

Reduction in feather pecking and improvement of feather condition with the presentation of a string device to chickens

Feather pecking remains a serious problem in commercial egg production. It has been argued that feather pecking occurs as a result of misdirected pecking, so a possible solution would be to increase the likelihood that such pecking was targeted at another object in the environment rather than to the feathers of conspecifics. Chickens of various strains and ages will readily peck at a device consisting of strands of white string but it is not yet known if pecking at that device would substitute for pecking at conspecifics. Therefore, the effects of providing string devices on feather pecking in an experimental situation (Experiment 1) and on feather condition under commercial conditions (Experiment 2) were examined. In Experiment 1, 300 chicks of a high-feather pecking strain of white leghorn-type layers were housed in groups of five in litter-floor pens. The 60 pens were randomly allocated to one of five treatments: devices incorporated in the chicks’ pens continuously from 1 day of age till the end of the experiment at 57 days; devices presented for 4 h per day from 1 day of age; first presented from 22 days of age; first presented from 52 days of age; and finally, devices never presented. Feather pecking was virtually eliminated when the devices remained in the pens from 1 day of age or when they were presented for 4 h per day. Feather pecking was most pronounced among birds that had never received the device whereas its introduction at 22 or 52 days of age yielded intermediate results. This orderly pattern of more pecking at feathers when the device was added at later ages was significant ( p < 0.005). In Experiment 2, 768 Lohmann LSL laying chickens were housed in rearing cages and 720 were transferred in groups of three to conventional laying cages when 16 weeks old. The birds were allocated to one of four treatments: devices present from 1 day of age; presented for 24 h every 4 weeks; continuously present from 16 weeks of age; and finally, devices never presented. At 35 weeks of age, hens with access to the device had significantly better plumage condition than those that had never received the device ( p < 0.05). In conclusion, the addition of a simple string device to the pens of non-beak-trimmed high-feather-pecking birds decreased feather pecking behaviour (Experiment 1), and to the cages of non-beak-trimmed commercial layers significantly improved feather condition (Experiment 2).