Is there a positive side to stress?

An effective environmental enrichment framework for the continual improvement of production animal welfare

Substrates and objects are provided to farm animals on the assumption that they improve animal welfare by enriching the environment, but these often fail to consider the extent to which an environmental enrichment (EE) improves animal welfare, if at all. Furthermore, there are numerous definitions of EE, each with a unique expectation. If expectations of animal welfare improvement are set too high, industry uptake may be thwarted, but if thresholds are set too low it will not result in meaningful improvements to animal welfare. We propose an EE framework based on revised definitions of EE that reflect improvements to various components of animal welfare: (i) pseudo-enrichment; (ii) EE for meeting basic needs; (iii) EE for pleasure; and (iv) EE for positive welfare balance. This framework requires short- and long-term assessments to determine the impact of the EE, although many are lacking in the production animal literature. Redefining EE with a focus on specific animal welfare outcomes will assist producers in identifying the optimal EE for their enterprise. Subsequently, we encourage dialogue between farmers, researchers and industry stakeholders when designing environmental enrichment programmes. This framework is a science-based tool that can be used to inform the development of clear EE assessment protocols and requirements for animal welfare legislation, assurance programmes and industry. This evidence-based framework ensures that the focus is on the outcome of EE programmes rather than the intent. Importantly, this framework has the flexibility to adapt even as baseline environments evolve, ensuring the continual improvement to production animal welfare.

Environmental Complexity: Additional Human Visual Contact Reduced Meat Chickens’ Fear of Humans and Physical Items Altered Pecking Behavior

Increased environmental complexity can improve animal welfare, depending on the resources provided and use by the animal. We provided chickens either with physical items that posed no biosecurity risk and were inexpensive (balls, chains, perches and rope) (P; n = 36) or additional visual human contact (10 min daily) (HC; n = 36) compared to farm-like standard control groups (C; n = 36) with 3 pens per treatment. Additional human contact reduced fear of humans at 35 days of age, but not general fearfulness. P birds required more inductions to induce tonic immobility compared to HC and C birds at 21 days of age. However, other indicators of fear (open field test and plasma corticosterone concentration) did not significantly differ. P birds favored the woodblock for resting, and the perch but preferred to sit underneath the perch rather than on top. When pecking items were not provided, C and HC chickens redirected their pecking behavior toward the litter. Overall, there was little evidence that our physical items improved the chickens’ behavioral time budget, fear, physiological stress or production. Additional human contact should be investigated in large scale experiments to ensure its effectiveness to reduce fear of humans on farm.

Effects of heat stress and a low energy diet on blood parameters and liver hsp70 and iNOS gene expressions in local chickens

Two experiments were conducted to compare effects of heat stress and its combination with low dietary energy on blood indices, liver hsp70 and iNOS gene expressions in three Tanzanian local chicken ecotypes. In experiment one, five weeks old Kuchi (K), Ching'wekwe (C) and Morogoro medium (M) were randomly allocated to separate pens in a 3 × 2 factorial design in two adjacent rooms with controlled temperature. The study had three replicates consisting of 39 chickens per room, 13 per ecotype per pen making a total of 234 chickens. In one room, temperature was maintained at 26.5 ± 0.5 °C while in another it was maintained at 32±1 °C for 7 days and thereafter 37±1 °C for 10 days. A similar design was used in experiment two except that chickens were fed 55% less energy. In experiment one, serum corticosterone levels increased (p<0.05) in C and K. Gene expressions for hsp70 and iNOS were unchanged though hsp70 levels for K were higher (p<0.05). In experiment two, corticosterone levels were significantly elevated (p<0.05) in all ecotypes. Heterophil/lymphocyte ratios were markedly increased and changes in Hb and Hct at higher temperatures showed ecotype differences. Serum triglycerides were significantly reduced in all ecotypes. Hsp70 and iNOS levels were up-regulated in all ecotypes with levels in K higher (p<0.05) than in M. In both experiments, there were marked reductions in serum total protein. These results suggest that ecotype-based differences exist in local chickens’ responses to heat stress and its combination with low energy diets. M and C demonstrated better tolerance than K when only heat stress was applied but a synergistic effect of heat stress and low dietary energy suggested M is more tolerant.

