138 results on '"Edward Narayan"'
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2. Editorial: Reviews in animal welfare
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Edward Narayan and Barbara Padalino
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animal welfare ,farming and wildlife ,health ,food ,Five Domains Model ,Veterinary medicine ,SF600-1100 - Published
- 2024
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3. Non-invasive wool hormone assessment of Australian merino rams (Ovis aries): a pilot investigation of cortisol and testosterone
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Dylan Fox, Benn Wilson, and Edward Narayan
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stress ,non-invasive biomarkers ,HPA axis ,fibre ,reproduction ,Veterinary medicine ,SF600-1100 - Abstract
IntroductionNon-invasive hormone assessment is growing in interest as producers and livestock researchers seek new methods to assess animal welfare. Non-invasive wool assessment offers long-term, historic reflections of hormone concentration at the scale of weeks and months - and are not limited by sampling stress - thus making wool an appropriate tissue for long-term hormone analysis. This pilot study quantified cortisol and testosterone concentrations of ram fleece and determined if there is a significant difference between segments of the sample staple, and whether there is a correlation between hormones. Cortisol is a glucocorticoid produced within the adrenal glands and secreted in anticipation of or in response to a stressor. Testosterone is an androgen mainly synthesised within the testes of males and responsible for several critical functions including regulation of muscle growth, libido and spermatogenesis.MethodsIn our study, 70 topknot wool samples were collected from rams on a commercial stud property in Dirranbandi, Queensland, Australia. Of these animals, 12 samples were selected at random to undergo cortisol and testosterone quantification. In the laboratory, a single, intact staple was isolated from the total sample, divided into 10 mm segments and prepared for their respective (cortisol or testosterone) immunoassays.ResultsNo significant difference (p > 0.05) was found between wool segments for either cortisol or testosterone, however, statistical differences (p
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- 2024
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4. Effects of stocking density during simulated transport on physiology and behavior of largemouth bass (Micropterus salmoides)
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Yifei Yang, Edward Narayan, Sonia Rey Planellas, Clive J. C. Phillips, Lu Zheng, Bingying Xu, Lei Wang, Yuechong Liu, Yuxiao Sun, Gladstone Sagada, Hao‐Yu Shih, Qingjun Shao, and Kris Descovich
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behavior ,fish welfare ,largemouth bass ,physiology ,simulated transport ,skin mucus cortisol ,Aquaculture. Fisheries. Angling ,SH1-691 - Abstract
Abstract The live transport of farmed fish is an important practice in Chinese aquaculture due to consumer preferences in its domestic market. However, live transport can be stressful for fish and may cause many welfare issues. This study aimed to examine the effects of transport density on the welfare of largemouth bass (Micropterus salmoides). Adult fish were allocated to four experimental treatments in a two‐factor design (N = 5 groups per treatment). Factor one was stocking density of either 39 (low density) or 78 (high density) g L−1. Factor two was transport, with half of the fish groups exposed to simulated transport stress for 3 h using a motion platform, and the other half kept in static tanks for the same length of time. Baseline behavior and physiology were determined from a subset of fish after acclimation but before selection into groups and application of transport. To determine the effects of transport, stocking density, and their interaction on the experimental groups, physiological sampling and behavioral recording were carried out immediately after simulated transport, and water quality was measured both before and after transport. Changes in water quality were observed between two timepoints, with decreased dissolved oxygen levels and increased water temperature. Total ammonia nitrogen levels significantly increased in all treatments over time, particularly in the high‐density groups. Fish ventilation rates were significantly elevated in the groups kept at a high stocking density regardless of whether they also experienced transport stress. Fish transported at a high stocking density also showed more fear‐related behaviors such as freezing and thigmotaxis than non‐transported groups. Serum cortisol, catalase, and aspartate transaminase levels were significantly higher in the transported treatment groups compared to the baseline fish, but no difference was found for serum glucose, lactate, and glutathione peroxidase. We concluded that 3 h of simulated transport was stressful to largemouth bass kept at 78 g L−1, as evidenced by altered fish physiological and behavioral indicators of stress, as well as deteriorated water quality. Additionally, we identified a positive correlation between serum and skin mucus samples for cortisol, glucose, and lactate in transported fish, providing important information for developing less invasive methods for the welfare assessment of largemouth bass.
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- 2024
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5. Loss of a grooming enrichment impacts physical, behavioural, and physiological measures of welfare in grazing beef cattle
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Emily J. Dickson, Jessica E. Monk, Caroline Lee, Paul G. McDonald, Edward Narayan, and Dana L.M. Campbell
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Angus ,Brush ,Extensive management ,Positive Welfare ,Steers ,Animal culture ,SF1-1100 - Abstract
Pasture-based beef cattle are raised in a range of production environments. Some paddocks may contain trees and other objects that allow for grooming, hence being naturally enriching, whilst others may be barren without these opportunities. Additionally, it is not uncommon for cattle to move between these enriched and barren environments as part of routine management. While the benefits of enrichment are well studied, how this ‘enrichment loss’ impacts cattle welfare as access to stimuli is removed is unknown. This trial assessed the impacts of the loss of an enriching object (grooming brush) on grazing beef cattle welfare and production characteristics. When grooming brush access was blocked, cattle became dirtier, showed reduced average daily gain, and had elevated faecal cortisol metabolites, although this varied according to the degree of initial individual brush use. Additionally, allogrooming and grooming on other objects were reduced when access to the brush was returned, potentially indicating a rebound effect. These results demonstrate that the loss of adequate grooming objects can impair the overall welfare of grazing cattle; however, further work is needed to determine exactly which natural or artificial objects provide adequate grooming opportunities.
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- 2024
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6. Relationship between wool cortisol, wool quality indices of Australian Merino rams and climatic variables in Tasmania
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Troy Cobb, Georgia-Constantina Hantzopoulou, and Edward Narayan
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merino sheep ,climatic stress ,cortisol ,wool phenotype ,merino sheep stress ,merino sheep stress mitigations ,Veterinary medicine ,SF600-1100 - Abstract
IntroductionAustralia is the world’s largest producer and exporter of fine wool. External factors (i.e., non-genetic) that affect wool phenotype need to be identified and managed to minimize any negative effects on wool quality. Climatic stress is one external event that can affect wool phenotype, other stressors include shearing, nutrition, disease, pregnancy, and lambing. This study focuses on the relationship between Saxon Merino ram wool phenotype and wool cortisol. The hypotheses had two parts (i) wool cortisol levels would vary seasonally and variations would correlate with wool phenotype (ii) that these seasonal variations would also correlate with thermal indices.MethodsCortisol levels in Saxon Merino ram wool samples were determined using a cortisol enzyme-immunoassay (EIA) using polyclonal cortisol antibody. The wool cortisol results were correlated for significance with thermal indices including Temperature Humidity Index [THI] and Chill Index [CI] obtained from the Australian Bureau of Meteorology.ResultsPart 1 of hypothesis one was supported with wool cortisol showing significant seasonal variation. Part 2 of hypothesis 1 was not supported, with no statistically significant causality present between total wool cortisol levels and the price index of Saxon Merino ram wool. However, there was significant causality between wool cortisol and coarse edge measurement (CEM) of wool. Hypothesis 2, the proposal that thermal indices would impact on wool cortisol was also not supported.DiscussionIt can be concluded that although conclusive causality between total wool cortisol and wool phenotype quality could not be ascertained, there were indirect effects of cortisol levels on wool phenotypes with significant effects on the CEM. The CEM of Merino Saxon ram wool can be manipulated by assessing and managing cortisol levels during the growth cycles of Merino wool, through appropriate nutrition and husbandry procedures stress could be managed.
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- 2023
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7. Human-wildlife interaction: past, present, and future
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Edward Narayan and Naureen Rana
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Zoology ,QL1-991 - Abstract
Abstract Human-wildlife interaction is a broad and complex topic. Due to rapid world population growth, there have been greater human impacts on wildlife through agriculture and land fragmentation. In many countries, significant challenges exist with managing wildlife and its negative impacts on humans and wildlife. This special issue discusses human-wildlife co-existence.
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- 2023
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8. Correction: A 29-year retrospective analysis of koala rescues in New South Wales, Australia.
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Renae Charalambous and Edward Narayan
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Medicine ,Science - Abstract
[This corrects the article DOI: 10.1371/journal.pone.0239182.].
