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The rearing environment of layer chicks can differ greatly in degree of complexity. With the industry moving towards cage-free housing systems, greater demands are placed on the birds’ cognitive abilities in order for them to find resources such as food, water and nest-boxes. Because early environmental complexity can influence cognition, we aimed at increasing our knowledge of how two different rearing environments affect the cognitive abilities of the hens. We habituated 64 hens to a spatial holeboard test, half of which were reared in cages and the other half in an aviary. Out of these 64 hens, 14 cage- and 14 aviary-reared White Leghorn hens were tested twice a day every workday in a holeboard test from 32 to 40 weeks of age. The test consisted of 4 consecutive phases, namely the uncued, cued, over-training and reversal phases, during which the hens had to find baits in a subset of cups in an arena. All cups were identical, so hens had to rely on spatial cues to find the baits which were always hidden in the same cups. During the cued phase, cues were added to the baited cups to give additional information to the hens. During the reversal phase, baits were hidden in a new subset of cups to study cognitive flexibility. The results show the birds were able to successfully complete the task. Aviary-reared hens had a higher reference memory score than cage-reared hens in the first block of the cued phase (F1,26= 4.21, p1,26= 5.26, p1,26= 6.32, p1,26= 6.29, p1,26= 6.19, p1,26= 5.87, p&nbsp

Studies using classical conditioning have shown that hens display high frequencies of dopamine-controlled cue-induced anticipatory behaviours in the cue-reward interval when signalling mealworm rewards. However, it is not known whether anticipatory behaviours are reward specific, and whether the opioid system is involved in their control. The purpose of the present study was to investigate (1) effect of incentive value of rewards, and (2) the involvement of μ-opioid receptor activation, on the expression of cue-induced anticipatory behaviours in laying hens. Incentive value was manipulated by reward type (mealworm and whole wheat) and by physiological state (sated and fasted hens). Hens ( n =14) were trained to associate a cue (green or red light) with a reward (whole wheat or mealworms). Blue light served as an unrewarded control stimulus. Cue-induced anticipatory head movements (latency to first head movement after cue presentation, and frequency of head movements in the cue-reward interval), steps (frequency), and pecking at reward (latency), were registered in sated and fasted hens during a 25s cue-reward interval. An involvement of the opioid system in mediating cue-induced anticipatory behaviours was tested by intraperitoneal injection of the μ-opioid receptor antagonist naloxone at 5.0mgkg −1 . Saline served as control. Injections were administered 30min before the light cues. Individual hens were tested on all treatment combinations: sated/saline, fasted/saline, sated/naloxone, and fasted/naloxone. Incentive value of signalled reward was differentially reflected by the frequency of cue-induced head movements ( P P P =0.0003, respectively), but there was no difference between the rewarded cues. Latency to initiate the first head movement was longer in response to the unrewarded cue than to cues signalling whole wheat and mealworms ( P =0.051 (tendency) and P =0.0017). Hunger amplified the frequency of head movements ( P P

Granulomatous peritonitis is often induced by intraperitoneal vaccination in fish. Peritonitis is a very painful condition in mammals, but little is known about how fish experience this condition. In a previous experiment we found increased latency to eat and a tendency to decreased swimming during feeding in vaccinated salmon housed in groups of three. These changes in behaviour correlated with the severity of the peritonitis. However, dominance relationships may influence the degree of pain-related changes in behaviour and physiology shown by group-housed fish, and we therefore conducted the present study using singly-housed fish. The aim was to describe changes in latency to eat, hiding, swimming and bottom behaviour after vaccination, to test whether morphine would alleviate changes in behaviour, and finally to test whether vaccination and/or morphine would influence the response of the fish in the novel object test. In addition, we looked for microscopic changes of peritonitis two days after vaccination to test whether we would be able to detect inflammation at an early stage. Four treatment groups were used: VS (injected with vaccine intraperitoneally (ip) and saline intramuscularly (im)), VM (injected with vaccine ip and 300 mg kg −1 morphine im), SS (saline ip, saline im) and SM (saline ip, morphine 300 mg kg −1 im). Swimming during feeding decreased in the VS fish 2 days after treatment, both compared to baseline ( p = 0.031) and to the SS group ( p = 0.023). The latency to eat differed significantly between groups at 6.5 h after treatment ( p = 0.027), and showed a tendency towards a difference 2 days after treatment ( p = 0.092). The VS group showed significantly higher latency to eat compared with the saline group 6.5 h and 2 days after treatment ( p = 0.024 and 0.043, respectively). Contrary to predictions, we did not find an increase in bottom behaviour after vaccination. We could not detect any microscopic signs of peritonitis 48 h after vaccination. Morphine did not seem to have an analgesic effect in that there were no differences between the VM and VS groups. However, the SM fish spent significantly more time in the open during the novel object test compared with the SS fish ( χ 2 = 6.97, df = 1, p = 0.0083) one day after injection, indicating an anxiolytic effect of morphine at that time-point. It is important that the lack of analgesic effect is not taken to indicate lack of pain perception in salmon. Inter species differences in analgesic efficacy is well known in veterinary medicine, and the results from this paper indicate that we need to look at alternatives to morphine to find effective analgesics for Atlantic salmon.

