Chimpanzees are sometimes housed in conditions of restricted social contact during use in biomedical research, a practice that may adversely affect their behaviour. This study measured the impact of such conditions on levels of stereotyped body rocking in six young, nursery-reared chimpanzees. Subject age at the beginning of the biomedical research protocol ranged from 1.1 to 3.8 years. Over a six-month period the subjects were moved to a different facility. During this time they were used in a biomedical research study which involved some periods of single housing. They were then returned to their original facility. The percentage of time subjects devoted to stereotyped rocking was measured for 36 weeks before and 36 weeks after participation in the biomedical protocol. Data on body rocking were also analysed for a post-test control group of animals (n = 9) who had a similar history of handrearing, but who did not leave the facility to participate in a biomedical research study. The behavioural analyses included 263 hours of focal animal observational data and revealed that the experimental subjects devoted equivalent amounts of time to rocking before and after participation in the biomedical research protocol. The experimental subjects and the control subjects showed similar levels of rocking. These findings indicate that participation in this particular short-term biomedical research protocol did not affect the expression of stereotyped rocking in chimpanzees.

Studies of the brain inform us about the cognitive abilities of animals and hence affect the extent to which animals of that species are respected. However, they can also tell us how an individual is likely to be perceiving, attending to, evaluating, coping with, enjoying, or disturbed by its environment, and so can give direct information about welfare. In studies of welfare, we are especially interested in how an individual feels. Since this depends upon high-level brain processing, we have to investigate brain function. Brain correlates of preferred social, sexual and parental situations include elevated oxytocin in the para-ventricular nucleus of the hypothalamus. Abnormal behaviour may have brain correlates, for example, high frequencies of stereotypy are associated with down-regulated μ and κ receptors and dopamine depletion in the frontal cortex. Such results help in evaluating the effects of treatment on welfare. Some brain changes, such as increased glucocorticoid receptors in the frontal lobes or increased activity in the amygdala, may be a sensitive indicator of perceived emergency. Active immunological defences lead to cytokine production in the brain, vagal nerve activity and sickness effects. Some aspects of brain function can be temporarily suppressed, for example, by opioids when there is severe pain, or permanently impaired, for example, in severely impoverished environments or during depression. Coping attempts or environmental impact can lead to injury to the brain, damage to hippocampal neurons, remodelling of dendrites in the hippocampus, or to other brain disorganisation. Brain measures can explain the nature and magnitude of many effects on welfare.

Techniques to reduce or prevent behavioural disturbances in singly caged primates vary in form and effectiveness, with some behaviours being exceptionally resistant to treatment. Seven singly caged adolescent male olive hybrid baboons (Papio hamadryas anubis) were selected for behavioural intervention because of their severe abnormal behaviour. A continuous, all-occurrence sampling method yielded mean durations of abnormal and normal behaviour throughout the 10-week study. Analysis of baseline behaviour verified substantial durations of abnormal behaviour (mean = 9.80 min per 30-min observation period). We tested the effectiveness of four enrichment techniques: positive reinforcement training (PRT), food enrichment, non-food enrichment, and social enrichment (pair/trio housing). Each of the four enrichment conditions was implemented for a two-week period, with 10 30-min observations conducted per subject. We used repeated-measures analysis of variance to examine differences in behaviour durations between baseline and each enrichment condition. The social enrichment condition resulted in the most positive behavioural changes, including increased social behaviour and near elimination of abnormal behaviours (mean = 0.69 min per 30-min observation). Significant reductions in total abnormal behaviour levels were also found for other types of enrichment, but only social enrichment and PRT were effective in reducing whole-body stereotypies. Cage-directed and self-directed behaviours significantly decreased, whereas activity levels significantly increased during all enrichment conditions. The results of this project indicate that animate enrichment (human or conspecific stimulation), as opposed to inanimate enrichment, provides optimal means of behaviour modification for singly caged baboons. These findings have substantial implications for the welfare of captive primates in promoting successful therapeutic approaches for the behavioural management of laboratory primate species and for allocating limited enrichment resources.

Primates are highly social animals and appropriate enrichment is required to ensure their psychological well-being. Mirrors are sometimes used as social or sensory environmental enrichment. In this paper we investigate the suitability of mirrors as enrichment for captive primates, by reviewing the literature on mirror implementation in captive primate environments. Mirror-directed responses are mainly social as the mirror self-image is often seen as a conspecific. Although positive exploration and affiliative behaviours are observed, negative aggressive behaviours towards the mirror are most frequently recorded, and abnormal behaviours in primates do not decrease in mirror-enriched environments. There appear to be differences in habituation rates to mirrors amongst primates. While habituation to enrichment is generally perceived to be undesirable, this criterion should not apply when mirrors elicit negative behaviours. Primates that show mirror self-recognition, which are mostly great apes, may be best suitable for mirror enrichment, as they do not perceive the mirror self-image as a threatening conspecific. Increasing the understanding of the reflective properties of a mirror might help primates to understand that the image in the mirror is not real. This could be attained by using small, mobile mirrors. We suggest that mirrors can make decent primate enrichment if the primate understands its reflective properties, which should be evaluated on an individual level. Appropriate use of mirrors as sensory enrichment can improve primate well-being and prevent suffering.