A review of environmental enrichment for laying hens during rearing in relation to their behavioral and physiological development

Globally, laying hen production systems are a focus of concern for animal welfare. Recently, the impacts of rearing environments have attracted attention, particularly with the trend toward more complex production systems including aviaries, furnished cages, barn, and free-range. Enriching the rearing environments with physical, sensory, and stimulatory additions can optimize the bird's development but commercial-scale research is limited. In this review, "enrichment" is defined as anything additional added to the bird's environment including structurally complex rearing systems. The impacts of enrichments on visual development, neurobehavioral development, auditory stimulation, skeletal development, immune function, behavioral development of fear and pecking, and specifically pullets destined for free-range systems are summarized and areas for future research identified. Visual enrichment and auditory stimulation may enhance neural development but specific mechanisms of impact and suitable commercial enrichments still need elucidating. Enrichments that target left/right brain hemispheres/behavioral traits may prepare birds for specific types of adult housing environments (caged, indoor, outdoor). Similarly, structural enrichments are needed to optimize skeletal development depending on the adult layer system, but specific physiological processes resulting from different types of exercise are poorly understood. Stimulating appropriate pecking behavior from hatch is critical but producers will need to adapt to different flock preferences to provide enrichments that are utilized by each rearing group. Enrichments have potential to enhance immune function through the application of mild stressors that promote adaptability, and this same principle applies to free-range pullets destined for variable outdoor environments. Complex rearing systems may have multiple benefits, including reducing fear, that improve the transition to the layer facility. Overall, there is a need to commercially validate positive impacts of cost-effective enrichments on bird behavior and physiology.

Effects of adipokine zinc-α2-glycoprotein on adipose tissue metabolism after dexamethasone treatment

Zinc-α2-glycoprotein (ZAG) has been demonstrated to play a role in stimulating lipid mobilization under normal conditions. However, further studies are required to determine whether ZAG overexpression can alleviate the reduction in plasma lipid levels under stress conditions. In the present study, we investigated the effects of ZAG on lipometabolism in white adipose tissue (WAT) after dexamethasone (DEX) stimulation using C57BL/6 male mice as the experimental models. Transcript and protein levels of genes associated with the β-adrenoreceptor (β-AR)/cyclic adenosine monophosphate/protein kinase a (PKA) pathway, lipid mobilization, and energy metabolism were determined by quantitative real-time polymerase chain reaction and Western blotting. Plasma levels of nonesterified fatty acid (NEFA) were measured using an automatic biochemical analyzer. Results indicated that plasma NEFA levels were decreased in the DEX group, but NEFA levels were rescued by ZAG overexpression. ZAG overexpression resulted in the upregulation of β3-AR and phosphorylated PKA protein relative to those of the DEX group. Analysis of lipometabolism showed that protein levels of phosphorylated hormone-sensitive lipase was reduced upon DEX treatment but were restored by ZAG overexpression. For energy metabolism, ZAG significantly upregulated the protein expression of carnitine palmitoyltransferase1a and cytochrome c oxidase subunit 1 relative to those of the DEX group. In conclusion, ZAG could alleviate DEX-induced decrease in plasma NEFA levels and this could be associated with the promoting lipid mobilization in WAT.

Glucocorticoids modulate gastrointestinal microbiome in a wild bird

It has recently been hypothesized that stress exposure (e.g. via glucocorticoid secretion) may dysregulate the bacterial gut microbiome, a crucial 'organ' in animal health. However, whether stress exposure (e.g. via glucocorticoid secretion) affects the bacterial gut microbiome of natural populations is unknown. We have experimentally altered the basal glucocorticoid level (corticosterone implants) in a wild avian species, the yellow-legged gull Larus michahellis, to assess its effects on the gastrointestinal microbiota. Our results suggest underrepresentation of several microbial taxa in the corticosterone-implanted birds. Importantly, such reduction included potentially pathogenic avian bacteria (e.g. Mycoplasma and Microvirga) and also some commensal taxa that may be beneficial for birds (e.g. Firmicutes). Our findings clearly demonstrate a close link between microbiome communities and glucocorticoid levels in natural populations. Furthermore, they suggest a beneficial effect of stress in reducing the risk of infection that should be explored in future studies.