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- 2023
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9. Editorial: Animal welfare assessment, Volume III
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Edward Narayan
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animal welfare ,behavior ,physiology ,stress ,assessment ,Veterinary medicine ,SF600-1100 - Published
- 2023
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10. Editorial: Insights in animal behavior and welfare: 2021
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Edward Narayan
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animal welfare ,animal behavior ,animal assisted interventions ,animal therapy ,stress ,affective neuroscience ,Veterinary medicine ,SF600-1100 - Published
- 2022
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11. Editorial: Minimally Invasive Monitoring of Stress in Farm Animals (Volume 1)
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Edward Narayan and Surinder Singh Chauhan
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physiology ,welfare ,stress management ,livestock ,biomarkers ,Veterinary medicine ,SF600-1100 - Published
- 2022
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12. Intra- and Inter-sample Variation in Wool Cortisol Concentrations of Australian Merino Lambs Between Twice or Single Shorn Ewes
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Georgia-Constantina Hantzopoulou, Gregory Sawyer, Alan Tilbrook, and Edward Narayan
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sheep ,stress ,wool ,individual variation ,reproduction ,shearing ,Veterinary medicine ,SF600-1100 - Abstract
Stress in Merino sheep can cause a reduction in the quantity and quality of fine wool production. Furthermore, it has been found that environmental stress during pregnancy can negatively affect the wool follicles of the developing fetus. This study was part of a larger field investigation on the effects maternal shearing frequency on sheep reproductive and productivity outcomes. For this study, we investigated the intra- and inter- sample variation in wool cortisol levels of weaner lambs. We conducted two experiments, the first was to determine the intra- and inter- sample variation in wool samples taken from the topknot of weaned lambs, and the other aim was to determine any difference between maternal shearing treatment (single or twice shearing) on absolute wool cortisol levels of weaned lambs. In the first experiment, topknot wool was collected from 10 lambs, and each sample was further divided into four subsamples, leading to a total of 40 wool subsamples. For the second experiment, we collected the topknot from the 23 lambs produced by the shearing frequency treatment ewes (once or twice shorn). The samples were then extracted and analyzed using a commercially available cortisol enzyme-immunoassay in order to determine the concentration of cortisol in each of the samples. Statistical analysis for the first experiment showed that there was no significant difference between the subsamples of each topknot wool sample taken from each lamb (p = 0.39), but there was a statistical difference between samples (p < 0.001), which was to be expected. In the second experiment, there was a significant difference between the lambs born to the one shearing and two shearing treatments (p = 0.033), with the lambs of the twice sheared ewes having higher average wool cortisol levels [2.304 ± 0.497 ng/g (SE); n = 14] than the ones born to once shorn ewes [1.188 ± 0.114 ng/g (SE), n = 8]. This study confirms that the topknot wool sampling can be a reliable method adapted by researchers for wool hormonal studies in lambs. Second, ewes shorn mid-pregnancy gave birth to lambs with higher cortisol concentrations than ewes that remained unshorn during pregnancy. This result warrants further investigation in a controlled study to determine if maternal access to nutrition (feed and water) may impact on the HPA-axis of lambs.
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- 2022
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13. Interplay Between Stress and Reproduction: Novel Epigenetic Markers in Response to Shearing Patterns in Australian Merino Sheep (Ovis aries)
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Edward Narayan, Gregory Sawyer, Dylan Fox, Ryan Smith, and Alan Tilbrook
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welfare ,shearing ,wool ,DNA ,reproduction ,Veterinary medicine ,SF600-1100 - Abstract
In this study, we determined the effect(s) of early shearing on Australian Merino ewes (Ovis aries) and their lambs. To test this research question, we used a suite of field and laboratory methods including GPS collars, wool cortisol, and epigenetic change between ewes and lambs identified using Illumina NovaSeq RRBS. Once shorn ewes (n = 24) were kept on their full fleece throughout the entire gestation period, whereas twice (early) shorn ewes (n = 24) had their wool shorn pre-joining. Top-knot wool sample was taken from ewes during pre-joining, day 50 (mid-gestation), and day 90 (late gestation) for laboratory analysis. Ewes were pregnancy scanned at mid-gestation to determine whether they were early or late parturition (this confirmation is provided by the pregnancy scanner based on fetus size). Top-knot wool sample was also taken from the lambs at weaning for hormone and wool quality testing. Ear tissue was taken from ewes at day 50 (mid-gestation) and from lambs at lamb marking for DNA analysis. Results showed that twice or early shorn ewes grazed 10% higher and maintained stronger body condition than once shorn ewes. Wool cortisol levels were also significantly lower in the early shorn ewes between mid- and late gestation. Lambs bred from twice shorn ewes had on average better visual wool quality parameters in terms of micron, spin finesses, and curvature. For the DNA methylation results, when comparing a group of once sheared with twice sheared ewes, we have discovered one locus (Chr20:50404014) that was significantly differentially methylated [False Discovery Rate (FDR) = 0.005]. This locus is upstream of a protein-coding gene (ENSOARG00000002778.1), which shows similarities to the forkhead box C1 (FOXC1) mRNA using BLAST searches. To further our understanding of the potential interaction between pregnancy status and shearing frequency of the ewes, we performed further differential methylation analysis using a combination of shearing treatment and pregnancy scanning status. The comparisons (1) late pregnancy vs. early pregnancy for ewes with one shearing treatment and (2) late pregnancy vs. early pregnancy for sheep with two shearing treatments were carried out to identify associations between loci and pregnancy duration for sheep with either one or two shearing events. We discovered that 36 gene loci were significantly modulated either between different shearing treatments or late vs. early pregnancy status of ewes. This result suggests that maternal pregnancy and nutritional status during gestation influence DNA methylation. We further investigated DNA methylation in lambs and identified 16 annotated gene loci that showed epigenetic modulation as a result of being born from an early or late stage pregnancy. From the genomics data, we pointed out that ewes go through epigenetic modifications during gestation, and there is a degree of intra-individual variation in the reproductive performance of ewes, which could be due to combination of intrinsic (genetic and physiological) and extrinsic (management and climatic) factors. Collectively, this research provides novel dataset combining physiological, molecular epigenetics, and digital tracking indices that advances our understanding of how Merino ewes respond to shearing frequency, and this information could guide further research on Merino sheep breeding and welfare.
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- 2022
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14. Editorial: Animal Welfare Assessment: Edition 2
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Edward Narayan and Alan G. McElligott
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precision livestock farming ,health ,animal welfare ,physiology and behavior ,human-animal interaction ,Veterinary medicine ,SF600-1100 - Published
- 2021
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15. Pre- and post-partum variation in wool cortisol and wool micron in Australian Merino ewe sheep (Ovis aries)
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Gregory Sawyer, Dylan Russell Fox, and Edward Narayan
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Wool microns ,Fibre diameter ,Stress ,Pregnancy ,Lambing ,Wool cortisol ,Medicine ,Biology (General) ,QH301-705.5 - Abstract
An individual merino sheep’s output of wool production is influenced by synergistic interactions of sheep genetics, climate, farm management, and nutrition available to the whole flock. The price paid to the producer for this wool commodity is determined via numerous tested parameters and /or subjective appraisal of the raw greasy wool. This research investigated the level of variation in wool cortisol (a physiological stress biomarker) and wool micron (MIC) in Merino ewes (Ovis aries), pre-partum and post-lambing (lactation/lambs at foot), using maiden ewe (n = 38) managed in an outdoor paddock in a commercial farm. The key findings of this study are; (1) wool quality indicators showed a significant variation between pre- and post- parturition including significant reduction in MIC and (2) there was a negative correlation between wool cortisol levels and wool micron pre-parturition (rs = − 0.179, p
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- 2021
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16. Editorial: Animal Welfare Assessment: Edition 1
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Edward Narayan, Alan McElligott, and Alan Tilbrook
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stress ,animal welfare ,livestock ,wildlife ,domesticated animals ,biomarkers ,Veterinary medicine ,SF600-1100 - Published
- 2021
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17. A 29-year retrospective analysis of koala rescues in New South Wales, Australia.
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Renae Charalambous and Edward Narayan
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Medicine ,Science - Abstract
The koala (Phascolarctos cinereus) is currently listed by both the IUCN and the Australian Governments' Threatened Species Scientific Committee as vulnerable to extinction with an overall decreasing population trend. It is unknown exactly how many koalas remain in the wild, but it is known that habitat fragmentation and bushfires have ultimately contributed to the decline of the koala all over Australia. This novel study is a retrospective analysis of data over a 29-year period (1989-2018) using records for 12,543 sightings and clinical care admissions for wild koalas from the major koala hot-spots (Port Stephens, port Macquarie and Lismore) in New South Wales, Australia. This study aims to understand the long-term patterns and trends of key stressors that are contributing to the decline of koalas in New South Wales, and the synergic interactions of factors such as rescue location, sex and age of the koala, and if their decline is influenced progressively by year. The main findings of this retrospective analysis indicated that between all 3 rescue sites, the most common prognosis was disease, the most common disease was signs of chlamydia, and the most common outcome was release. The location where the highest number of koalas were found prior to being reported as sighted or admitted into clinical care was within the regional area of Lismore. Furthermore, sex was not a discriminating factor when it came to prognosis or outcome, but age was significant. Finally, incidents of disease were found to increase over long-term, whereas release decreased over time and euthanasia increased. The wealth of data available to us and the retrospective analysis enabled us in a way to 'zoom out' and reveal how the key environmental stressors have fluctuated spatially and temporally. In conclusion, our data provides strong evidence of added pressures of increased human population growth in metropolitan zones, which increases risks of acute environmental trauma and proximate stressors such as vehicle collisions and dog-attacks as well as increased sightings of virtually healthy koalas found in exposed environments. Thus our 'zoom out' approach provides support that there is an urgent need to strengthen on-ground management, bushfire control regimes, environmental planning and governmental policy actions that should hopefully reduce the proximate environmental stressors in a step wise approach. This will ensure that in the next decade (beyond 2020), NSW koalas will hopefully start to show reversed trends and patterns in exposure to environmental trauma and disease, and population numbers will return towards recovery and stability.
