De-arousal properties of stereotyped behaviour: Evidence from pituitary—Adrenal correlates in pigs

Environmental Enrichments for a Group of Captive Macaws: Low Interaction Does Not Mean Low Behavioral Changes

Environmental enrichment has been widely used to improve conditions for nonhuman animals in captivity. However, there is no consensus about the best way to evaluate the success of enrichments. This study evaluated whether the proportion of time spent interacting with enrichments indicated the proportion of overall behavioral changes. Six environmental enrichments were introduced in succession to 16 captive macaws, and interaction of the animals with them as well as the behaviors of the group were recorded before and during the enrichments. All of the enrichments affected the proportions of time spent in different behaviors. Macaws interacted more with certain items (hibiscus and food tree) than with others (a toy or swings and stairs), but introduction of the enrichments that invoked the least interaction caused as many behavioral changes as those that invoked the most. Moreover, feeding behavior was only affected by the enrichment that invoked the least interaction, a change not detected by a general analysis of enrichment effects. In conclusion, little interaction with enrichment does not mean little change in behavior, and the effects of enrichments are more complex than previously considered.

Influence of degree of food restriction, age and time of day on behaviour of broiler breeder chickens

Six groups of 25 growing female broiler breeder chickens in pens were fed either on a commercial restricted ration (R), twice that amount (2R), or ad libitum (AL). R and 2R birds were fed daily at 09.00 h and ate all their food in < 15 min. Behaviour was observed systematically at three times of day (once before and twice after feeding time) at 6,9,12, 15 and 18 weeks of age. In general, restricted-fed (R and 2R) birds were much more active than AL birds. There were significant (P < 0.05) effects of feeding treatment on all activities recorded except preening and pecking at the empty feeder (R and 2R birds only); age affected drinking, preening, walking, standing and sitting; and time of day affected all activities except feeding (AL birds only). Activities that appeared to reflect feeding motivational state closest were walking before feeding time, and drinking, pecking floor litter and sitting after feeding time. AL birds (only) panted for about a third of the time at moderate ambient temperatures, and changes in their behaviour with age were thermoregulatory. It is proposed that activities of restricted-fed animals that are dominant after feeding time may be substitutable and have common causation and consequences. Distinction between stereotyped and non-stereotyped behaviour in this context may therefore be misleading.

Food restriction as a cause of stereotypic behaviour in tethered gilts

The behaviour of Large White × Landrace gilts tethered in stalls was studied by scan sampling from 07.00 to 17.00 h on 3 days consecutively every 5 weeks. Results are presented on 30 gilts sampled during their first 5 weeks in the house, period 1, and on 36 gilts during the following 5-week period, period 2. Twenty individuals were common to both samples. Gilts were fed at 08.00 h with a pelleted complete diet, either on low food levels (1·25 to 2·00 kg) or on high food levels (2·2 to 4·0 kg).

In both periods behaviour was strongly related to food allowance in individual gilts. Gilts on low food levels spent a greater proportion of their time in the standing position than those on high food levels (period 1, medians 0·31 and 0·12 respectively; period 2, medians 0·27 and 0·11 respectively), spent more time in repetitive behaviour (period 1, medians 0·22 and 0·04 respectively; period 2, medians 0·16 and 0·07 respectively) and spent a greater proportion of their standing time in repetitive behaviour (period 1, medians 0·46 and 0 respectively; period 2, medians 0·30 and 0 respectively). Similarly, all three measures of behaviour correlated negatively with food allowance overall, but there was some indication that food level had a threshold effect, with more activity and repetitive behaviour occurring on food levels below about 2 kg.

These results suggest that if food allowances are low tether stalls are not a suitable system of housing for pregnant sows.

The influence of degree of adaptation to tether-housing by sows in relation to behaviour and energy metabolism

In response to tethering, many sows develop seemingly non-functional repetitive behaviour (stereotypies), which may be performed for several hours in a day.

The quality and quantity of activity performed by sows with different degrees of adaptation to tethering was studied in relation to energy expenditure. Three groups of five sows were recognized: (1) High, sows which showed a high incidence of stereotyped activity after prolonged tethering; (2) T/Low, sows with limited experience of tethers; and (3) G/Low, the same sows as in group 2 after regrouping.

