Fecal Corticosterone Concentrations Research Articles

336 Effects of feeding an immunomodulatory feed additive (NutraGen) on metabolite concentrations and cortisol production in calves following exposure to a combination bovine respiratory disease challenge

Abstract Two 89-d experiments (Exp 1 and Exp 2) evaluated the effects of feeding an immunomodulatory feed additive (NutraGen; NG) in calves following exposure to bovine viral diarrhea virus (BVDV) on d -3 and Mannheimia haemolytica (MH) infection on d 0. For each experiment, steers [body weight (BW) = 251 ± 38.2 kg)] were randomly allocated to 1 of 3 treatments. Treatments included a placebo (CON; Exp 1 n = 5; Exp 2 n = 5), a placebo fed from d -18 to d -3 followed by NG fed from d -3 to d 28 (CHLG; Exp 1 n = 5; Exp 2 n = 6), and NG fed from d -18 to d 28 (PREC; Exp 1 n = 6; Exp 2 n = 5). Data were analyzed using the GLIMMIX procedure of SAS Version 9.4 (SAS Institute, Cary, N.C.). Animal served as the experimental unit and time served as a repeated measure. Treatment, time, and the treatment × time interaction served as fixed effects. Block was included as a random effect. Multiple treatment × time interactions and time effects occurred for serum glucose, lactate, blood urea nitrogen, and non-esterified fatty acid concentrations (P ≤ 0.003) in both experiments. There was a general trend for serum glucose to decrease over time post-challenge, suggesting increased cellular utilization of glucose in response to the challenge. In Exp 1, treatment effects occurred for serum glucose (P ≤ 0.001) and serum lactate (P ≤ 0.01), where calves assigned to the CHLG treatment displayed the greatest concentrations of the metabolites. Blood urea nitrogen concentrations peaked at h 48 in Exp 1 and h 6 in Exp 2. There were no treatment effects or treatment × time interactions for serum cortisol, hair cortisol, or fecal corticosterone concentrations in either experiment (P ≥ 0.17). There were, however, multiple time effects for serum cortisol, hair cortisol, and fecal corticosterone concentrations in both experiments (P ≤ 0.02), indicating that the challenge directly impacted cortisol and corticosterone production. Serum cortisol steadily increased from h 96 to h 168 in both experiments. Trends in cortisol and corticosterone production were similar in both experiments; however, peak concentration times for these variables occurred later in Exp 2. These data suggest that feeding NG to calves may alter glucose availability and nutrient utilization in response to infection resulting from a bovine respiratory disease challenge.

Research Note: Welfare and stress responses of broiler chickens raised in conventional and animal welfare-certified broiler farms

The present study was conducted to assess the animal welfare status of broiler chickens raised in conventional and welfare-certified farms. One conventional farm (30,000 birds/house, 1,488 m2/house, 2 houses) and one animal welfare-certified farm (32,000 birds/house, 1,920 m2/house, 2 houses) were selected to measure productivity, stress responses, and animal welfare indicators in 3 broiler flocks (2 farms/season, n = 6 flocks/farm type) during summer, autumn, and spring. Upon farm visits, body weight, uniformity, and animal welfare indicators (i.e., fecal and feather corticosterone, footpad dermatitis, hock burn, feather dirtiness, and gait score) were measured at 26 d posthatch. Also, moisture, nitrogen, and pH of litter, light intensity, ammonia concentration, and body surface temperature of head, chest, and legs were measured. There was no difference in body weight and uniformity between farm types. Fecal corticosterone concentrations were higher (P = 0.021) in welfare-certified vs. conventional farm, but no significant difference was found in feather corticosterone. Welfare-certified vs. conventional farm had lower percentages of hock burn (P = 0.018), feather dirtiness scores (P = 0.009), and gait score (P = 0.040), and there was no difference in footpad dermatitis. Nitrogen content in litter samples tended to be higher in conventional vs. welfare-certified farms (P = 0.094), and there was no difference in moisture and pH between farm types. Ammonia concentration within the broiler houses was not different between 2 farms. However, animal welfare farm was found to be brighter than conventional farm (P < 0.001). The body surface temperature of head, chest, and legs was not different between farm types. In conclusion, the welfare-certified farm had higher welfare measures, including lower hock burn, feather dirtiness, and gait score, confirming an overall improvement in welfare indicators. However, the observation on the elevated feather corticosterone noted in welfare vs. conventionally raised chickens warrants further studies.