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- 2020
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18. Knowledge of, and Attitudes towards, Live Fish Transport among Aquaculture Industry Stakeholders in China: A Qualitative Study
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Yifei Yang, Tingyun Wang, Clive J. C. Phillips, Qingjun Shao, Edward Narayan, and Kris Descovich
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animal welfare ,fish welfare ,fish ,live transport ,China ,stakeholder ,Veterinary medicine ,SF600-1100 ,Zoology ,QL1-991 - Abstract
China is the largest food fish producer in the world. Chinese consumers normally purchase fish that are still alive to ensure freshness. Therefore, the live transport of fish is important in China’s aquaculture, although it carries potential risks for animal welfare. This study investigated the attitudes and knowledge of stakeholders within Chinese aquaculture towards the live transport and welfare of fish. Semi-structured interviews were conducted with 12 participants who were involved with the aquaculture industry in China. Most participants self-rated their transport-related knowledge as moderate and had some understanding of animal welfare, although this term was generally considered only relevant to terrestrial animals. Participants’ responses indicated that the live transport of fish occurs frequently in China, generally using sealed tanks, plastic bags, and foam boxes, in purpose-built vehicles. Seasonal changes, such as changes in ambient and water temperature, are considered to be important contributors to successful live transport, as well as sufficient oxygen supplies and stocking density. The use of anesthetics was not commonly reported, particularly in food fish, and fish capture is predominantly by conventional dipnets. The health status of transported fish is determined mostly by morphology (body injury, body or eye color, and fin condition), as well as vigor and swimming ability. Our results indicate that live transport poses a number of welfare risks to fish but that participants in the process associated welfare concerns more with terrestrial animals, not fish.
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- 2021
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19. Influences of the stress endocrine system on the reproductive endocrine axis in sheep (Ovis aries)
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Edward Narayan and Simone Parisella
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sheep ,stress ,reproduction ,hypothalamic–pituitary– adrenal axis ,hypothalamic–pituitary–gonadal axis ,reproductive wastage ,Animal culture ,SF1-1100 - Abstract
The hypothalamic–pituitary–adrenal (HPA) axis and the hypothalamic–pituitary–gonadal (HPG) axis systems are inversely related in humans and animals. Although livestock animals, such as sheep (Ovis aries), tend to be well adapted to their environment, it is known that the livestock production processes subject animals to a multitude of physical and psychological stressful stimuli that have the potential to elevate the HPA axis activity. Chronic stress is one of the major challenges in sheep production, as it is difficult to detect and can result in prolonged dysfunction of the HPA axis, causing downstream negative physiological effects such as immunosuppression, increased susceptibility to disease and reproductive dysfunction. The elevation of HPA axis activity during chronic stress has been suggested as the primary neuroendocrine mechanism underlying the aetiology of reproductive dysfunction in sheep. Research in sheep has demonstrated that glucocorticoids act on the HPG axis at the level of the hypothalamus and hypophyseal portal system to decrease gonadotrophin secretion and at the level of the pituitary gland to reduce responsiveness and sensitivity of gonadotroph cells and their receptors to GnRH. Sheep farming enterprises rely on the breeding efficacy of ewes to optimise lambing percentage and reproductive success in order to ensure a profitable business. This review discusses the influences of the HPA axis on the HPG axis and defines any significant reproductive function consequences caused by stress in ewes and places them into perspective for sheep management and productivity.
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- 2017
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20. Measuring wool cortisol and progesterone levels in breeding maiden Australian merino sheep (Ovis aries).
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Gregory Sawyer, Danielle Webster, and Edward Narayan
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Medicine ,Science - Abstract
Hormonal assessment tools are important for determining the reproductive success of production animals. This study used non-invasive wool assessment to quantify changes in progesterone and cortisol levels in reproducing female merino sheep. Wool samples were collected from a group of n = 46 maiden merino ewes (22-25 months old), naturally joined under natural light conditions in southern New South Wales (NSW), Australia. Three shearing opportunities were conducted as part of standard on-farm management practices. The wool samples were collected at three different dates during 2017, January (prior to rams being put out with the mob and to provide a baseline level since previous shearing in May 2016), September (during very late stages of gestation-approximately 2 weeks prior to parturition) and December (ewes had given birth and ~2-month-old lambs were at foot). Analysis of cortisol and progesterone was conducted concurrently from the same sample of wool. The hormones in wool samples quantified using commercially available cortisol and progesterone enzyme-immunoassay kits. Wool cortisol concentrations increased significantly (p = 3.04E-14) from pre-joining in January (1.33±0.12 ng/g) to late gestation in September (3.59±0.12 ng/g). Concentration of wool cortisol post-lambing in December (3.27±0.14 ng/g) did not decline significantly (p = 0.124) after gestation however remained significantly higher (p = 3.82E-10) than pre-joining levels. Wool progesterone (PG) concentrations increased significantly (p = 1.83E-33) from pre-joining (0.04±0.005 ng/g) in January to late gestation in September (5.53±0.13 ng/g) with a significant (p = 5.44E-59) decline observed in December (0.05±0.003 ng/g) to post- pregnancy concentrations. No significant difference was shown between pre-joining and post lambing PG concentrations (p = 0.057). Our results showed that non-invasive assessment of hormones in Merino sheep wool reflected significant increase in both cortisol and progesterone guided by pregnancy.
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- 2019
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21. Physiological Stress in Rescued Wild Koalas Are Influenced by Habitat Demographics, Environmental Stressors, and Clinical Intervention
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Edward Narayan and Tayla Vanderneut
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koala ,rescue ,rehabilitation ,stress ,environmental trauma ,disease ,Diseases of the endocrine glands. Clinical endocrinology ,RC648-665 - Abstract
Koalas are rescued from the wild often with incidence of burns from bushfire, injury from animal attacks, vehicle collision, and diseases. Exposure to environmental stressors (trauma and disease) could generate physiological stress and potentially impact the outcomes of clinical management intervention and rehabilitation of rescued wild koalas. It is important to quantify the stress physiology of wild koalas upon registering into clinical care. This study demonstrates the first report of physiological stress assessment in rescued wild koalas (n = 22) to determine the potential influences of habitat-specific demographics, stressor category, and clinical diagnosis. Fecal samples were collected from the koalas at rescue and routinely during hospitalization to provide a longitudinal assessment of the koala's stress response throughout clinical care. Fecal glucocorticoid metabolites (FCM) enzyme-immunoassay was used to index physiological stress non-invasively. Koalas were admitted with exposure to various categories of environmental trauma such as vehicle collision, dog attack, burns from forest fire (this also related to conditions such as copious drinking and flat demeanor), and other injury. The main disease diagnosed was chlamydial infections. In terms of environmental interactions, it was found that habitat-specific demographics, location where the rescued koala was found, especially the rural-urban fringe, influenced FCM levels. Furthermore, there was significant interaction between location, stressor category, and clinical diagnosis for mean FCM levels. However, these factors were not predictive of the clinical outcome (euthanized or released). Overall, the results provide invaluable insights into how wild koalas respond physiologically to environmental trauma and disease and how methods of care, husbandry, and treatment can be used to further reduce the impacts of stress with the ultimate aim of increasing the rehabilitation and future release of rescued koalas to revive the declining mainland populations.
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- 2019
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22. A Retrospective Literature Evaluation of the Integration of Stress Physiology Indices, Animal Welfare and Climate Change Assessment of Livestock
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Edward Narayan, Michelle Barreto, Georgia-Constantina Hantzopoulou, and Alan Tilbrook
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animal welfare ,stress biomarkers ,livestock production ,climate change ,future sustainability ,Veterinary medicine ,SF600-1100 ,Zoology ,QL1-991 - Abstract
In this retrospective study, we conducted a desktop-based analysis of published literature using the ScienceDirect™ search engine to determine the proportion of livestock research within the last 7 years (2015–2021) that have applied animal welfare assessment combining objective measures of physiological stress and evaluation of climate change factors in order to provide an account of livestock productivity. From the search results, 563 published articles were reviewed. We found that the majority of the literature had discussed animal production outcomes (n = 491) and animal welfare (n = 453) either individually or in conjunction with another topic. The most popular occurrence was the combination of animal welfare assessment, objective measures of stress physiology and production outcomes discussed collectively (n = 218). We found that only 125 articles had discussed the impact of climate change (22.20%) on livestock production and/or vice versa. Furthermore, only 9.4% (n = 53) of articles had discussed all four factors and published research was skewed towards the dairy sector. Overall, this retrospective paper highlights that although research into animal welfare assessment, objective measures of stress and climate change has been applied across livestock production systems (monogastrics and ruminants), there remains a shortfall of investigation on how these key factors interact to influence livestock production. Furthermore, emerging technologies that can boost the quantitative evaluation of animal welfare are needed for both intensive and extensive production systems.
