Behaviour and welfare.

1. We have chosen papers which we feel are representative of important subjects which have been covered by the Journal over a period of 50 years. We would not claim that these are objectively the best papers, for that is a matter of personal judgement, but we consider that they have made significant contributions to knowledge and understanding in poultry behaviour and welfare. 2. John Savory has selected 8 papers from Volumes 1-25 of British Poultry Science (1960-1984), which deal with 5 different aspects of behaviour and welfare: embryonic responses, feather pecking and cannibalism, cage floor preferences, lameness in broilers and myopathy in turkeys. 3. Barry Hughes has selected 11 papers from Volumes 26-50 (1985-2009) of British Poultry Science. Four topics been chosen: broken bones in layers, furnished cages, interaction of birds with machines, and stocking density and bird space.

Circadian variation in heart rate, blood pressure, body temperature and EEG of immature broiler breeder chickens in restricted-fed and ad libitum-fed states.

1. Heart rate, intra-aortic blood pressure, deep body temperature and telencephalic EEG were monitored by radiotelemetry in 6 freely moving immature broiler breeders (three in each of two years), during routine food restriction and then ad libitum feeding, over two 24-h periods in each feeding state.2. Heart rate, blood pressure and body temperature were all higher during ad libitum than restricted feeding, and heart rate and body temperature were higher by day (12 h) than at night (12 h). The decreases in heart rate and body temperature at night were greater during restricted than ad libitum feeding. Blood pressure tended to be higher at night, except in year 2 during restricted feeding. Body temperature and ambient temperature were higher in year 2 than year 1.3. During restricted feeding, marked peaks in heart rate, blood pressure and body temperature in the 15 min after provision of the daily food ration at 09:00 h, when birds were eating, were equivalent to corresponding values seen during ad libitum feeding.4. Relative powers in delta (1 to 4 Hz) and theta (4 to 8 Hz) frequency bands of the EEG power spectrum were higher at night in year 2 only, while power in the alpha (8 to 12 Hz) band was higher at night in both years.5. It is concluded that most of the variation in heart rate, blood pressure and body temperature between feeding states and times of day/night can be accounted for in terms of variation in food intake and energy expenditure. The greater slow wave (delta, theta) EEG activity seen after lights-off in year 2 may reflect non-paradoxical sleep at that time.

Behavioural responses to different floor space allowances in small groups of laying hens.

Under Council Directive 1999/74/EC, minimum space allowances per laying hen range from 550 cm(2) in unfurnished cages to 1111 cm(2) in alternative housing, and to 40,000 cm(2) outdoors for free-range hens. In official reports on the welfare of laying hens, there is recognition that knowledge of their space requirements is inadequate. This experiment studied expression of behaviour, including spacing, in five groups of six and one group of five ISA Brown hens aged 21-33 weeks in an adjustable test pen providing 600, 2400, 4800, 7200, 9600, and 12,000 cm(2) floor area per hen. Each group was tested with every treatment. Home pens provided 2400 cm(2) per hen. The main aim was to identify a hypothetical point at which mutual repulsion equals mutual attraction (a 'broken stick' response). Sequencing of treatments was according to a Latin square design, daytime tests lasted 2 h and had no feeder or drinker present, and overnight tests were done with 2400, 7200 and 12,000 cm(2) per hen with a feeder and drinker present. Groups were video-recorded from above to allow repeated measurements of spacing and other behaviours. In daytime tests, the relationship between mean distance to nearest neighbour and floor space allowance was asymptotic, rather than a 'broken stick'. The steepest part of the response was between 600 and 4800 cm(2) per hen. Changes in other behaviours were greatest between 600 and 2400 cm(2), and there was no significant change above 7200 cm(2). Spacing behaviour responses at night were the same as by day. It is concluded that any space allowance of less than about 5000 cm(2) per hen imposes at least some constraint on free expression of behaviour, and that hens would benefit from any increase above the current minimum 1111 cm(2) usable area in alternative housing.

Preen gland function in layer fowls: factors affecting preen oil fatty acid composition.