Effects of different monochromatic LED light colours on fear reactions and physiological responses in Mulard ducks

Although the effects of monochromatic light on behaviour and performance of birds have been extensively studied, it is not known how rearing Mulard ducks in different monochromatic lights affects their fear reactions, physiological responses to stress and welfare. A total of 108 newly hatched Mulard ducks, representing three replicates, were housed in either blue light (BL), green light (GL), red light (RL) or white light (WL) for 12 weeks. Ducks were exposed to a light/dark schedule of 23 L/1 D, and food and water were provided ad libitum. At the beginning of the 13th week of the rearing period, behavioural measurements of fear were assessed by using a tonic immobility test, open field test and fear of man test. Physiological responses of the birds to stress such as heterophil : lymphocyte ratio, total leukocyte count and plasma concentrations of corticosterone were also assessed. Results demonstrated that birds exposed to both RL and WL displayed higher levels of behavioural indicators of fear including tonic immobility durations (P < 0.01), latency to first immobilisation (P < 0.001) and avoidance of man index (P < 0.001), and higher levels of physiological indicators of stress such as heterophil : lymphocyte ratios (P < 0.001) and plasmas concentrations of corticosterone (P < 0.001), and lower total leukocytic counts (P < 0.01) compared with birds exposed to either BL or GL. Rearing Mulard ducks in BL or GL appeared to reduce their fear reactions and physiological responses to stress and to enhance their ability to cope with the environment and may therefore improve their welfare.

Heat Stress and Lipopolysaccharide Stimulation of Chicken Macrophage-Like Cell Line Activates Expression of Distinct Sets of Genes

Acute heat stress requires immediate adjustment of the stressed individual to sudden changes of ambient temperatures. Chickens are particularly sensitive to heat stress due to development of insufficient physiological mechanisms to mitigate its effects. One of the symptoms of heat stress is endotoxemia that results from release of the lipopolysaccharide (LPS) from the guts. Heat-related cytotoxicity is mitigated by the innate immune system, which is comprised mostly of phagocytic cells such as monocytes and macrophages. The objective of this study was to analyze the molecular responses of the chicken macrophage-like HD11 cell line to combined heat stress and lipopolysaccharide treatment in vitro. The cells were heat-stressed and then allowed a temperature-recovery period, during which the gene expression was investigated. LPS was added to the cells to mimic the heat-stress-related endotoxemia. Semi high-throughput gene expression analysis was used to study a gene panel comprised of heat shock proteins, stress-related genes, signaling molecules and immune response genes. HD11 cell line responded to heat stress with increased mRNA abundance of the HSP25, HSPA2 and HSPH1 chaperones as well as DNAJA4 and DNAJB6 co-chaperones. The anti-apoptotic gene BAG3 was also highly up-regulated, providing evidence that the cells expressed pro-survival processes. The immune response of the HD11 cell line to LPS in the heat stress environment (up-regulation of CCL4, CCL5, IL1B, IL8 and iNOS) was higher than in thermoneutral conditions. However, the peak in the transcriptional regulation of the immune genes was after two hours of temperature-recovery. Therefore, we propose the potential influence of the extracellular heat shock proteins not only in mitigating effects of abiotic stress but also in triggering the higher level of the immune responses. Finally, use of correlation networks for the data analysis aided in discovering subtle differences in the gene expression (i.e. the role of the CASP3 and CASP9 genes).

Analysis of hematologic and serum chemistry values of Spheniscus magellanicus with molecular detection of avian malarial parasites (Plasmodium spp.)

