Pecking Behavior Research Articles

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.

Short-term item memory in successive same–different discriminations

Pigeons were tested in a successive same-different (S/D) discrimination procedure to examine the short-term memory for individual items in sequences of different or identical pictures. Item-by-item analyses of pecking behavior within single trials revealed this S/D discrimination emerged at the earliest possible point in the sequence--the presentation of the second item. Further, by comparing peck rates at points where different types of sequences diverged (e.g. ABA versus ABC), we determined that the pigeons remembered the first item for at least 4-8s and across one to two intervening items. These results indicate that this S/D discrimination was controlled by relational comparisons of pictorial content across memories of specific items, rather than the detection of low-level perceptual "transients" between items. A second experiment supported this conclusion by showing increased discrimination with longer first item viewing times, consistent with encoding of details about individual pictures. These findings further support a qualitative similarity among birds and primates in possessing a general capacity to judge certain types of stimulus relations, such as stimulus identity and difference. Implications for the temporal continuity of experience in animals are also considered.

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.

Effect of Diet Change on the Behavior of Chicks of an Egg-Laying Strain

Injurious pecking has serious welfare consequences in flocks of hens kept for egg laying, especially when loose-housed. Frequent diet change is a significant risk for injurious pecking; how the mechanics of diet change influence pecking behavior is unknown. This study investigated the effect of diet change on the behavior of chicks from a laying strain. The study included a 3-week familiarity phase: 18 chick pairs received unflavored feed (Experiment 1); 18 pairs received orange oil-flavored (Experiment2). All chicks participated in a dietary preference test (P); a diet change (DC); or a control group (C), 6 scenarios. All P chicks preferred unflavored feed. In Experiment 1, DC involved change from unflavored to orange-flavored; Experiment 2, orange- flavored to unflavored. Compared with controls, Experiment 2 DC chicks exhibited few behavioral differences; Experiment 1 DC chicks exhibited increased behavioral event rates on Days 1 and 7. They pecked significantly longer at their environment; by Day 7, they showed significantly more beak activity. There was little evidence of dietary neophobia. Change from more preferred to less preferred feed led to increased activity and redirected pecking behavior.

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.

Effects of genotype and feed restriction on the time-budgets of broiler breeders at different ages

Practical strategies to alleviate the negative effects of feed restriction on fast growing standard broiler breeders (S) were studied. A dwarf heavy broiler breeder selected for better viability and reproductive traits at the partial expense of growth experimentally (E) was compared to S. A slow growing dwarf broiler breeder used for Label chicken production (L) was used as a control. There were four treatments: S fed ad libitum (SA), S feed restricted (SR), E and L fed ad libitum from 0 to 40 weeks of age. Chicks were distributed in 48 pens of 14 birds with two marked focal birds per pen. Time-budgets of the 96 focal birds were measured over 3 weeks starting at 3, 9, 15, 21, 27 and 33 weeks of age, by scan sampling (12 scans/h) during 3 periods of 1 h (prior to, immediately after and 5 h after feed distribution). During the growing stage (3–17 weeks of age), in Period 1, E spent more time resting, SA preening and SR standing and pecking at the feeder than L. In Period 2, the major activity of SR was to eat and drink, whereas ad libitum-fed birds rested more often. In Period 3, SR substituted the time spent eating by birds of the other treatments, by pecking at the empty feeder (25%) or at the litter (20%). Average standing plus resting time during the growing stage were 44.6% for L, 37.6% for SA, 34% for SR and 50.1% for E. The E genotype had a better egg production and liveability than SA and consistently rested more. During the laying stage, results were similar except that sexual maturity was delayed by 6 weeks for SR and less severe feed restriction induced less total pecking behaviours. Taken together, these comparisons suggest that the behavioural characteristics of each genotype of broiler breeder is more important than the effect of feed allowance and/or selection for growth rate per se. In contrast to comparisons between treatments, the correlations between individual birds or pen means over time were low.

The effects of novel floorings on dustbathing, pecking and scratching behaviour of caged hens

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

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).