In order to understand the impact of different experimental and husbandry procedures on fish, and ensure that the behavioural and physiological needs of fish used in research are met, it is necessary to have detailed knowledge of their behaviour. This knowledge is largely lacking for Atlantic salmon. Results from behavioural studies of rainbow trout are often extrapolated to Atlantic salmon even though this may not be correct. Pre-smolt Atlantic salmon show diurnal variation in behaviour in the wild, but there are no published descriptions of behaviour during the dark hours for salmon held in the laboratory. Thus, the first aim of this paper was to describe the time budget of singly-held salmon both during the light and dark hours on the first and seventh day after introduction to a new environment. Statistical differences in time budget between morning, afternoon and night are described. In addition, three environmental enrichments were provided, and the time spent using each resource was scored. In general, no behaviours differed in frequency between morning and afternoon registrations, but there were significant differences in the time-budget between day and night and also between day 1 and 7. Fish hid less and displayed more behaviours during the night than during the day, and also after 7 days in the tank compared to at the first day. The exceptions were bottom behaviours which were displayed with the same frequency during day and night and during day 1 and day 7, and hovering, which was unchanged at night from day 1 to day 7. Thus, different behaviours seem to be influenced by light and by the novelty of the surroundings to different degrees. Of the three enrichments included in the study, the hiding place and the inlet current were used most frequently. As far as the authors know, this is the first paper describing the daytime and night time behaviour of parr Atlantic salmon in a research facility in detail.

Positive affective states may be as important for animal welfare as the absence of suffering. Thus, there is a need for knowledge of the mechanisms underlying positive affective states, including how they can be induced and assessed. Studies of behaviour during the anticipation of a signalled palatable food reward have been suggested as a promising tool for answering these questions for the following three reasons: Anticipatory behaviour is hypothesized to reflect an appetitive type of positive affective state associated with dopaminergic activity in the brain. Inducing anticipation is useful for inducing pleasure and reducing stress. Finally, anticipatory behaviour can be used to test a subject's sensitivity to reward. However, to test various hypotheses regarding anticipatory behaviour there is a need to develop standardized research protocols. The aim of the present study was to develop and test an automated method for studying anticipatory and consummatory behaviour in laying hens in their home environment based on trace conditioning. Experimental hens (EX) were first trained to acquire the association between CS (conditioned stimulus; a green light) and US (unconditioned stimulus; meal worm) using a trace interval of 3.5s. To test if EX hens had formed an association between CS and US, they were exposed to CS alone. Then, EX hens were trained to anticipate by gradually increasing the CS–US interval from the initial 3.5s trace interval with a 1s increment on every other CS+US presentation up to 22s after 3 days and 32s after 5 days of training. Finally, they were tested using a CS–US interval of 22 and 32s. Control hens (CO) were exposed to CS and US in a random order, and tested as described for the EX hens. The results demonstrated that the EX hens responded to the CS with an increased level of anticipatory behaviour compared to the CO hens, and that this difference between the groups was significant at a CS–US interval of 22s. No differences between treatments were found in any of the consummatory behaviours. In conclusion, trace classical conditioning can be used for inducing anticipatory behaviour in ad libitum fed laying hens freely moving in the home pen environment. This method will facilitate the testing of hypotheses about reward-related behaviour in laying hens.

