Feather pecking and cannibalism in a caged layer flock

Pecking at other birds and at string enrichment devices by adult laying hens

1. Bunches of white string (polypropylene twine) are particularly attractive pecking stimuli for both chicks and adult laying hens. Furthermore, these devices can retain the birds' interest over lengthy periods. It has also been demonstrated that birds with trimmed feathers elicit feather pecking. The present study was designed to determine whether string devices would retain their attractiveness in the presence of a competing stimulus: a trimmed hen. 2. Lohmann Brown hens were reared in 20 groups of 5 in floor pens with perches from 17 weeks of age. They were exposed to one of two treatments when they were 23 weeks old. One hen was removed from every pen and the feathers on her rump were trimmed. Immediately before her return two string devices were suspended from a perch in treatment 1 whereas no devices were included in treatment 2. Pecking behaviours were immediately observed for 30 min; this procedure was repeated later that day. The devices remained in the pens used in treatment 1 and these birds were observed again for 15 min after 14 d. 3. The string devices were pecked earlier and more than either the trimmed or untrimmed hens. Furthermore, the devices were still being pecked 2 weeks after their introduction. 4. The virtual absence of severe feather pecking and of aggressive head pecks precluded test of our hypothesis that the devices would divert potentially injurious pecking away from other birds. However, the fact that the birds showed sustained interest in the devices, even in the presence of a competing stimulus, supports our proposal that string may represent a practicable and effective form of environmental enrichment.

Divergent selection on feather pecking behaviour in laying hens (Gallus gallus domesticus)

A selection experiment was initiated in 1996 in which selection for (HP line) and against (LP line) feather pecking was performed. The foundation stock was a White Leghorn layer strain established in 1970 and maintained since then as a random bred control line at the Institute. Six hatches were produced over three generations. At the age of 68 weeks (generation 0, 1996), 35 weeks (generation 1, 1997), 30 weeks (generation 2, 1998), and 27 weeks (generation 3, 1999) female birds were transferred to observation pens and their feather pecking behaviour was recorded. In each generation, 30 females and 8 males were selected from approximately 200 females and 60 males. The selection criterion was breeding value estimated by animal model on the trait 'number of bouts of feather pecking per bird per hour'.Feather pecking behaviour in adult hens was significantly higher in HP than in LP. In generation 2 the following was recorded: 3.10 versus 1.37 bouts per bird per hour (P<0.01), 7.04 versus 3.58 pecks per bird per hour (P<0.05) and the proportion of hens recorded feather pecking in the 180min observation period was 67 versus 56% (P<0.05). In generation 3 the following was recorded: 4.56 versus 0.63 bouts per bird per hour (P<0.001), 13.9 versus 2.51 pecks per bird per hour (P<0.001) and the proportion of hens recorded feather pecking in the 180min observation period was 75 versus 49% (P<0.001).In generation 3, plumage condition was better in LP on neck, breast, back, wings and tail, as well as overall (P<0.001). Body weight did not differ between lines in generation 2, but in generation 3, HP hens were on average heavier than LP hens at the age of 27 weeks (1435g versus 1371g, P<0.001).

Development of pecking damage in layer pullets in relation to dietary protein source

1. In recent years, the UK egg industry has become increasingly dependent on plant protein sources, in particular soyabean meal, and it has been suggested that this trend (and/or the concomitant absence of animal protein in layer diets) might be causally related to increased feather pecking and cannibalism. 2. This study examined the development of pecking damage in relation to dietary protein source, by rearing 12 groups of 12 layer pullets to 24 weeks of age on diets based on 'animal' (fishmeal) or 'plant' (soyabean meal) protein. 3. Damaging pecking began at 6 weeks of age, in three groups (one plant and two animal). Injurious pecking began at 18 weeks of age, and affected four groups (two plant and two animal). 4. Greater numbers of vigorous pecks/pulls were observed in plant protein groups throughout the experiment, although they were significantly higher only between 13 to 16 weeks of age. Pecking damage scores did not differ between treatments. 5. Dietary protein source did not affect plasma oestradiol, progesterone or egg production. 6. These results do not support the notion that inclusion of fishmeal in laying hen diets prevents or alleviates feather pecking and cannibalism.

