Immunity in barren and enriched housed pigs differing in baseline cortisol concentration

Hair Cortisol in Service Dogs for Veterans with Post-traumatic Stress Disorder Compared to Companion Dogs (Canis Familiaris)

Service dogs are trained to assist humans. This assistance potentially exposes them to stressors To investigate if service dogs are exposed to more stressors than companion dogs we questioned whether hair cortisol levels differed between both groups. We studied this by cutting a tuft of hair from the neck of 19 companion and 11 service dogs. Cortisol levels were subsequently analyzed via immunoassay and compared via a simple linear regression model. The influence of coat color, season, sex, other dogs, pets, or mental health diagnoses in the household was also checked . Results showed that cortisol values did not differ between service and companion dogs. Furthermore, none of the additional variables had an influence on cortisol levels. This lead to the conclusion that the service dogs in this study did not have higher hair cortisol levels than companion dogs Further study should be conducted as to why no difference did occur between groups and if this difference is persistent over time given that we only studied a period of up to two months' worth of hair cortisol.

Do Service Dogs for Veterans with PTSD Mount a Cortisol Response in Response to Training?

Simple Summary

A growing number of people are supported by specialized service dogs. These dogs are highly trained to improve human welfare, yet not much is known about their own welfare. One of the ways in which welfare can be measured is through the expression of stress via the hormone cortisol. In this study, we investigated the level of cortisol in saliva, a measure for physiological stress, in 19 service dogs. We measured cortisol in the dogs’ saliva 15 min after arrival at a training ground, before partaking in a training session for service dogs, after participation in the training session, and after a 45-min free play period. We found no elevated levels of cortisol after the training session. Instead, we found that cortisol had lowered when compared to before the training. Additionally, we found that cortisol was highest 15 min after arriving at the training round and after 45 min of free play. This led to the conclusion that dogs in our study did not seem to have a stress response in response to participation in the training.

Abstract

Only a few studies have investigated the welfare of animals participating in animal-assisted interventions (AAIs). Most of these studies focus on dogs in therapeutic settings. There are, however, also dogs—service dogs—that are employed to continuously support a single human. Because the welfare of these service dogs is important for the sustainability of their role, the aim of this study was to investigate their stress response to service dog training sessions. To do this, we took repeated salivary cortisol samples from dogs who participated in a training session (n = 19). Samples were taken just after arrival at the training ground, before training, after training, and after a period of free play. Our results showed that mean cortisol levels in all samples were relatively low (between 1.55 ± 1.10 and 2.73 ± 1.47 nmol/L) compared to similar studies. Analysis further showed that samples taken before and after participation in the training’s session did not differ from one another. Mean cortisol levels in both situations were additionally lower than those upon arrival at the training site and after a period of free play. This led to the conclusion that the dogs in our study did not seem to experience training as stressful.

Early and later life environmental enrichment affect specific antibody responses and blood leukocyte subpopulations in pigs

This study addressed the impact of early and later life environmental enrichment, and their combination, on specific antibody responses and peripheral blood leukocyte subpopulations in pigs. Pigs were kept in either barren (B1) or enriched (E1) housing from birth, and half of the pigs switched to barren or enriched housing on day 47, resulting in four treatment combinations: B1B2, B1E2, E1B2, E1E2). Pigs were immunized with keyhole limpet hemocyanin-conjugated trinitrophenyl (KLH-TNP) on day 74 and 109 to induce primary and secondary antibody responses. Blood samples were taken weekly until day 130, and IgM and IgG antibody responses were measured. Leukocyte subpopulations were measured on day 74 and 130. Time course of the antibody responses was not affected by housing. Early life enrichment increased the IgG response to KLH, particularly the primary one. At day 74 the relative frequency of lymphocytes, DC and SLA-II expression on monocytes were higher in E1 pigs, whereas the percentage of granulocytes tended to be lower in E1 pigs at day 74. Early life enrichment increased the SLA-II expression on monocytes, the granulocyte to lymphocyte ratio, and tended to increase the percentage of granulocytes, but tended to decrease the percentage of monocytes at day 130. Later life enrichment reduced percentages of CD4+CD8α⁺ T cells before and after immunization and the SLA-II expression on monocytes at day 74, the percentage of granulocytes and the granulocyte to lymphocyte ratio at day 130. Notably, early and later life housing interacted in their effects on several immune parameters. KLH-IgM responses (both primary and secondary) were affected by the interaction between early and later life housing. IgM titers were higher for B1B2 than for E1E2, with the switched animals (B1E2 and E1B2) moving towards the titers of the animals kept in their later life environment from birth onwards. At day 130 the percentage of gamma delta T cells, CD8α⁺ cytotoxic T cells and DC were not different between pigs kept in B1B2 and E1E2, but there was a clear impact of the switch in housing conditions, particularly for the pigs that changed from barren to enriched housing. We also found effects of coping style (personality) and sex on some immune parameters. In conclusion, both early life and later life enrichment, and, notably a switch in housing conditions influenced specific antibodies and leukocyte subpopulations in pigs. The current study implies that the early life history of animals and the (mis)match with their current environment could thus be of major importance for their immune system. Further research is needed to investigate potential consequences for the pigs' health.