The question of whether fish can perceive pain is controversial, and pain is a potentially grave threat to fish welfare. To be able to study pain in a species, knowledge of its nociceptive system is necessary. There is therefore a need for standardised, repeatable and quantifiable measures of nociception and pain in fish. Sensitivity to noxious heat is readily quantifiable. We developed an apparatus to expose goldfish to controlled, localised heat stimulation, and tested the hypothesis that goldfish perceive heat as aversive. We predicted that they would respond to increasing heat with an escape response, that morphine would decrease their heat sensitivity and that the heat stimulation would affect post-test behaviour. A safety cut-off temperature of 50 8C was built into the test apparatus. All 16 fish responded to the heat with an escape response, with a mean baseline of 38 8C. However, morphine at 40 and 50 mg kg

Previous experiments indicate that artificial elevation of egg corticosterone content prior to incubation may increase fear of humans, reduce the willingness to compete with conspecifics and reduce the growth rate of chicks hatching from these eggs. It can also be hypothesized that corticosterone-treated chicks might be more sensitive to the effects of stress after hatching. Accordingly, we tested the effect of embryonic corticosterone exposure (5.5 ng/ml egg) and intermittent handling after hatching on the behaviour and growth of 88 vehicle-treated (40 males and 48 females) and 88 corticosterone-treated (40 males and 48 females) chicks. The injection treatment did not have any significant effects on tonic immobility ( P ≤ 0.23), but tended to increase the male's willingness to feed in a competitive environment ( P ≤ 0.10). However, post-hatch handling increased the duration of tonic immobility in corticosterone-treated birds but not in controls ( P ≤ 0.01), as reflected in the interaction between the injection and handling treatments ( P ≤ 0.01). Intermittent handling but not corticosterone treatment reduced the willingness of male birds to eat in a competitive situation, but neither treatment affected this behaviour in females. The present results suggest that the effect of embryonic corticosterone exposure may be dependent on the hormone dosage and the environment to which birds are exposed after hatching.

This experiment aimed at testing the hypothesis that exposing hens to stress increases their corticosterone secretion and leads to elevated corticosterone concentrations in their eggs. Furthermore, exposure to stress and the associated changes in egg hormone content was predicted to alter offspring behaviour. Parental hens were 40 White Lohmann Selected Leghorns, half of which were exposed to an unpredictable feed restriction treatment. After application of the treatment, birds in the treatment group had higher concentrations of faecal corticosterone metabolites than birds in the control group. The treatment had no effect on the weight of treated birds or on the concentration of corticosterone in the yolk or albumen of their eggs. Sixty progeny (30 per treatment) were tested for effects on growth and behaviour. No effects of the treatment on the hatchability of eggs or progeny body weight were registered, but treated birds had a higher duration of tonic immobility in response to manual restraint and spent less time eating, when competing with birds from the control group for access to feed in a novel environment. These results confirm that pre-hatch stress may influence behavioural development in chickens. The lack of an effect on the concentration of corticosterone in eggs suggests that other steroid hormones in addition to or rather than corticosterone may mediate the effects of pre-hatch stress in chickens.

This experiment aims at validating the percentage of visible white in the eye as an emotional indicator, related to the frustration–contentedness axis, in cattle. Earlier experiments showed that the calculated percentage of white in the eyes was larger in frustrated or scared cows compared to cows that were offered a positive stimulus. This eye change was therefore suggested to be a dynamic indicator of emotions in dairy cattle, a high percentage of white in the eye indicating frustration, and a low percentage indicating satisfaction. In the present paper, the hypothesis was that treatment with the anti-anxiety drug diazepam should reduce the percentage of white in the eye in frustrated cows, but have no effect on the percentage of eye white in non-frustrated or rewarded cows. The test animals were 20 randomly selected commercial dairy cows (Norwegian Red Cattle). Two experiments were performed on hungry cows. The four different groups in the first experiment are described in the following. Ten cows were introduced to a frustrating situation, being thwarted from access to visible food (treatment I). Ten cows were introduced to a positive situation, access to food (treatment II). The 10 cows in group I were introduced to the same frustrating situation, but were now pretreated with diazepam (treatment III). The 10 cows in group II were introduced to the same positive situation after pretreatment with diazepam (treatment IV). The two groups in the second experiment were 20 untreated (treatment I) and 20 diazepam-treated (treatment II) cows introduced to a positive, conditioned stimulus, a stockman entering the stall at concentrate feeding time. All predictions were confirmed, supporting the hypothesis that increased percentage of eye white is an emotional indicator of frustration in cows.

