Appearance matters: artificial marking alters aggression and stress.

Artificial marking of animals for identification is frequently employed by researchers in the behavioral, biomedical, agricultural, and environmental sciences. The impact of artificial marking on experimental results is rarely explicitly considered despite evidence demonstrating that changes in phenotypic appearance can modify animal behavior and reproductive success. Here we present evidence that artificial marking of individuals within a social group has frequency-dependent effects on the behavior and physiology of domestic fowl (Gallus gallus domesticus). We demonstrate that when only 20 or 50% of individuals within a group were artificially marked, the marked birds received more aggression and had lesser body mass than the unmarked individuals within the same group. Furthermore, in groups in which only a small proportion of the individuals were marked, we report altered plasma epinephrine and dopamine levels in marked individuals. These effects of marking were imperceptible when all birds in a group were marked. This finding has important implications for animal research because, when only a subset of group members is artificially marked and used for data collection, the results obtained may not be representative of the population.

Climate change impacts and risks for animal health in Asia.

The threat of climate change and global warming is now recognised worldwide and some alarming manifestations of change have occurred. The Asian continent, because of its size and diversity, may be affected significantly by the consequences of climate change, and its new status as a 'hub' of livestock production gives it an important role in mitigating possible impacts of climate variability on animal health. Animal health may be affected by climate change in four ways: heat-related diseases and stress, extreme weather events, adaptation of animal production systems to new environments, and emergence or re-emergence of infectious diseases, especially vector-borne diseases critically dependent on environmental and climatic conditions. To face these new menaces, the need for strong and efficient Veterinary Services is irrefutable, combined with good coordination of public health services, as many emerging human diseases are zoonoses. Asian developing countries have acute weaknesses in their Veterinary Services, which jeopardises the global surveillance network essential for early detection of hazards. Indeed, international cooperation within and outside Asia is vital to mitigating the risks of climate change to animal health in Asia.

Intracerebroventricularly administered oxytocin attenuated cortisol secretion, but not behavioral responses, during isolation in Holstein steers.

In rodents, intracerebroventricular oxytocin administration attenuated hypothalamo-pituitary-adrenal (HPA) responses and anxiety behavior during stress. We examined the effects of intracerebroventricular injection of oxytocin on isolation-induced stress responses in cattle. In a methodological test, we determined the dosage of oxytocin applied in a main test which did not induce an increase in plasma cortisol concentration or stereotyped behaviors. In a main test, 5 steers aged from 199 to 250 days were assigned to the following three treatments randomly: T1, no isolation after injection of 200 microl of artificial cerebrospinal fluid (aCSF); T2, isolation after aCSF injection; and T3, isolation after 0.5 microg of oxytocin in 200 microl aCSF injection. The isolation was conducted by leaving the experimental steer alone in its stall for one hour while its peers were taken outside. In T2, the isolation induced a rapid increase in plasma cortisol concentration. The maximum %-changes from the pre-isolation value were significantly attenuated by oxytocin injection (T2 vs. T3, p<0.05). The isolation also induced an increase in the frequency (number of occurrences/1 hr isolation) of vocalizations and body orientation changes, and a decrease in the percentage of time spent lying and ruminating. The effect of oxytocin on these behavioral responses to isolation was not apparent. These results indicate that intracerebroventricularly injected oxytocin at low dose attenuated the cortisol response to isolation in steers while the effect on behavior was very small in this experimental condition.

Differential gene expression analysis in European eels (Anguilla anguilla, L. 1758) naturally infected by macroparasites.