Robust Responses of Female Caribou to Changes in Food Supply.

AbstractUngulates can respond to changes in food supply by altering foraging behavior, digestive function, and metabolism. A multifaceted response to an environmental change is considered robust. Short seasons of plant growth make herbivores sensitive to changes in food supply because maintenance and production must be accomplished in less time with fewer options in a more fragile response. Caribou live at high latitudes where short summers constrain their response to changes in food supply. We measured the ability of female caribou to resist and tolerate changes in the quality and quantity of their food supply during winter and summer. Caribou resisted changes in food abundance and quality by changing food intake and physical activity with changes in daily temperature within each season. Peak food intake rose by 134% from winter pregnancy to summer lactation (98 vs. 229 g kg-0.75 d-1), as digestible requirements to maintain the body increased by 85% for energy (1,164 vs. 2,155 kJ kg-0.75 d-1) and by 266% for N (0.79 vs. 2.89 g N kg-0.75 d-1). Caribou required a diet with a digestible content of 12 kJ g-1 and 0.8% N in pregnancy, 18 kJ g-1 and 1.9% N in early lactation, and 11 kJ g-1 and 1.2% N in late lactation, which corresponds with the phenology of the wild diet. Female caribou tolerated restriction of ad lib. food intake to 58% of their energy requirement (680 vs. 1,164 kJ kg-0.75 d-1) during winter pregnancy and to 84% of their energy requirement (1,814 vs. 2,155 kJ kg-0.75 d-1) during summer lactation without a change in stress level, as indicated by fecal corticosterone concentration. Conversely, caribou can respond to increased availability of food with a spare capacity to process digestible energy and N at 123% (2,642 vs. 2,155 kJ kg-0.75 d-1) and 145% (4.20 vs. 2.89 g N kg-0.75 d-1) of those respective requirements during lactation. Robust responses to changes in food supply allow caribou to sustain reproduction, which would buffer demographic response. However, herds may decline when thresholds of behavioral resistance and physiological tolerance are frequently exceeded. Therefore, the challenge for managing declining populations of caribou and other robust species is to identify declines in robustness before their response becomes fragile.

Immune and stress physiology of two captively-housed tortoise species.

Ecoimmunology affords us the ability to better understand immunological processes through consideration of external factors, such as the thermal microenvironment. This consideration is imperative when examining the immunological processes of ectothermic organisms like reptiles. Reptiles uniquely rely heavily on their innate immune function but remain poorly understood in immunological studies. In this study, we examined innate immunity in two zoo-housed tortoise species, the Indian star tortoise (Geochelone elegans, Schoepff, 1795) and northern spider tortoise (Pyxis arachnoides brygooi, Vuillemin & Domergue, 1972). Bacterial killing assays (BKAs) were optimized and used to assess the monthly immunocompetence of these tortoises to three different bacteria: Escherichia coli, Salmonella enterica, and Staphylococcus aureus. We evaluated differences in blood biochemistry values (lactate and glucose) among months and species as well as fecal corticosterone (CORT) between species. Lastly, we examined the potential influences of individual thermal microenvironments on bactericidal ability. Both G. elegans and P. a. brygooi demonstrated immunocompetence against all bacterial challenges, but only bactericidal ability against E. coli varied over months. Optimal BKA serum dilutions, blood glucose levels, and fecal CORT concentrations differed between the two species. Finally, there was evidence that the thermal microenvironment influenced the tortoises' bactericidal ability against E. coli. Through use of nonmodel organisms, such as tortoises, we are given insight into the inner workings of innate immunity and a better understanding of the complexities of the vertebrate immune system.

Effects of Cohousing Mice and Rats on Stress Levels, and the Attractiveness of Dyadic Social Interaction in C57BL/6J and CD1 Mice as Well as Sprague Dawley Rats.

