Positive Reinforcement Training for Blood Collection in Grizzly Bears (Ursus arctos horribilis) Results in Undetectable Elevations in Serum Cortisol Levels: A Preliminary Investigation

Feeding during hibernation shifts gene expression toward active season levels in brown bears (Ursus arctos)

Hibernation in bears involves a suite of metabolical and physiological changes, including the onset of insulin resistance, that are driven in part by sweeping changes in gene expression in multiple tissues. Feeding bears glucose during hibernation partially restores active season physiological phenotypes, including partial resensitization to insulin, but the molecular mechanisms underlying this transition remain poorly understood. Here, we analyze tissue-level gene expression in adipose, liver, and muscle to identify genes that respond to midhibernation glucose feeding and thus potentially drive postfeeding metabolical and physiological shifts. We show that midhibernation feeding stimulates differential expression in all analyzed tissues of hibernating bears and that a subset of these genes responds specifically by shifting expression toward levels typical of the active season. Inferences of upstream regulatory molecules potentially driving these postfeeding responses implicate peroxisome proliferator-activated receptor gamma (PPARG) and other known regulators of insulin sensitivity, providing new insight into high-level regulatory mechanisms involved in shifting metabolic phenotypes between hibernation and active states.

Evaluation of physiological stress in free-ranging bears: current knowledge and future directions

Stress responses, which are mediated by the neurogenic system (NS) and hypothalamic-pituitary-adrenal (HPA) axis help vertebrates maintain physiological homeostasis. Fight-or-flight responses are activated by the NS, which releases norepinephrine/noradrenaline and epinephrine/adrenaline in response to immediate stressors, whilst the HPA axis releases glucocorticoid hormones (e.g. cortisol and corticosterone) to help mitigate allostatic load. There have been many studies on stress responses of captive animals, but they are not truly reflective of typical ranges or the types of stressors encountered by free-ranging wildlife, such as responses and adaptation to environmental change, which are particularly important from a conservation perspective. As stress can influence the composition of age and sex classes of free-ranging populations both directly and indirectly, ecological research must be prioritised towards more vulnerable taxa. Generally, large predators tend to be particularly at risk of anthropogenically driven population declines because they exhibit reduced behavioural plasticity required to adapt to changing landscapes and exist in reduced geographic ranges, have small population sizes, low fecundity rates, large spatial requirements and occupy high trophic positions. As a keystone species with a long history of coexistence with humans in highly anthropogenic landscapes, there has been growing concern about how humans influence bear behaviour and physiology, via numerous short- and long-term stressors. In this review, we synthesise research on the stress response in free-ranging bear populations and evaluate the effectiveness and limitations of current methodology in measuring stress in bears to identify the most effective metrics for future research. Particularly, we integrate research that utilised haematological variables, cardiac monitors and Global Positioning System (GPS) collars, serum/plasma and faecal glucocorticoid concentrations, hair cortisol levels, and morphological metrics (primarily skulls) to investigate the stress response in ursids in both short- and long-term contexts. We found that in free-ranging bears, food availability and consumption have the greatest influence on individual stress, with mixed responses to anthropogenic influences. Effects of sex and age on stress are also mixed, likely attributable to inconsistent methods. We recommend that methodology across all stress indicators used in free-ranging bears should be standardised to improve interpretation of results and that a wider range of species should be incorporated in future studies.

Moving toward Fear-Free Husbandry and Veterinary Care for Horses

Husbandry and veterinary procedures have the potential to generate fear and stress in animals. In horses, the associated responses can pose a significant safety risk to the human personnel involved in the procedure, as well as to the animal itself. Traditionally, physical restraint, punishment, and/or threat of an aversive, have been the most common strategies used to achieve compliance from the horse. However, from a welfare perspective, this is less than ideal. This approach also has the potential for creating a more dangerous response from the horse in future similar situations. When caring for companion animals, and captive animals within zoological facilities, there has been a steady transition away from this approach, and toward strategies aimed at reducing fear and stress during veterinary visits and when undertaking routine husbandry procedures. This review discusses the current approaches to horse care and training, the strategies being used in other animal sectors, and potential strategies for improving human safety, as well as the horse's experience, during husbandry and veterinary procedures.