High sows were about three times more active than T/Low sows: the proportions of time involved in 24 h were 0·35 and 0·13 respectively. Most of the former sows' activity was in the form of sterotypies. The activity level of the G/Low sows was between that of the two tether treatments (proportionately 0·17 of 24 h). Both tethered treatments spent proportionately about 0·05 of 24 h in using drinkers compared with proportionately less than 0·02 of the time for the G/Low sows.

High sows produced proportionately 0·36 more heat than T/Low sows during the 12-h light period in each day. During this period, proportionately 0·40 and 0·20 of heat production from High and T/Low sows was associated with activity. The diurnal activity of the G/Low sows was associated with proportionately 0·24 of heat production.

Stereotypies and excessive drinker use accounted for proportionately 0·86, 0·52 and 0·24 of the activity of High, T/Low and G/Low sows. The proportions of metabolizable energy intake required for these activities were 0·23, 0·07 and 0·04 respectively for the three treatments. The study concludes that tethering is stressful when sows develop, and then indulge in frequent coping behavioural patterns which increase metabolic rate.

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.

Rituals, stereotypy and compulsive behavior in animals and humans

From a survey of the behavior of animals in the wild, in captivity, under the influence of psychoactive drugs and in a model of obsessive-compulsive disorder (OCD), we identify that the behavioral repertoire invariably includes motor rituals, and that such rituals are performed at a few specific locations/objects in the environment with an orderly transition amongst locations/objects. The concept and parameters of this stable organization of rituals in time and space were used to analyze rituals of OCD patients, compared with control individuals performing the same actions (e.g. car locking). It was found that human rituals also converged to a few places/objects where repetitive acts were performed in a regular order, with the acts in OCD patients overlapping with those of control individuals. Across a very diverse range of animals and conditions, motor rituals are thus characterized by their close linkage to a few environmental locations and the repeated performance of relatively few acts. Such similarity in form may reflect a similarity in the mechanisms that control motor rituals in both animals and humans.

Behavioural Reactivity Affected by Chronic Stress: An Experimental Approach in Calves Submitted to Environmental Instability

Whereas physiological and behavioural responses to acute stressors are well documented, chronic stress remains difficult to assess in farm animals. The aim of the present paper is to investigate whether calves’ behavioural reactions to acute events are modified during chronic intermittent stress. Thirty-two calves housed in pairs were used. For half of the calves the partner and the pen were changed once a week for 14 weeks (regrouped calves) while the others remained unchanged (controls). Four behavioural tests were performed to assess calves’ reactivity to novel or sudden events, to predator cues and to restraint. In the water spray test, regrouped calves were startled more often. In the umbrella test, regrouped calves took a longer time to feed in front of the closed umbrella but no differences between the two treatments were observed on opening the umbrella. In the dog test, regrouped calves moved more and looked at the dog more often. In the restraint test, regrouped calves were more agitated. These differences disappeared when the tests were repeated. In conclusion, repeated changes in the social and physical environment of calves enhances their behavioural reactivity to novelty. This is likely to make them more adaptive to potential changes in their environment.

Brain opioid receptor density relates to stereotypies in chronically stressed pigs

Opioid receptor densities were measured in the hippocampus of chronically stressed (tethered) pigs to study the involvement of endogenous opioid systems in stereotypy performance. Three groups of animals were housed tethered for 2 (n=12), 5.5 (n=12) and 8-9 months (n=8), respectively, and the intensity of stereotypy performance was determined. Opioid receptor densities were measured post mortem using membrane binding assays with [(3)H]naloxone as a ligand. A negative correlation was found between the density of opioid receptors and the intensity of stereotypy performance in the animals that had been housed tethered for 2 months. This correlation seemed to disappear with increasing duration of tethered housing. The data further suggest that, associated with the duration of tediered housing, there was a gradual decrease in the density of opioid receptors in the left hippocampal lobe of the low-stereotyping animals, but not in the right lobe, nor in the left and right lobes of the high-stereotypers. This suggests that chronic stress leads to a (asymmetrically expressed) progressive loss of opioid receptors in the hippocampus, and that stereotypies exert a mitigating effect on stress-induced changes in opioid receptor densities, supporting the hypothesis that stereotypies help the animals cope wife the adverse effects of chronic stress.