Plumage condition and health of aviary-kept hens fed mash or crumbled pellets

In the present experiment, we evaluated the effects on plumage condition and health of feeding a mash or a crumbled diet to two hybrids of laying hens in an aviary system. The two diets had the same composition and calculated nutrient content. A total of 3,204 birds was studied from 20 to 80 wk of age. Two hybrids, Lohmann Selected Leghorn and SLU-1329 (two line crosses of Leghorn and Rhode Island Red), were housed in six pens each of an aviary system with groups of 269 and 265 birds, respectively. There were three replicates per treatment (diet x hybrid). Diet generally had little effect on plumage condition, health, and tonic immobility. However, birds fed the crumbled diet had significantly fewer problems with bumble foot than those fed the mash diet. Hybrids reacted differently in most traits studied; SLU-1329 had better health scores but more problems with cannibalism and salpingitis than Lohmann Selected Leghorns, whereas the reverse was found in the proportion of cases with coccidiosis. The hybrid differences found underline the importance of genotype.

Is there social transmission of feather pecking in groups of laying hen chicks?

Feather pecking is an abnormal behaviour where laying hens peck the feathers of conspecifics, damaging the plumage or even injuring the skin. If it occurs in a flock, more and more birds show it within a short period of time. A possible mechanism is social transmission. Several studies have shown that laying hen chicks, Gallus gallus domesticus, are able to modify their own behaviour when observing the behaviour of other chicks, for example, when feeding and foraging. As there is good experimental evidence that feather pecking originates from foraging behaviour, we hypothesized that feather pecking could also be socially transmitted. To test this, we reared 16 groups of 30 chicks. After week 4, the birds were regrouped into 16 groups of 20 chicks into each of which we introduced either five chicks that showed high frequencies of feather pecking or, as controls, five chicks that had not developed feather pecking. We then determined the feather-pecking rate and the frequency of foraging, dustbathing, feeding, drinking, preening, moving, standing and resting of all birds in a group. Data from the introduced birds were analysed separately and excluded from the group data. Chicks in groups with introduced feather-pecking chicks had a significantly higher feather-pecking rate than chicks in the control groups. In addition, birds in groups with introduced feather peckers showed significantly lower foraging frequencies than those in the control groups, although the housing conditions were identical and there were no differences in either the number or the quality of the stimuli relevant to foraging behaviour. The study therefore suggests that feather pecking is socially transmitted in groups of laying hen chicks. Copyright 2000 The Association for the Study of Animal Behaviour.

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.

Effect of foraging material and food form on feather pecking in laying hens

1. The aim was to test whether provision of foraging material and food form influence feather pecking and feather damage in laying hens. 2. From week 19 of age, 16 groups of 11 hens (white Lohman Selected Leghorn hybrids) were kept in pens with or without access to long-cut straw as foraging material and fed on either mash or pellets. 3. Foraging behaviour was increased in hens with access to straw and time spent feeding was increased in hens fed on mash. In addition, hens fed on mash had longer feeding bouts and higher rates of pecking at the food during feeding than hens fed on pellets. 4. There were interaction effects of foraging material and food form on both feather pecking and feather damage. High rates of feather pecking and pronounced feather damage were only found in hens housed without access to straw and fed on pellets. In groups characterised by high rates of feather pecking the hens also showed more severe forms of this behaviour. 5. Differences in the time budgets of hens kept in different housing conditions suggested that birds fed on mash used the food not only for feeding but also as a substrate for foraging behaviour. 6. In order to avoid problems with feather pecking it is recommended that laying hens are provided with foraging material and fed on mash.