A beary good genome: Haplotype-resolved, chromosome-level assembly of the brown bear (Ursus arctos)

The brown bear (Ursus arctos) is the second largest and most widespread extant terrestrial carnivore on Earth and has recently emerged as a medical model for human metabolic diseases. Here, we report a fully phased chromosome-level assembly of a male North American brown bear built by combining Pacific Biosciences (PacBio) HiFi data and publicly available Hi-C data. The final genome size is 2.47 Gigabases (Gb) with a scaffold and contig N50 length of 70.08 and 43.94 Megabases (Mb), respectively. Benchmarking Universal Single-Copy Ortholog (BUSCO) analysis revealed that 94.5% of single copy orthologs from Mammalia were present in the genome (the highest of any ursid genome to date). Repetitive elements accounted for 44.48% of the genome and a total of 20,480 protein coding genes were identified. Based on whole genome alignment to the polar bear, the brown bear is highly syntenic with the polar bear, and our phylogenetic analysis of 7,246 single-copy orthologs supports the currently proposed species tree for Ursidae. This highly contiguous genome assembly will support future research on both the evolutionary history of the bear family and the physiological mechanisms behind hibernation, the latter of which has broad medical implications.

Influence of season, age, sex, and time of day on the endocrine profile of the common bottlenose dolphin (Tursiops truncatus)

Understanding baseline hormone levels, the magnitude of intra-individual variability, and their variation as a function of life history is difficult in toothed whales (e.g. dolphins and porpoises) because of the effects of capture stress. To determine the endocrine profile of the common bottlenose dolphin (Tursiops truncatus) as a function of season, time of day (TOD), age, sex, and reproductive status, blood corticosteroids, thyroid hormones, and catecholamines were repeatedly measured in a managed-care population exposed to ambient light and water temperatures of San Diego Bay. Additionally, fecal hormone metabolites were assessed for cortisol, aldosterone, and triiodothyronine. Samples were collected at two to four-week intervals over a period of two years, and multiple times within a day at monthly intervals over a year. Samples were collected through the voluntary participation of the dolphins in the blood draws and fecal collections in order to avoid the effects of handling stress. All serum hormones except aldosterone significantly varied with season and all serum hormones except total thyroxine significantly varied as a function of TOD. Fecal glucocorticoid metabolites significantly correlated with circulating cortisol levels, and there was a significant seasonal effect on triiodothyronine fecal metabolites. Strong seasonal effects demonstrated complex interactions with age and sex suggesting that contextual information is critical to interpreting differences in endocrine profiles. Strong circadian patterns further suggest that sampling design is important to the interpretation of blood or fecal collections, particularly since diurnal changes in some serum hormone levels are similar to the magnitude of seasonal differences. Despite potential impacts of feeding schedules on diurnal patterns, managed care populations can provide important insights into seasonal and age-related endocrine changes in toothed whales.

Analysis of hair steroid hormones in polar bears (Ursus maritimus) via liquid chromatography-tandem mass spectrometry: comparison with two immunoassays and application for longitudinal monitoring in zoos