We analyzed the relationships between the macroparasite community of the European eel and the expression of genes involved in the host physiology during its continental life. The genes studied are implicated in (1) host response to environmental stress, i.e., heat shock protein 70 (HSP70) and metallothionein (MT); (2) osmoregulation, i.e., beta thyroid hormone receptor (betaTHR) and Na+/K+ATPase; and (3) silvering, i.e., betaTHR, freshwater rod opsin (FWO), and deep-sea rod opsin (DSO). All were enumerated by quantitative reverse-transcription polymerase chain reaction. The epizootiological results for 93 yellow eels caught in the Salses-Leucate Lagoon (France) included 11 species: 1 nematode, 2 acanthocephalans, 1 monogenean, and 7 digeneans. The molecular results revealed (1) a significant negative relationship between digenean abundance and the expression level of all the tested genes, except FWO; (2) a significant negative relationship between the abundance of the nematode Anguillicola crassus and the expression level of the Na+/K+ATPase gene; and (3) a significant positive relationship between the A. crassus abundance and the expression level of the MT gene. Eels infected with digeneans had, on average, a lower level of expressed genes. We hypothesize that the parasites may disturb the eel's ability to withstand environmental stress and delay their migration to the Sargasso Sea because of degeneration of the gut. We further propose that the effect of the invasive species, A. crassus, on the gene expression was mainly linked to an increased trophic activity of infected eels. Moreover, it is possible that the parasite may have an effect on the fish's migratory behavior, which is tied to reproductive purposes. Additional work, including an experimental approach, is required to confirm our hypotheses.

Influences of maternal corticosterone and selection for contrasting adrenocortical responsiveness in Japanese quail on developmental instability of female progeny.

Differences in developmental instability were assessed in female offspring of Japanese quail hens selected for reduced (low stress, LS) or exaggerated (high stress, HS) plasma corticosterone (B) response to stress and treated with a placebo or B during egg formation. Hens of each line were implanted (s.c.) with either a silastic tube containing no B (controls) or one filled with B. Female chicks hatched from each of the 4 line x implant treatment combinations were retained for examination of 3 bilateral traits at 130 d of age: length of the tibiotarsus, middle toe length, and distance between the auditory canal and the nares (face length, FL). Greater bilateral trait size variances were associated with measurement of tibiotarsus length (P < 0.04) and middle toe length (P < 0.06) in the HS line, supporting our previous findings in the opposite sex that developmental instability (i.e., fluctuating asymmetry, FA) of certain morphological traits is more pronounced in HS than LS adult quail. The HS quail are also known to exhibit greater adrenocortical responsiveness to a wide range of stressors, and they are more easily frightened than LS birds. Therefore, the line differences in FA (HS > LS) found previously in males and herein in females may simply reflect the differential responsiveness of the birds to chronic social and physical environmental stressors. In addition, the present study detected more (albeit marginally so, P < 0.06) bilateral variability (i.e., heightened FA) in FL of quail hatched from mothers treated with B, a finding entirely due to the very high FL variance observed in the female offspring of B-treated HS hens. Because others have found in ovo B treatment to be associated with heightened FA in chick tarsus bone length and because we have also demonstrated that greater yolk B deposition occurs in eggs from both unstressed and stressed HS quail hens than their LS counterparts, the present maternal B treatment may be acting independently, or in combination with HS genomic effects, to adversely affect developmental stability.

Effect of bad collocation of wing tag on feather amelanosis, heterophil-to-lymphocyte ratio, fluctuating asymmetry, and tonic immobility duration in white-faced black spanish hens.

The purpose of the present study was to analyze the effects of bad collocation of the wing tag on feather amelanosis, the heterophil-to-lymphocyte ratio, fluctuating asymmetry, and tonic immobility duration at 140 d of age in hens from the White-Faced Black Spanish breed. A total of 52 females were used. There was a significant difference (P < 0.05) for the heterophil-to-lymphocyte ratio and the tonic immobility duration between groups of females with bad or good collocation of the wing tag, with the ratio being higher and the duration being longer in the former group. Females with bad collocation of the wing tag had significant heterophilia and lymphopenia (P < 0.05). There was a significant difference (P < 0.05) in the fluctuating asymmetry of the middle and hind toe lengths, the combined asymmetry of the 4 toes, the fluctuating asymmetry of the earlobe area, and the combined asymmetry of toe and leg lengths and earlobe and wattle areas, with the asymmetry of birds with bad collocation of the wing tag being larger than that of birds with good collocation of the wing tag. Results indicate that bad collocation of the wing tag negatively affects measures of stress, such as the heterophil-to-lymphocyte ratio, fluctuating asymmetry, and tonic immobility duration.