Associations between behavioural indicators of "stress" in weaner pigs and respiratory lesions at slaughter

The aim of the study was to investigate associations on the individual-pig level between eight behavioural indicators of 'stress' (defined in a very general sense), in seven to eight-week old piglets four weeks after weaning and the occurrence of atrophic rhinitis (AR) and chronic pleuritis (CP) at slaughter. The study was designed as a cohort study, including 512 pigs from two commercial farms. With one exception Actinobacillus pleuropneumoniae serotype 2 (App2) infection was not associated with any of the behaviour patterns observed. Using random-effects logistic regression, weak statistical associations, positive as well as negative, were found between the performance of several behaviour patterns and the two pathological lesions. This suggests the existence of biological associations between oral behaviour patterns in young pigs and the health status later in life. However, the results were not consistent between specific oral behaviour patterns or between the two herds indicating that the associations found are either due to chance or reflect the existence of herd-specific confounders. Therefore, results based on studies within only one herd should not be generalized to other herds without care. Behavioural observations on seven- to eight-week-old piglets on the basis of the present investigation cannot be recommended for use as early predictors of AR or CP at slaughter. Further studies are needed in order to elucidate causal relations between behaviour and health.

Is there a role for corticosterone in expression of abnormal behaviour in restricted-fed fowls?

Growing parent stock (breeders) of meat-type chickens (broilers), subjected routinely to chronic food restriction, show increased pacing before a single daily meal and increased drinking and pecking at non-food objects (oral stereotypies) afterwards. Expression of these activities is correlated positively with the level of restriction imposed, and is thought to be controlled mainly by central dopaminergic mechanisms. There is published evidence that glucocorticoids can amplify dopamine mediated behaviours, and this paper describes four experiments examining the relationship between corticosterone and behaviour in individually caged broiler breeders. In Experiment 1 (with 3 levels of food restriction), plasma corticosterone concentration was correlated positively with the level of restriction imposed when blood samples were taken in the morning, but not when they were taken in the afternoon. This may be because corticosterone level declines from morning to afternoon with mild but not severe restriction. In Experiment 2 (severe restriction only), plasma corticosterone level did not change significantly with time of day, and mean values of individual birds were not correlated with their observed times spent in oral stereotypies. In Experiment 3 (severe restriction), object pecking increased in a dose-related way after systemic injection of 1-4 mg/kg corticosterone (significant) and 7.5-30 IU/kg ACTH (not significant), and 10-40 mg/kg metyrapone (corticosterone synthesis inhibitor) had no effect. In Experiment 4 (severe restriction), 180 mg/day metyrapone administered in food for 5 days reduced the plasma corticosterone response to injection of 15 IU/kg ACTH on the fourth day, but otherwise had no effect. Significant increases in drinker directed activity after injection of ACTH on the fourth day and 4 mg/kg corticosterone on the fifth day coincided with greatly elevated plasma levels of corticosterone. It is concluded that the oral stereotypies of restricted-fed broiler breeders do respond to induced increases in plasma corticosterone concentration that are supra-physiological, but there may be only a weak association between behaviour and corticosterone within the physiological range.

Stereotypic Behaviour in Wild Caught and Laboratory Bred Bank Voles (Clethrionymus Glareolus)