Influence of Housing Conditions on Reliability of Immunocastration and Consequences for Growth Performance of Male Pigs

Simple Summary

Surgical castration of male piglets is societally criticized as it is painful and violates the integrity of the animals. Pork production with boars and immunocastrates are possible alternatives. Even if immunocastration is an animal-welfare-friendly alternative, its market share is low and the reliability of this technique is discussed controversially within the pork chain. Currently, the number and the reason for non-responders to vaccination are not clear. Various factors may contribute to impaired immune response including adverse and stressful housing conditions. This study, therefore, examines the influence of different housing conditions on the immune response after two Improvac^® vaccinations. To determine vaccination success, testosterone concentrations, GnRH-binding, and boar taint compounds were evaluated. Furthermore, the growth performance of male pigs was compared. The results show that immunocastration is reliable under different housing systems and prevents boar taint. Moreover, the growth performance of immunocastrates is high and even superior to that of boars and barrows after the 2nd vaccination. Accordingly, immunocastration is not only animal-welfare-friendly but also economically attractive and suitable for different housing systems.

Abstract

Immunocastration is a sustainable alternative to piglet castration but faces limited market acceptance. The phenomenon of non-responders has not to date been examined in detail, but adverse and stressful housing conditions (e.g., mixing of groups) might impair the success of vaccinations. Therefore, we evaluated the influence of housing conditions on the immune response after two Improvac^® vaccinations at an age of 12 and 22 weeks, respectively. Boars, immunocastrates and barrows (n = 48 each) were assigned to three different housing conditions (n = 36 enriched, n = 36 standard n = 72 repeated social mixing). Immune response was quantified by measuring GnRH-binding and its consequences for testosterone concentrations, development of the genital tract and boar taint. Growth performance was evaluated via average daily gain (ADG). GnRH-binding and testosterone levels revealed that immunocastration reliably suppressed testicular functions after the 2nd vaccination. Housing conditions did not modify testicular function but influenced ADG as animals under mixing grew slower than those under enriched conditions. Gonadal status had only a slight impact on ADG except in immunocastrates, which showed a temporarily higher ADG after the 2nd vaccination. The results show that immunocastration is a reliable procedure under different housing conditions and competitive in terms of growth performance.

Provision Point-Source Materials Stimulates Play in Sows but Does Not Affect Aggression at Regrouping