Corticosterone alters meat quality by changing pre-and postslaughter muscle metabolism.

Two experiments were conducted to investigate the effect of acute preslaughter stress mimicked by exogenous corticosterone (CORT) administration on postmortem muscle metabolism of broiler chickens. Altered protein metabolism, glycogen depletion, and meat quality characteristics were investigated in the musculus pectoralis major (PM) and musculus biceps femoris of broiler chickens. Results showed that CORT administration resulted in increased proteolysis and gluconeogenesis, whereas the capacity for protein synthesis was not obviously changed. Plasma levels of glucose, urate, and total free amino acids were all significantly decreased by CORT treatment. The effect of CORT administration on muscle R-values remained uncertain. The initial muscle buffer capacity was increased by CORT treatment in both musculus pectoralis major and musculus biceps femoris. The results suggested that the acute premortem up-regulation of CORT decreased muscle ultimate pH by increasing the antemortem muscle glycogen content and its depletion rate postmortem, which in turn induced a decrease in water-holding capacity. Muscle buffering capacity might be altered by CORT administration, and its involvement in the change of muscle pH needs to be investigated further.

Efficacy of dog-appeasing pheromone in reducing stress associated with social isolation in newly adopted puppies.

This study was designed to determine the potential value of dog-appeasing pheromone (dap) in reducing stress in puppies newly adopted from a pet shop. The trial was triple-blinded and placebo-controlled. After their arrival at the pet shop, 32 puppies were fitted with a dap collar and 34 were fitted with a control collar, according to a randomisation protocol. Adopting owners were contacted by telephone, three and 15 days after they had adopted a puppy, to obtain information about the puppy's integration into the family, and particularly about any signs of distress shown by the puppy when it was socially isolated. All the isolated puppies from the control group vocalised during the first night. Signs of distress, particularly vocalisation, were significantly lower in the dap group on day 3 and throughout the rest of the study, and vocalisation during the night ceased significantly sooner in this group. These differences were observed in puppies of small, medium and large breeds. The dap collars had no effect on the incidence of house soiling.

The responses of Atlantic cod (Gadus morhua L.) to ultrasound-emitting predators: stress, behavioural changes or debilitation?

A previous study has reported that Atlantic cod can be conditioned to detect ultrasonic sound pulses of high intensity. This capability has been proposed as a mean for detection and avoidance of echolocating toothed whales that emit intense ultrasonic clicks. In this study, we use acoustic playbacks to test the hypotheses that unconditioned cod can detect and respond to intense ultrasound from toothed whales and from echosounders. Intense ultrasound exposure of 210 dB re. 1microPa (pp) did not cause a short-term stress response in the form of bradycardia in unconditioned cod. Free-swimming cod exposed to ultrasonic clicks and echosounder pulses with received levels of more than 204 dB re. 1 microPa (pp) did not elicit flight responses as seen in ultrasound detecting Alosinae. Furthermore, we tested the debilitating effects of high intensity ultrasound on swimming cod with no detected changes in swimming ability when exposed to more than 213 dB re. 1 microPa (pp). It is concluded that intense ultrasound exposure induces neither an antipredator nor a stress response in Atlantic cod, and that echosounder pulses and biosonar clicks therefore most probably play no ecophysiological role in wild cod populations.

Stress reduction through consolation in chimpanzees.

Consolation, i.e., postconflict affiliative interaction directed from a third party to the recipient of aggression, is assumed to have a stress-alleviating function. This function, however, has never been demonstrated. This study shows that consolation in chimpanzees reduces behavioral measures of stress in recipients of aggression. Furthermore, consolation was more likely to occur in the absence of reconciliation, i.e., postconflict affiliative interaction between former opponents. Consolation therefore may act as an alternative to reconciliation when the latter does not occur. In the debate about empathy in great apes, evidence for the stress-alleviating function of consolation in chimpanzees provides support for the argument that consolation could be critical behavior. Consistent with the argument that relationship quality affects their empathic responses, we found that consolation was more likely between individuals with more valuable relationships. Chimpanzees may thus respond to distressed valuable partners by consoling them, thereby reducing their stress levels, especially in the absence of reconciliation.