Stereotypic behaviour is generally associated with animals maintained in restrictive environments, and has rarely been described in wild or free-ranging animals. The difference between captive and wild populations may be due to their genetic predisposition or to experience of environmental factors. To investigate genetic and environmental factors, we compared the behaviour of 12 wild caught voles and their 9 pups with that of 12 laboratory reared voles and 14 laboratory bred pups. All voles were observed twice. Adults were observed after 10 days housing in a cage, containing food, water, sawdust and hay, and again after 60 days. Pups were observed in the same cages 10 and 60 days after weaning. For each observation, the voles’ behaviour was recorded both undisturbed in this cage, and following introduction to an unfamiliar cage. Locomotor stereotypies were observed in laboratory adults, but not in wild caught voles, which spent less time on all locomotor activities and more time under cover than laboratory voles. There was no difference in mortality or fecundity of laboratory and wild caught voles, so there appeared to be no selective advantage to stereotyping. There was no difference in the behaviour of wild and laboratory pups, so early environmental experience of the cage environment, rather than parental background, was an important factor in the development of locomotor stereotypies in this species. Pups that developed stereotypies by 60 days spent less time under cover and more time walking and climbing after 10 days than voles that did not develop stereotypic behaviour. Stereotypic behaviour may therefore have been derived from persistence of locomotor behaviour. Wild caught voles may have failed to develop locomotor stereotypies, either because they did not perform a locomotor response to captivity or because older voles are less prone to develop novel responses to external cues. It would, therefore, be dangerous to use the absence of stereotypic behaviour as a reliable indicator of welfare without taking into account the animal's prior experience.

The effect of chronic stress on plasma cortisol concentrations in cyclic female pigs depends on the time of day

The influence of tethered housing (a condition of chronic stress) on morning and evening basal plasma cortisol levels was investigated in a longitudinal study in cyclic female nulliparous pigs (gilts). After a period of loose housing in individual pens ("nonstress" estrous cycles), six cannulated gilts were tethered by a neck chain and housed for a period of 20 wk (chronic stress estrous cycles). Blood was sampled twice daily (1000 and 1800 hr) for cortisol determination. Plasma cortisol levels showed a diurnal rhythm with significantly higher levels at 1000 hr than at 1800 hr. Tethered housing induced a significant increase in the 1800-hr plasma cortisol concentrations during the first three estrous cycles after tethering, whereas the 1000-hr plasma cortisol concentrations did not change throughout the experimental period. During the period of increased 1800-hr levels, cortisol was still released in a circadian fashion, albeit, the rhythm was flattened. In control gilts, housed loose during the entire experimental period, plasma cortisol concentrations at 1000 hr and at 1800 hr remained unaltered and 1000-hr cortisol concentrations were significantly higher than the 1800-hr concentrations during the experimental period. Therefore, possible effects of the experimental procedure or age-related effects could be excluded. These data indicate that, in tethered gilts, the chronic stress-induced hypercortisolemia is of transient nature, suggesting adaptive changes in the regulation of the hypothalamic-pituitary-adrenocortical axis. In addition, the data reveal circadian differences in the effect of chronic stress on hypothalamic-pituitary- adrenocortical function.

Stress and Animal Welfare

When individual vertebrates loose grip on their life conditions stress symptoms appear and their welfare becomes problematic. Present day research supports the view that stress can originate when an organism experiences a substantial reduction of predictability and/or controllability (PIC) of relevant events. Behavioural (conflict and disturbed behaviour) and physiological (neuro-endocrine and autonomic processes) aspects of a reduction of PIC are reviewed. The highly dynamic patterns of the homeostatic mechanisms activated during stress make it difficult to deduce any simple relationship between stress and welfare.

A list of relevant stress symptoms has been presented, all of which indicate some stage of serious welfare problems. Their occurrence should never be typical of animals living in a farm, laboratory or zoo housing system. However, if after all this is the case, such systems have to be corrected and replaced by more appropriate ones as soon as possible.

Stereotypic behavior and heart rate in pigs

Heart rate responses to feeding of both loose-housed and tethered sows, some of which engaged in persistent behavioral stereotypies, were recorded telemetrically in order to determine if stereotypic behavior occurs in response to, and serves to reduce increased sympathetic nervous activity. Heart rates rose in response to feeding (after which stereotypic behavior is most common) and this was greater for tethered sows. This response was partly blocked by a beta-adrenoreceptor antagonist (carazolol), but not by naloxone, although the latter tended to lead to overall increases in heart rate. Thus long-term tethering of sows leads to greater sympathetic nervous responses to feeding. No consistent relationships were found between heart rate and the performance of stereotypic behavior. In Experiment 1, using sows tethered for 6-8 months, neither basal heart rates nor heart rates following naloxone or carazolol differed between high- and low-stereotyping sows. In Experiment 2, using sows tethered for 1-2 months, high-stereotyping sows had lower basal heart rates than low-stereotyping sows. Marked reductions in heart rate caused by a beta-adrenoreceptor blocker did not lead to any change in stereotypic behavior, and preventing stereotypic behavior led to a reduction not an increase in heart rates. The results suggest that stereotypies are performed in situations where heart rate is high, but they provide no evidence that stereotypies reduce this heart rate.