Variance components and selection response for feather-pecking behavior in laying hens

Variance components and selection response for feather pecking behavior were studied by analyzing the data from a divergent selection experiment. An investigation indicated that a Box-Cox transformation with power lambda = -0.2 made the data approximately normally distributed and gave the best fit for the model. Variance components and selection response were estimated using Bayesian analysis with Gibbs sampling technique. The total variation was rather large for the investigated traits in both the low feather-pecking line (LP) and the high feather-pecking line (HP). Based on the mean of marginal posterior distribution, in the Box-Cox transformed scale, heritability for number of feather pecking bouts (FP bouts) was 0.174 in line LP and 0.139 in line HP. For number of feather-pecking pecks (FP pecks), heritability was 0.139 in line LP and 0.105 in line HP. No full-sib group effect and observation pen effect were found in the 2 traits. After 4 generations of selection, the total response for number of FP bouts in the transformed scale was 58 and 74% of the mean of the first generation in line LP and line HP, respectively. The total response for number of FP pecks was 47 and 46% of the mean of the first generation in line LP and line HP, respectively. The variance components and the realized selection response together suggest that genetic selection can be effective in minimizing FP behavior. This would be expected to reduce one of the major welfare problems in laying hens.

P.8.002 Dextromethorphan attenuates apomorphineinduced pecking behavior in chick

P.8.002 Dextromethorphan attenuates apomorphineinduced pecking behavior in chick

Quantitative trait loci for behavioural traits in chickens

The detection of quantitative trait loci (QTL) of behavioural traits has mainly been focussed on mouse and rat. With the rapid development of molecular genetics and the statistical tools, QTL mapping for behavioural traits in farm animals is developing. In chicken, a total of 30 QTL involved in pecking-related traits, open-field behaviour, tonic immobility, response to novel objects, and response to a restraint test were detected in different studies. In the search for a useful early predictor for feather pecking (FP) behaviour in adult laying hens, the following was found: FP in young animals is not a predictor for FP in adult animals, however, open-field behaviour in young animals is genetically correlated with FP in adult hens. Before the implementation of FP behaviour or open-field behaviour in breeding programmes, it is essential to know more about the correlation between these behavioural traits and also their relationship with production traits. Nevertheless, with the QTL for behavioural traits and the chicken genome sequence in progress, a better understanding of the underlying genetic mechanisms of behavioural traits will be feasible.

A Comparison of the Pecking and Resting Behaviour of Native and Exotic (Layer Type) Chickens in a Humid Tropical Environment

A Comparison of the Pecking and Resting Behaviour of Native and Exotic (Layer Type) Chickens in a Humid Tropical Environment

Chronic increase of dietary l-tryptophan decreases gentle feather pecking behaviour

Many studies show the involvement of the serotonergic (5-HT) system in the performance of abnormal behaviour in both human and animals. Recently, we showed that acute reduction of 5-HT turnover in the forebrain, increased gentle and severe feather pecking behaviour in chicks from a high (HFP) and low feather pecking (LFP) line of laying hens, suggesting that the performance of feather pecking behaviour involves low 5-HT neurotransmission. In the present study, we postulated that if low 5-HT is causally underlying feather pecking, increasing 5-HT turnover in the forebrain will decrease the development and performance of feather pecking. Augmentation of 5-HT neurotransmission in the brain was induced by chronically increasing dietary levels of the essential amino acid l-tryptophan (TRP) from which 5-HT is synthesised. From the age of 34 days, LFP and HFP chicks were fed a diet containing 2% TRP, whereas control birds of both lines were continuously fed with the normal rearing feed (0.16% TRP). From 35 days of age, litter was removed from the pens (10 pens/line-treatment) and all chicks (10 chicks/pen) were housed on a slatted floor until the end of the experiment. At 49 days of age, feather pecking behaviour was studied for 30 min. At 50 days of age baseline corticosterone, TRP and other large amino acids (LNAAs) were measured in the blood plasma of decapitated chicks (10 chicks per line-treatment). Furthermore, plasma corticosterone and central 5-HT turnover levels in response to manual restraint (5 min) were determined (10 chicks/line-treatment). For neither gentle nor severe feather pecking a significant line × treatment interaction was found. However, TRP treatment resulted in a significant [ P = 0.02] overall decrease of the frequency of gentle feather pecking. For severe feather pecking a similar but not significant pattern was found. Significant line effects were found for gentle and severe feather pecking. HFP birds showed significantly higher levels of gentle and severe feather pecking behaviour than LFP birds [ P < 0.001]. TRP treatment significantly increased the TRP/LNAA ratio in the plasma of the chicks. Furthermore, TRP treatment overall increased baseline and stress-induced levels of plasma corticosterone (although more pronounced in the LFP line). TRP supplementation significantly increased 5-HT turnover in the hippocampus and archistriatum and tended to do so in the remainder of the forebrain. The results confirm our hypothesis that feather pecking behaviour is triggered by low serotonergic neurotransmission, as increasing serotonergic tone, by increasing dietary TRP, decreases gentle feather pecking behaviour.