Increasing daily feeding occasions in restricted feeding strategies does not improve performance or well being of fattening pigs.

BACKGROUND: The natural feeding behaviour of the pig is searching for feed by rooting activities throughout the day; self-feeding pigs randomly space their eating and drinking periods throughout the day consuming ten to twelve meals per day. Pigs in conventional fattening pig production are normally fed 2-3 times daily with the feed consumed within 15 minutes. The aim of this study was to determine if more frequent feedings could improve the performance of conventionally kept fattening pigs. METHODS: The experiment was carried out on 360 fattening pigs (27-112 kg live weight), weighed and assigned to pens stratified by weight and sex. Each treatment group consisted of 180 pigs, allocated to 20 pens with nine pigs in each pen. To evaluate how more feeding occasions affects performance and well-being the pigs were divided into two groups and fed three (control group) or nine (treatment group) times daily. The same total amount of liquid feed was fed to each group and the feed ration was correlated to the live weight of the pigs. All weight and slaughter recordings were made individually and recordings of feed consumption were made pen-wise. At slaughter the stomach of each pig was examined for lesions in the pars oesophagea and scored on a scale from 1-6. RESULTS: Frequent feeding occasions influenced both performance and status of gastric lesions of the pigs adversely. Pigs in the treatment group grew slower compared to pigs in the control group; 697 g/day (+/- 6.76) versus 804 g/day (+/- 6.78) (P < 0.001) with no difference in within-pen variation. There was also a lower prevalence of gastric lesions within pigs in the control group (2.4 (+/- 0.12) compared to 3.0 (+/- 0.12) (P < 0.01)). There was a positive correlation between gastric lesions in the treatment group and daily weight gain (r = 0.19; P < 0.01). CONCLUSION: Increased daily feeding occasions among group housed pigs resulted in a poorer daily weight gain and increased mean gastric lesion score as compared with pigs fed three times daily. This may be a consequence of more frequently occurring competition for feed in the treatment group. The present study does not support increased daily feeding occasions in fattening pigs.

Stress alters the cellular and proteomic compartments of bovine bronchoalveolar lavage fluid.

The stresses of transportation, weaning and commingling are associated with an increased incidence of bacterial and viral pneumonia in cattle. Proteins expressed in the epithelial lining fluid (ELF) of the lungs, in conjunction with resident leukocytes, represent the first line of defence against opportunistic pathogens, and stress-induced alterations in their expression may reveal markers of disease susceptibility. Bronchoalveolar lavage fluid was sampled in weaned and transported calves and ELF protein expression was compared to a control group of calves using two-dimensional electrophoresis (2DE). Serum and pulmonary haptoglobin were increased following stress concurrent with the number of blood neutrophils. Using 2DE, significant changes in expression were observed in spots identified by mass spectrometry as annexin A1 and A5, odorant-binding protein (OBP), isocitrate dehydrogenase, fibrinogen, heme-binding protein, alpha-2-HS-glycoprotein, alpha-1-antichymotrypsin and albumin. Quantification of OBP mRNA by real-time RT-PCR and OBP protein by western blot revealed gender-dependent differences in relative OBP expression in response to stress. These findings reveal stress-associated protein changes in pulmonary ELF and suggest a mechanism through which stress alters respiratory disease susceptibility.

Plasma concentrations of substance P and cortisol in beef calves after castration or simulated castration.