Stress and feather pecking in laying hens in relation to housing conditions

1. Possible association between high rates of feather pecking and increased stress were investigated in laying hens. 2. From week 19 to week 30 after hatching, 16 groups of 11 hens (white Lohman Selected Leghorn hybrids) were kept in pens with or without long-cut straw as foraging material and provided with food in the form of pellets or mash. 3. Stress was assessed by egg production, weight gain, tonic immobility (TI), heterophil/lymphocyte (H/L) ratio and antibody titres to sheep red blood cells (SRBC), tetanus toxoid (TT) and human serum albumin (HSA). 4. Provision of foraging material and food form influenced feather pecking. Rates of feather pecking were highest in groups housed without straw and fed on pellets. 5. Egg production was reduced in pens without straw but not affected by food form. Both the duration of TI and H/L ratios were influenced by provision of foraging material and food form. TI was longer and H/L ratios were increased in hens housed without straw and in those fed on pellets. Antibody titers to SRBC and TT were lower in pens without straw than with straw but not influenced by food form. 6. In conclusion, foraging material and food form affected both feather pecking and indicators of stress, suggesting that feather pecking in laying hens is associated with stress.

Incidence of pecking damage in growing bantams in relation to food form, group size, stocking density, dietary tryptophan concentration and dietary protein source

1. This paper reports 4 experiments with groups of 10 to 20 growing bantams in multi-unit brooders, which investigated effects of certain environmental and dietary factors on development of feather pecking damage to 6 weeks of age. Damage was assessed according to a subjective scoring system. 2. A test of food form (pellets, mash, mash diluted with 100 g/kg powdered cellulose) confirmed that pecking damage tends to be greater with pellets than with mash but there was no significant difference between the low damage scores associated with undiluted and diluted mash treatments. 3. A test of group size (10, 20 birds) and stocking density (744, 372, 186 cm2/bird) showed that variation in pecking damage was associated with group size x density interactions. 4. A test of dietary supplementation with L-tryptophan (0, 10, 20 g/kg) showed suppression of pecking damage with the higher (20 g/kg) dose, compared with the control (0 g/kg) treatment. 5. A test of dietary protein source (plant, mainly animal, mainly semipurified) showed no difference in pecking damage scores between treatments.

Analysis of risk factors for the occurrence of feather pecking in laying hen growers

1. Potential risk factors for the occurrence of feather pecking in laying hen growers raised under commercial conditions were investigated on Swiss farms with more than 500 rearing places. On-farm interviews were conducted on a sample of 64 flocks which represented 42.6% of all farms concerned. 2. All variables considered were dichotomised and their univariate correlation with the occurrence of feather pecking was tested for significance at P <0.20 using chi2 tests. Logistic regression with backward elimination was then used with the significant variables to identify the potentially most important factors influencing feather pecking. These variables included stocking density, light intensity, intensity of care, access to elevated perches, access to a roofed and littered outdoor area ('bad weather run'), time of access to the feeding facilities of the housing system, stocking density in the restricted area at the beginning of the rearing period, additional open feeding areas in the beginning and air quality. 3. The final model contained stocking density and access to elevated perches as significant factors (P<0.05). Flocks kept in high density (> or = 10 birds per m2) and with no access to elevated perches were 6.4 (95% Confidence interval 1.7 to 24.2) and 4.0 (95% Confidence interval 1.2 to 12.9) times more likely to be affected by feather pecking, respectively. 4. The study identified 2 risk factors for the occurrence of feather pecking in flocks of laying hen growers reared under commercial conditions. It is concluded that in order to reduce feather pecking chicks should be reared at low density and with access to elevated perches.

Changes in feather condition in relation to feather pecking and aggressive behaviour in laying hens

The aim of this experiment was to describe and examine the relationship between pecks received by individual birds and the feather and skin damage of those birds at different ages. The effect of group size was also studied. Laying hens were raised in floor pens in group sizes of 15, 30, 60 and 120 birds, each with 4 replicates. Behavioural observations were performed at the ages of 22, 27, 32 and 37 weeks. Detailed feather scoring was carried out at the ages of 18, 23, 28 and 33 weeks. Behavioural observations focused on the number of feather pecks (gentle and severe) and aggressive pecks received, and on the part of the body that was pecked. Scoring of feather and skin damage focused on the same 11 parts of the body. Increasing numbers of aggressive pecks received were associated with decreased body weight and increased feather damage at the ages of 27 and 32 weeks. The number of severe feather pecks received was significantly related with feather damage at all ages; however, no relation with gentle feather pecks received was found. Group size had a significant effect on feather condition, with large group sizes having most feather damage.