Genetic and phenotypic correlations between feather pecking and open-field response in laying hens at two different ages.

The object of this research was to study the relationship between feather pecking and open-field activity in laying hens at two different ages. A population of 550 birds of a laying hen cross was subjected to an open-field test at 5 and 29 weeks of age and to a social feather pecking test at 6 and 30 weeks of age. Factor analysis was used to identify underlying factors for each test: pecking behavior (social test) and open-field activity (open-field test). In young birds, a positive phenotypic correlation of 0.24 was found between high open-field activity and high levels of pecking behavior (ground pecking, preening, gentle feather pecking, and wall pecking). In adults, a similar genetic correlation of 0.62 was found. At adult age, the factor pecking behavior consisted mainly of gentle and severe feather pecking. Between ages, a strong, negative genetic correlation of -0.65 was found between open-field activity at young age and pecking behavior at adult age, indicating that open-field activity levels in young birds may predict pecking behavior in adult hens.

Genetic and Phenotypic Correlations Between Feather Pecking Behavior, Stress Response, Immune Response, and Egg Quality Traits in Laying Hens

The objective of the current study was to estimate genetic and phenotypic correlations among feather pecking (FP) behavior and stress response, immune response, and egg quality parameters. These traits have been measured in an F2 cross, coming from a cross between a high and a low FP line of laying hens. Heritabilities (h2) of stress response (32 wk), primary immune response to keyhole limpet hemocyanin (KLH) (36 wk) and Mycobacterium butyricum (39 wk), and egg quality parameters (35, 44, and 50 wk of age) were calculated. The h2 was 0.05 ± 0.05 (SE) for stress response, 0.15 ± 0.07 for antibody response to KLH, and 0.08 ± 0.06 for antibody response to M. butyricum. The h2 for egg quality traits were in the range of 0.12 to 0.30. Significant phenotypic correlations were found between gentle FP in adult hens and stress response, egg weight at 44 and 50 wk, and egg deformation at 50 wk. Significant additive genetic correlations were found between severe FP in adult hens and antibody response to KLH (0.79 ± 0.35), and between ground pecking in adult hens and egg deformation at 50 wk (0.63 ± 0.26), and between ground pecking and eggshell strength at 35, 44, and 50 wk of age (-0.86 ± 0.29, -0.81 ± 0.20, -0.76 ± 0.24, respectively).

Between breed genetic variation for welfare-related behavioural traits in domestic fowl

Feather pecking (FP) resulting in feather loss and cannibalism (C) is an important welfare problem in domestic fowl ( Gallus gallus domesticus). Behavioural hypotheses to explain this behaviour have generally been proposed on the basis of within breed experiments or by comparing two lines. We examined these hypotheses by utilising a multi-breed experimental design to estimate the between breed genetic variation for feather pecking and cannibalism, behavioural time budgets and measures of fear, sociality and coping strategy. There was extensive between breed (genetic) variation in feather pecking, cannibalism and general pecking behaviour. There was no evidence for between breed genetic variation in time budgets; that for fear and coping strategy was slight whereas some measures of sociality were moderately high. Between breed genetic correlations between behavioural traits and feather score, skin score and mortality were low and those between sociality and skin lesions and culling were labile. We conclude that there is a strong genetic basis for damaging feather pecking and cannibalism and that these behaviours are not strongly related genetically to other behavioural traits.

Environmental enrichment for ostrich, Struthio camelus, chicks

AbstractCommercially reared ostrich chicks are typically kept in barren, indoor environments. This experiment investigated the effects of environmental enrichment on the pecking behaviour, exploration, food consumption and novelty responses of ostrich chicks aged 10 to 21 days. Four groups of 20 randomly selected ostrich chicks were housed in heated huts at one day of age (Day 1), and at Day 10 were allowed access to sand-covered areas (30 m2) that were either barren (control: n = 2 groups) or enriched with cabbage, coniferous cones and sticks (enriched: n = 2 groups). Pecking behaviour was recorded by focal sampling the behaviour of five chicks per group for four 5 min periods per day on Day 10 and Day 13. All enriched chicks pecked at the cabbage, of which they consumed considerable amounts (26 ± 3 g/chick/day). The enriched chicks did not have higher overall pecking frequencies but tended to peck less at fixtures in the pen, compared to control chicks. Additionally, the enriched chicks showed increased exploration in terms of the percentage of chicks observed outside the heated huts. In a novel object test, enriched chicks stayed closer to and delivered more pecks at sorrel (Rumex acetosa) than did control chicks, whereas there was no difference between the treatment groups in their response to adult ostrich feathers. Enriched chicks consumed more food (79 ± 0.4 g/chick/day) than did control chicks (67 ± 09 g/chick/day) during the experimental period. We suggest that environmental enrichment improves the welfare of ostrich chicks in terms of increasing exploration and reducing pecking at fixtures in the pen, without compromising food consumption.