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- 2021
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23. Introduction to the Special Issue: Assessing the Environmental Adaptation of Wildlife and Production Animals: Applications of Physiological Indices and Welfare Assessment Tools
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Edward Narayan
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n/a ,Veterinary medicine ,SF600-1100 ,Zoology ,QL1-991 - Abstract
Wild animals under human care as well as domesticated farm production animals are often exposed to environmental changes (e [...]
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- 2020
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24. Leveraging Technology for Animal Anatomy Practicals
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Suresh Krishnasamy and Edward Narayan
- Abstract
To deliver a comprehensive learning experience while shifting to online teaching due to COVID-19, educators at The University of Queensland (Australia) adopted Lt, a cloud-based platform, to overcome the challenges of delivering animal anatomy practicals. A two-phased study was conducted to evaluate the use of Lt for both online and on-campus students and its impact on student satisfaction and performance. Phase 1 investigated students' satisfaction with the practical experience, with online students expressing greater satisfaction across all constructs related to the practical: design, Lt, and feedback. Phase 2 investigated end-of-course evaluations, with all evaluated items increasing from 2019 to 2020 and 2021, along with student performance showing no difference between the online and on-campus students for practical assessment items and final examinations. The findings give confidence for technology adoption to enhance the learning experience for online students and provides an exemplar for similar adoption for practical delivery across other science disciplines.
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- 2024
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25. Identifying the Stressors Impacting Rescued Avian Wildlife
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Kimberley Janssen, Crystal Marsland, Michelle Orietta Barreto, Renae Charalambous, and Edward Narayan
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wildlife ,environmental stress ,urbanisation ,birds ,Veterinary medicine ,SF600-1100 ,Zoology ,QL1-991 - Abstract
Urbanisation exposes avian wildlife to an array of environmental stressors that result in clinical admission and hospitalisation. The aim of this pilot study was to conduct a retrospective analysis of clinical data and characterise this based on categories of stress experienced by avian wildlife patients. The results from this study indicated that impact injuries (n = 33, 25%) and vehicle-related injuries (n = 33, 25%) were the most common occurring preliminary stressors that resulted in the hospitalisation of avian wildlife. The most common outcome of avian patients that suffered from vehicle-related injuries was euthanasia (n = 15, 45%), as was avian patients that suffered from impact injuries (n = 16, 48%). Immobility (n = 105, 61%) and abnormal behaviour (n = 24, 14%) were the most commonly occurring primary stressors of avian patients. Finally, trauma (n = 51, 32%) and fractures (n = 44, 27%) were the most common occurring secondary stressors in avian patients. The most common outcome of all these stressors was euthanasia. This study provided further evidence towards the notion that human- and urbanisation-related stressors are the main causes of hospitalisation of avian wildlife, but also indicated that birds admitted as a result of human-related stressors are more likely to be euthanised than released. This study also provided a categorisation system for the stressors identified in avian wildlife patients (preliminary, primary and secondary) that may be used to monitor the stress categories of wildlife patients and gain a deeper understanding of the complex notion of stress.
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- 2020
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26. Faecal glucocorticoid metabolites and body temperature in Australian merino ewes (Ovis aries) during summer artificial insemination (AI) program.
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Edward Narayan, Gregory Sawyer, and Simone Parisella
- Subjects
Medicine ,Science - Abstract
Reproductive wastage is a key issue for sheep producers, both regionally and globally. The reproductive output of farm animals can be influenced by physiological and environmental factors. Rapid and reliable quantification of physiological stress can provide a useful tool for designing and testing on-farm management interventions to improve farm animal welfare and productivity. In this study, we quantified physiological stress non-invasively using faecal glucocorticoid metabolites-FGMs analysis and body temperature measurements of 15 superovulated donor merino ewes (Ovis aries) during participation in artificial insemination (AI) program conducted during 2015/2016 Australian summer. We hypothesized that low percentage transferable embryos in donor merino ewes will be associated positively with higher body temperature and/or higher FGMs in these ewes. Temperature humidity index (THI) was calculated and found within high thermal stress range during the two AI trials. Overall, results showed none of the factors (ewe ID, AI trial no., THI or FGMs) were significant for reduced percentage transferrable embryos, except ewe body temperature was highly significant (p = 0.014). Within AI trial comparisons showed significant positive associations between higher FGMs and body temperature with reduced transferrable embryos. These results suggest that Australian merino ewes participating in summer AI trials can experience physiological stress. Prolonged activation of the stress endocrine response and high body temperature (e.g. ensued from heat stress) could impact on ewe reproductive output. Therefore, future research should apply minimally invasive physiological tools to gather baseline information on physiological stress in merino sheep to enable the development of new farm-friendly methods of managing stress.
- Published
- 2018
- Full Text
- View/download PDF
27. Absence of invasive Chytrid fungus (Batrachochytrium dendrobatidis) in native Fijian ground frog (Platymantis vitiana) populations on Viwa-Tailevu, Fiji Islands
- Author
-
Edward Narayan, Frank Molinia, and Jean-Marc Hero
- Subjects
Zoology ,QL1-991 - Abstract
We report on the first survey of chytridiomycosis (Batrachochytrium dendrobatidis- Bd) in the endangered Fijian ground frog (Platymantis vitiana) population on Viwa-Tailevu, Fiji Islands. This fungal pathogen has been implicated as the primary cause of amphibian declines worldwide. Few cases have been reported from tropical Asia however it was recently documented in 4 species of frogs in Indonesia. Two hundred individual frogs were swabbed from 5 different sites on Viwa Island. Swabs were tested to quantify the number of Bd zoospore equivalents using real-time Polymerase Chain Reaction (qPCR) technique. We found zero (%) prevalence of Bd in ground frogs. The lack of Bd may be due to 1) hot weather all year round inhibiting the spread of Bd, 2) Bd may be absent from Viwa Island due to a lack of amphibian introductions (not introduced or importation of exotic frogs such as Rana catesbeia-na, or Xenopus spp or pet trade spp) or 3) the lack of introduction by human vectors due to the geographic isolation, and low visitation of non-local people into the island. While it is difficult to test these hypotheses, a precautionary approach would suggest an effective quarantine is required to protect Fiji’s endemic frogs from future disease outbreak. Conservation effort and research is needed at international level to assist the Fiji government in monitoring and protecting their unique endemic amphibians from outbreaks of B. dendrobatidis.
- Published
- 2011
- Full Text
- View/download PDF
28. Comparative Endocrinology of Animals
- Author
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Edward Narayan and Edward Narayan
- Published
- 2019
29. Chytridiomycosis in Sri Lanka: Predicting the future of a global amphibian hotspot
- Author
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Ruvinda K. de Mel, H. G. Salindra K. Dayananda, G. A. Sanoj Wijayasekara, Tharindu Ranasinghe, Amila P. Sumanapala, Surendranie Judith Cabral de Mel, Edward Narayan, Dinesh E. Gabadage, and Kanishka D. B. Ukuwela
- Subjects
Ecology ,Aquatic Science ,Nature and Landscape Conservation - Published
- 2023
30. Heat stress in horses: a literature review
- Author
-
Hyungsuk Kang, Rebeka R. Zsoldos, Albert Sole-Guitart, Edward Narayan, A. Judith Cawdell-Smith, and John B. Gaughan
- Subjects
Atmospheric Science ,Ecology ,Health, Toxicology and Mutagenesis - Abstract
Healthy adult horses can balance accumulation and dissipation of body heat to maintain their body temperature between 37.5 and 38.5 °C, when they are in their thermoneutral zone (5 to 25 °C). However, under some circumstances, such as following strenuous exercise under hot, or hot and humid conditions, the accumulation of body heat exceeds dissipation and horses can suffer from heat stress. Prolonged or severe heat stress can lead to anhidrosis, heat stroke, or brain damage in the horse. To ameliorate the negative effects of high heat load in the body, early detection of heat stress and immediate human intervention is required to reduce the horse’s elevated body temperature in a timely manner. Body temperature measurement and deviations from the normal range are used to detect heat stress. Rectal temperature is the most commonly used method to monitor body temperature in horses, but other body temperature monitoring technologies, percutaneous thermal sensing microchips or infrared thermometry, are currently being studied for routine monitoring of the body temperature of horses as a more practical alternative. When heat stress is detected, horses can be cooled down by cool water application, air movement over the horse (e.g., fans), or a combination of these. The early detection of heat stress and the use of the most effective cooling methods is important to improve the welfare of heat stressed horses.