1. Preen oil derived from the preen gland has previously been shown to differ in its composition between birds of different ages, sex and diet. As a part of a larger study on preening behaviour and its components, the relative percentages of fatty acids in preen oil were examined in laying hens that differed in age, beak trimmed status, feather pecking status (pecker and pecked) and method of sampling (either direct from the preen gland or from lipid extracted from feathers). 2. Five experiments are described. Fatty acids extracted from lipid were analysed by gas chromatography (GC). Fatty acid composition was affected by age, by whether or not a bird was feather pecked (but not if it was a feather pecker) and by lipid source. 3. Changes in preen oil composition with age (shown here) may be due to changes in circulating concentrations of hormones. Differences in preen oil composition between feather pecked and non-pecked birds may influence plumage odour and therefore taste, making the plumage of some birds more attractive to pecking than others. 4. The proportions of some fatty acids derived from feathers differed to those extracted from the preen gland. Lipid found on feathers is most likely a combination of that from the preen gland and from sebaceous secretions from the skin.

Ontogeny of behaviour in intact and beak trimmed layer pullets, with special reference to preening.

1. The effects of commercial beak trimming on layer pullet behaviour were investigated, with special reference to preening. 2. One-d-old chicks, 96 in all, were housed in 12 litter floor pens, with 8 birds in each, to 20 weeks of age. Approximately one quarter of the beak was trimmed in all birds in half of the pens (BT) at 8 d of age using a hot blade debeaker. The birds in the other pens remained intact (NBT). 3. There was no significant effect of beak trimming on body weight at any age. At the end of the study, upper mandible lengths were shorter in BT birds. 4. Beak trimming had very little effect on behaviour. NBT birds showed more litter-directed behaviour than did BT birds, and BT birds spent more time in preening directed at the preen gland, and at the back while sitting. 5. Feather damage was minimal and there was no difference in mean feather damage scores between treatments at any age. 6. The young age and small amount of beak removed during beak trimming may be at least partly responsible for the lack of effects of beak treatment on behaviour and plumage condition.

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

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

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.

Use of perches and nestboxes by laying hens in relation to social status, based on examination of consistency of ranking orders and frequency of interaction.

Four groups of 15-19 adult ISA Brown hens were studied in pens to assess the relationship between social status and use of perches and nestboxes. This was to test the hypothesis that subordinate hens use these resources more by day, for avoiding dominants, but that dominants use perches more at night, for roosting. The experiment consisted of a 5-week pre-treatment period, when no perches were present, and a 4-week treatment period, when each group was tested with different perch treatments (No, Low, Medium, High). All groups were observed systematically in each week, when all interactions of three types (aggressive peck, non-aggressive peck, approach/avoidance) in a group were recorded by noting the instigator and recipient (from numbered wing tags) onto a matrix. Proportions of time that each bird spent using perches and nestboxes, by day and at night, were also recorded. The results indicate that social status of individual laying hens is relatively stable across time and can be based reliably on counts of either aggressive pecks or approach/avoidances, but not non-aggressive pecks. Aggressive pecks were the most frequent type of interaction observed, and were reduced by the presence of perches. Use of nestboxes, but not perches, was greater at night than by day. There were weak tendencies for perches, and to a lesser extent nestboxes, to be used more by lower ranking birds by day, but not at night. There was some evidence of increased use of these resources by higher ranking birds at night. It is concluded that provision of perches reduces bird density on the floor (where nearly all interactions occurred), allows subordinates a means of avoiding dominants by day, reduces frequency of agonistic interactions, and should thus benefit laying hen welfare.

Influence of food restriction on dopamine receptor densities, catecholamine concentrations and dopamine turnover in chicken brain.

To investigate further a putative role of dopamine in control of food restriction-induced behavioural stereotypies, chickens were fed during rearing on either a daily restricted ration recommended by a breeding company, twice the recommended restricted ration, or ad libitum food. They were killed at 60 days of age and their excised brains were dissected into six regions and homogenized. Densities of dopamine D1 and D2 receptors were assessed, after first estimating binding parameters for [3H]SCH 23390 (D1) and [3H]spiperone (D2) in chicken brain homogenates. Specific binding of both ligands was highest in basal telencephalon. Concentrations of dopamine and its metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid were also highest in basal telencephalon, whereas noradrenaline and adrenaline levels were highest in diencephalon. Dopamine concentration in basal telencephalon and noradrenaline concentration in diencephalon were increased significantly in response to food restriction, but no effect of feeding treatment was found in dopamine turnover, adrenaline levels, or D1 and D2 receptor densities in any brain region studied. The observed changes in brain catecholamine levels are consistent with roles for dopaminergic and adrenergic mechanisms in the control of food restriction-induced behavioural stereotypies in chickens.