Effect of rearing factors on the prevalence of floor eggs, cloacal cannibalism and feather pecking in commercial flocks of loose housed laying hens

1. Effects of rearing conditions on behavioural problems were investigated in a cohort study of commercial flocks of laying hens housed in 2 different loose housing systems. The sample population was 120 385 laying hens from 59 flocks of various hybrids at 21 different farms. 2. Logistic regression modelling was used to test the effects of selected factors on floor eggs, cloacal cannibalism and feather pecking. In addition to early access to perches or litter, models included hybrid, stocking density, group size, housing system, age at delivery, identical housing system at the rearing farm and at the production farm and, in models for floor eggs and cloacal cannibalism, nest area per hen. Odds ratios were calculated from the results of the models to allow risk assessment. 3. No significant correlations were found between the prevalence of floor eggs, cloacal cannibalism and feather pecking. 4. Access to perches from not later than the 4th week of age decreased the prevalence of floor eggs during the period from start-of-lay until 35 weeks of age, odds ratio 0-30 (P<0-001). Furthermore, early access to perches decreased the prevalence of cloacal cannibalism during the production period, odds ratio 0-46 (P=0.03). 5. No other factor had a significant effect in these models. Although it was not significant, early access to litter had a non-significant tendency to reduce the prevalence of feather pecking.

Time-budgets, comfort behaviours and injurious pecking of turkeys housed in pairs

1. Large group size and high stocking density can compromise the welfare of poultry. This study, the first in a series of trials to determine the effect of these factors, examined the behaviour of turkeys under conditions in which group size and stocking density would have minimal influence, that is, when the birds were housed as pairs in pens measuring 3.0 x 3.6 m. 2. The 24 h time-budgets, frequency of comfort behaviours and incidence of injurious pecking were recorded on 12 occasions when the birds were between 4 and 22 weeks of age. 3. Over the duration of the study the proportion of time engaged in drinking or pecking other birds remained constant, but decreased for sleeping, environment pecking, wing-flapping, and running, increased for stretching, and varied throughout for feeding, standing, sitting, strutting, preening whilst standing, preening whilst sitting, and walking. 4. Some of the changes in activity were probably attributable to age effects per se. though other changes may have been related to increased musculo-skeletal weakness. 5. At 18 weeks of age, the turkeys spent a considerable proportion (30%) of time performing a sexual courtship display, strutting. Although the prevalence of this activity subsequently decreased, the likelihood of increased metabolic costs and potential for frustration indicate further investigation is warranted. 6. The turkeys behaved socially and were strongly influenced by social facilitator. 7. There were considerable differences between the behaviour of the turkeys and other common poultry species: the turkeys performed a running or frolicking behaviour and strutting, but did not exhibit other behaviours commonly observed such as dustbathing and ground-scratching whilst feeding. 8. Injurious pecking was infrequent. Only 14 bouts of behaviour likely to cause injury were recorded in 1,656 turkey-hours of continuous observation; no turkey required attention as a consequence of this behaviour. Feather pecking and cannibalism did not occur despite higher than conventional light intensities; the low frequency of injurious pecking could be attributed to the small group size/low stocking density.