We tested the hypothesis that exposure of chick embryos to corticosterone leads to increased fear, reduced competitive ability, reduced ability to cross a barrier and reduced growth in juvenile chicks. Behaviour was studied in birds subjected to three different egg injection treatments: a negative control (no treatment of eggs), a positive control (100 μl sesame oil vehicle) and a corticosterone treatment (0.6 μg corticosterone in 100 μl sesame oil). Eggs were injected prior to incubation and the behaviour of chicks was studied during the first 4 weeks of life. Corticosterone treatment increased fear in chicks, as indicated by greater avoidance of an observer in the home pen at 2 weeks of age (P

The coping styles hypothesis states that animals have consistent behavioural and physiological coping responses that can be characterised on a continuum from reactive to proactive. According to this hypothesis, animals can be characterised by consistency in responses across social and non-social situations as well as over time. We evaluated the validity of this hypothesis for predicting the coping responses of pigs by testing for predicted correlations between responses to a variety of challenges. Animals were exposed to an immobility test at 3 weeks of age. At 8 and 24 weeks, animals were exposed to an unknown pig in the test animal’s home cage, a human in the home cage, and a novel object (bucket) in a novel arena. None of the predicted correlations were found between the duration of immobility and behaviour in the later tests. Many behavioural measures had some repeatability between the ages of 8 and 24 weeks, despite significant changes in the observed level of responses, but there were few correlations between responses to social and non-social situations. Responses to a human and novel object were positively correlated when measured at 8 weeks but not at 24 weeks. The results indicate that the coping styles hypothesis has very limited value in predicting the coping responses of pigs representing the population as a whole. The existing correlations could more parsimoniously be described as reflecting responses to specific or closely related stimuli. It is suggested that future research on pig personality should investigate the possibility that specific coping behaviours—for example, those mediated by fear and anxiety—may have consequences for different elements of coping ability related to welfare and productivity.

The present experiment compared the anxiety- and activity-related behaviour of sub-adult females from a mouse strain selected for over 106 generations for high litter size with that of a randomly selected control strain, to illuminate possible differences in their ability to cope with exposure to a novel environment. Selected for large litter size, the H-strain has an average litter size of 21 pups, whereas the randomly bred C-strain has an average litter size of 10 pups. The elevated plus-maze was used to measure the behaviour of the mice expressed in response to novelty. The results are described and discussed in relation to the ability to cope with novel environmental challenges. In the elevated plus-maze, the H-strain was significantly more anxious (having a lower percentage of entries into and percentage of time spent on open arms) and less active (having a lower number of entries into closed arms, and a lower total number of arm entries) than the C-strain. Thus, there were clear anxiety- and activity-related differences between the strains, which may be related to selection for large litter size. A tentative hypothesis is presented whereby selection for large litter size may accelerate adaptation to the home environment, but decrease the ability of selected animals to cope with exposure to novelty.

The aim of the present experiment was to examine the effects of pre-test transport duration and animal age on the behaviour of 40 weaned pigs in a porcine elevated plus-maze (PEPM). The transport constituted of holding test animals together with pen mates in a transport trolley kept in motion by the experimenter. Multiple regression of behaviour on transport duration and animal age (between 33 and 54 days) indicated that longer duration of pre-test transport was associated with increases in the activity-related measure closed entries (CLE) in the PEPM, but was not associated with changes in the activity-related variable total entries (TE) or either of the anxiety-related behavioural elements percent open time (POT) or percent open entries (POE). Increasing animal age, on the other hand, was associated with decreases in both activity-related measures, but not with anxiety-related parameters. These results imply that animal age and the duration of transport prior to testing should be standardised across treatments in experiments in which evaluation of activity in this novel environment is important, but that measures related to PEPM anxiety are robust to the effects of variation in transport duration and animal age.