Magellanic penguins (Spheniscus magellanicus) routinely migrate from their breeding colonies to Southern Brazil often contracting diseases during this migration, notably avian malaria, which has been already reported in Brazil and throughout the world. Detection of Plasmodium spp. in blood smears is the routine diagnostic method of avian malaria, however it has a low sensitivity rate when compared to molecular methods. Considering the negative impact of avian malaria on penguins, the aim of this study was to detect the presence of Plasmodium spp. in Magellanic penguins using Polymerase Chain Reaction (PCR) and by verifying clinical, hematological, and biochemical alterations in blood samples as well as to verify the likely prognosis in response to infection. Blood samples were obtained from 75 penguins to determine packed cell volume (PCV), red blood cell (RBC) and white blood cell (WBC) counts, mean corpuscular volume (MCV), uric acid, total protein, albumin, globulin and aspartate aminotransferase (AST) activity levels. Whole blood samples were used for PCR assays. Plasmodium spp. was detected in 32.0% of the specimens using PCR and in 29.3% using microscopic analyses. Anorexia, diarrhea and neurological disorders were more frequent in penguins with malaria and a significant weight difference between infected and non-infected penguins was detected. PCV and MCV rates showed no significant difference. RBC and WBC counts were lower in animals with avian malaria and leukopenia was present in some penguins. Basophil and lymphocyte counts were lower in infected penguins along with high monocyte counts. There was no significant difference in AST activities between infected and non-infected animals. There was a significant increase in uric acid values, however a decrease in albumin values was observed in infected penguins. Based on this study, we concluded that Plasmodium spp. occurs in Magellanic penguins of rehabilitation centers in Southeastern Brazil, compromising the weight of infected animals with clinical alterations appearing in severe cases of this disease. It was also noted that, although the hematological abnormalities presented by these animals may not have been conclusive, leukopenia, monocytosis and the decrease of basophils and lymphocytes revealed an unfavorable prognosis, and Plasmodium spp. infections may progress with elevated uric acid concentration and low albumin levels.

Separation at weaning from the family is stressful for naturally group-living, but not solitary-living, male African striped mice Rhabdomys

Early separation from a family is stressful for young mammals, but might be more stressful for group-living than solitary species. Using juvenile males of three African striped mice Rhabdomys taxa that are either group (R. pumilio) or solitary (R. dilectus dilectus and R. d. chakae) living, we predicted greater separation anxiety in R. pumilio than R. dilectus because group-living could reduce anxiety in R. pumilio. Three brothers from each of 10 litters per taxon were randomly assigned soon after natural weaning (25 days) to one of three treatments for 10 days: (1) remained with the family (philopatric); (2) separated from the family by a wire mesh barrier (separated); and (3) isolated from the family (isolated). Males were individually tested in a four-arm maze to assess their anxiety responses and sampled for corticosterone concentrations 20 mins and 10 days later. Compared to R. dilectus males, R. pumilio males showed a greater treatment response to separation: philopatric males used the light arms of the maze less and had higher corticosterone concentrations compared to isolated males, which spent the most time in the light arms and had the lowest corticosterone concentrations overall; separated males showed an intermediate behavioural response, but had similar corticosterone concentrations to philopatric males. Thus, separation from a family group is more stressful in group-living Rhabdomys and this stress response dissipates with time. Philopatry and group-living may be more important for young R. pumilio, whereas dispersal at weaning is an important life history event for solitary R. dilectus.

Changes in blood parameters and electroencephalogram of cattle as affected by different stunning and slaughter methods in cattle

The present study aimed to provide a comparative analysis of the effects of penetrative stunning, non-penetrative stunning and post-slaughter stunning on biochemical parameters and electroencephalogram (EEG) associated with stress in heifers and steers. Ten animals were assigned to each of the following four treatment groups: (1) animals were subjected to conventional halal slaughter (a clean incision through the structures on the ventral neck at the approximate level of vertebrae C2–C3 – the trachea, oesophagus, carotid arteries and jugular veins) and post-cut penetrating mechanical stun within 10–20 s of the halal cut (U); (2) high-power non-penetrating mechanical stunning using a mushroom-headed humane killer, followed by conventional halal slaughter (HPNP); (3) low-power non-penetrating mechanical percussive stunning using a mushroom-headed humane killer, followed by conventional halal slaughter (LPNP); and (4) penetrative stunning using a captive-bolt pistol humane killer, followed by conventional halal slaughter (P). For each animal, blood samples and electroencephalogram recordings were taken before stunning, post-stunning (if applicable) and post-slaughter, and plasma concentrations of cortisol, adrenocorticotrophic hormone (ACTH), adrenaline, noradrenaline and β-endorphin were determined. Irrespective of the stunning method, except for percentage change in plasma concentrations of noradrenaline, the values of blood parameters attained before and after stunning were not significantly different. The plasma noradrenaline concentration of the HPNP animals was significantly elevated following stunning. Following slaughter, the percentage change of plasma ACTH concentration in the P animals was significantly elevated. Neither stunning method nor sampling time had a significant effect on plasma β-endorphin concentration. On the basis of the EEG results, penetrative stunning seemed to be better in maximising the possibility of post-stunning insensibility, whereas U animals appeared to demonstrate an evident increase in EEG activity which is consistent with the presence of post-slaughter noxious stimuli associated with tissue cut and injury. The U animals had consistently higher, if not the highest, RMS values than did other stunned animals. This indicates a degree of EEG changes associated with stress and pain. On the basis of EEG data, our results suggested that penetrative stunning would be the most reliable method of ensuring insensibility and minimising pain. However, at slaughter, the P animals showed a dramatic elevation in the percentage change of circulating ACTH, suggesting physiological stress response. On a cautionary note, the results are not unequivocal, and it may be that the range of analyses available to researchers at this point of time are not sufficiently specific to allow definitive conclusions to be drawn.