OBJECTIVE: To evaluate plasma concentrations of substance P (SP) and cortisol in calves after castration or simulated castration. ANIMALS: 10 Angus-crossbred calves. PROCEDURES: Calves were acclimated for 5 days, assigned to a block on the basis of scrotal circumference, and randomly assigned to a castrated or simulated-castrated (control) group. Blood samples were collected twice before, at the time of (0 hours), and at several times points after castration or simulated castration. Vocalization and attitude scores were determined at time of castration or simulated castration. Plasma concentrations of SP and cortisol were determined by use of competitive and chemiluminescent enzyme immunoassays, respectively. Data were analyzed by use of repeated-measures analysis with a mixed model. RESULTS: Mean +/- SEM cortisol concentration in castrated calves (78.88+/-10.07 nmol/L) was similar to that in uncastrated control calves (73.01+/-10.07 nmol/L). However, mean SP concentration in castrated calves (506.43+/-38.11 pg/mL) was significantly higher than the concentration in control calves (386.42+/-40.09 pg/mL). Mean cortisol concentration in calves with vocalization scores of 0 was not significantly different from the concentration in calves with vocalization scores of 3. However, calves with vocalization scores of 3 had significantly higher SP concentrations, compared with SP concentrations for calves with vocalization scores of 0. CONCLUSIONS AND CLINICAL RELEVANCE: Similar cortisol concentrations were measured in castrated and control calves. A significant increase in plasma concentrations of SP after castration suggested a likely association with nociception. These results may affect assessment of animal well-being in livestock production systems.

Proliferation and transmission patterns of Pasteurella multocida B:2 in goats.

This report describes the proliferation and transmission patterns of Pasteurella multocida B:2 among stressful goats, created through dexamethasone injections. Thirty seven clinically healthy adult goats were divided into three groups consisted of 15 goats in group A, 11 goats in group B and the remaining 11 in group C. At the start of the study, all goats of group A were exposed intranasally to 1.97 x 10(10) CFU/ml of live P multocida B:2. Dexamethasone was immediately administered intramuscularly for 3 consecutive days at a dosage rate of 1 mg/kg. The exposed goats were observed for signs of HS for a period of 1 month. At the end of the 1-month period, 11 goats from group B were introduced into and commingled with the surviving goats of group A before all goats from both groups were immediately injected intramuscularly with dexamethasone for 3 consecutive days. The treatment with dexamethasone was then carried out at monthly interval throughout the 3-month study period. Goats of group C were kept separately as negative control. Three surviving goats from each group were killed at 2-week interval for a complete post-mortem examination. Two (13%) goats of group A were killed within 24 hours after intranasal exposure to P multocida B:2 while another two (13%) goats from the same group were killed on day 40, approximately 10 days after the second dexamethasone injection. All four goats showed signs and lesions typical of haemorrhagic septicaemia. Bacteraemia was detected in 3 goats of group A that were having rectal temperature higher than 41degrees C. The P. multocida B:2 isolation pattern was closely associated with dexamethasone injections when significantly (p < 0.05) higher rate of isolations from both groups were observed after each dexamethasone injection. Transmission of P multocida B:2 from goats of group A to group B was successful when P multocida B:2 was isolated from goats of group B for a period of 28 days. There was a strong correlation between dexamethasone injections, rate of bacterial isolation and serum cortisol level. The IgG level showed an increasing trend 2 weeks after exposure to P multocida B:2 and remained high throughout the study period.

Dexamethasone depletes gammadelta T cells and alters the activation state and responsiveness of bovine peripheral blood lymphocyte subpopulations.

Administration of dexamethasone (DEX) to cattle is commonly used in models of stress-induced effects on host defense, including models investigating interactions of microorganisms with their host. Much less is known about the effects of DEX on the adaptive immune response in cattle compared with other species. The objective of the present study was to characterize subsets of circulating lymphocytes in calves before and 48 h after the onset of parenteral DEX treatment. Treatment significantly reduced the overall percentage of circulating lymphocytes and disproportionately depleted the population of gammadeltaTCR(+)/CD8alpha(-) cells. Analysis within the CD8alpha(+) population of T cells revealed that DEX treatment also reduced the CD8alpha(low) subset of gammadeltaT cells coexpressing the activation marker ACT-2(+). By contrast, DEX treatment did not affect the percentage of CD8alpha(low)/CD25(+) cells, indicating that cells with a special activation state were affected. Dexamethasone treatment reduced the number of gammadeltaT cells but increased the percentages of CD14(+) monocytes and activated CD25(+) cells (both CD4(-) and CD4(+)) in peripheral blood mononuclear cell (PBMC) preparations. Although DEX treatment reduced the overall proliferative capacity of PBMC, it enhanced the relative number of proliferating CD4(+) lymphocytes. Lower levels of mRNA for several Th-prototype cytokines (IL-2, IFN-beta, IL-4, transforming growth factor-beta) were detected in short-term PBMC cultures established from DEX-treated calves compared with PBMC cultures from control calves; the amount of il-10 transcripts, however, was unaffected. Results of the study reported here clearly show that DEX treatment does not uniformly suppress the bovine immune system but has differential effects on lymphocyte sub-populations and functions. This information must be considered when using DEX treatment as a bovine stress model.