Feather pecking in growers: a study with individually marked birds

1. The aim of the present study was to investigate whether individual birds specialise in feather pecking. Growers were individually marked and reared in groups of 30 or 31 in pens with a slatted floor. At an age of 4 to 6 weeks feather pecking was frequent in all pens. 2. On average 83% of all group members (10 groups, experiment 1) were recorded at least once as initiator of a feather pecking interaction. In each group 2 to 6 individuals feather pecked more than twice as often as the average for the group, and were defined as 'high rate peckers'. They initiated 39% of all recorded feather pecking interactions. 3. Every interaction was classified (with increasing intensity) as pecking, pinching, pulling or plucking. Compared to the others, 'high rate peckers' had more of their feather pecking classified as plucking and less classified as pecking. 4. There was no evidence that particular individuals specialised in pecking at other specific birds, at specific areas of the body or at birds engaged in specific activities. 5. Growers (3 groups, experiment 2) that had just feather pecked engaged in more feather pecking during a subsequent 2-min focal observation than control birds that had not pecked before the start of the observation. 6. It was concluded that feather pecking interactions are clustered in time and that the behaviour is not performed by just a few members of a group. However, some individuals are characterised by relatively high rates and more severe forms of feather pecking.

Feather pecking in domestic chicks: its relation to dustbathing and foraging

Feather pecking is a serious problem in poultry housing, as it may lead to feather damage, injuries and even mortality. We tested predictions of the two prevalent hypotheses claiming that feather pecking is related to dustbathing and foraging, respectively. Forty-two groups of 30 laying hen chicks, Gallus gallus domesticuswere reared in pens with a slatted floor. Access to sand as a dustbathing substrate and straw as a foraging substrate was varied between groups. The rate of feather pecking was measured in early development up to week 7. The provision of a sand area did not prevent the chicks from developing high rates of feather pecking that caused injuries. Chicks that had access to sand from day 10 showed higher rates of feather pecking than chicks that had access to sand from day 1. The provision of straw to chicks that had developed high rates of feather pecking led to a decrease in this behaviour. Chicks that could use both sand and straw from day 1 on did not show high rates of feather pecking, and no injuries were observed in these groups. There was no significant difference in dustbathing activity between housing conditions characterized by high or low rates of feather pecking. On the other hand, foraging activity was inversely related to the rate of feather pecking, and the occurrence of feather pecking could be delayed from week 4 to week 7 by postponing procedures that led to changes in foraging behaviour. In conclusion, the results show that the presence of an appropriate substrate for dustbathing does not prevent domestic chicks from developing feather pecking. On the other hand, housing conditions that promote foraging behaviour are effective in reducing and preventing feather pecking.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour

Feather pecking behaviour in White Leghorns, a genetic study

1. Genetic variables of feather pecking (FP) behaviour in a 1993 commercial pure line of White Leghorns were estimated at the age of 6, 38 and 69 weeks. 2. Heritability estimates of performing FP were 0.05 +/- 0.06, 0.14* +/- 0.07 and 0.38** +/- 0.12 for 6, 38 and 69 weeks respectively for sum of pecks (PECKS) and 0.13* +/- 0.07, 0.13* +/- 0.07 and 0.35** +/- 0.12 for sum of bouts (BOUTS). 3. Heritability estimates of receiving FP were not significantly different from 0 except at 6 weeks (0.15* +/- 0.07 and the average of the 3 age classes (AVG) (0.22** +/- 0.09) for PECKS and at 6 weeks (0.15* +/- 0.07) using BOUTS. 4. Genetic correlations of performing FP among age classes were in general high and significant. This was not the case with receiving FP. 5. Plumage cover at 51 weeks had a negative genetic correlation with performing FP at 69 weeks and AVG, but not with receiving FP. No phenotypic correlations were significant between plumage and FP. 6. Body weight at 51 weeks had a negative genetic correlation with performing FP at AVG. 7. Heritability estimates for performing and receiving FP at 6 weeks correspond to those in the literature. No estimates have previously been reported on feather pecking at 38 weeks or 69 weeks. 8. Selection of birds with no or a very low tendency to perform feather pecking should, on the basis of our results, be feasible.