Simple SummaryRats may kill mice. Therefore it is standard practice in many research animal housing facilities—despite often very limited space-to separate mice from rats (i.e., the predators) to minimize stress for the mice. We tested the effect of cohousing on the stress levels of mice from either the C57BL/6J (BL6) or the CD1 strain and Sprague Dawley rats by quantifying their fecal corticosterone and metabolites (FCM) concentration and investigated how cohousing impacts a behavioral assay, i.e., conditioned place preference for mouse-mouse or rat-rat social interaction. Mice from the BL6 strain (but not CD1 mice) that were cohoused with rats had significantly increased FCM concentrations, indicative of higher stress levels. In contrast to their elevated stress levels, the attractiveness for contextual cues associated with mouse-mouse social interaction even increased in rat-cohoused mice, albeit nonsignificantly. Thus, cohousing BL6 mice and rats did not impair a behavior of BL6 mice that had proved to be sensitive to social factors, especially handling by humans, in our laboratory. Our findings suggest that the effect of cohousing rats and mice on their stress levels and behavior might be less clearcut than generally assumed and might be overriden by conditions that cannot be controlled, i.e., different deliveries. Our findings can help to use research animal housing resources more efficiently.Rats, including those of the Sprague Dawley strain, may kill mice. Because of this muricidal behavior, it is standard practice in many research animal housing facilities to separate mice from rats (i.e., the predators) to minimize stress for the mice. We tested the effect of cohousing on the stress levels of mice from either the C57BL/6J (BL6) or the CD1 strain and Sprague Dawley rats (SD rat) by quantifying their fecal corticosterone and metabolites (FCM) concentration. We also investigated cohousing impacts a behavioral assay, i.e., conditioned place preference for intragenus (i.e., mouse–mouse or rat–rat) dyadic social interaction (DSI CPP) that was shown be sensitive to social factors, especially to handling by humans. We found that the two delivery batches of BL6 mice or SD rats, respectively, had different stress levels at delivery that were statistically significant for the BL6 mice. Even so, the BL6 mice cohoused with rats had significantly increased FCM concentrations, indicative of higher stress levels, as compared to (1) BL6 mice housed alone or (2) BL6 mice at delivery. In contrast to their elevated stress levels, the attractiveness of contextual cues associated with mouse–mouse social interaction (DSI CPP) even increased in rat-cohoused BL6 mice, albeit non-significantly. Thus, cohousing BL6 mice and rats did not impair a behavioral assay in BL6 mice that was proven to be sensitive to handling stress by humans in our laboratory. SD rats cohoused with BL6- or CD1 mice, and CD1 mice cohoused with SD rats, showed DSI CPP that was not different from our previously published data on SD rats and BL6 mice of the Jackson- or NIH substrain obtained in the absence of cohousing. CD1 mice cohoused with rats did not show an increased FCM concentration compared to delivery. Our findings suggest that the effect of cohousing rats and mice under the conditions described above on their stress levels as opposed to their behavior might be less clearcut than generally assumed and might be overriden by conditions that cannot be controlled, i.e., different deliveries. Our findings can help to use research animal housing resources, which are usually limited, more efficiently.

Inhaled corticosteroids as treatment for adolescent asthma: effects on adult anxiety-related outcomes in a murine model.

Allergic asthma, typically controlled with inhaled corticosteroids (ICS), is the leading chronic health condition for youth under 18years of age. During this peri-adolescent period, significant brain maturation occurs. Prior studies indicate that both chronic inflammation and corticosteroid medications increase risk for developing an internalizing disorder like anxiety. To determine if chronic ICS treatments exacerbate or alleviate anxiety symptoms associated with developmental allergic asthma, we used a mouse model to isolate the influence of ICS (fluticasone propionate, FLU) vs. airway inflammation (induced with house dust mite extract, HDM). During development, male and female BALB/cJ mice were repeatedly exposed to HDM or saline plus one of four FLU doses (none/vehicle, low, moderate, or high). In adulthood, we assessed lung inflammation, circulating and excreted corticosteroids, anxiety-like behavior, and gene expression in stress and emotion regulation brain regions. FLU treatment decreased body weight and anxiety-like behavior and increased fecal corticosterone metabolite concentrations and Crhr2 gene expression in ventral hippocampus. FLU effects were only observed in saline/non-HDM-exposed mice, and the FLU doses used did not significantly decrease HDM-induced airway inflammation. Females had greater serum and fecal corticosterone concentrations, less anxiety-like behavior, and lower Crhr1 gene expression in ventral hippocampus and prefrontal cortex than males. These findings suggest that steroid medications for youth with allergic asthma may not exacerbate anxiety-related symptoms, and that theyshould be avoided in children/adolescents without a health condition. The results are informative to future work on the use of corticosteroid medications during childhood or adolescent development.