Trypanosoma cruzi: effects of social stress in Calomys callosus a natural reservoir of infection.

Social environment can represent a major source of stress affecting cortisol and/or corticosterone levels, thereby altering the immune response. We have investigated the effects of social isolation on the development of Trypanosoma cruzi infection in female Calomys callosus, a natural reservoir of this protozoan parasite. Animals were divided in groups of five animals each. The animals of one group were kept together in a single cage. In a second group, four females were kept together in a cage with one male. In the final group, five individuals were kept isolated in private cages. The isolated animals showed body weight reduction, decreased numbers of peritoneal macrophages, lower global leucocytes counts, smaller lytic antibody percentage and a significantly higher level of blood parasites compared to the other animals. Their behavior was also altered. They were more aggressive than grouped females, or females exposed to the presence of a male. These results suggest that isolation creates a distinct social behavior in which immunity is impaired and pathogenesis is enhanced.

The effects on heart rate and temperature of mice and vas deferens responses to noradrenaline when their cage mates are subjected to daily restraint stress.

Performing stressful procedures in view of cage mates may cause stress in observer animals. However, it is not known if stressful procedures performed in close proximity to, but not in view of cage mates are stressful for the (observer) cage mates. Radiotelemetry and postmortem in vitro studies of the vas deferens were used to determine the effects of stress on observers. Heart rate (HR) and core body temperature (cBT) were recorded for 1 h following weighing of a cage mate or 1 h during restraint of a cage mate and the hour following return of the restrained mouse to the cage. This procedure was repeated daily for 15 days. HR and cBT were increased in observers during both restraint and weighing of cage mates. Analysis of the area under the curve showed that HR and cBT in observers were significantly higher during restraint of a cage mate than after weighing of a cage mate. When mice were returned to the cage after weighing or restraint, HR and cBT were significantly higher in the cage mates of restrained animals. Comparison between days 1, 3, 7 and 14 found that, as the experiment progressed, HR and cBT were significantly reduced in the observer mice during the hour following return of the cage mates after restraint. Results from previous studies have shown that chronic stress causes the vas deferens to become hypersensitive to exogenous application of noradrenaline (NAd). In this study, vas deferens from observers of restraint had a significantly increased response to NAd. These results indicate that stressful procedures should be conducted in isolation from other mice.

Hyperthermia in captured impala (Aepyceros melampus): a fright not flight response.

To investigate the patterns and mechanisms of capture-induced hyperthermia, we surgically implanted 26 impala (Aepyceros melampus) with miniature thermometric data loggers, which measured body temperatures continuously throughout capture procedures. Four groups of impala, which were habituated to varying levels of handling and boma-housing, were captured by net restraint or by chemical immobilization. The study took place between July 1999 and December 2005. Irrespective of whether impala were chemically captured, net-captured, or disturbed by exposure to a stressor, they developed a precipitous increase in body temperature. This increase in body temperature was not related to activity levels; animals that had low activity levels before immobilization had larger increases in body temperature compared to those that had high activity levels but were not immobilized (t = 3.6, P = 0.001, n = 5). Similarly this increase in body temperature was not related to environmental heat load at the time of darting and immobilization (r = -0.05, P = 0.85). Body temperature increase also did not depend on whether the animals were captured using drugs or not. However, we found that those animals that were habituated more to handling and boma-housing had smaller increases in body temperatures (F = 37, P<0.001) and smaller stress responses, indicated by lower plasma cortisol concentrations (F = 5.5, P<0.05), and less fractious behavior, compared to those animals that were habituated less or not at all. Therefore we believe that capture-induced hyperthermia in impala is caused predominantly by stress, which induces a rapid rise in body temperature.