In the wild, rabbits (Oryctolagus cuniculus) are social but territorial. Recent surveys suggest that over half of pet rabbits are housed singly. We aimed to compare welfare in single versus paired rabbits. We predicted singletons would show more abnormal or escape behaviour, greater stress responses to handling, and reduced body temperature (being unable to huddle with another individual when cold), but that pairs may show aggression. This study was conducted during winter at a rabbit-only rescue centre, and included 45 rabbits, comprising 15 housed singly and 15 pairs. Like most pet rabbits, they were housed either outdoors or in unheated outbuildings. Singletons were mostly in smaller enclosures than pairs. Home-pen observations (40 min) revealed bar-biting in 8/15 single rabbits compared with 0/30 of the paired ones. No other behavioural effects of social housing reached significance, and enclosure size showed no significant effects. Body temperature was significantly lower in singletons than pairs, with at least 0.5°C mean difference. On colder days, rabbits adopted compact postures more, and relaxed postures less frequently. After handling, pairs resumed normal behaviour significantly more quickly than singletons in the home-pen (3.0 [± 0.3] versus 8.3 [± 1.3] s, respectively). Aggression was never observed. The results indicate that social housing reduces bar-biting, aids thermoregulation, and may help buffer stress. Rabbit owners should be encouraged to meet the need for rabbits to be housed with an appropriate conspecific in a suitably large, sheltered enclosure.

Tail-biting in pigs (Sus scrofa) reduces welfare and production. Tail-docking reduces (but does not eliminate) tail-biting damage. The reason tail-docking reduces tail damage is unknown. It may reduce pigs’ attraction to tails (H1), or increase tails’ sensitivity to investigation (H2). To investigate these hypotheses, behavioural differences between 472 individually marked grower pigs with intact tails (nine groups of 25-34 pigs) or docked tails (nine groups of 22-24 pigs) were observed from 5-8 weeks of age on a commercial farm in Denmark. Pens had part-slatted floors, dry feeding and two handfuls of straw per day, and enrichment objects were provided. Behavioural sampling recorded actor and recipient for tail-directed (tail interest, tail in mouth, tail reaction) and investigatory behaviours (belly-nosing, ear-chewing, interaction with enrichment). Scan sampling recorded pig posture/activity and tail posture. Intact-tail pigs performed more overall investigatory behaviours but tail type did not affect the amount of tail-directed behaviours. Larger pigs performed more investigatory and tail-directed behaviours than smaller pigs and females performed slightly more tail investigation. Tail-directed behaviours were not consistent over time at the individual or group level. However, ear-chewing was consistent at the group level. One group with intact tails was affected by a tail-biting outbreak in the final week of the study (evidenced by tail-damage scores) and showed an increase over time in tail posture (tail down) and tail-directed behaviour but not activity. Overall, there were few behavioural differences between docked and undocked pigs: no evidence of reduced tail investigation (H1) or an increased reaction to tail investigation (H2) in docked pigs, and yet docked pigs had less tail damage. We propose that docking might be effective because longer tails are more easily damaged as pigs are able to bite them with their cheek teeth.

The influence of several factors on abnormal behaviour was investigated in 46 singly housed sooty mangabeys (Cercocebus atys) (eight nursery-reared, 38 mother-reared), including self-injurious, self-directed, stereotypic locomotion, and faeces/urine-related behaviours (SIB, SDB, SL, FUR, respectively). An analysis of behavioural assessments spanning a mean of four years per subject showed that 83% displayed at least one form of AB during that time, with SL being the most common (mean of 3.06% of observation sessions and displayed by 59% of subjects) and SIB the least common (mean of 0.09% of all observation sessions and displayed by 20% of subjects). Like other primate species, displaying AB was influenced by the percent of life spent singly housed and by nursery-rearing during infancy. However, unlike some other primates, there was no influence of the number of yearly sedations or room relocations on AB; also, females were more likely to display AB than male mangabeys. To investigate the effects of nursery-rearing further, we compared the eight nursery-reared, singly housed subjects with eight nursery-reared subjects that were socially housed since the age of three years. While nursery-reared subjects in single housing displayed SL and FUR in higher proportions than those in social housing, subjects from both environments displayed SIB and SDB in equal proportions, suggesting that they are persistent forms of AB for nursery-reared mangabeys even after long-term social housing. To reduce future incidence of AB in captive mangabeys, we recommend minimising nursery-rearing and the duration of single-housing whenever feasible or avoiding them altogether.