When sows are mixed into groups, hierarchies form and resulting aggression and stress can affect production and welfare. This study determined the effect of providing point-source materials on aggressive and play behaviors in gestating sows. Large white cross Landrace sows were mixed after insemination; six pens of 12 sows were housed in 'standard' pens, and six pens of 12 sows were housed in 'enhanced' pens. The 'enhanced' pens each contained two rubber mats, eight strands of 24 mm-thick sisal rope and two yellow plastic disks, suspended from the roof. The sows remained in these pens until pregnancy confirmation. Salivary cortisol concentration, injury counts, and sow behaviors were recorded the day before mixing (day 1), mixing (day 0) and post-mixing day 1, day 4, day 7 and day 20. At farrowing, reproductive outcomes were obtained. Play was observed (including locomotor and object play) in the 'enhanced' pen, and percentage of time spent playing was greater on d4 (1.48 ± 0.3 Square root transformed data (2.84% non-transformed adjusted mean)), d7 (1.43 ± 0.3 (2.97%)) and d20 (1.64 ± 0.3 (3.84%)), compared to d0 (0.56 ± 0.3 (0.70%)) and d1 (0.87 ± 0.3 (1.67%) (p < 0.05)). No play was observed in standard housing. Aggression, salivary free cortisol concentrations and injuries were unaffected (p > 0.05). The provision of materials had no impact on aggression, although their presence maintained sow interest and play behavior, suggesting a positive effect.

Enrichment in the Sucker and Weaner Phase Altered the Performance of Pigs in Three Behavioural Tests

We tested the hypothesis that provision of enrichment in the form of enrichment blocks during the sucker and weaner phases would affect the behaviour of pigs. We measured the performance of pigs in an open field/novel object test, a maze test, an executive function test and the cortisol response of the pigs after exposure to an open field test. The provision of enrichment blocks altered the behaviour of the pigs in all three tests and these changes suggest an increased willingness to explore and possibly an increased ability to learn. The behavioural tests highlighted that young pigs have the capacity to learn complex tasks. Our findings support the notion that the benefits of enrichment cannot be evaluated by measuring the interactions the animal has with the enrichments in the home pen and it may simply be beneficial to live in a more complex environment. We have highlighted that the early rearing environment is important and that the management and husbandry at an early age can have long-term implications for pigs. The enrichment we used in this study was very simple, an enrichment block, and we provide evidence suggesting the provision of enrichment effected pig behavioural responses. Even the simplest of enrichments may have benefits for the welfare and development of young pigs and there is merit in developing enrichment devices that are suitable for use in pig production.

Key determinants of pig welfare: implications of animal management and housing design on livestock welfare

The present review using the pig as a model has highlighted the importance of the design of the housing system on the welfare of farm animals. It has emphasised the need for research on animal welfare in new and modified housing systems, as well as current but contentious systems, to be attentive to the design contributions of these systems to animal welfare. The review has highlighted areas for future research to safeguard sow and piglet welfare, including the following: effective environmental enrichment for gestating sows in intensive, indoor and non-bedded systems; opportunities to increase foraging and feeding times in feed-restricted gestating sows; design features that allow both access to important resources, such as feed, water and a comfortable lying area, and escape opportunities to reduce aggression and minimise risks to the welfare of group-housed sows; and less confined farrowing and lactation systems. The review also shows that animal welfare problems may be less a function of the type of housing system than of how well it operates. The skills, knowledge and motivation of stockpeople to effectively care for and manage their animals are integral to the standard of welfare experienced by their animals. Attitudes influence not only the manner in which stockpeople handle animals, but also their motivation to care for their animals. Thus, training targeting technical skills and knowledge as well as the attitudes and behaviours of stockpeople should be a primary component of the human resource management practices at a farm. While public concerns and policy debates often focus on intensive housing systems, research indicates that the design and management of both indoor and outdoor housing systems is probably more important for animal welfare than is generally recognised.

Effect of enriched housing on levels of natural (auto-)antibodies in pigs co-infected with porcine reproductive and respiratory syndrome virus (PRRSV) and Actinobacillus pleuropneumoniae

Housing of pigs in barren, stimulus-poor housing conditions may influence their immune status, including antibody responses to (auto-)antigens, and thus affect immune protection, which will influence the onset and outcome of infection. In the present study, we investigated the effects of environmental enrichment versus barren housing on the level of natural (auto-)antibodies (NA(A)b) and their isotypes (IgM and IgG) binding keyhole limpet hemocyanin (KLH), myelin basic protein (MBP), and phosphorycholine conjugated to bovine serum albumin (PC-BSA) in pigs co-infected with porcine reproductive and respiratory syndrome virus (PRRSV) and Actinobacillus pleuropneumoniae (A. pleuropneumoniae). Pigs (n = 56) were housed in either barren or enriched pens from birth to 54 days of age. They were infected with PRRSV on 44 days of age, and with A. pleuropneumoniae 8 days later. Blood samples were taken on 7 different sampling days. Housing significantly affected the overall serum levels of NA(A)b binding KLH, MBP and PC-BSA, and before infection barren housed pigs had significantly higher levels of NA(A)b than enriched housed pigs, except for KLH-IgM and PC-BSA-IgG. Infection only affected the IgM, but not the IgG isotype. Moreover, changes in MBP-IgM and PC-BSA-IgM following infection were different for enriched and barren housed pigs. These results suggest that the effect of infection on NA(A)b is influenced by housing conditions and that NA(A)b, especially IgM may be affected by infection.