Analysis of hair cortisol concentrations (HCCs) is a promising method for monitoring long-term stress in mammals. However, previous measurements of HCCs in polar bears (Ursus maritimus) have yielded highly variable results, which are likely due to different methodological approaches. In this study, hair samples of zoo-housed polar bears were analyzed for cortisol with two independent immunoassays [an enzyme-linked immunoassay (EIA) and a chemiluminescence assay (CLIA)] and liquid chromatography-tandem mass spectrometry (LC-MS/MS). HCC measurements depended significantly on assay type applied, sample processing (cutting vs. powdering hair) and their interaction. Best agreement was observed between LC-MS/MS and CLIA (R² = 0.81 for powdered hair) and sample processing had a minor, albeit significant, effect on obtained HCC measurements in these assays (R² > 0.9). EIA measurements were consistently higher than with the other assays. HCC measurement was validated biologically for CLIA and LC-MS/MS in one male polar bear that experienced considerable stress for a prolonged period of time (> 18 weeks). Subsequently, by using the validated LC-MS/MS the measurement of cortisol could be complemented by the analysis of other steroids including cortisone, testosterone and progesterone levels from hair samples collected over a 9-month period (5-13 months) from six zoo-housed polar bears (five males, one female). No seasonal steroid variation was observed except in male progesterone levels. For all steroids except cortisone, a strong body region effect (neck or paw) was observed. Cortisol and cortisone, as well as progesterone and testosterone, concentrations were positively correlated. We show that hair steroid concentrations can be used to longitudinally measure stress and reproductive hormone axes in polar bears. The data established herein provide important basic information regarding methodology and study design for assessing hair steroid hormones.

Can offsetting the energetic cost of hibernation restore an active season phenotype in grizzly bears (Ursus arctos horribilis)?

Hibernation is characterized by depression of many physiological processes. To determine if this state is reversible in a non-food caching species, we fed hibernating grizzly bears (Ursus arctos horribilis) dextrose for 10 days to replace 53% or 100% of the estimated minimum daily energetic cost of hibernation. Feeding caused serum concentrations of glycerol and ketones (β-hydroxybutyrate) to return to active season levels irrespective of the amount of glucose fed. By contrast, free fatty acids (FFAs) and indices of metabolic rate, such as general activity, heart rate, strength of heart rate circadian rhythm, and insulin sensitivity were restored to approximately 50% of active season levels. Body temperature was unaffected by feeding. To determine the contribution of adipose to the metabolic effects observed after glucose feeding, we cultured bear adipocytes collected at the beginning and end of the feeding and performed metabolic flux analysis. We found a ∼33% increase in energy metabolism after feeding. Moreover, basal metabolism before feeding was 40% lower in hibernation cells compared with fed cells or active cells cultured at 37°C, thereby confirming the temperature independence of metabolic rate. The partial depression of circulating FFAs with feeding likely explains the incomplete restoration of insulin sensitivity and other metabolic parameters in hibernating bears. Further depression of metabolic function is likely to be an active process. Together, the results provide a highly controlled model to examine the relationship between nutrient availability and metabolism on the hibernation phenotype in bears.

Cortisol levels in blood and hair of unanesthetized grizzly bears (Ursus arctos) following intravenous cosyntropin injection

Hair cortisol concentration (HCC) is being used increasingly to evaluate long‐term stress in many mammalian species. Most of the cortisol is assumed to passively diffuse from circulating blood into hair follicles and gradually accumulate in growing hair. However, our research with free‐ranging grizzly bears (Ursus arctos) suggests HCC increases significantly within several hours following capture, a time too brief to be explained by this mechanism alone. In this study with captive grizzly bears, we sought to determine if a brief spike in blood cortisol concentration, thus mimicking a single stressful event, would cause an increase in HCC over a 7‐day period. To do this, we administered a single intravenous dose (5 μg/kg) of cosyntropin to three captive unanaesthetised adult female grizzly bears on two occasions, during April when hair growth was arrested and during August when hair was growing. In both trials, the cosyntropin caused a two‐fold or greater increase in serum cortisol levels within 1 hr but did not appear to influence HCC at 1, 48, and 168 hr following cosyntropin administration. We conclude the cosyntropin‐induced cortisol spike was likely insignificant when compared to the adrenocortical response that occurs in free‐ranging bears when captured. We suggest further study with a larger sample of captive bears to evaluate the combined effects of anaesthesia and multiple doses of cosyntropin administered over several hours would better simulate the adrenocortical response of free‐ranging grizzly bears during capture.