Review of human-animal interactions and their impact on animal productivity and welfare

Humans and animals are in regular and at times close contact in modern intensive farming systems. The quality of human-animal interactions can have a profound impact on the productivity and welfare of farm animals. Interactions by humans may be neutral, positive or negative in nature. Regular pleasant contact with humans may result in desirable alterations in the physiology, behaviour, health and productivity of farm animals. On the contrary, animals that were subjected to aversive human contact were highly fearful of humans and their growth and reproductive performance could be compromised. Farm animals are particularly sensitive to human stimulation that occurs early in life, while many systems of the animals are still developing. This may have long-lasting impact and could possibly modify their genetic potential. The question as to how human contact can have a positive impact on responses to stressors, and productivity is not well understood. Recent work in our laboratory suggested that pleasant human contact may alter ability to tolerate various stressors through enhanced heat shock protein (hsp) 70 expression. The induction of hsp is often associated with increased tolerance to environmental stressors and disease resistance in animals. The attitude and consequent behaviour of stockpeople affect the animals’ fear of human which eventually influence animals’ productivity and welfare. Other than attitude and behaviour, technical skills, knowledge, job motivation, commitment and job satisfaction are prerequisites for high job performance.

Behavioural and physiological fear responses in ducks: genetic cross effects

Mule duck, a cross between a Muscovy drake and a Pekin female, is reported by the farmers to frequently express fear behaviours, such as man avoidance. The genetic basis of fear responses in mule ducks was therefore investigated in this study. According to a previous experiment, the dominant effect of Pekin genotype was hypothesised; however, due to the absence of birds from the reciprocal cross, a superiority of the Pekin in additive effect could not be distinguished from a direct maternal additive effect. In order to clarify this, ducks from the mule genotype, the two parental genotypes (Pekin and Muscovy) and the reciprocal intercross (hinny) underwent a set of physiological and individual behavioural tests of fear. Both parental genotypes were highly fearful but exhibited responses of different patterns: Pekin ducks manifested a higher locomotor activity, whereas the Muscovy ducks showed a higher avoidance to man. Hybrids expressed higher panic responses and specific fear of man than the two parent breeds. Both hybrids expressed similar patterns and the maternal effects were not significant. Significant heterosis effects were found for most of the behavioural responses, in agreement with the fact that higher fear responses were expressed by the hybrids compared to the parental genotypes. A significant heterosis effect was also found for basal adrenal activity; hybrids having higher basal level than parental genotypes. Maximum capacity of adrenal response appeared to be determined by direct additive effects with a superiority of the Pekin genotype.

Effects of different levels of organic and inorganic chromium on growth performance and immunocompetence of broilers under heat stress