Temporal control of feeding behaviour and its association with gastrointestinal function.

This paper summarises knowledge about temporal control of ad libitum feeding in poultry, from minute to minute, hour to hour and day to day, and about how it relates to aspects of gastrointestinal function. Evidence is presented of only loose control over initiation and termination of spontaneous meals, and it is proposed that degrees of hunger and satiety determine probabilities of feeding starting and stopping. Voluntary regulation of food intake can be considered in terms of adjustments in mean meal size, meal frequency or both. Short-term variation is associated more with meal frequency and longer-term changes more with meal size. Short-term adjustments appear to depend more on alimentary control and longer-term adjustments more on metabolic control (not considered here). Long-term changes affecting meal size are associated with changes in capacity of parts of the alimentary tract. Food can accumulate in the crop and gizzard, and meal initiation and termination are associated with varying degrees of emptying and filling of these diverticula during most of the day. Later in the day there is usually a conditioned change to cumulative filling of the crop (and gizzard) with food that is digested overnight. Possible roles of osmo-/chemoreceptors and gut peptides are discussed.

Feather pecking in groups of growing bantams in relation to floor litter substrate and plumage colour.

1. As part of a programme investigating the causation of pecking damage in fowls, this experiment tested a proposal that birds may receive more feather pecks when their plumage colour contrasts with floor litter colour, because litter particles on plumage (as a consequence of dustbathing) may then have greater stimulus value. 2. Groups consisting of 7 light- and 7 dark-coloured bantams were reared from 1 to 11 weeks of age in pens with either wood shavings (light coloured, n=6) or peat (dark coloured, n=6) floor litter. 3. Feather loss from pecking commenced in the 3rd week of life and increased thereafter, but observed pecking damage scores were not consistent with the hypothesis being tested. 4. Despite many more pecks at birds being seen (over 10 weeks) in the wood shavings groups' (661 at particles on plumage, 1795 not at particles) than in peat groups (205, 787), there was no effect of litter substrate on pecking damage. The only evidence supporting the proposal was the finding that, in groups on wood shavings, significantly more pecks at particles on plumage were directed from light coloured birds towards dark ones, than from light to light, dark to light, or dark to dark. 5. Feather eating was confirmed from the presence of feather material in 2% to 15% of faecal droppings collected from each group at 11 weeks, but these proportions were not correlated with pecking damage scores. 6. The results imply that only some feather pecks/pulls were damaging and only some eaten feathers were pulled from other birds.

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.

Stress-induced oviposition delays in laying hens: duration and consequences for eggshell quality.

1. This study investigated relationships between the timing of stress, duration of oviposition delays and consequences for eggshell quality, in 2 experiments with ISA Brown hens. 2. Periods of up to 6 h of environmental stress (relocation from an individual cage to a larger one containing 3 unfamiliar hens), commencing up to 4.5 h before predicted oviposition time, reliably induced oviposition delays. Many hens still retained their egg when stress ended. 3. Ovipositions that occurred during stress were never delayed for more than 3.0 h beyond the expected time. Ovipositions that occurred after the period of stress ended usually did so after <1 h if the delay at the end of stress was less than about 2.4 h. Delays that ended either during stress or <2 h after stress ended were classified as short-term. 4. If an oviposition delay was more than about 2.4 h when stress ended, the egg concerned was usually laid much later, after a delay of 7 to 15 h. Delays that ended >5 h after stress ended were classified as long-term. 5. Eggs delayed long-term were white-banded and the subsequent egg was slab-sided, or occasionally soft-shelled. Short-term delays often caused eggshell dusting with varying amounts of superficial calcification. Hence, duration of oviposition delay affects both the number of abnormal eggshells and the degree of abnormality. 6. The present findings are of potential importance to both the egg industry and breeders, because abnormal eggshells cause downgrading and can impair embryonic development. Also, numbers of abnormal eggshells and degree of abnormality can be used as indicators of environmental stress.

Oviposition delays induced by social stress are reversed by treatment with the beta-adrenergic blocking agent propranolol.

Contact with unfamiliar conspecifics (social stress) caused hens to delay oviposition. These delays were prevented by propranolol (10 mg/kg), suggesting that beta-adrenergic receptors are involved in their physiological causation.