Exploring the Role of Chemokine Receptor 6 (Ccr6) in the BXD Mouse Model of Gulf War Illness.

Gulf War illness (GWI) is a chronic and multi-symptomatic disorder with persistent neuroimmune symptomatology. Chemokine receptor 6 (CCR6) has been shown to be involved in several inflammation disorders in humans. However, the causative relationship between CCR6 and neuroinflammation in GWI has not yet been investigated. By using RNA-seq data of prefrontal cortex (PFC) from 31 C57BL/6J X DBA/2J (BXD) recombinant inbred (RI) mouse strains and their parental strains under three chemical treatment groups – saline control (CTL), diisopropylfluorophosphate (DFP), and corticosterone combined with diisopropylfluorophosphate (CORT+DFP), we identified Ccr6 as a candidate gene underlying individual differences in susceptibility to GWI. The Ccr6 gene is cis-regulated and its expression is significantly correlated with CORT+DFP treatment. Its mean transcript abundance in PFC of BXD mice decreased 1.6-fold (p < 0.0001) in the CORT+DFP group. The response of Ccr6 to CORT+DFP is also significantly different (p < 0.0001) between the parental strains, suggesting Ccr6 is affected by both host genetic background and chemical treatments. Pearson product-moment correlation analysis revealed 1473 Ccr6-correlated genes (p < 0.05). Enrichment of these genes was seen in the immune, inflammation, cytokine, and neurological related categories. In addition, we also found five central nervous system-related phenotypes and fecal corticosterone concentration have significant correlation (p < 0.05) with expression of Ccr6 in the PFC. We further established a protein-protein interaction subnetwork for the Ccr6-correlated genes, which provides an insight on the interaction of G protein-coupled receptors, kallikrein-kinin system and neuroactive ligand-receptors. This analysis likely defines the heterogeneity and complexity of GWI. Therefore, our results suggest that Ccr6 is one of promising GWI biomarkers.

Chronic repeated predatory stress induces resistance to quinine adulteration of ethanol in male mice

BackgroundTrauma related psychiatric disorders, such as posttraumatic stress disorder (PTSD), and alcohol use disorder (AUD) are highly comorbid illnesses that separately present an opposing, sex-specific pattern, with increased prevalence of PTSD in females and increased prevalence of AUD diagnoses in males. Likewise, PTSD is a risk factor in the development of AUD, with conflicting data on the impact of sex in the comorbid development of both disorders. Because the likelihood of experiencing more than one traumatic event is high, we aim to utilize chronic repeated predatory stress (CRPS) to query the extent to which sex interacts with CRPS to influence alcohol consumption, or cessation of consumption. MethodsMale (n = 16) and female (n = 15) C57BL/6 J mice underwent CRPS or daily handling for two weeks during adolescence (P35-P49) and two weeks during adulthood (P65-P79). Following the conclusion of two rounds of repeated stress, behavior was assessed in the open field. Mice subsequently underwent a two-bottle choice intermittent ethanol access (IEA) assessment (P90-131) with the options of 20 % ethanol or water. After establishing drinking behavior, increasing concentrations of quinine were added to the ethanol to assess the drinking response to adulteration of the alcohol. ResultsCRPS increased fecal corticosterone concentrations and anxiety-like behaviors in the open field in both male and female mice as compared to control mice that had not been exposed to CRPS. Consistent with previous reports, we observed a sex difference in alcohol consumption such that females consumed more ethanol per gram of body mass than males. In addition, CRPS reduced alcohol aversion in male mice such that higher concentrations of quinine were necessary to reduce alcohol intake as compared to control mice. CRPS did not alter alcohol-related behaviors in female mice. ConclusionCollectively, we demonstrate that repeated CRPS can induce anxiety-like behavior in both sexes but selectively influences the response to ethanol adulteration in males.

The effects of floor space and nest box access on the physiology and behavior of caged laying hens.