This experiment was carried out to investigate the effects of different levels of organic and inorganic chromium on the performance, immune function and some serum mineral concentrations of broilers under heat stress condition (23.9-37°C cycling). A total of 150 one-day-old broiler chicks according to a completely randomized design were assigned into five treatment groups. Each treatment consisted of three replicates and each replicate contained ten chicks. Chicks were fed on corn-soybean meal basal diets with added different concentrations of chromium (0, 600 and 1,200 μg kg(-1) chromium chloride or 600 and 1,200 μg/kg chromium L-methionine) from 1 to 49 days of age. Humoral immunity was assessed by intravenous injection of 7% sheep red blood cell (SRBC) followed by evaluation of serum for antibody titers in primary and secondary responses. Cell-mediated immunity was assessed by the cutaneous basophil hypersensitivity (CBH) test to phytohemagglutinin (PHA)-P at day 32 and PHA-M at day 48. Heterophil/lymphocyte (H/L) ratio was also measured as a reliable indicator of stress. The body mass, feed intake and conversion ratio were not influenced by dietary chromium (P > 0.05). Dietary supplementation of both organic and inorganic chromium significantly increased primary and secondary antibody responses (P < 0.01), and also improved H/L ratio (P < 0.05), CBH response (P < 0.01) as well as relative weights of thymus (P < 0.05) and spleen (P < 0.01). Both dietary organic and inorganic chromium caused an increase in serum concentrations of Cr and Zn (P < 0.01), but decreased the serum concentration of Cu (P < 0.01). These results suggest that supplemental chromium especially in organic form offers a good management practice to reduce heat stress-related depression in immunocompetence of broiler chicks.

The relationship between adrenocortical function and Hsp70 expression in socially isolated Japanese quail

Physiological responses to social isolation stress were compared in 56-day-old male Japanese quail. Birds were fed pretreated diets for 3 days as follows: (i) Basal diet (control); (ii) Basal diet+1500 mg/kg metyrapone (BM); (iii) Basal diet+30 mg/kg corticosterone (BCO); (iv) Basal diet+250 mg/kg ascorbic acid (BC); (v) Basal diet+250 mg/kg α-tocopherol (BE); (vi) Basal diet+250 mg/kg ascorbic acid and 250 mg/kg α-tocopherol (BCE). The birds were subsequently socially isolated in individual opaque brown paper box for 2 hours. Plasma corticosterone (CORT) concentration and heart and brain heat shock protein 70 (Hsp 70) expressions were determined before stress and immediately after stress. Two hours of isolation stress elevated CORT concentration significantly in the control and BE birds but not in the BC, BCE and BM birds. There was a significant reduction in CORT concentration after isolation stress in the BCO group. Isolation stress increased Hsp 70 expression in the brain and heart of control and BM birds. However, brain and heart Hsp 70 expressions were not significantly altered in the isolated BC, BCE and BE birds. Although, the CORT concentration of BM birds was not affected by isolation stress, Hsp70 expression in both brain and heart were significantly increased. Moreover, exogenous corticosterone supplementation did not result in elevation of Hsp 70 expression. It can be concluded that, although Hsp 70 induction had not been directly affected by CORT concentration, it may be modulated by the HPA axis function via activation of ACTH.

Understanding stress-induced immunosuppression: exploration of cytokine and chemokine gene profiles in chicken peripheral leukocytes

At present, the poultry meat and egg industry has gained a lot of ground, being viewed as a provider of a healthy alternative to red meat and other protein sources. If this trend is to be maintained, solutions must be found to improve resistance of chickens to disease, which often is weakened by stressful conditions. In poultry, stress-induced immunosuppression is manifested by failures in vaccination and increased morbidity and mortality of flocks. Currently, several modern cellular and molecular approaches are being used to explore the status of the immune system during stress and disease. It is likely that these new techniques will lead to the development of new strategies for preventing and controlling immunosuppression in poultry. Using quantitative reverse transcription-PCR assays, a broad spectrum of cytokine, chemokine, and their receptor genes can be quantified in birds and then be used as markers to assess the effects of stress on the immune system. Currently, we are investigating immune and endocrine interactions in the chicken, in particular the cells and molecules that are known to be involved in such interactions in mammals. We have evaluated the effects of corticosterone administration in drinking water on peripheral lymphocyte and heterophil cytokine and chemokine gene profiles. In particular, there seems to be effects on cytokine and chemokine mRNA expression levels in both lymphocytes and heterophils, especially expression of the proinflammatory cytokines interleukin (IL)-1beta, IL-6, and IL-18 and chemokines C-C motif, ligand 1 inflammatory (CCLi1); C-C motif, ligand 2 inflammatory (CCLi2); C-C motif, ligand 5 (CCL5); C-C motif, ligand 16 (CCL16); C-X-C motif ligand 1 inflammatory (CXCLi1); and C-X-C motif ligand 2 inflammatory (CXCLi2), which are initially upregulated and are potentially involved in modulating the adaptive immune response. A chronic treatment with corticosterone downregulates proinflammatory cytokines and chemokines, suggesting that the delayed effects of chronic stress can suppress the immune response. Messenger RNA expression levels of transforming growth factor-beta4 (TGF-beta4) are also upregulated in cortisosterone-treated birds. It appears that the balance between T-helper (Th) 1 and Th2/T regulatory cytokine production is altered in conditions associated with significant changes in plasma corticosterone concentration. Experiments are underway to decipher the cytokine and chemokine responses to vaccination and bacterial challenge on the background of stress-induced immunosuppression.