Effects of haloperidol, a dopamine D2 receptor antagonist, on feather pecking behaviour in laying hens

Two experiments investigating general behavioural activity and specific pecking behaviour in laying hens under the effect of a dopamine D2 receptor antagonist, haloperidol, were performed. In experiment 1, a total of 240 White Leghorn hens aged 70 weeks were housed in 30 floor pens. Fifty-five of these hens acted as subjects in a dose-response experiment. Behaviour was recorded 30 min before and 30 min after injection of haloperidol or saline. The changes in behaviour were corrected for the effect of saline treatment. The results showed that doses of 0.05, 0.10, 0.20 and 0.50 mg haloperidol/kg body weight (BW) did not give any clear sedative effect, while 1.0 mg haloperidol did so. Thus, the sedative effect seemed to arise at a dose between 0.50 and 1 mg haloperidol/kg and it was concluded that 0.50 mg haloperidol/kg could be used in White Leghorn hens without inducing sedation. In experiment 2, a total of 48 ISA Brown hens aged 118 weeks were used as subjects. The birds were paired with 82-week-old White Leghorn hens chosen at random from an experimental line selected against feather pecking and housed in battery cages. Feather pecking and aggressive pecking were recorded for a period of 50 min before and 50 min after injection of either saline or 0.50 mg haloperidol/kg BW. Feather pecking, but not aggressive pecking, was significantly reduced in the haloperidol treatment (from 1.7 to 0.29 bouts per bird/h, Mann–Whitney U-test N=18, P<0.05; 10.1 to −2.7 pecks per bird/h, P<0.001). The negative value was due to correcting for effect of injection. The results supported our hypothesis that feather pecking behaviour in the adult hen is influenced by dopamine.

Communication of young black‐tailed gulls,larus crassirostris, in response to parent's behavior

In the breeding colony of black‐tailed gull, as nests of conspecific neighbors are very closely located, chicks are permanently exposed by sound and visual stimuli produced by adult conspecifics approaching their nests. The chicks, therefore, may need to learn ways to appropriately respond to their parents approach. In this study we experimentally manipulated sensory stimulation that is potentially provided by the parents to the offspring. Chicks incubated in the laboratory were exposed to a mew call of the conspecific adult. Then they were tested in three situations differing in sensory stimulation: 1) visual stimulation only, 2) auditory stimulation only, and 3) Simultaneous visual and auditory stimulations. We observed occurrence of different response of the chicks, which were categorized into three behaviors (begging call response, chirirah call and pecking behavior). We also investigated intensity of the chick's call in response to the different stimulations and the degree of response with age. The c...

Two Solitudes: The Behaviour of Pigeons in Competitive Feeding

AbstractPrevious research showed that pigeons foraging for preferred grains of maize and less preferred grains of wheat respond to the presence of a competitor by becoming less choosy ( i.e. they more readily choose wheat). We extended this work by disentangling the presence of the competitor from the resource depletion associated with it. In Experiment 1, eight birds foraged for maize and wheat in a flight cage. They were tested both alone and with another bird in different foraging sessions. Two groups were formed and differed in how they were treated when the birds foraged in pairs: both birds had access to food (Both Eat) versus only one bird had access to food (Only One Eats) while the other was placed behind a transparent curtain. For the latter treatment, no effect of the mere presence of the other bird on choice was found. Pigeons were, however, less choosy in the presence of a real competitor that exploited the food. At the end of the experiment, the pigeons that had been tested in the 'Both Eat' treatment, were tested in the 'Only One Eats' treatment. They behaved as if foraging alone. Experiment 2 introduced a new condition in which one bird ate and the other was placed behind the curtain where it pecked at grain but could not eat it. Even though this other bird behaved as if it were a potential competitor, it had no effect on the forager in the pair. The only significant difference in choice proportions was between birds foraging in real competition ( i.e. where the other bird caused resource depletion) or not. In competitive feeding situations, pigeons react to what is most directly associated with the dwindling food conditions but are insensitive to the presence and to the pecking behaviour of the animal that creates them.