Confinement housing appears to be at the forefront of concern about laying hen welfare. This experiment examined the effects of floor space during rearing (315 or 945 cm2/bird) and adulthood (542 or 1648 cm2/bird) and access to a nest box on the welfare of caged laying hens. Measurements of the normality of biological functioning, such as plasma, egg albumen and yolk and fecal corticosterone concentrations, and heterophil to lymphocyte ratios, behavioral time budgets, mortality and efficiency of productivity, and measurement of hen preferences, such as choice behavior in Y maze tests, were used to assess hen welfare. There were no effects of treatment on physiological measurements. Hens given less space during adulthood spent less time mobile, inedible pecking, drinking, and preening and spent more time resting and feed pecking and sitting (P < 0.05). Hens with access to a nest box spent more time resting (P = 0.046) and less time sham dust bathing (P = 0.044) than hens without access to a nest box. There were no effects of space allowance on choice behavior for space or a nest box over food; however, hens with access to a nest box chose the nest box over food more than hens without access to a nest box (P = 0.0053). The present experiment provides no convincing evidence that either reducing space allowance in adulthood from 1648 to 542 cm2/bird or eliminating access to a nest box results in disruption of biological function. Less space and no access to a nest box did not increase the choice for more space or a nest box, respectively, over food in the preference tests. However, reduced floor space reduced behavioral freedom and denying access to a nest box eliminated the opportunity for the motivated behavior of laying their eggs in a discrete enclosed nest box, both of which presumably provide hens with the opportunity for positive affective experiences.

Mercury and lead exposure in avian scavengers from the Pacific Northwest suggest risks to California condors: Implications for reintroduction and recovery

Mercury (Hg) and lead (Pb) are widespread contaminants that pose risks to avian scavengers. In fact, Pb exposure is the primary factor limiting population recovery in the endangered California condor (Gymnogyps californianus) and Hg can impair avian reproduction at environmentally relevant exposures. The Pacific Northwest region of the US was historically part of the condor's native range, and efforts are underway to expand recovery into this area. To identify potential threats to reintroduced condors we assessed foraging habitats, Hg and Pb exposure, and physiological responses in two surrogate avian scavenger species (common ravens [Corvus corax] and turkey vultures [Cathartes aura] across the region between 2012 and 2016. Mercury exposure near the Pacific coast was 17–27-fold higher than in inland areas, and stable carbon and sulfur isotopes ratios indicated that coastal scavengers were highly reliant on marine prey. In contrast, Pb concentrations were uniformly elevated across the region, with 18% of the birds exposed to subclinical poisoning levels. Elevated Pb concentrations were associated with lower delta-aminolevulinic acid dehydratase (δ-ALAD) activity, and in ravens there was an interactive effect between Hg and Pb on fecal corticosterone concentrations. This interaction indicated that the effects of Hg and Pb exposure on the stress axis are bidirectional, and depend on the magnitude of simultaneous exposure to the other contaminant. Our results suggest that condors released to the Pacific Northwest may be exposed to both elevated Hg and Pb, posing challenges to management of future condor populations in the Pacific Northwest. Developing a robust monitoring program for reintroduced condors and surrogate scavengers will help both better understand the drivers of exposure and predict the likelihood of impaired health. These findings provide a strong foundation for such an effort, providing resource managers with valuable information to help mitigate potential risks.

Female rats display fewer optimistic responses in a judgment bias test in the absence of a physiological stress response

Metabolic cages are a type of housing used in biomedical research. Metabolic cage housing has been demonstrated to elicit behavioural and physiological changes in rodents housed within them. The nature of this effect has been characterized as anxiogenic. However, few studies have evaluated positive affect in response to metabolic cage housing and the interaction between this, sex and traditional physiological measures of stress. Cognitive biasing, as measured through a judgment bias paradigm has proven a reliable measure of animal affective state, particularly through its ability to measure positive affect. The current study investigated differences in cognitive biasing between male and female rats when transferred from open-top, grouped housing to a metabolic cage. Rats (Rattus norvegicus) (n=60) were trained in a judgment bias paradigm previously validated for use in the rat model. Upon exposure to an intermediate, ambiguous probe rats responded with either an optimistic or pessimistic decision. The animals were also subjected to the sucrose preference test to identify the presence of anhedonia. Faecal corticosterone and changes in adrenal tyrosine hydroxylase were also measured to establish whether a stress-like state was experienced. There was a significant interaction between sex and metabolic cage housing on the number of optimistic decisions made F (1, 56)=7.461, p=0.008. Female rats that remained in control housing responded with a reduced number of days featuring an optimistic decision compared to males in control housing (p=0.036). However, both males and females responded with significantly fewer optimistic decisions in the metabolic cage compared to control (p<0.001). There was a significant negative correlation between treatment and sucrose consumption (rpb=−0.654, n=195, p<0.001). There was also a significant sex effect for faecal corticosterone concentrations F (1, 30)=6.305, p=0.018) with female rats (4.050±1.285), displaying greater corticosterone concentrations than males (2.291±0.495). No differences between treatment were observed for either corticosterone or tyrosine hydroxylase levels. This data demonstrates that movement into a metabolic cage resulted in rats displaying significantly greater pessimistic cognitive biases as determined through the judgment bias test. Interestingly, male rats that remained in control housing demonstrated cognitive biases that were not equivalent to female rats. Furthermore, despite a behavioural change being evident, a physiological change in corticosterone or tyrosine hydroxylase levels was not observed.