The elevated plus-maze, a widely used and well-validated test for studying anxiety-related behaviour in rodents, has recently been suggested for studying anxiety- or fear-related behaviour in swine. There are, however, clear evolutionary, and thus behavioural differences, between these two species. The aim of the present experiment was therefore to compare the behaviour of mice and swine in the murine and porcine elevated plus-maze (PEPM), respectively. To analyse the behaviour of swine, a database including 84 naive weaned pigs was used, while the analysis of mouse behaviour was based on a database of 79 naive individuals. Plus-maze behaviour of the two species was compared on the basis of factor analysis. Based on the hypothesis that the elevated plus-maze induces behaviour related to anxiety in pigs, as well as in mice, it was predicted that factor analysis of pig behaviour should produce factor loadings similar to those found for mice. More specifically, elements predicted to be anxiety-related for pigs (percent open entries, open arm time, percent open arm time) should load highly and independently on a single factor. Furthermore, elements predicted to be activity-related (closed entries and total entries) should also load highly and independently on a separate factor. The orthogonal factor pattern confirmed these predictions. On the other hand, pigs did not express the unconditioned avoidance of open arms observed for mice. It is therefore concluded that the present data provide only equivocal support for the validity of the PEPM.

Models of anxiety and fear of novelty were evaluated using correlations and principal component analysis. A total of 84 pigs (Landrace×Yorkshire) from nine different litters were subjected to a tonic immobility (TI) test at the age of 2.5 weeks, an elevated plus-maze (EPM) at the age of 6 weeks, a light/dark (L/D) exploration test at the age of 7 weeks and an open-field (OF) test at the age of 8 weeks. The first component from the principal component analysis had the highest correlation with number of entries into open arms in the EPM but was also highly correlated to variables from the other three tests confirming a common aversion-related element in the four experimental tests. The second component was negatively correlated with percent entries into and time spent on open arms in the EPM, but positively correlated with the number of entries into closed arms in the same test, number of lines crossed in the OF and time spent in the lit compartment of the L/D test. The last point illustrates a negative relationship between “anxiety” and “activity” in the EPM and OF. To achieve purer measures of fear of novelty and activity in the tests, the components were rotated using the Varimax criterion. The rotated factor pattern demonstrated a simple structure where variables related to “anxiety” or “fear of novelty” (i.e., percent entries into open arms and time spent on open arms of the EPM) had the highest loading on factor 1, whereas variables related to activity (i.e., number of entries into the closed arms in the EPM, number of lines crossed in the OF and time spent in the lit compartment of the L/D test) had the highest loading on factor 2. TI duration loaded more strongly on factor 1 (“fear of novelty”) than on factor 2 (“activity”), but did not represent any pure measure of either fear of novelty or activity. In conclusion, all of the test variables were related to one another. Open-arm avoidance represented the purest measure of fear of novelty, whereas entries into closed arms and number of lines crossed in the OF were the purest measures of activity. The EPM appeared to provide the best way to separate the fear of novelty and activity-related elements, indicating that the EPM may be a useful behavioural model of fear of novelty or avoidance in pigs.

The present study examined the effects of diazepam (a widely used anxiolytic benzodiazepine) on the behavioural response of pigs to three novel experimental situations used to measure anxiety-related behaviour in rodents. Twelve weaned pigs (two pairs from each of the three litters) were tested in an elevated plus-maze at the age of 6 weeks, a light/dark test at the age of 7 weeks and an open-field test at the age of 8 weeks. Six of the pigs were pre-treated with diazepam (valium) and the other six with saline (control). In the elevated plus-maze, diazepam-treated pigs had a higher number of entries into open arms (P=0.04), spent more time on open arms (P=0.07), and had a higher number of total arm entries (P=0.05) than pigs from the control group. However, diazepam had no significant effects on behaviour in the light/dark test (i.e., latency to enter lit compartment, number of entries into lit compartment and the time spent in lit compartment) or the open-field test (i.e., number of lines crossed, number of entries into centre). In summary, the anxiolytic effects of diazepam on the pigs' behaviour were only demonstrated in the elevated plus-maze, where the time spent on open arms and the number of entries into open arms could be interpreted as measures of anxiety in pigs.

The elevated plus-maze is a widely used model of anxiety in rodents and has recently been suggested as a putative model of anxiety or fear in swine. The aim of the present experiment was to examine the effects of a pretest blood sampling procedure on the behaviour of weaned pigs in an elevated plus-maze. Animals in the control group were lifted one-by-one into a transport trolley and moved to the test apparatus, where they were observed for a 5-min period. The treatment group differed from the control group in that these animals were immobilized with a nose snare and a blood sample was extracted from the jugular vein prior to transport to the test room. Behaviour in the porcine elevated plus-maze did not differ significantly between the two handling procedures.