Effect of environmental enrichment and herbal compound supplementation on physiological stress indicators (chromogranin A, cortisol and tumour necrosis factor-α) in growing pigs

Stress response induces physiological, behavioural, immunological and biochemical changes that directly affect health and well-being. Provision of environmental enrichment and herbal compounds may reduce stress in current commercial pig husbandry systems. The aim of this study was to evaluate the effect of providing different environmental enrichment materials (EE) and a herbal compound (HC) on physiological indicators of acute and chronic stress in growing pigs (salivary cortisol and chromogranin A (CgA), hair cortisol and tumour necrosis factor-α (TNF-α)). Salivary cortisol and CgA have been reported as biomarkers basically of acute stress, whereas hair cortisol and TNF-α have been more related to chronic stress. For this purpose, eight groups of seven pigs each (14 pigs/treatment, 56 pigs in total) were used: (a) two EE groups, (b) two groups supplemented with HC, (c) two groups provided both with EE and HC and (d) two control groups. Samples of hair, saliva and blood were taken to measure cortisol (in hair and saliva), CgA (in saliva) and TNF-α (in blood) at three different times: before starting the experiment (T0), and after 1 (T1) or 2 months (T2) of providing the materials and herbal compound. No differences were found at T0 in salivary or hair cortisol, CgA or TNF-α, whilst at T2, the control group showed significant increased concentrations of CgA and hair cortisol, when compared with the rest of the treatments (P<0.001). These differences were significant at T1 only for CgA (P<0.001). Furthermore, an overall correlation was reported between hair cortisol and salivary CgA (r=0.48, P<0.001). These results support that providing enrichment material or an herbal compound may reduce stress in growing pigs. Furthermore, the results support that hair cortisol and CgA may be proper non-invasive tools to detect stress, specially associated with factors of chronic exposure.

Acute social stress-induced immunomodulation in pigs high and low responders to ACTH

Pig husbandry is known as an intensive breeding system, piglets being submitted to multiple stressful events such as early weaning, successive mixing, crowding and shipping. These stressors are thought to impair immune defences and might contribute, at least partly, to the prophylactic use of antibiotics. Robustness was recently defined as the ability of an individual to express a high-production potential in a wide variety of environmental conditions. Increasing robustness thus appears as a valuable option to improve resilience to stressors and could be obtained by selecting piglets upon their adrenocortical activity. In this study, we aimed at depicting the consequences of an acute social stress on the immune capacity of piglets genetically selected upon divergent hypothalamic-pituitary-adrenocortical (HPA) axis activity. For this purpose, we monitored neuroendocrine and immune parameters, in high- (HPA^hi) and low- (HPA^lo) responders to ACTH, just before and immediately after a one-hour mixing with unfamiliar conspecifics. As expected, stressed piglets displayed higher levels of circulating cortisol and norepinephrine. Blood cell count analysis combined to flow cytometry revealed a stress-induced leukocyte mobilization in the bloodstream with a specific recruitment of CD8α⁺ lymphocytes. Besides, one-hour mixing decreased LPS-induced IL-8 and TNFα secretions in whole-blood assays (WBA) and reduced mononuclear cell phagocytosis. Altogether, our data demonstrate that acute social stress alters immune competence of piglets from both groups, and bring new insights in favour of good farming practices. While for most parameters high- and low-responders to ACTH behaved similarly, HPA^hi piglets displayed higher number of CD4⁺ CD8α^- T cells, as well as increased cytokine production in WBA (LPS-induced TNFα and PIL-induced IL-8), which could confer them increased resistance to pathogens. Finally, a principal component analysis including all parameters highlighted that overall stress effects were less pronounced on piglets with a strong HPA axis. Thus, selection upon adrenocortical axis activity seems to reduce the magnitude of response to stress and appears as a good tool to increase piglet robustness.