Considerations of context and scale when using fecal glucocorticoids to indicate stress in large mammals: A study of wild american plains bison

Abstract— Noninvasive measures of stress response are used to understand impacts of natural and anthropogenic disturbances on wild animals and can be challenging to interpret without additional contextual information and specifics of the animals in question. We used fecal samples collected from the Henry Mountains American plains bison (Bison bison) herd in Utah to measure the glucocorticoid hormone corticosterone (CORT), a hormone that is indicative of stress. We compared site-specific measures of fecal CORT concentration with measures of covariates related to geography, bison physiology, and human activity to determine whether an unexpected habitat selection pattern could be a response to human disturbance and thus whether ecological covariates could explain variations in fecal CORT concentration in free-ranging bison. No meaningful relationships were found for any of the covariates included in the study, in part due to a scale mismatch between the physiological stress response of bison and the spatiote...

Relationship of glucocorticoids and hematological measures with feed intake, growth, and efficiency of finishing beef cattle.

The objective of this experiment was to determine the association of glucocorticoids and markers for immune status in finishing beef steers and heifers with DMI, growth, and efficiency. Steers ( = 127) and heifers ( = 109) were individually fed a finishing ration for 84 d with BW measured every 21 d. Blood samples were collected via jugular venipuncture for metabolite (glucose and lactate) and cortisol analysis and rectal grab samples of feces were collected for corticosterone analysis on d 83 of the experiment. Plasma cortisol was not correlated to DMI ( = -0.08, > 0.05) or fractional DMI (g DMI/kg BW; = -0.03, > 0.05) but was negatively correlated with ADG ( = -0.17, < 0.01) and G:F ( = -0.20, < 0.01) and positively correlated to residual feed intake (RFI; = 0.14, < 0.05). Fecal corticosterone was positively correlated to fractional DMI ( = 0.15, < 0.05) and RFI ( = 0.23, < 0.01) and negatively correlated to G:F ( = -0.18, < 0.01). Using a mixed model analysis, none of the metabolites or hormones were associated with DMI ( > 0.05) but fecal corticosterone was positively associated with fractional DMI only in heifers ( = 0.04). Plasma lactate ( < 0.01) was and plasma cortisol ( < 0.10) tended to be negatively associated with ADG. Plasma cortisol ( < 0.05) and fecal corticosterone tended ( < 0.10) to be negatively associated with G:F. Fecal corticosterone was positively associated with RFI in heifers ( < 0.04). In a mixed model analysis, total leukocyte count was positively associated with ADG ( < 0.04) and tended to be positively associated with G:F ( < 0.06). Among leukocyte subtypes, neutrophil count was positively associated with ADG in steers ( < 0.02) and monocytes were positively associated with ADG in heifers ( < 0.03). Lymphocyte counts (LY) in steers were negatively associated with DMI ( = 0.03) and fractional DMI ( < 0.03). In heifers, LY tended to be positively associated with DMI ( < 0.09) and fractional DMI ( < 0.06). Lymphocyte count was also positively associated with ADG ( < 0.01) and G:F ( = 0.05) in heifers. The association of production traits with immune status seems to be different between steers and heifers. There was a stronger relationship of cortisol than fecal corticosterone to feed efficiency measures, suggesting that cortisol concentrations could be a better marker for feed efficiency traits than fecal corticosterone concentrations.