Is the mechanisation of catching broilers a welfare improvement?

In most European countries broilers are currently caught manually: broilers are caught by the leg, inverted and carried by a catcher with 3–4 birds in each hand. This method of catching broiler chickens is a welfare concern as it causes severe stress to the birds. A possible alternative to manual catching may be mechanical catching. The aim of this study was to compare the level of stress and injuries of broilers caught manually or with a harvesting machine (CIEMME Super Apollo L harvester) under commercial conditions. The results indicated that there was no significant difference in plasma corticosterone concentrations and duration of tonic immobility, which suggested that mechanically caught broilers were no more stressed than those caught manually. At the end of the catching process, mechanically caught broilers had even lower plasma corticosterone concentrations and shorter durations of tonic immobility, indicating that at this moment these broilers were less stressed than the manually caught birds. The incidence of wing haemorrhages was also reduced for broilers caught mechanically; however, there was no significant difference in the incidence of haemorrhages in the breast or legs between the two catching methods. As injuries are associated with pain and stress, this parameter is important not only for the welfare of the birds but also for product quality and the subsequent financial return. Therefore, it can be concluded that the use of the mechanical harvesting machine, CIEMME Super Apollo L, appears to be a good alternative to manual catching. Nevertheless, some aspects of mechanical catching require further improvement.

Physiological responses of broiler chickens to heat stress and dietary electrolyte balance (sodium plus potassium minus chloride, milliequivalents per kilogram)

Individually caged male Cobb broilers (24), 44 d of age, were used to evaluate effects of heat stress (1 d of data collection) and dietary electrolyte balance (DEB; Na + K - Cl, mEq/kg from 1 d of age). During summer rearing, mortality was variable, but DEB 240 improved growth, feed conversion ratio, water intake, and water:feed ratio vs. DEB 0. The temperature sequence for heat stress was 24 to 32 degrees C in 30 min, 32 to 36 degrees C in 30 min, 36 to 37 degrees C in 15 min, and 37 to 41 degrees C in 45 min. Maximum temperature was held for 15, 60, 90, or 360 min for data collection (relative humidity averaged 42 +/- 7%). Results from the same room before and after heat stress were analyzed by DEB (1-factor ANOVA) and before vs. after heat stress compared across DEB (2-sample t-test). Heat stress decreased blood Na, K, and pCO2, and lymphocytes but increased heterophils. Blood HCO3 rose, Cl declined, and hematocrit gave a concave pattern (lowest at DEB 120) as DEB increased. After heat stress, DEB 0 decreased blood Na and K, and DEB 0 and 120 levels decreased blood HCO3. After heat stress blood pCO2 and hemoglobin decreased with DEB 240, but it had highest pCO2, a key factor. The DEB 120 gave longest times to panting and prostration with DEB 0 and 240 results lower but similar statistically. In heat stress, DEB 360 was excessive, DEB 120 and 240 were favorable, and DEB 0 was intermediate based on hematology, panting, and prostration responses.