Effects of positive reinforcement training for heifers on responses to a subcutaneous injection

Cattle are subjected to routine procedures that require restraint and close contact to humans, which are both potentially aversive to the animal. Positive reinforcement training techniques may affect how animals perceive and respond to these procedures. The objectives of the current study were to describe a positive reinforcement regimen used to train cattle to stand still for a sham injection, and to assess the effects of this training on the responses to an actual injection. Eight "agency" heifers were trained, over an average of 85 ± 4.6 sessions, with positive reinforcement (i.e., animals received a grain reinforcer for desired behaviors) to enter a headlock, and they were habituated with counterconditioning and desensitization to a sham injection (i.e., animals were gradually exposed to the sensation of the sham injection, paired with access to grain). The headlock remained open at all times to allow heifers to leave. Eight "habituation" heifers were exposed to the treatment area and headlock for an equal number of sessions and duration as agency heifers, and 7 "naïve" heifers were provided no exposure to the treatment area. Once agency heifers tolerated the sham injection, all animals received a 1-mL subcutaneous injection of 0.9% NaCl while in the head lock (habituation and naïve heifers were locked in but agency heifers were free to withdraw). Immediate responses to the injection, starting with tenting of the skin, were video recorded and summarized as a reactivity score, which included the number of steps, head tosses, and backing-up movements; we also recorded the latency to approach the treatment area and headlock for 3 d after the injection. Of the agency heifers, 5 remained standing for the actual injection, whereas 3 heifers moved out of the headlock for a brief period (1, 3, and 5 s, respectively). Habituation heifers had a higher reactivity score [17.5 (10.5-28); median (IQR)] than agency [6 (2-13.5)] and naïve heifers [6 (5-7)]. Averaged over the 3 d after injection, agency heifers showed lower latencies to come to the treatment area [8.7 (7.2-24.2) s] than did habituation [50.5 (28-60) s] and naïve [53.7 (18-60) s] heifers. Agency heifers voluntarily entered the headlock within 1.3 (1-1.5) s but, with one exception, none of the other heifers did so within the allowed 15 s. These results indicate that dairy heifers can be trained with positive reinforcement and counterconditioning to voluntarily accept a painful procedure, and that training can reduce avoidance behaviors during and after the procedure.

Training Petting Zoo Sheep to Act Like Petting Zoo Sheep: An Empirical Evaluation of Response-Independent Schedules and Shaping with Negative Reinforcement

Simple Summary

The present study examines the use of response-independent food schedules (food delivered independent of what an animal is doing) and negative reinforcement in the form of a trainer removing themselves from the presence of an animal to effectively train approach and contact behaviors in petting zoo sheep. All sheep had previously been reported to avoid/escape the presence of zoo staff and caretakers, as well as refuse to eat in the presence of any persons. In Experiment 1, we were able to effectively use response-independent schedules to produce both approach and contact behaviors in a Hampshire sheep. In Experiment 2, a Jacob sheep was trained for approach/contact via a shaping procedure that initially rewarded approach behaviors by removing the presence of the trainer (negative reinforcement), and was later switched to rewarding responses directly with food (positive reinforcement) once the sheep began to regularly eat in the trainer’s presence. The results are discussed with respect to how both procedures are effective in examining the applied approach/avoidance behaviors with zoo animals, as well as the greater ethical considerations involved in using negative vs. positive reinforcement to train animals.

Abstract

Shaping through differential reinforcement of successive approximations to a target response has been a cornerstone procedure for the training of novel behavior. However, much of how it has traditionally been implemented occurs through informal observation, rather than any direct, systematic measurement. In the present study, we examine the use of response-independent food schedules and shaping for increasing approach and contact behaviors in petting zoo sheep. In Experiment 1, a fixed-time (FT) 15 s food schedule was used to effectively increase approach and contact behaviors in one sheep. In Experiment 2, negative reinforcement in the form of removal of the presence of a trainer was made contingent on the successful completion of approximations within a shaping procedure and later switched to food rewards. A changing-criterion design was used to empirically examine the effects of the shaping procedure during each step of the program. The result is one of the first studies to demonstrate the utility of using negative reinforcement within a shaping procedure to successfully intervene on approach/avoidance behaviors in an applied animal setting.