Effect of Cage Type on Fecal Corticosterone Concentration in Buck Rabbits During the Reproductive Cycle

Fecal corticosterone concentration (FCC) was measured in 14 buck rabbits individually housed in standard-dimension cages (SC) or in bigger cages (BC; with a volume more than double that of SC and equipped with a plastic foot mat) during 4 consecutive reproductive cycles. Cage type and reproductive phase (estrous synchronization of doe rabbits, artificial insemination, partum, preweaning, and postweaning) were not statistically significant but tendentially affected FCCs (.05 < p < .10). Buck rabbits housed in SC showed higher FCCs than those housed in BC (27.42 pg g− 1 dried feces and 25.57 pg g− 1, respectively; SEM = 2.952). The highest FCC values were detected at artificial insemination (BC, 27.91 pg g− 1; SC, 30.45 pg g− 1; SEM = 3.520), highlighting that the phase of semen collection could be one of the most critical moments for buck rabbits, although further investigations are needed. These preliminary results suggest that measurement of FCC could be used as an indicator of chronic stress in buck rabbits.

Faecal corticosterone levels of dogs relinquished to a shelter in Japan

This study investigated the baseline level of faecal corticosterone in dogs relinquished to a shelter and compared changes in it caused by social events that dogs experienced. Faecal corticosterone was...

Ecological correlates of stress for a habitat generalist in a biofuels landscape

Understanding the success of habitat generalist species requires knowledge of how individuals respond to stressors that vary across habitats within landscapes. Habitat structure can affect stress by altering predation risk, conspecific densities, and densities of heterospecific competitors. Increased demand for biofuels will alter habitat structure for species in agroecosystems worldwide. We measured stress responses of deer mice (Peromyscus maniculatus (Wagner, 1845)), a widespread habitat generalist, in a biofuels landscape. We quantified fecal corticosterone concentrations for individuals in four biofuel crops: switchgrass (Panicum virgatum L.), miscanthus (Miscanthus × giganteus Greef &amp; Deuter ex Hodkinson &amp; Renvoize), mixed prairie, and corn (Zea mays L.). We also evaluated stress responses of deer mice to the annual harvesting of corn. Deer mice inhabiting switchgrass and mixed prairie had higher fecal corticosterone concentrations compared with mice in corn and miscanthus. Fecal corticosterone concentrations correlated positively with abundances of conspecifics and behaviorally dominant voles (prairie vole, Microtus ochrogaster (Wagner, 1842); meadow vole, Microtus pennsylvanicus (Ord, 1815)) across habitats. Stress levels of deer mice depended on how habitat structure modified the competitive environment. Deer mice did not exhibit increased fecal corticosterone concentrations in response to corn harvest, a rapid and extensive habitat disturbance common to agroecosystems. Our research is the first to investigate how landscape change due to biofuels expansion can affect stress levels of individuals.

Comparative Effects of Vasectomy Surgery and Buprenorphine Treatment on Faecal Corticosterone Concentrations and Behaviour Assessed by Manual and Automated Analysis Methods in C57 and C3H Mice

Establishing effective cage-side pain assessment methods is essential if post-surgical pain is to be controlled effectively in laboratory animals. Changes to overall activity levels are the most common methods of assessment, but may not be the most appropriate for establishing the analgesic properties of drugs, especially in mice, due their high activity levels. Use of drugs that can affect activity (e.g. opioids) is also a problem. The relative merits of both manual and automated behaviour data collection methods was determined in two inbred mouse strains undergoing vasectomy following treatment with one of 2 buprenorphine dose rates. Body weights and the effects of surgery and buprenorphine on faecal corticosterone were also measured.Surgery caused abnormal behaviour and reduced activity levels, but high dose buprenorphine caused such large-scale increases in activity in controls that we could not establish analgesic effects in surgery groups. Only pain-specific behaviour scoring using the manual approach was effective in showing 0.05 mg/kg buprenorphine alleviated post-vasectomy pain. The C57 mice also responded better to buprenorphine than C3H mice, indicating they were either less painful, or more responsive to its analgesic effects. C3H mice were more susceptible to the confounding effects of buprenorphine irrespective of whether data were collected manually or via the automated approach. Faecal corticosterone levels, although variable, were higher in untreated surgery mice than in control groups, also indicating the presence of pain or distress.Pain-specific scoring was superior to activity monitoring for assessing the analgesic properties of buprenorphine in vasectomised mice. Buprenorphine (0.01 mg/kg), in these strains of male mice, for this procedure, provided inadequate analgesia and although 0.05 mg/kg was more effective, not completely so. The findings support the recommendation that analgesic dose rates should be adjusted in relation to the potential severity of the surgical procedure, the mouse strain, and the individual animals' response.