Group and individual sow behavior is altered in early gestation by space allowance in the days immediately following grouping

Aggression between domestic sows is greatest when sows are first introduced to each other and hierarchies form. The aim of this study was to determine the effect of a spacious "mixing pen" on sow aggression and stress. Sows were mixed into groups of 6 and allowed 2 (LOW; 8 groups and 48 sows), 4 (MED; 7 groups and 42 sows), or 6 m/sow (HIGH; 7 groups and 42 sows) for 4 d after mixing, at which point all pens were equalized to 2 m/sow. Salivary cortisol concentration and injury counts were measured on d -1, 0, 1, 3, and 4 relative to mixing, and behavior was also recorded on each of these days following mixing. Reproductive performance was assessed at farrowing. A linear mixed model was applied to the data. Data are presented as least squares means and standard error of the mean. Where transformations occurred, nontransformed adjusted means are presented in parentheses following the presentation of transformed data. In the primary analyses where measures were considered at the pen level, there were no effect of space allowance on fight number per sow, duration of fights, percentage of total time spent fighting, displacements, bites, knocks, and lunges ( > 0.05). These measures were higher on d 0 (i.e., fight number 1.0 ± 0.1 [13.8]) compared with d 1 (0.4 ± 0.1 [4.2]), 3 (0.7 ± 0.1 [5.3]), and 4 (0.7 ± 0.1 [5.5]; < 0.05), with no increase in aggression on d 4 when pen sizes were standardized ( > 0.05). There was increased percentage of time spent active (1.5 ± 0.02 [33.7] for LOW, 1.5 ± 0.02 [36.5] for MED, and 1.6 ± 0.02 [43.4] for HIGH) and time spent exploring (1.8 ± 0.1 [3.5] for LOW, 2.0 ± 0.1 [4.0] for MED, and 2.3 ± 0.1 [5.7] for HIGH) and number of nonaggressive sow-sow contacts (0.3 ± 0.09 [2.2] for LOW, 0.4 ± 0.07 [3.2] for MED, and 0.5 ± 0.07 [4.5] for HIGH) in HIGH compared with LOW ( < 0.05). Farrowing rate and total piglets born were not affected by treatment ( > 0.05). A secondary analysis was conducted that examined individual sow behavior within each pen, and this identified increased injury number in the lowest ranked sows (involved in no fights on d 0 and no displacements on d0 to d4) in LOW (9.3 ± 1.2 [107.9] for LOW, 6.2 ± 0.8 [53.0] for MED, and 5.1 ± 0.8 [28.1] for HIGH) and also decreased fight number and duration in HIGH compared with LOW on d 0 and 1 ( < 0.05). Our primary data analysis demonstrates positive exploratory and social behaviors with increased space and suggests that a reduction in space following hierarchy formation is not a significant stressor. Additionally, there is some evidence at an individual sow level that increased space at mixing benefits sow welfare parameters, especially for low-ranked sows.

Effect of enriched housing on welfare, production performance and meat quality in finishing lambs: the use of feeder ramps

This study analyses the effect of environmental enrichment on the welfare, productive traits and meat quality of lambs housed in feedlots. Sixty lambs were placed in enriched (EE) or conventional (CO) pens (3 pens for each treatment, 10 lambs/pen) where EE had a wooden platform with ramps that provided access to a concentrate hopper, cereal straw as bedding and forage, and one play ramp. The CO pen was barren, similar to commercial feedlots. The physiological adaptation response of EE lambs was more efficient than CO, since the latter mobilised more body reserves (i.e., increased NEFA, P<0.05), and had lower levels of immunity (i.e., increased N/L, P<0.05), which indicate chronic stress, probably associated with the barren environment. The EE lambs had a higher (P<0.05) average daily gain, with heavier carcasses and higher fattening scores, as well as lower pHult, higher L and b values, and lower values of texture (P<0.05).