- Published
- 2023
31. Linking the roles of personality and stress physiology for managing the welfare of captive big cats
- Author
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Alan McElligott, Edward Narayan, and JANICE VAZ
- Subjects
General Veterinary ,Animal Science and Zoology ,General Biochemistry, Genetics and Molecular Biology - Abstract
Animal welfare is important for the humane treatment of animals under our care. Zoos and rescue centres manage various charismatic animals, such as big cats, with limited resources. It is therefore essential for caretakers to understand the needs of an individual big cat to ensure its welfare. However, these needs may differ due to a big cat's personality, which may be identified by its coping style in a stressful situation. In addition, stress is one of the major factors affecting animal welfare. There is limited evidence showing strong associations between personality and stress physiology in big cats. This review focuses on the integration of personality and stress physiology of captive big cats, to highlight possible improvements in their husbandry. Our review identifies key factors that may influence big cat responses to stressors. These influencing factors include: i) social interactions; ii) environment; iii) life history and evolutionary traits; iv) genetics; and v) health. The first two factors are relatively well covered in the literature; however, the final three are potentially very promising avenues for future research to better understand how we can improve big cat welfare.
- Published
- 2022
32. Resident wild koalas show resilience to large-scale translocation of bushfire-rescued koalas
- Author
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Julian E Beaman, Connor Mulligan, Claire Moore, Dana Mitchell, Edward Narayan, and Karen Burke da Silva
- Subjects
Physiology ,Ecological Modeling ,Management, Monitoring, Policy and Law ,Nature and Landscape Conservation - Abstract
Wildlife translocation is increasingly utilized as a conservation management action, to mitigate the immediate negative effects of habitat loss and fragmentation (e.g. from land clearing or bushfires). Previous research has shown that stress responses can help or hinder survival in translocated wildlife and determine the efficacy of translocation as a conservation action. Yet these translocated animals are only one side of the equation, with translocation also potentially impacting the animals in the recipient population. We measured physiological markers of stress (faecal cortisol metabolite concentrations and neutrophil-lymphocyte ratios) and assessed health condition in a wild koala population one year after a major translocation of bushfire-rescued koalas on Kangaroo Island. We expected to find a high population density at the site (>0.75 koalas per hectare) and that resident koalas would show signs of chronic stress and ill health as a result of territorial conflict over food trees and reproductive opportunities. In contrast, we found that only one-fifth of the population remaining at the site were translocated koalas. The overall population density was also much lower (0.21 koalas per hectare) than anticipated. With no evidence of mass mortality at the site, we suggest that the majority of translocated koalas dispersed away from the site. Our stress marker measurements did not differ between the wild koalas and a sample of captive (non-display) koalas at the nearby Kangaroo Island Wildlife Park and were generally low compared to other studies. Veterinary examinations found that most koalas were in good body condition with very few diagnostic indicators of systemic ill health. Overall, our results suggest that, if there is adequate landscape-scale habitat connectivity and opportunity for dispersal, translocated koalas are likely to disperse from the site of release, with limited impacts on recipient koala populations at translocation release sites.
- Published
- 2023
33. Discussion paper on 'Comparing the agreement of a commercial cortisol kit with a biologically validated assay in evaluating faecal cortisol metabolite levels in koala joeys'
- Author
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Harsh Pahuja and Edward Narayan
- Subjects
Physiology ,Molecular Biology ,Biochemistry - Published
- 2023
34. Comparing the agreement of a commercial cortisol kit with a biologically validated assay in evaluating faecal cortisol metabolite levels in koala joeys
- Author
-
HARSH PAHUJA and Edward Narayan
- Subjects
Physiology ,Molecular Biology ,Biochemistry - Abstract
Orphaned koala joeys constitute a substantial number of wildlife rescues. Mortality is highly prevalent in rehabilitating joeys, with little knowledge about the causes of mortality. The hypothalamic-pituitary-adrenal axis plays a vital role in mediating stress by producing glucocorticoids (e.g. cortisol), however, no studies have quantified glucocorticoids in koala joeys. Traditional cortisol enzyme immuno-assay (e.g. R4866) are limited in supply and are process intensive, whereas, modern enzyme immuno-assay (EIA) kits (e.g. Arbor Assay cortisol kit) are available world-wide and provide rapid results. Biological validation is unsuitable to be performed in recuperating joeys due to ethical considerations, hence, we compared the results from biologically validated R4866 assay with the commercially available Arbor Assay cortisol kit. Thirty-four faecal samples were collected, processed and analysed for faecal cortisol metabolites (FCM) using both, R4866 assay and Arbor Assay kit. The joeys presented a suite of clinical conditions which provided the natural variation in stress response for comparing the assay sensitivity and range. The results indicated that there were no significant differences between the FCM values measured by both the assays. Furthermore, the Bland-Altman plot indicated a very strong agreement between the FCM concentrations measured by the two assays. This study is only a step towards recommending the routine use of commercial kit in clinical settings with basic resources, for rapid quantification of stress in koala patients. It is crucial for future studies to perform laboratory validation procedures to confirm the efficacy of the commercial kit before practical use for FCM monitoring in koalas.
- Published
- 2023
35. Reproductive Rates of Merino Ewes and Offspring Quality under AI Program
- Author
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Gregory Sawyer, Edward Narayan, Natalie Hoskins, and Greg Curren
- Subjects
Animal science ,Offspring ,media_common.quotation_subject ,Quality (business) ,Biology ,media_common - Abstract
Reproductive wastage is a major economic burden in sheep production globally, especially within Australia as livestock production systems face increased pressure from climatic variability (e.g. prolonged droughts or flooding). Sheep are sensitive to acute changes in their environment such as heat stress, which if not adequately monitored will result in significant production losses such as reproductive failure, increased parasite and worm burden, morbidity and mortality risks. Through basic and applied research in the areas of stress and reproductive physiology our team has made significant advancements in the understanding of sheep behaviour and physiological responses to acute and chronic stressors. Using minimally invasive hormone monitoring technology in combination with field based assessment of sheep health and productivity traits, our team has delivered new knowledge on how sheep react to acute environmental stress and how it impacts on sheep reproduction. In this chapter, we evaluated the fertility rates and embryo quality of Merino ewes under AI breeding program. We discuss factors such as heat stress that can impact on ewe and offspring quality.
- Published
- 2022
36. Annual changes in corticosterone and its response to handling, tagging and short-term captivity in Nyctibatrachus humayuni
- Author
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Edward Narayan, Amruta M. Joshi, and Narahari P. Gramapurohit
- Subjects
biology ,Ecological Modeling ,Energy reserves ,Stressor ,Zoology ,Captivity ,biology.organism_classification ,030227 psychiatry ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,chemistry ,Nyctibatrachus humayuni ,Corticosterone ,Seasonal breeder ,Animal Science and Zoology ,030217 neurology & neurosurgery ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation - Abstract
Glucocorticoids (GCs) are primarily involved in mobilising energy reserves to various physiological processes including reproduction. During situations of stress, GCs also help in coping with stress by diverting energy away from processes such as growth and reproduction. Hence, studying annual and seasonal changes in GCs of wild populations can help in understanding their role in stress management and reproduction. The quantification of GCs in wild animals involves capturing, handling and restraining, which could be stressful. Moreover, different species may exhibit differential sensitivity to different stressors. Hence, determining species-specific sensitivities and responses to different stressors may help in developing effective conservation measures. In this context, we studied the annual and seasonal variations in corticosterone metabolites of the Bombay night frog, Nyctibatrachus humayuni. In addition, the effects of handling, marking and short-term captivity (24 h) on corticosterone metabolite levels of N. humayuni were determined. Our results show that urinary corticosterone metabolites (UCM) varied significantly annually and between the sexes; in males, the levels were highest during the breeding season, whilst in females, the levels were highest just before the breeding season. Interestingly, UCM levels of both the sexes were not affected by tagging with visual implant elastomer (VIE), and by short-term captivity, suggesting that these manipulations were not stressful in terms of corticosterone responses.
- Published
- 2020
37. Interplay Between Stress and Reproduction: Novel Epigenetic Markers in Response to Shearing Patterns in Australian Merino Sheep (
- Author
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Edward Narayan, Gregory Sawyer, Dylan Fox, Ryan Smith, and Alan Tilbrook
- Subjects
General Veterinary - Abstract
In this study, we determined the effect(s) of early shearing on Australian Merino ewes (Ovis aries) and their lambs. To test this research question, we used a suite of field and laboratory methods including GPS collars, wool cortisol, and epigenetic change between ewes and lambs identified using Illumina NovaSeq RRBS. Once shorn ewes (n = 24) were kept on their full fleece throughout the entire gestation period, whereas twice (early) shorn ewes (n = 24) had their wool shorn pre-joining. Top-knot wool sample was taken from ewes during pre-joining, day 50 (mid-gestation), and day 90 (late gestation) for laboratory analysis. Ewes were pregnancy scanned at mid-gestation to determine whether they were early or late parturition (this confirmation is provided by the pregnancy scanner based on fetus size). Top-knot wool sample was also taken from the lambs at weaning for hormone and wool quality testing. Ear tissue was taken from ewes at day 50 (mid-gestation) and from lambs at lamb marking for DNA analysis. Results showed that twice or early shorn ewes grazed 10% higher and maintained stronger body condition than once shorn ewes. Wool cortisol levels were also significantly lower in the early shorn ewes between mid- and late gestation. Lambs bred from twice shorn ewes had on average better visual wool quality parameters in terms of micron, spin finesses, and curvature. For the DNA methylation results, when comparing a group of once sheared with twice sheared ewes, we have discovered one locus (Chr20:50404014) that was significantly differentially methylated [False Discovery Rate (FDR) = 0.005]. This locus is upstream of a protein-coding gene (ENSOARG00000002778.1), which shows similarities to the forkhead box C1 (FOXC1) mRNA using BLAST searches. To further our understanding of the potential interaction between pregnancy status and shearing frequency of the ewes, we performed further differential methylation analysis using a combination of shearing treatment and pregnancy scanning status. The comparisons (1) late pregnancy vs. early pregnancy for ewes with one shearing treatment and (2) late pregnancy vs. early pregnancy for sheep with two shearing treatments were carried out to identify associations between loci and pregnancy duration for sheep with either one or two shearing events. We discovered that 36 gene loci were significantly modulated either between different shearing treatments or late vs. early pregnancy status of ewes. This result suggests that maternal pregnancy and nutritional status during gestation influence DNA methylation. We further investigated DNA methylation in lambs and identified 16 annotated gene loci that showed epigenetic modulation as a result of being born from an early or late stage pregnancy. From the genomics data, we pointed out that ewes go through epigenetic modifications during gestation, and there is a degree of intra-individual variation in the reproductive performance of ewes, which could be due to combination of intrinsic (genetic and physiological) and extrinsic (management and climatic) factors. Collectively, this research provides novel dataset combining physiological, molecular epigenetics, and digital tracking indices that advances our understanding of how Merino ewes respond to shearing frequency, and this information could guide further research on Merino sheep breeding and welfare.