Context dependency of baseline glucocorticoids as indicators of individual quality in a capital breeder

Identifying markers of individual quality is a central goal of life-history theory and conservation biology. The ‘corticosterone (CORT)-fitness hypothesis’ postulates that low fitness signals impaired ability to cope with the environment, resulting in elevated baseline CORT levels. CORT can, however, be negatively, positively or neutrally related to fitness, depending on the context. In order to clarify this controversial issue, we elucidate the utility of using baseline CORT as a correlate of individual fitness in incubating female eiders across variable environments. An increase in serum CORT with decreasing body condition was evident in older, more experienced breeders, while increased clutch mass was associated with elevated serum CORT in females breeding late in the season. For faecal CORT, the expected negative association with body condition was observed only in early breeders. We found a strong increase in faecal CORT with increasing baseline body temperature, indicating the utility of body temperature as a complementary stress indicator. Females in good body condition had a lower baseline body temperature, but this effect was only observed on open islands, a harsher breeding habitat less buffered against weather variability. Females with higher reproductive investment also maintained a lower baseline body temperature. Nest success strongly decreased with increasing serum and faecal CORT concentrations, and individual stress hormone and body temperature profiles were repeatable over years. Although our data support the tenet that baseline CORT is negatively related to fitness, the complex context-dependent effects call for cautious interpretation of relationships between stress physiology and phenotypic quality.

Effect of Breed, Cage Type, and Reproductive Phase on Fecal Corticosterone Levels in Doe Rabbits

Fecal corticosterone concentration (FCC) is increasingly being used as a noninvasive indicator of stress in assessment of nonhuman animal welfare. The aim of this study was to evaluate effects of breed, cage type, reproductive phase, and their interactions on FCC levels in doe rabbits. A total of 252 doe rabbits were randomly assigned to 2 groups. Does were individually housed in either standard dimension cages (SC) or in cages with a volume more than double that of the SC. Bigger cages (BC) were equipped with a plastic foot mat. Breed, cage type, and reproductive phase significantly affected FCC. New Zealand hybrids showed higher FCCs (p < .001) when compared witho the autochthonous breed (27.77 ± 0.47 vs. 24.61 ± 0.36 pg g−1, respectively). Increased cage size coupled with a plastic foot mat resulted in a significant decrease in doe FCC. The highest FCCs were detected at partum (BC: 30.40 ± 0.81 pg g−1; SC: 33.36 ± 0.86 pg g−1; p ≤ .05), followed by postweaning (BC: 25.09 ± 0.95 pg g−1; SC: 27.63 ± 0.95 pg g−1; p ≤ .05). These results support the hypothesis that measurement of FCC provides a useful indicator of chronic stress in doe rabbits.

Fecal corticosterone concentrations and reproductive success in captive female southern white rhinoceros

Prolonged or frequent secretion of adrenal glucocorticoids in response to aversive stimuli can negatively impact reproduction. Because female southern white rhinoceros ( Ceratotherium simum simum) reproduce poorly in captivity, we compared fecal corticosterone metabolite concentrations among parous, nulliparous, and adolescent females and examined social and physical aspects of the captive environment that might be related to differences in corticosterone metabolite concentrations. Aggression, dominance, sexual and play interactions, social group size and composition, enclosure size, and other housing characteristics were assessed though behavioral observations and review of historical and institution records. Concentrations of metabolized corticosterone in fecal samples were analyzed by enzyme immunoassay. The proportion of nulliparous females did not differ ( p > 0.05) between subordinate and dominant animals, and subordinates did not have a higher mean fecal corticosterone concentration than dominants ( p > 0.05). Of the behaviors examined, only the frequency of sexual play behaviors differed ( p < 0.05) between dominants and subordinates. Average corticosterone concentrations differed ( p < 0.05) across housing institutions but were not consistently elevated ( p > 0.05) for females housed in most of the environmental conditions assessed. Housing with a female companion known from adolescence, however, tended to be associated ( p = 0.06) with a lower mean corticosterone concentration than that when housing with a female companion introduced during adulthood or no female companion. Wild-caught females had a higher ( p < 0.05) average corticosterone concentration than captive-born females. Average corticosterone concentration did not differ ( p > 0.05) between acyclic and cycling, or nulliparous and parous females.