Physiological indicators of stress and meat and carcass characteristics in tail bitten slaughter pigs

Background

Tail biting is a common welfare problem in pig production and in addition to being a sign of underlying welfare problems, tail biting reduces welfare in itself. The aim of this study was to evaluate the effects of tail biting on different pre and post mortem indicators of stress in slaughter pigs and on carcass and meat characteristics. A total of 12 tail bitten (TB) and 13 control (C) pigs from a farm with a long-term tail biting problem were selected for salivary cortisol analyses before and after transport to the slaughterhouse. After stunning, samples were taken for the analysis of serum cortisol, blood lactate, intestinal heat shock protein 70 (HSP70), and meat quality characteristics. In addition, body temperature immediately after and muscle temperature 35 min after stunning were measured, as well as lean meat percentage and carcass weight.

Results

TB pigs showed a lower cortisol response to the transport-induced stress than C pigs and also had a lower serum cortisol concentration after stunning. HSP70 content in the small intestine was higher in the TB pigs than in C pigs. TB pigs had a considerably lower carcass weight therefore produced a lower total amount of lean meat per carcass than C pigs.

Conclusions

This study suggests that prolonged or repeated stress in the form of tail biting causes a blunted stress response, possibly a sign of hypocortisolism. In addition, it underlines the importance of reducing tail biting, both from an animal welfare and an economic point-of-view.

Health and immune traits of Basque and Large White pigs housed in a conventional or enriched environment

Since decades, production traits such as growth rate, feed efficiency or body composition have been drastically increased in pigs by genetic selection. Whether this selection impacted animal robustness is still unclear. In this study, we compared Large White (LW) pigs, a breed submitted to intense genetic selection for production traits, and Basque (B) pigs, a local rustic breed, reared in two different housing environments (conventional v. enriched). Adaptation to housing conditions among each breed was evaluated at the level of endocrine and immune traits. These are known to be impacted by housing conditions and breed; however, the interaction effects between genotype and environment are less described. Animals (20 per breed and housing environment) entered the experiment at 35 kg of live weight. Levels of cortisol, acute-phase inflammatory proteins, immunoglobulins and hydrogen peroxide, blood formula, lymphocyte proliferation and in-vitro cytokine expression were measured at ∼115 kg of live weight. Animals were checked for skin injuries during the growing period. At slaughter, at the average live weight of 145 kg, carcasses were examined for pathological conditions of the respiratory tract. The major result was that the two breeds exhibited differences in response to the housing environment. Among the 24 sanitary, endocrine or immune traits investigated, the housing conditions affected eight variables in both breeds (salivary cortisol at 0700 and 1900 h, severity of pneumonia at slaughter) or only in B pigs (severe skin lesions) or LW pigs (salivary cortisol at 1500 h, granulocyte numbers and lymphocyte/granulocyte ratio and lymphocyte proliferation). These observations strengthen the hypothesis that selection for high meat production level might be associated with an increased susceptibility of animals to environmental stressors.

The delayed type hypersensitivity assay using protein and xenogeneic cell antigens

The delayed-type hypersensitivity (DTH) assay has a lengthy history in immunotoxicity testing since it was one of the original functional assays included in the National Toxicology Program (NTP) immunotoxicology test panel. Based on NTP data analysis, the DTH assay is among the most predictive immunotoxicity tests when included with at least two other immune parameters. The DTH assay has the advantage of being: (1) a useful measure of cell-mediated immunity, (2) an in vivo assay where there is less opportunity for ex vivo confounders and (3) a clinically significant human correlate to the tuberculin test. Disadvantages of the DTH assay are that it is potentially labor-intensive to perform, it is somewhat resistant to automation and, when compared with the cyctotoxic T lymphocyte (CTL) assay, it is a relatively crude measurement. However, some groups have been attempting to address the limitations of the DTH assays (see Note 1).The assay is related to the contact hypersensitivity response (CHR), which is covered in another chapter. The DTH response has been used as an indicator of cell-mediated immune status and is dependent upon both T helper 1(Th1)-driven responses as well as cell recruitment and chemotaxis to a local site. As a result, the DTH functional response may be influenced by disruption of either Th1-driven, antigen-dependent T cell development or mobilization of sensitized T cells to a local site. The present chapter describes four common protocols with consideration restricted to protein and xenogeneic cell immunogens.