- Published
- 2021
38. Indexing Baselines: Determining Physiological Stress in Rescued Orphaned Koala Joeys Under Rehabilitation by Comparing Faecal Cortisol Levels Between Healthy and Impaired Individuals
- Author
-
Edward Narayan and Harsh Pahuja
- Subjects
Rehabilitation ,business.industry ,medicine.medical_treatment ,medicine ,Physiology ,business ,Cortisol level ,Physiological stress ,animal_sciences_zoology - Abstract
Koala (Phascolarctos cinereus) is an iconic folivorous marsupial native to the sclerophyll forests and woodlands of Australia. Due to the ever-changing habitat, this species is highly vulnerable to anthropogenic factors such as habitat loss and fragmentation, and this is reflected in the increasing number of injured and/or diseased koalas over the years. The majority of adult koalas admitted at wildlife hospitals are deceased, either due to natural causes, or have to be euthanized. Thus, orphaned koala joeys constitute a substantial number of wildlife rescues, and mortality is also prevalent in koala joeys being hand-reared/rehabilitated, with little knowledge about the causes of such high rates of mortality. Wildlife hospitals/rehabilitation centres are inherently stressful, and although the hypothalamic–pituitary–adrenal (HPA) axis plays a vital role in mediating the stress endocrine function (by producing glucocorticoids such as cortisol), there are no studies quantifying glucocorticoids in koala joeys. To contribute to this dearth of research, we sampled a total of seven individuals residing at Port Macquarie Koala Hospital and noted their clinical information. Faecal samples were collected from all seven koala joeys during routine cage cleaning. In total, 123 faecal samples were collected, processed and analysed for cortisol using enzyme-immunoassay (EIA). We used the iterative baseline approach to determine baseline and peak concentrations of FCM in koala joeys. Baseline concentrations ranged between 14.11 ng/g – 51.10 ng/g (healthy – sick), whereas, peak FCM concentrations ranged between 25.65 ng/g – 56.58 ng/g (healthy – sick). There was a significant difference (p < 0.05) between FCM concentrations of healthy and impaired individuals. Healthy individuals displayed relatively consistent FCM concentrations, whereas, diseased individuals displayed a significant increase in FCM concentrations over time. Our study provides the first record of baseline and peak FCM concentrations in rescued koala joeys with their associated clinical condition. Future studies can use the iterative baseline approach to determine FCM concentration in wild koala joeys that can serve as a baseline to compare glucocorticoid levels of rescued joeys.
- Published
- 2021
39. Physiological Stress in Rescued Wild Koalas (Phascolarctos cinereus) Being Held in a Rehabilitation Sanctuary: A Pilot Study
- Author
-
Edward Narayan, Matthew Peel, Troy Simonato, and Renae Charalambous
- Subjects
endocrine system ,medicine.medical_treatment ,Veterinary medicine ,Physiology ,stress ,Phascolarctos cinereus ,biology.animal ,SF600-1100 ,medicine ,Chronic stress ,Feces ,Marsupial ,Wildlife rehabilitation ,Rehabilitation ,General Veterinary ,biology ,glucocorticoids ,Stressor ,biology.organism_classification ,animal_sciences_zoology ,QL1-991 ,Animal Science and Zoology ,faeces ,Zoology ,Glucocorticoid ,medicine.drug ,fur - Abstract
Koalas (Phascolarctos cinereus) are one of Australia’s most charismatic native small marsupial species. Unfortunately, populations of koalas are rapidly declining throughout Australia as they continue to face increasing pressure from a changing ecosystem. All wildlife species to some degree will use their hypothalamic–pituitary–adrenal (HPA) axis in response to stress. Depending on the duration of activation, the stress response can lead to either acute or chronic side effects and is modulated through the neuroendocrine stress system with the release of catecholamines and glucocorticoids (e.g., cortisol). It is well known that rehabilitation sanctuaries are inherently stressful for all animals, in particular for rescued wild koalas, as it is an unfamiliar environment where the animals cannot predict or control what will happen to them. In this pilot study, we set out to quantify faecal and fur cortisol metabolites in wild rescued koalas undergoing wildlife rehabilitation. Absolute levels of acute and chronic stress were indexed non-invasively, with faecal samples taken to evaluate acute stress, and fur samples taken to evaluate chronic stress. Sampling occurred sporadically over four months (the start of September 2018 to the end of December 2018), and was performed on three rescued koalas (Maree, Tai, and Solstice) being held at the rehabilitation centre. Results of this study show that between the three koalas, the highest recorded faecal cortisol result was 241 ng/g, and the lowest recorded faecal cortisol result was 4 ng/g, whereas the highest recorded fur cortisol result was 1.75 ng/g, and the lowest recorded fur cortisol result was 0.10 ng/g. Statistically, there was a significant difference between all three koalas and their faecal cortisol responses, as well as their fur cortisol responses. Statistically for Maree and Solstice, there was a significant difference in their faecal cortisol response between days when a stressor was recorded, and days when a stressor was not recorded. However, statistically for Tai, this was not the case, as there was no significant difference in his faecal cortisol response between days when a stressor was recorded, and days when a stressor was not recorded. In summary, the hypothesis that faecal glucocorticoids and fur glucocorticoids between koalas will differ based on individual responses to stressors was true as a whole, but individually, this hypothesis was true for Maree and Solstice, but untrue for Tai. The use of biological samples such as faeces and fur to obtain readings of glucocorticoids is a method of measuring absolute levels of physiological stress that is still evolving for koalas, and there is no current glucocorticoid baseline with which to compare the results of this study; although, measuring faecal and fur glucocorticoids is the first step in understanding how koalas undergoing wildlife rehabilitation respond to stressors.
- Published
- 2021
40. Vocalisation and its association with androgens and corticosterone in a night frog (Nyctibatrachus humayuni) with unique breeding behaviour
- Author
-
Edward Narayan, Narahari P. Gramapurohit, and Amruta M. Joshi
- Subjects
0106 biological sciences ,Pulse (signal processing) ,media_common.quotation_subject ,05 social sciences ,Zoology ,Context (language use) ,Biology ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Courtship ,chemistry.chemical_compound ,Mate choice ,Nyctibatrachus humayuni ,chemistry ,Corticosterone ,Sexual selection ,Vocal effort ,0501 psychology and cognitive sciences ,Animal Science and Zoology ,050102 behavioral science & comparative psychology ,Ecology, Evolution, Behavior and Systematics ,media_common - Abstract
In anurans, vocalisation is used to communicate within and between the sexes during reproduction. Knowledge of vocal repertoire and its diversity is essential in understanding its significance in sexual selection. In this context, we studied the vocal behaviour of Nyctibatrachus humayuni and quantified the urinary metabolites of androgens and corticosterone to understand the associations among hormones, body condition index and vocalisation. Our results show that males of N. humayuni produce an amplitude-modulated call consisting of a train of pulses. Interestingly, a high degree of inter-individual variation was observed in the call parameters. The dominant frequency and pulse interval were negatively correlated with male body size, whereas pulse duration and pulse duty cycle were positively correlated with it. Dominant frequency was negatively correlated with androgens and corticosterone, whereas pulse interval was negatively correlated with corticosterone. Further, pulse duty cycle, pulse duration and pulses per call were positively associated with corticosterone. Surprisingly, none of the acoustic parameters was associated with male body temperature and body condition. A significant variation was evident in the vocal effort, dominant frequency and amplitude of advertisement calls produced under different social situations. Calls produced during territory establishment had lower dominant frequency but higher vocal effort, whereas those produced during courtship had higher amplitude and vocal effort than the calls produced in the absence of a competitor/female. Our results suggest that greater inter-male variability in the advertisement call of N. humayuni could be important in female choice as it may help females to assess the quality of a male. Further, androgens and corticosterone could be important in modulating crucial parameters of the advertisement call.