An Examination of Shaping with an African Crested Porcupine (Hystrix cristata)

Shaping through differential reinforcement of successive approximations to a target response has been a cornerstone procedure for the training of novel behavior. However, much of how it has traditionally been implemented occurs through informal observation, rather than any direct, systematic measurement. In the following study, an African crested porcupine (Hystrix cristata) was trained to touch and hold to a target for 30 s. A changing-criterion design with one reversal was used to assess the success of the shaping procedure and empirically examine the effects of the shaping procedure during each step of the program. The study allowed for the examination of each approximation across all other approximations, as well as across aberrant (e.g., trial-terminating) responses. The design and procedure allow for a simple and systematic way to examine the effects and success of shaping procedures across a variety of settings, species, and purposes.

Endocrine response to simulated U.S. Navy mid-frequency sonar exposures in the bottlenose dolphin (Tursiops truncatus)

Little information exists on endocrine responses to noise exposure in marine mammals. In the present study, cortisol, aldosterone, and epinephrine levels were measured in 30 bottlenose dolphins (Tursiops truncatus) before and after exposure to simulated U.S. Navy mid-frequency sonar signals (3250-3450 Hz). Control and exposure sessions, each consisting of ten trials, were performed sequentially with each dolphin. While swimming across the experimental enclosure during exposure trials, each dolphin received a single 1-s exposure with received sound pressure levels (SPLs, dB re 1 μPa) of 115, 130, 145, 160, 175, or 185 dB. Blood samples were collected through behaviorally conditioned, voluntary participation of the dolphins approximately one week prior to, immediately following, and approximately one week after exposure were analyzed for hormones via radioimmunoassay. Aldosterone was below detection limits in all samples. Neither cortisol nor epinephrine showed a consistent relationship with received SPL, even though dolphins abandoned trained behaviors after exposure to the highest SPLs and the severity of behavioral changes scaled with SPL. It remains unclear if dolphins interpret high-level anthropogenic sound as stressful, annoying, or threatening and whether behavioral responses to sound can be equated to a physiological (endocrine) response.

Patterns of animal-enrichment interaction in captive brown bears

We studied the behavioral responses of three brown bears (Ursus arctos) to different types of enrichment devices to assess the predominant pattern of animal-enrichment interaction (PAI) to each type of enrichment. We assessed the bears' responses to feeding, sensory, and occupational enrichments over nine sessions. Using Pearson's correlation (r) and the coefficient of variation (CV)-we describe four models of PAIs: habituation, increasing, continuous, and fluctuating. The habituation model (r < 0 and p < 0.05; CV (%) > 0) consists of a loss of interest in the device over time and it occurred with the occupational device. The increasing model (r > 0 and p < 0.05; CV (%) > 0) consists of a sustained interest in the device over time and it was not observed for any device of this study. The continuous model (0 > r > 0 and p > 0.05; CV (%) < 100) consists of a consistent and unchanging interaction over time and it occurred with the feeding enrichments used in this study. The fluctuating PAI (0 > r > 0 and p > 0.05; CV (%) ≥ 100) consists of wide oscillations in the degree of interaction over time and we observed this pattern with sensory devices. Review of previous literature supports these classes of PAI, and suggests similar relationships between PAIs and the type of enrichment as we observed in this study.