Measuring and Monitoring Animal Welfare: Transparency in the Food Product Quality Chain

Animal welfare is of increasing significance for European consumers and citizens. Previously, agricultural production focused mainly on supply, price and competition but consumers now expect their food to be produced and processed with greater respect for the welfare of the animals. Food quality is therefore determined by the welfare status of the animals from which it was produced as well as the nature and safety of the end product. Thus, practical welfare improvement strategies and reliable on-farm monitoring systems for assessing the animals’ welfare status and evaluating potential risks are urgently required to accommodate societal concerns and market demands. It is also of paramount importance to define the kind of information that consumers want about the final products and to develop effective strategies for communicating welfare standards to the public. Generating an intensified dialogue with all factions of society on welfare issues as well as appropriate labelling of animal products and farming systems that offer guarantees about welfare issues and production conditions will, in turn, promote transparency and the societal sustainability of European agriculture. Welfare is multidimensional. It cannot be measured directly but only inferred from external parameters. Therefore, the integration of the most appropriate specialist expertise in Europe is essential to develop, refine, standardise and intercalibrate welfare monitoring systems and to identify and validate remedial measures. We must establish a European standard for welfare assessment systems in order to facilitate intra-European trade and marketing. Only then can we harmonise labelling that is informative and relevant to all European consumers.

Genetic Selection for Poultry Behaviour: Big Bad Wolf or Friend in Need?

Although genetic selection for certain characteristics has compromised the well-being of domestic animals, selective breeding could and probably should be used to improve welfare. Three of the major behavioural problems facing the poultry industry are fear, feather pecking and social stress. However, these and many other behavioural traits respond readily to genetic selection. The present paper reports the results of selective breeding studies in which underlying fearfulness, sociality, feather pecking, adrenocortical responsiveness, and growth rate were manipulated in Japanese quail, Coturnix japonica, or in chickens, Gallus gallus domesticus. The apparent benefits of selection for appropriate levels of these characteristics are discussed, as are the ethical issues involved. The ultimate aims of the selection programmes and the studies described here are to improve the birds ‘ welfare and productivity by increasing their ability to interact successfully with their physical environment, with one another, and with human beings.

Early T-maze behaviour and subsequent growth in commercial broiler flocks

Two batches of 2000 mixed-sex broiler chicks were obtained, one in summer and one in winter. Each flock was housed on the floor at a commercial farm. At 2 or 3 d of age, the latencies to escape from a T-maze were measured in 1044 and 1180 chicks in the summer and winter flocks, respectively. Chicks were assigned to high (HP), moderate (MP) or low (LP) performance categories if their escape latencies were below 40 s, between 40 to 90 s, or above 90 s, respectively. Ninety male and 90 female chicks from each of the 3 categories were weighed when they were 3 d old. The birds then remained undisturbed, apart from routine maintenance, until similar numbers were weighed at 49 d of age. Some birds may have been weighed at both ages. Body weights were higher in males than females and higher in the winter than summer flock at 3 d of age. Significant main effects of chick category as well as gender and season were found at 49 d of age. There were no significant interactions. As expected, 49-d body weights were higher in males than females and in the flock reared in winter than in summer. 5. HP chicks (those that showed rapid escape from the T-maze at 3 d) were also significantly heavier at 49 d than their LP counterparts, with MP chicks occupying an intermediate position. This suggests that early performance in a T-maze test is positively associated with subsequent growth. Furthermore, this relationship was apparent in each of the 2 flocks. Given this positive association, we suggest that this simple, rapid and non-invasive behavioural test could be a useful selection criterion for future breeding programmes.

Involvement of corticosterone in food intake, food passage time and in vivo uptake of nutrients in the chicken (Gallus domesticus)

To evaluate the effect of corticosterone on nutrient transport, 10-week-old male chickens were grouped in 4 categories and treated as follows: sham-operated, adrenalectomised, corticosterone (4 mg/kg injected subcutaneously for 5 d) in both sham-operated and adrenalectomised. The food intake, food passage time and uptake of calcium, phosphorus and glucose were determined by standard procedures. Corticosterone administration to both sham-operated and adrenalectomised groups stimulated significantly higher food intake, delayed food passage time and increased uptake of calcium, phosphorus and glucose, as compared to sham-operated control and adrenalectomised groups. Corticosterone administration increased absorption of these nutrients significantly more in the adrenalectomised group than in the sham-operated controls. Corticosterone also significantly elevated the plasma concentrations of these nutrients. The responses to the hormone were significantly greater in adrenalectomised birds. It is concluded that corticosterone increases food intake and retention and the absorption of calcium, phosphorus and glucose in the alimentary tract.