Effects of plastic anti-pecking devices on food intake and behaviour of laying hens fed on pellets or mash

1. This study investigated effects of plastic anti-pecking devices on food intake and behaviour to assess their applicability in commercial layer flocks. 2. In experiment 1, 72 individually caged ISA Brown pullets were fitted at 16 weeks of age (point of lay) with either 'ring' or 'bumper' beak devices or no device (control), half being fed on pellets and half on mash. The devices were held in place by lugs inserted in the nares. 3. There was evidence of discomfort immediately after fitting the devices, but not thereafter. In the first week, the devices reduced food intake, and were removed from 7 (15%) birds that lost weight consistently. Between 16 and 21 weeks, however, there were no significant effects of beak treatment or food form on either total food intake or egg production with the 65 remaining birds. 4. Beak treatment did not affect feeding efficiency (food intake per minute of feeding). The only behaviour affected was pecking at birds in adjacent cages, which was reduced with the ring device. 5. At 21 weeks, the birds were placed together in groups of 4 to 6 in 12 pens, each group consisting of birds from one of the 6 original treatments, and their behaviour was observed in experiment 2 between 21 and 23 weeks. 6. The only effects of beak treatment on behaviour were that pecking at pen walls was increased with the ring device, while pulling and eating feathers from group mates was seen mainly with control birds fed on pellets. Two birds were cannibalised in a control group on pellets. 7. Devices came off 3 (7%) birds in experiment 1 and were replaced, and rings slipped over lower mandibles of 2 (5%) birds in experiment 2 and were corrected. 8. At 23 weeks, beak lengths were increased with ring and bumper treatments, and pecking damage scores were low with all treatments. 9. It is concluded that these devices are not applicable commercially, but further trials would be justified with new improved designs.

Behavioural development in groups of pen-housed pullets in relation to genetic strain, age and food form

1. Behavioural development in groups of 8 pullets kept in pens with litter floors, and fed on either mash or pellets, was studied from 0 to 10 weeks in a White Leghorn x broiler (F2) hybrid line (experiment 1) and from 0 to 24 weeks in Hisex, White Leghorn and Brown Leghorn strains (experiment 2). The aim was to identify precursors of feather pecking and cannibalism. 2. Rates of body weight gain were consistently greater with pellets than with mash in both experiments. In experiment 2, the onset of lay was at 17 weeks of age in Hisex, 21 weeks in White Leghorns and 23 weeks in Brown Leghorns. 3. Persistent feather pecking, which was not seen in experiment 1, developed in 2 of 12 groups (one Hisex and one White Leghorn, both fed on pellets) in experiment 2, and was studied in detail at 23 and 24 weeks. The more damaging pecking in the Hisex group was followed by cannibalism in the same group. 4. Based on the (often inconsistent) effects of genetic strain, age and food form on behaviour that were observed, a working hypothesis was constructed to account for the aetiology of feather pecking and cannibalism in situations where there is floor litter. 5. An age-related decline in one or more foraging activities may coincide with increases in preening and non-damaging pecking at other birds. Consumption of litter particles and moulted feathers may be reinforcing. Dustbathing may enhance the stimulus value of litter particles when they are contrasted against background plumage colour. This may direct pecking towards the backs of birds, where feathers as well as litter particles may be removed and eaten. Regular pecking and feather removal may lead eventually, after the onset of lay, to vent pecking and cannibalism. This sequence of events may be more likely in groups where activity levels are high.

Space and density effects on group size preferences in laying hens

1. T-maze preference tests were used to study group size and space preferences in laying hens kept on deep litter. The first experiment revealed a non-significant tendency to prefer a larger group (120 hens) in a large space (9 m2) over a smaller group (5 hens) in a small space (1 m3), but when the space was constant and large, a strong preference for the smaller group in a large space emerged. 2. In experiment 2, 5 different group size/space options were tested using a T-maze and test hens were non-randomly selected, choosing more aggressive "peckers' and more subordinate "receivers'. Chi-squared tests showed preferences for (1) a larger group (70 over 4 or 0 hens), (2) a larger space (9 m2 over 1 m2) and (3) 4 hens rather than an empty space. Although both peckers and receivers preferred the same size companion hen groups, receivers were more consistent in their choice than peckers. 3. The results have important implications for hens in all group size and suggest that while smaller group sizes may be important, they need to be combined with sufficient space. Furthermore, the "ideal group size' may differ depending on the individual hen's dominance status.