Linking stress and immunity: Immunoglobulin A as a non-invasive physiological biomarker in animal welfare studies

As the animal welfare community strives to empirically assess how care and management practices can help maintain or even enhance welfare, the development of tools for non-invasively measuring physiological biomarkers is essential. Of the suite of physiological biomarkers, Immunoglobulin A (IgA), particularly the secretory form (Secretory IgA or SIgA), is at the forefront because of its crucial role in mucosal immunity and links to physical health, stress, and overall psychological well-being. While interpretation of changes in SIgA concentrations on short time scales is complex, long-term SIgA patterns are consistent: conditions that create chronic stress lead to suppression of SIgA. In contrast, when welfare is enhanced, SIgA is predicted to stabilize at higher concentrations. In this review, we examine how SIgA concentrations are reflective of both physiological stress and immune function. We then review the literature associating SIgA concentrations with various metrics of animal welfare and provide detailed methodological considerations for SIgA monitoring. Overall, our aim is to provide an in-depth discussion regarding the value of SIgA as physiological biomarker to studies aiming to understand the links between stress and immunity.

Endogenous Opiates and Behavior: 2016

This paper is the thirty-ninth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2016 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

The quantification of reproductive hormones in the hair of captive adult brown bears and their application as indicators of sex and reproductive state

Recognizing the potential value of steroid hormone measurements to augment non-invasive genetic sampling, we developed procedures based on enzyme-linked immunoassays to quantify reproductive steroid hormone concentrations in brown bear (Ursus arctos) hair. Then, using 94 hair samples collected from eight captive adult bears over a 2-year period, we evaluated (i) associations between hair concentrations of testosterone, progesterone, estradiol and cortisol; (ii) the effect of collecting by shaving vs. plucking; and (iii) the utility of reproductive hormone profiles to differentiate sex and reproductive state. Sample requirements (125 mg of guard hair) to assay all hormones exceeded amounts typically obtained by non-invasive sampling. Thus, broad application of this approach will require modification of non-invasive techniques to collect larger samples, use of mixed (guard and undercoat) hair samples and/or application of more sensitive laboratory procedures. Concentrations of hormones were highly correlated suggesting their sequestration in hair reflects underlying physiological processes. Marked changes in hair hormone levels during the quiescent phase of the hair cycle, coupled with the finding that progesterone concentrations, and their association with testosterone levels, differed markedly between plucked and shaved hair samples, suggests steroids sequestered in hair were likely derived from various sources, including skin. Changes in hair hormone concentrations over time, and in conjunction with key reproductive events, were similar to what has been reported concerning hormonal changes in the blood serum of brown bears. Thus, potential for the measurement of hair reproductive hormone levels to augment non-invasive genetic sampling appears compelling. Nonetheless, we are conducting additional validation studies on hair collected from free-ranging bears, representative of all sex, age and reproductive classes, to fully evaluate the utility of this approach for brown bear conservation and research.

Life in the fat lane: seasonal regulation of insulin sensitivity, food intake, and adipose biology in brown bears

Grizzly bears (Ursus arctos horribilis) have evolved remarkable metabolic adaptations including enormous fat accumulation during the active season followed by fasting during hibernation. However, these fluctuations in body mass do not cause the same harmful effects associated with obesity in humans. To better understand these seasonal transitions, we performed insulin and glucose tolerance tests in captive grizzly bears, characterized the annual profiles of circulating adipokines, and tested the anorectic effects of centrally administered leptin at different times of the year. We also used bear gluteal adipocyte cultures to test insulin and beta-adrenergic sensitivity in vitro. Bears were insulin resistant during hibernation but were sensitive during the spring and fall active periods. Hibernating bears remained euglycemic, possibly due to hyperinsulinemia and hyperglucagonemia. Adipokine concentrations were relatively low throughout the active season but peaked in mid-October prior to hibernation when fat content was greatest. Serum glycerol was highest during hibernation, indicating ongoing lipolysis. Centrally administered leptin reduced food intake in October, but not in August, revealing seasonal variation in the brain's sensitivity to its anorectic effects. This was supported by strong phosphorylated signal transducer and activator of transcription 3 labeling within the hypothalamus of hibernating bears; labeling virtually disappeared in active bears. Adipocytes collected during hibernation were insulin resistant when cultured with hibernation serum but became sensitive when cultured with active season serum. Heat treatment of active serum blocked much of this action. Clarifying the cellular mechanisms responsible for the physiology of hibernating bears may inform new treatments for metabolic disorders.