Although barbering is common in laboratory mice (Mus musculus), little is known about its effects, both on animal welfare and the research data collected from barbered mice. To gain information on the occurrence of barbering and related risk factors in animal facilities in Germany, we performed an online survey. All the respondents (n = 32 animal facilities) had experienced barbering in their facility. In most cases, less than 10% of the mice were affected, and the age of onset was mostly observed to be 2 to < 6 months. A greater susceptibility was reported in females and in C57BL/6 mice, but this could not be verified as the prevalence of females and the C57BL/6 strain was unknown. One facility reported differences in barbering between commercial animal suppliers. Barbering was also recorded in mice provided with enrichments, such as houses, wood-gnawing blocks, tunnels, running wheels/discs or cage dividers. None of the responding facilities provided swings, structural elements such as an elevated platform or foraging and cognitive enrichment. The questions of whether barbering may have an impact on study results and whether victims of barbering can be used for experiments revealed mixed opinions, most likely due to a lack of data on potential effects. This survey clearly demonstrated barbering to be a widely underestimated problem that is not given enough attention. We suggest that the occurrence of barbering should be systematically documented in every animal facility and reported in research articles, to provide a greater understanding of barbering and its potential effects.

Regurgitation and reingestion (R/R) of foodstuffs is a common abnormal behaviour in captive western lowland gorillas (Gorilla gorilla gorilla) and certain other non-human primates, but it is not part of their normal feeding mechanism. It is similar to a behavioural problem seen in humans, human rumination syndrome (HRS), which can occur in association with anxiety or a poor relationship with a caregiver. Patients with HRS often regurgitate stomach acid with the food matter which can result in clinical problems; until this study, it was not known if stomach acid is regurgitated by gorillas also. Thus, samples of regurgitated matter were collected opportunistically and non-invasively, and pH was measured using an electronic meter. Results were compared with the pH of samples of the original food eaten by the gorillas, and show that regurgitated food has significantly higher acidity than the originally-ingested meal. By comparison, samples of saliva were collected from gorillas opportunistically, in the absence of recent ingestion, and were found to be alkaline and, thus, saliva should not have contributed to the increased acidity of regurgitated matter. The results imply that stomach acid is being regurgitated, as in human patients with potentially-injurious rumination syndrome, and it is indicative of sub-optimal welfare. Causes and effects of R/R should be investigated further, to lead to potential treatment and prevention and to promote the welfare of captive gorillas.

Non-human primates occasionally exhibit behaviours thought to occur only in captivity that are considered abnormal. In particular, hair-plucking behaviour occurs across many species of mammals and birds. This study was the first to assess the phenomenology, demography and aetiology of this behaviour in captive gorillas across the Association of Zoos and Aquariums (AZA) population. A survey was sent to 52 AZA institutions housing western lowland gorillas. Hair-plucking behaviour occurred in 15% of the surveyed population with 62% of institutions housing a hair plucker. Individuals were most likely to self-pluck using their fingers. Individuals that were exposed as youngsters to a hair-plucking group member were significantly more likely to develop the behaviour themselves. There was also a trend toward solitary individuals being more likely to perform this behaviour. Future research needs include identifying hormonal correlates to this behaviour, understanding its relationship to acute or chronic stressors, and examining what causes this behaviour to fluctuate in frequency once it has developed.

The aim of the study was to analyse the influence on tail-biting in undocked pigs during the rearing period of crude fibre in piglets' rations. All pigs were fed the same pre-starter until weaning. The study comprised two trials with four experimental groups each. The first trial contained: a control group (CG1) with conventional feed (up to 40 g/kg crude fibre), two groups with an increased crude fibre content of up to 50 g/kg (G5) and 60 g/kg (G6), respectively, and one group with conventional feed and crude fibre provision ad libitum (AL). The second trial consisted of a control group (CG2) which received the same conventional feed as CG1 and three treatment groups with either soya hulls (SS), dried sugar beet pulp (DP) or oat fibre (OF) admixed to their ration, to achieve a crude fibre content of 60 g/kg in all three groups. The rearing week, the batch, the treatment group (only in trial one) and the interaction between batch and treatment group had a significant influence on tail-lesions (P < 0.05). The tail-biting process started in rearing week 3 (trial one) and 5 (trial two), respectively. Due to the low frequency of tail-biting during the present study, crude fibre seems to have no major influence on tail-biting during the rearing period. This unexpected result may be caused by the optimized conditions in which the piglets were kept and the intensive animal observation carried out by the employees. However, the batch effect was most influential.