Environmental enrichment for maned wolves (Chrysocyon brachyurus): group and individual effects

Procedures that increase foraging and exploratory behaviours are generally accepted as effective at improving welfare and reducing stereotypies in captive animals. To determine the effect of food and toy enrichment on the behaviour and hormonal levels of maned wolves (Chrysocyon brachyurus), 11 wolves were submitted to a baseline-enrichment-baseline schedule with four enrichment conditions: food scattering, toy presentation, edible toy presentation, and a combination of food and toy conditions. Behaviour and glucocorticoid metabolite concentrations (GCM) were assessed throughout the experiment. Our hypotheses were that enrichment procedures would lead to an increase in activity in the short and long term, a decrease in pacing, and a reduction in GCM concentrations. We also hypothesised that the concentrations of GCM would show a correlation with behaviour. Enrichment conditions increased immediate locomotion but did not produce long-term changes of activity nor reduced pacing. The procedures had a clear effect on individual behaviour and induced, under food enrichment conditions, an increased interest in food. Enrichment did not lead to decreased GCM concentration in the group as a whole, but there was a tendency for male and female animals to differ in hormonal reactions to environmental change. A positive correlation between GCM concentrations and pacing behaviour and a negative correlation between GCM concentrations and social behaviour were found. Results suggest that food scattering as an enrichment procedure may be used with maned wolves to enhance welfare, whilst also revealing the importance of taking individual and gender differences into account when planning enrichment techniques.

Welfare assessment of captive Asian elephants (Elephas maximus) and Indian rhinoceros (Rhinoceros unicornis) using salivary cortisol measurement

The measurement of salivary cortisol allows non-invasive assessment of welfare in captive animals. We utilised this technique to test the effect of zoo opening on six Asian elephants and two Indian rhinoceros at the Terra Natura Zoological Park, Alicante, Spain, during pre-opening, opening and post-opening periods. Salivary cortisol concentrations were found to be significantly higher during the opening period than during pre- and post-opening periods for both species. This method could prove a useful tool in monitoring the success of decisions taken to improve the welfare of captive animals.

Dietary antioxidants and behavioral enrichment enhance neutrophil phagocytosis in geriatric Beagles

The study objective was to determine the effects of feeding food enriched in antioxidants and a program of environmental/cognitive enrichment on selected ex vivo assays of inflammatory and immune cells in healthy geriatric Beagle dogs (n=21). Four groups of dogs were tested using a 2 x 2 factorial design. The 2-year longitudinal study included both nutritional (control food or antioxidant-fortified food) and behavioral (normal level or cognitive enrichment) interventions. Behavior enrichment included increased exercise, environmental enrichment, and a series of learning tasks. Phagocytosis of opsonized latex-coated beads by peripheral blood neutrophils was measured by flow cytometry and found to be significantly increased in dogs receiving both dietary antioxidants and cognitive enrichment. Simultaneous stimulation of cells with Con A and suppression with Dex resulted in decreased lymphocyte proliferation in dogs receiving both dietary antioxidants and cognitive enrichment, compared to dogs receiving dietary antioxidants or cognitive enrichment alone. There were no significant differences between the groups of dogs for percentages of CD4 and CD8 T-lymphocyte subpopulations before or after lymphocyte stimulation with Con A. These results support our hypothesis that both dietary antioxidants and behavioral enrichment enhance host defense mechanisms.