- Published
- 2019
41. Urinary corticosterone metabolite responses to capture and visual elastomer tagging in the Asian toad (Duttaphrynus melanostictus)
- Author
-
Edward Narayan and Narahari P. Gramapurohit
- Subjects
0106 biological sciences ,0301 basic medicine ,Amphibian ,Ecological Modeling ,Metabolite ,Urinary system ,Zoology ,Context (language use) ,Toad ,Biology ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Mark and recapture ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,chemistry ,Corticosterone ,biology.animal ,Duttaphrynus ,Animal Science and Zoology ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation - Abstract
Herpetological research involving amphibians is increasingly using mark and recapture methods, employing various techniques such as toe-clipping and visible implant alphanumeric tags. Visual Implant Elastomer (VIE) is a new method available for herpetological surveys, involving a coloured dye inserted into the epidermal skin surface of frogs. Previously, there has been only one study which demonstrated that the VIE method does not generate a significant physiological stress response (using a faecal glucocorticoid method) in a captive amphibian species. Physiological stress can also be quantified non-invasively using urinary corticosterone metabolite (UCM) enzyme-immunoassay in amphibians. In this study, we tested the physiological stress response of a common amphibian species, wild caught Asian toads (Duttaphrynus melanostictus), by comparing UCM responses to capture handling, sham control or VIE marking method. Adult males (n = 38) were captured and sampled for baseline UCM (t = 0 h) then marked either using the VIE or sham (saline control), or only handled during capture. Subsequently, urine samples were collected at t = 2, 12 and 24 h for toads within each group. UCM levels were quantified using an enzyme immunoassay (EIA) to determine differences among treatment groups and over time following capture. Toads generated acute stress responses to all three groups, showing a change in UCMs between baseline samples, 12 h, and 24 h samples. The mean UCM levels were not significantly different between the VIE method and the control groups (capture handling or sham operated). These results indicate that VIE method of tagging is no more stressful than routine handling of amphibians, hence in this context, the method does not have any additional welfare implications. Future research should explore the limitations of VIE tagging for long-term mark recapture studies, however, our current findings support its application as a minimally-invasive method for marking amphibians.
- Published
- 2019
42. Extreme Competence: Keystone Hosts of Infections
- Author
-
Rebecca E. Koch, Andrew S. Flies, Laura F. Grogan, Edward Narayan, Anne Peters, Katherine L. Buchanan, Constanza Napolitano, Nynke Raven, Manuel Ruiz-Aravena, Lee A. Rollins, Justin R. Eastwood, Michael J. Roast, Lee Peacock, Lynn B. Martin, Ondi L. Crino, Andrew G. D. Bean, Rodrigo Hamede, Beata Ujvari, Helena S. Stokes, Johanne M. Martens, Alice Risely, Marcel Klaassen, BriAnne Addison, Geoffrey E. Hill, Alison J. Peel, and Daniel Selechnik
- Subjects
0106 biological sciences ,0301 basic medicine ,disease ,Bufo marinus ,Disease ecology ,Biology ,zoonosis ,010603 evolutionary biology ,01 natural sciences ,Article ,epidemic ,infection ,Host-Parasite Interactions ,03 medical and health sciences ,030104 developmental biology ,Evolutionary biology ,Animals ,Parasite transmission ,Parasites ,Competence (human resources) ,Ecology, Evolution, Behavior and Systematics ,Super-spreader - Abstract
Individual hosts differ extensively in their competence for parasites, but traditional research has discounted this variation, partly because modeling such heterogeneity is difficult. This discounting has diminished as tools have improved and recognition has grown that some hosts, the extremely competent, can have exceptional impacts on disease dynamics. Most prominent among these hosts are the superspreaders, but other forms of extreme competence (EC) exist and others await discovery; each with potentially strong but distinct implications for disease emergence and spread. Here, we propose a framework for the study and discovery of EC, suitable for different host–parasite systems, which we hope enhances our understanding of how parasites circulate and evolve in host communities., Highlights A few members of host populations, so-called superspreaders, have disproportionate impacts on the risk of infectious disease emergence and spread. Several other forms of EC exist; some of which might be exceptionally protective. To discover and understand forms of EC, it is imperative to describe the distribution of, and covariation among, traits of individual hosts that mediate the many stages of host–parasite interactions. Here, we provide a framework to do so, emphasizing how interplay among host traits related to parasite exposure behavior, susceptibility, replicability of parasites on/in hosts, and transmissibility, comprise host competence. We hope this framework helps reveal new forms of EC and informs and improves management of disease risk.
- Published
- 2019
43. Evaluating physiological stress in Asiatic black bears (Ursus thibetanus) rescued from bile farms in Vietnam
- Author
-
T. Bendixsen, M. Hunter-Ishikawa, Andy Willis, R.C.A. Thompson, and Edward Narayan
- Subjects
0301 basic medicine ,General Veterinary ,Zoology ,Biology ,Ursus thibetanus ,biology.organism_classification ,Stress hormone ,General Biochemistry, Genetics and Molecular Biology ,Stress level ,03 medical and health sciences ,030104 developmental biology ,Animal welfare ,Animal Science and Zoology ,Chronic stress ,Physiological stress ,Feces - Abstract
Asiatic black bears (Ursus thibetanus) face chronic stress in bile farms. In this study, we investigated whether bile-farmed bears show significantly high levels of stress at rescue and whether stress levels reduce over time in a bear sanctuary where the bears are supported with environmental enrichment and veterinary care to improve animal welfare. We measured stress hormone levels using faecal cortisol metabolites (FCM) in 16 Asiatic black bears freshly rescued from bile farms in Vietnam. Fresh faeces were collected from each bear on the rescue truck and on a weekly basis for a 22-week study period at a bear sanctuary in Vietnam. Results showed that for all 16 rescued bears (with one exception) individual FCM levels from truck samples were above mean baseline FCMs of bears previously rehabilitated to a bear sanctuary. This suggested the majority of the rescued bears were still capable of showing a stress endocrine response during the rescue operation despite being exposed to conditions causing chronic stress in bears on bile farms. Results showed that mean FCM levels of the rescued bears differed significantly between time-periods (higher at the rescue [on truck samples] compared to week 22 samples) and mean FCM levels showed an overall decline over the first 22 weeks after they arrived at the bear sanctuary. The bears also demonstrated acute FCM stress responses to management interventions at the sanctuary, such as veterinary health checks and transportation. In conclusion, rescued bears tend to modulate their stress endocrine response after rehoming at the bear sanctuary. This is an important result, indicating that the rescue effort and rehabilitation of bile-farm bears is effective. Whether this also coincides with behavioural adjustments in rehabilitating bears (eg lessening of stereotypic behaviour) warrants further investigation.
- Published
- 2018
44. Assessing the Environmental Adaptation of Wildlife and Production Animals
- Author
-
Edward Narayan
- Subjects
Faecal analysis ,media_common.quotation_subject ,Wildlife ,Production (economics) ,Cervus elaphus ,Environmental adaptation ,Business ,Blood parameters ,Environmental planning ,Environmental stress ,Welfare ,media_common - Published
- 2021
45. Evaluating the Stressors Impacting Rescued Reptilian Wildlife
- Author
-
Edward Narayan and Harsh Pahuja
- Subjects
Rehabilitation ,business.industry ,medicine.medical_treatment ,Environmental health ,Stressor ,Wildlife ,Medicine ,Disease ,Clinical care ,business ,animal_sciences_zoology - Abstract
Direct and indirect anthropogenic factors play a massive role in driving wildlife species towards extinction. Longitudinal retrospective studies identify key ‘factors’ responsible for the decline in numbers of wildlife, however, lack the reasoning behind the events leading to mortality. The overarching aim of this study was to categorize these ‘factors’ into different stressor categories faced by reptiles to understand its impact on an individual, and to compare how each stressor category influences the survival of an individual. The results from this study indicated that almost half of the number of reptiles being hospitalized were due to exposure to preliminary stressors such as lawn mowing incidents and pet attack. Primary and secondary admissions were fairly equal in number, however the mortality rate for secondary admissions was drastically high (~80%). The discussion integrates species’ ecology and stress physiology which can prove to have multi-faceted benefits across the fields of ecology and animal welfare. Ecologists can use the results from this study to comprehend species’ activity patterns to better plan reptilian conservation programs, whereas, for wildlife clinicians and rehabilitators, assignment of stressor categories could be a beneficial tool for bolstering the welfare monitoring program for small native reptiles in clinical settings.