Stereotypic behavior, adrenocortical function, and open field behavior of individually confined gestating sows

The adrenocortical response and open field behavior of a random sample of 37 individually confined gestating sows in different parities were tested around day 85 of pregnancy. The sows were classified as stereotyped [S] and nonstereotyped [N] based on 8-h individual behavioral observations during daytime. Behavioral analysis from time-lapse video recordings included percentage of time spent standing and sitting, as well as the duration spent performing elements of stereotyped actions. Blood samples were drawn for cortisol analysis by suborbital sinus puncture before and after adrenocortical stimulation with 200 IU ACTH. Locomotor activity in an open field, isolated visually and auditorily from other sows, was also studied. Seventeen sows exhibited stereotyped behavior for 54.9 +/- 4.8% of the 8-h observation period during daytime. The total time the sows spent standing and sitting was positively correlated with age and was significantly higher for [S] sows than for [N] sows. Sows in the [S] group exhibited a higher adrenocortical response to ACTH stimulation than [N] sows. Mean locomotor scores in the open field were higher for [S] than for [N] sows but these did not correlate with the physical activity and adrenocortical function in the home crate. Our results provide no evidence that the performance of stereotypies constitutes a mechanism that helps sows to cope in an environment of low complexity.

Stereotypic or obsessive-compulsive disorders in dogs and cats

Stereotypic and obsessive-compulsive behaviors are defined, and examples are given for both dogs and cats. The cause of these behaviors is discussed; and it is maintained that they result from conflict and are influenced by genetics, early experience, and learning. Treatment options, such as changes in environment and management, behavior modification, and the use of various drugs are reviewed.

Stereotypic behavior, endogenous opioids, and postfeeding hypoalgesia in pigs

Tethered sows, some of which performed marked behavioral stereotypies after feeding, were injected IM with 1 mg/kg of naloxone 30 min before feeding (with 2 saline control days). Tail-flick latencies on a pain-sensitivity test were recorded before and after feeding. On control days, tail-flick latencies after feeding were longer than those before feeding, and this effect was abolished by naloxone pretreatment. Thus, there is an opioid-based hypoalgesia after feeding. However, sows with marked behavioral stereotypies had shorter tail-flick latencies after feeding. Thus, we have no evidence that performance of behavioral stereotypies results in increased opioid activity. Naloxone reduced the time spent in behavioral stereotypies by approximately 30% but this may be due to a reduction in time spent active. Naloxone increased the frequency and reduced the mean duration of bouts of chain manipulating, operating the drinker and rooting. We suggest that endogenous opioids are involved in the positive feedback that maintains the persistence of behavior and inhibits switching between different activities.

Changes in naloxone and haloperidol effects during the development of captivity-induced jumping stereotypy in bank voles

Captivity-induced stereotypies in bank voles (Clethrionomys glareolus) were inhibited at the age of 1, 2, 4, 6, 8 and 10 months by 0.2 mg/kg haloperidol s.c., while 35 mg/kg naloxone s.c. only inhibited them at the age of 4-6 months. Other activities were not significantly inhibited. The change in the naloxone effect was not due to desensitization as animals treated only at 6 or 8 months reacted similarly. It is suggested that the expression of such stereotypies is influenced by endogeneous brain opioid peptides during an early stage of their development, but that thereafter only motoric automatisms remain, essentially under dopaminergic control.

Genetic analysis of strain differences in pre-laying behaviour in battery cages

The behaviour of hens of two strains during the 10 min before laying in battery cages was studied. Hens of one strain typically exhibited backward-and-forward pacing before laying. Hens of the other strain did not pace and tended to sit. Individual hens of both strains were consistent in their expression of pacing and sitting before laying. There was genetic variation in the expression of both pacing and sitting before laying, and both traits responded to selection. Crosses between the two lines indicated additive genetic variation in the expression of sitting behaviour and non-additive variation in the expression of pacing behaviour.