Behaviour, health and integument of four hybrids of laying hens in modified and conventional cages

1. In 2 trials the health and behaviour of a total of 3552 caged laying hens of 4 hybrids, Dekalb XL, Lohmann Selected Leghorn (LSL) and Shaver 288 in trial 1 and ISA Brown and LSL in trial 2, were studied. The cage designs were Get-away cages (GA) with 15 hens per cage, a special version of the 'Edinburgh modified cage' called 'Modified and enriched cage' (ME) with 4 ISA or 5 Leghorn hens per cage, conventional metal cages with 4 hens per cage without (CO) and with a perch (PC) and conventional plastic cages (PL) with three hens per cage. GA and ME included nests, perches and sandbaths. 2. In the first trial f1p4nest models were used, artificial turf and welded wire floor. In the second trial both nest models were used in GA, while all nests in ME were equipped with artificial turf. In the second trial there were 4 sandbath treatments in ME; no sandbath, sandbath (25 x 50 cm) first opened at 16 weeks of age, sandbath first opened at 26 weeks and double size sandbath (50 x 50 cm) first opened at 16 weeks. Hens in GA were allowed access to the sandbaths from 26 weeks. 3. At 35 and 55 weeks the best plumage condition (feather cover) was found in PL and GA but plumage condition in ME was not significantly inferior than in GA. Hens in GA had the dirtiest plumage and most bumble foot but no toe pad hyperkeratosis. Some toe pad hyperkeratosis occurred in the other systems. Most keel bone lesions were found in systems with perches. The highest mortality was registered in GA. Hens in systems with perches, sandbaths and nests had increased strength of humerus at slaughter. 4. More eggs were laid in nests with artificial turf than in welded wire floor nests. LSL hens laid larger proportions of eggs in the nests (94% and 92% in the two trials) than the other hybrids. Less than 1% of the eggs in ME and 2% in GA were laid in the sandbaths. 5. The use of perches in ME and PC was approximately 30% in the day time. At night the use was 93% in ME and 89% in PC in trial 1 and 96% in ME and 81% in PC in trial 2. 6. Hens in ME with the double sized sandbath both visited the sandbath and performed dust bathing behaviour most, followed by hens in GA, hens in ME with access to the bath from 16 weeks and last, hens in ME with access to the bath from 26 weeks. 7. It is concluded that enrichments of laying cages are used by the hens to a large extent if properly constructed and managed, implying an increased behavioural repertoire of the hens compared with conventional cages. With perches at only one level and with smaller groups of birds, ME provided better hygiene and inspection properties than GA.

Effects of pecking incentives during rearing on feather pecking of laying hens

1. Additional straw or grain was supplied to hens during rearing in floor pens with litter floors. During lay, hens were housed in pens with partly-littered partly-slatted floors. The effects on foraging behaviour and feather pecking were studied and feather damage was scored at 17, 30 and 42 weeks of age. 2. Supply of grain in the litter during rearing caused an increase in ground scratching. Ground pecking also tended to increase. Supply of straw had no significant effect on the observed behaviours. 3. Feather damage in the laying period was significantly reduced by providing grain during rearing. A similar tendency was found for groups that received straw during rearing. On the basis of the behavioural observations it was concluded that this better plumage cover was caused by less feather pecking. 4. The frequency of pecking at food was decreased during rearing by the supply of grain. This could not be explained solely on the basis of a lower food intake. Apparently the efficiency of pecking at food had changed as well. Behavioural data from the laying period suggest that this change was of a more permanent character. 5. The incentive value of the ground and the substrate covering it might be increased by the supply of grain during the rearing period. This causes foraging-related behaviours like scratching and pecking to be directed to the ground. The hens' perception of incentive stimuli for pecking is apparently influenced by experience during rearing. 6. To prevent birds redirecting their ground pecks to the feathers of other birds, not only the peckability/scratchability of the ground seems to be important but also other aspects like nutritive value or taste.