- Published
- 2021
46. Reactive scope model and emergency life history stage provide useful tools for evaluating the stress responses of native Australian lizards living in disturbed landscapes
- Author
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HARSH PAHUJA and Edward Narayan
- Subjects
reproduction ,stress ,reactive scope model ,glucocorticoids ,Physiology ,Ecological Modeling ,Perspective ,AcademicSubjects/SCI00840 ,Management, Monitoring, Policy and Law ,survival ,Emergency life history stage ,Nature and Landscape Conservation - Abstract
Stress impacts on native wildlife because of added pressure from human-induced environmental change. The intrinsic variation in physiological stress responses [e.g. glucocorticoids (GCs)] can be evaluated using the emergency life history stage (ELHS), which has an adaptive value. The temporal and spatial variation in stress responses can also be evaluated using the reactive scope model (RSM). Using the blue-tongue lizard and the Eastern bearded dragon as examples we showed how short- and long-season breeding patterns impacted the adaptive value of the ELHS. Further, with the availability of field endocrinology data (e.g. plasma or faecal GCs), researchers can scope their study species’ stress responses using the RSM to guide conservation and management programs., Glucocorticoids (GCs) are used as biomarkers of physiological stress response in reptiles. Fundamental stress physiology tools including the emergency life history stage (ELHS) and the reactive scope model (RSM) can be useful to determine how individual variation of stress responses shape population ecology. In this perspective, we applied the RSM and ELHS into the context of two urban-dwelling small native Australian reptile species to compare the stress-response patterns in short- and long-breeding lizards. Firstly, by drawing inferences from the ELHS, we presented hypothetical scenarios using sample GC data for a short-breeding species (e.g. common blue-tongue lizard). We showed that activation of the physiological stress response would be non-adaptive due to the consequences of stress on reproduction. Therefore, blue-tongue lizards may become exposed to acute and chronic environmental stressors (e.g. human disturbance and habitat clearance) during the breeding season as they prefer not to activate their hypothalamo-pituitary interrenal (HPI) axis in support of their short-breeding season. On the contrary, long-breeding lizards (e.g. bearded dragons), which have multiple breeding opportunities and are accustomed to living around humans and altered urban environments, tended to operate above the critical adaptive value of the ELHS during their breeding period. This suggests that any future changes to the dynamics of habitat availability and breeding opportunities may favour the dragon differently over the blue-tongue lizard. To further capture the dynamics of stress responses along spatial and temporal scales, we suggested that researchers should collect field data (e.g. blood plasma or faecal GCs) and then use the ELHS and RSM to understand how the environment is shaping the animal’s stress physiology. The application of field stress monitoring and data visualization using the ELHS and RSM could guide environmental monitoring and conservation programs of native wildlife species.
- Published
- 2021
47. Animal Welfare Assessment: Volume 1
- Author
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Alan J Tilbrook, Alan G. McElligott, and Edward Narayan
- Subjects
Animal Welfare (journal) ,Natural resource economics ,Economics ,Volume (compression) - Published
- 2021
48. Identifying the Stressors Impacting Rescued Avian Wildlife
- Author
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Edward Narayan, Renae Charalambous, Michelle Barreto, Crystal Marsland, and Kimberley Janssen
- Subjects
0106 biological sciences ,lcsh:Veterinary medicine ,urbanisation ,General Veterinary ,040301 veterinary sciences ,business.industry ,wildlife ,Stressor ,Wildlife ,04 agricultural and veterinary sciences ,010603 evolutionary biology ,01 natural sciences ,Environmental stress ,Article ,environmental stress ,0403 veterinary science ,Environmental health ,birds ,lcsh:Zoology ,Retrospective analysis ,lcsh:SF600-1100 ,Medicine ,Animal Science and Zoology ,lcsh:QL1-991 ,business - Abstract
Simple Summary Stress evaluation in wildlife is valuable tool for rehabilitation and injury prevention. This pilot study investigated categories of stress in rescued birds. We determined three categories of stressors (preliminary, primary and secondary) using clinical data of rescued birds from Adelaide, South Australia. It was discovered that birds are highly susceptible to impact injuries (e.g., flying into a building window) and vehicle-related injuries as preliminary stressors, which often result in hospitalisation of birds. Immobility and abnormal behaviour represented the most common primary stressor, while the most common secondary stressors included trauma and fracture. Furthermore, the most common outcome in clinics due to exposure of birds to these three stressor categories was euthanasia. Abstract Urbanisation exposes avian wildlife to an array of environmental stressors that result in clinical admission and hospitalisation. The aim of this pilot study was to conduct a retrospective analysis of clinical data and characterise this based on categories of stress experienced by avian wildlife patients. The results from this study indicated that impact injuries (n = 33, 25%) and vehicle-related injuries (n = 33, 25%) were the most common occurring preliminary stressors that resulted in the hospitalisation of avian wildlife. The most common outcome of avian patients that suffered from vehicle-related injuries was euthanasia (n = 15, 45%), as was avian patients that suffered from impact injuries (n = 16, 48%). Immobility (n = 105, 61%) and abnormal behaviour (n = 24, 14%) were the most commonly occurring primary stressors of avian patients. Finally, trauma (n = 51, 32%) and fractures (n = 44, 27%) were the most common occurring secondary stressors in avian patients. The most common outcome of all these stressors was euthanasia. This study provided further evidence towards the notion that human- and urbanisation-related stressors are the main causes of hospitalisation of avian wildlife, but also indicated that birds admitted as a result of human-related stressors are more likely to be euthanised than released. This study also provided a categorisation system for the stressors identified in avian wildlife patients (preliminary, primary and secondary) that may be used to monitor the stress categories of wildlife patients and gain a deeper understanding of the complex notion of stress.
- Published
- 2020
- Full Text
- View/download PDF
49. A 29-year retrospective analysis of koala rescues in New South Wales, Australia
- Author
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Edward Narayan and Renae Charalambous
- Subjects
Male ,0106 biological sciences ,Common disease ,Disease ,Wildlife ,01 natural sciences ,Chlamydia Infection ,Geographical Locations ,Medical Conditions ,Medicine and Health Sciences ,Retrospective analysis ,Chlamydia ,0303 health sciences ,education.field_of_study ,Multidisciplinary ,Habitat fragmentation ,biology ,Eukaryota ,Agriculture ,Agricultural Methods ,Prognosis ,Infectious Diseases ,Geography ,Veterinary Diseases ,Medicine ,Female ,New South Wales ,Phascolarctidae ,Research Article ,Conservation of Natural Resources ,Science ,Oceania ,Population ,Sexually Transmitted Diseases ,History, 21st Century ,010603 evolutionary biology ,03 medical and health sciences ,Agricultural Production ,Phascolarctos cinereus ,Diagnostic Medicine ,biology.animal ,Animals ,Juvenile ,Population growth ,education ,Ecosystem ,Demography ,Retrospective Studies ,030304 developmental biology ,Bacteria ,Euthanasia ,Endangered Species ,Stressor ,Australia ,Organisms ,Biology and Life Sciences ,Chlamydia Infections ,History, 20th Century ,People and Places ,Threatened species ,Research studies ,Veterinary Science ,Zoology - Abstract
The koala (Phascolactos cinereus) is currently listed by both the IUCN and the Australian Governments’ Threatened Species Scientific Committee as vulnerable to extinction with a decreasing population trend. This listing can be attributed to climate change and its impact on ecosystems, and anthropomorphic environmental change due to extensive land clearing and habitat fragmentation. These have both been proven to induce stress, which influences the onset of disease. This novel study performed a retrospective analysis whereby records for 12,543 wild, rescued koalas in New South Wales (NSW), Australia were studied in order to determine trends in koala sightings, clinical admissions and injury diagnoses over a period of 29 years (1989-2018). Results indicated that between all three study locations (Port Stephens, Port Macquarie and Lismore), the most common reason koalas were admitted into care was because of disease, the most common disease diagnosed was signs of chlamydia, and the most common outcome for koalas admitted into care was released. At Port Stephens, mature and female koalas were diagnosed with a disease more than any other age or sex, while juvenile and male koalas were released (back into the wild) more than any other age or sex. Additionally, there were fewer koalas with a disease and fewer koalas released in Port Stephens as each year progressed. At Port Macquarie, mature and male koalas were diagnosed with a disease more than any other age or sex, while juvenile and female koalas were released more than any other age or sex. Additionally, there were more koalas with a disease and fewer koalas released in Port Macquarie as each year progressed. At Lismore, adult and female koalas were diagnosed with a disease more than any other age or sex, while joey and male koalas were released more than any other age or sex. Additionally, there were more koalas with a disease and fewer koalas released in Lismore as each year progressed. Determining trends in clinical admissions and diagnosis over such a substantial period of time is an important factor in preventing the continuing decline of koalas throughout Australia, and in particular NSW. It is important to note that there are cultural differences between koala rescue groups in the three study locations (Port Stephens, Port Macquarie and Lismore). These differences may be reflected in the outcomes of koala patients as each group are driven by their own management team. It is essential that any further decline of koala populations is prevented, however this can only be achieved through informed recommendations through research studies such as these. These recommendations should lead to government legislation which can provide stronger protection to koala habitat.
- Published
- 2020
- Full Text
- View/download PDF
50. Comparative Endocrine Stress Responses in Vertebrates
- Author
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Lluis Tort, John F. Cockrem, and Edward Narayan
- Subjects
Stress (mechanics) ,Endocrine system ,Physiology ,Biology - Published
- 2020
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