Effects of environmental enrichment on males of a docile inbred strain of mice

Environmental enrichment is intended to improve the welfare of laboratory animals. However, regarding male mice, numerous studies indicate an increase in aggressive behavior due to cage structuring. On the one hand, this might be a problem concerning animal welfare. On the other hand, enrichment is though to hamper environmental standardization and to increase variability of data. Furthermore, increasing fights, arousal, and/or injury in enriched housed animals might superimpose other (positive) environmental effects on behavior and physiology. Therefore, the present study investigated effects of environmental enrichment on behavioral, endocrinological, and immunological parameters in male mice of the docile inbred strain ABG. From weaning until day 77+/-3 of life, animals were kept in stable sibling groups of four under three different housing conditions: (A) nonstructured Makrolon type III laboratory cages ("standard housing"=S); (B) equivalent laboratory cages that were enriched with a box and scaffolding ("enriched housing"=E); and (C) spacious terrariums that were structured richly ("super-enriched housing"=SE). No differences in agonistic behavior, levels of plasma corticosterone (CORT), and activities of adrenal tyrosine hydroxylase (TH) existed among S-, E-, and SE-housed ABG males. Play behavior and general activity increased significantly with increasing enrichment. Concerning immunological parameters, males of both forms of enriched housing showed significantly lower percentages of CD4 and CD8 cells compared to S-housed mice. However, regarding the ratio of CD4/CD8 cells, IL-2, IL-4, IL-10, IFN-gamma, IgG1, and IgG2a, no significant housing-dependent differences were found. Enrichment did neither hamper standardization nor negatively influence the variability of physiological parameters. In summary, using a docile strain of mice revealed the positive effects of environmental enrichment also on male mice. The lack of adverse effects on behavior, physiology, standardization, and variability of data defuses these arguments against providing docile male mice with enrichment.

Effect of response to backtest and housing condition on cell-mediated and humoral immunity in adult pigs

Several recent studies in juvenile pigs demonstrated a relationship between the degree of resistance displayed early in life in a so-called "backtest" and parameters of cell-mediated and humoral immunity. Some of the immune characteristics were reported to depend on the interaction between backtest classification and housing system. In the present study, the effects of backtest classification and housing condition on immune reactivity in adult gilts were examined. At 10 and 17 days of age, female piglets were subjected to the backtest. In this test, each piglet is restrained on its back for 1 min and the number of escape attempts is scored. Pigs classified as high resisting (HR) or low resisting (LR) were selected and housed in groups of six gilts. At 7 months of age, half of the gilts were housed in individual stalls. At 12 months of age, gilts were challenged by immunization with DNP-KLH. Control gilts were treated similarly with a placebo. Blood samples were drawn prior to immunization (Day 0) and weekly thereafter until Day 28. No significant effects of backtest type on cellular and humoral responses against KLH were found. Furthermore, being housed in stalls as compared to groups had no consequences for the immune response and did not induce differences between HR and LR gilts. Differences in behavior and physiology found previously between HR and LR gilts, particularly in gilts in stall housing, may thus be of relatively little importance for immune-related health.

Effects of housing and individual coping characteristics on immune responses of pigs

The impact of environmental factors on immune responses may be influenced by coping characteristics of the individuals under study. The behavioral response of pigs in a so-called Backtest early in life seems indicative of their coping style at a later age. The present study investigated the effects of housing, barren versus enriched, and coping style, as assessed by Backtest classification, on immune responses of pigs. Pigs were housed either without a rooting substrate (barren housing) or in identical pens enriched with deep straw bedding (enriched housing) from birth. During the suckling period, pigs were subjected to the Backtest. Each pig was restrained on its back for 1 min and the resistance (i.e., number of escape attempts) was scored. Pigs classified as 'high-' or 'low-resisting' (HR and LR, respectively) were immunized with di-nitrophenyl-conjugated keyhole limpet haemocyanin (DNP-KLH) at 9 weeks of age. Blood samples were drawn before immunization (Day 0) and weekly thereafter, until Day 35. KLH-specific lymphocyte proliferation following immunization was higher for HR pigs than for LR pigs. Housing did not affect proliferative responses. Housing and coping style interacted in their effect on KLH-specific humoral immune responses. LR pigs from barren housing showed higher KLH-specific antibody titers than LR pigs from enriched housing. Differently housed HR pigs, however, showed similar antibody titers. These findings support other research indicating that individual coping styles of pigs are reflected in their immune responses. More important, the present study demonstrates that effects of housing on humoral immune responses of pigs may differ for pigs with divergent coping styles.