Selection and beak-trimming effects on behavior, cannibalism, and short-term production traits in White Leghorn pullets

Pullets of stocks derived from the North Central Randombred White Leghorn population without selection (C) or selected (S) on family performance when kept with beaks intact in multiple-hen cages were compared. Pullets had intact, one-fourth, or one-half of the beak removed (IN, 1/4R, and 1/2R, respectively). No stock differences were detected for behavior traits or other measures during the rearing period. However, beak-trimmed pullets were more inactive and feeding behavior was depressed in 1/2R pullets 1 wk after beak trimming. At 16 wk, 1/4R pullets' beaks had regrown but 1/2R pullets' beaks continued to be shorter than IN pullets' beaks. No differences in fearfulness were found between genetic stocks or among beak length treatments early in the laying period. Deaths from beak-inflicted injuries accumulated steadily from 18 wk until the study was ended at 40 wk. Cannibalistic deaths occurred less frequently in S as compared with C pullets within each beak treatment. As the amount of beak removal increased, beak-inflicted mortality decreased. The S pullets had earlier sexual maturity, lighter egg weights, and greater hen-housed egg production and egg mass than C pullets, and 1/2R pullets had greater egg production than 1/4R and IN pullets. Genetic stock by age and beak treatment by age interactions were present for hen-housed production and egg mass, and the interactions appeared to result primarily from increased mortality from cannibalistic pecking with increased age.

Beak trimming effects on behavior patterns, fearfulness, feathering, and mortality among three stocks of White Leghorn pullets in cages or floor pens

White Leghorn pullets of the Y1, Y2, and North Central Randombred (NCR) experimental stocks were used. Half of the birds of each stock had half of the upper and less of the lower mandible removed at 4 wk of age by making a V-shaped cut as viewed from the side (BT), whereas the other half retained their beaks intact (IN). Pullets were moved from growing pens to a layer house at 18 wk of age. Seventy-two cages and 30 floor pens were filled with 6 and 20 birds per unit, respectively. Pullets within a cage or floor pen were all of the same genetic stock and beak treatment. All measurements were performed within 10 wk after housing, except for mortality in cages. When kept in cages, genetic stocks did not show behavioral differences. However, in floor pens, stock differences were detected in feeding, crouching, and nonaggressive pecking. When kept in cages, the stocks also differed in 24-wk body weight, weight gain from 18 to 24 wk, and certain measures of fearfulness in both cages and pens, and in feather condition at 21 and 22 wk. Mortality from cannibalism and hen-days survival of caged IN pullets differed among genetic stocks. Mortality from cannibalism was absent among pullets kept in experimental floor pens. In cages, BT pullets were less active, gained less weight, and had lower incidence of cannibalism than IN pullets. Also, BT pullets were less nervous and had better feather condition than IN pullets. However, trimming beaks to prevent cannibalism was less effective in NCR pullets than in Y1 or Y2 pullets. In floor pens, BT pullets showed less activity and reduced feeding frequency and less fearfulness as indicated by duration of induced tonic immobility. Agonistic behaviors were not different between BT and IN pullets. From these results, beak trimming could be interpreted as having either stressful or stress-alleviating effects, depending on the criteria used. However, proper beak trimming appears beneficial when cannibalistic pecking is likely to be a problem. The relative benefits of beak trimming vary among genetic stocks.

Abnormal behavior

Farm animals exhibit abnormalities of sexual, maternal, and other social behaviors as well as many stereotyped behaviors. The types and incidence of these abnormal behaviors may depend on the species, its diet, and the environmental conditions under which it is normally maintained. An understanding of the causes of various abnormal behavior patterns will enable the producer and veterinarian to better manage populations of livestock and improve their well-being.

The effects of partial defeathering on energy metabolism in the laying fowl

1. The effects of a complete removal of feathers from the neck and/or breast on the energy metabolism of laying hens were measured by indirect calorimetry. 2. The daily heat production of fed birds was significantly increased if feathers were removed from the entire neck plus breast region but not if the neck only or breast only were denuded. 3. Removal of feathers from neck plus breast led to a 10% increase in food consumption. 4. The partially-defeathered birds laid more eggs.