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Local Extinction and Unintentional Rewilding of Bighorn Sheep (Ovis canadensis) on a Desert Island  [PDF]
Benjamin T. Wilder, Julio L. Betancourt, Clinton W. Epps, Rachel S. Crowhurst, Jim I. Mead, Exequiel Ezcurra
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091358
Abstract: Bighorn sheep (Ovis canadensis) were not known to live on Tiburón Island, the largest island in the Gulf of California and Mexico, prior to the surprisingly successful introduction of 20 individuals as a conservation measure in 1975. Today, a stable island population of ~500 sheep supports limited big game hunting and restocking of depleted areas on the Mexican mainland. We discovered fossil dung morphologically similar to that of bighorn sheep in a dung mat deposit from Mojet Cave, in the mountains of Tiburón Island. To determine the origin of this cave deposit we compared pellet shape to fecal pellets of other large mammals, and extracted DNA to sequence mitochondrial DNA fragments at the 12S ribosomal RNA and control regions. The fossil dung was 14C-dated to 1476–1632 calendar years before present and was confirmed as bighorn sheep by morphological and ancient DNA (aDNA) analysis. 12S sequences closely or exactly matched known bighorn sheep sequences; control region sequences exactly matched a haplotype described in desert bighorn sheep populations in southwest Arizona and southern California and showed subtle differentiation from the extant Tiburón population. Native desert bighorn sheep previously colonized this land-bridge island, most likely during the Pleistocene, when lower sea levels connected Tiburón to the mainland. They were extirpated sometime in the last ~1500 years, probably due to inherent dynamics of isolated populations, prolonged drought, and (or) human overkill. The reintroduced population is vulnerable to similar extinction risks. The discovery presented here refutes conventional wisdom that bighorn sheep are not native to Tiburón Island, and establishes its recent introduction as an example of unintentional rewilding, defined here as the introduction of a species without knowledge that it was once native and has since gone locally extinct.
Use of Exposure History to Identify Patterns of Immunity to Pneumonia in Bighorn Sheep (Ovis canadensis)  [PDF]
Raina K. Plowright, Kezia Manlove, E. Frances Cassirer, Paul C. Cross, Thomas E. Besser, Peter J. Hudson
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061919
Abstract: Individual host immune responses to infectious agents drive epidemic behavior and are therefore central to understanding and controlling infectious diseases. However, important features of individual immune responses, such as the strength and longevity of immunity, can be challenging to characterize, particularly if they cannot be replicated or controlled in captive environments. Our research on bighorn sheep pneumonia elucidates how individual bighorn sheep respond to infection with pneumonia pathogens by examining the relationship between exposure history and survival in situ. Pneumonia is a poorly understood disease that has impeded the recovery of bighorn sheep (Ovis canadensis) following their widespread extirpation in the 1900s. We analyzed the effects of pneumonia-exposure history on survival of 388 radio-collared adults and 753 ewe-lamb pairs. Results from Cox proportional hazards models suggested that surviving ewes develop protective immunity after exposure, but previous exposure in ewes does not protect their lambs during pneumonia outbreaks. Paradoxically, multiple exposures of ewes to pneumonia were associated with diminished survival of their offspring during pneumonia outbreaks. Although there was support for waning and boosting immunity in ewes, models with consistent immunizing exposure were similarly supported. Translocated animals that had not previously been exposed were more likely to die of pneumonia than residents. These results suggest that pneumonia in bighorn sheep can lead to aging populations of immune adults with limited recruitment. Recovery is unlikely to be enhanced by translocating na?ve healthy animals into or near populations infected with pneumonia pathogens.
A Review of Hypothesized Determinants Associated with Bighorn Sheep (Ovis canadensis) Die-Offs  [PDF]
David S. Miller,Eric Hoberg,Glen Weiser,Keith Aune,Mark Atkinson,Cleon Kimberling
Veterinary Medicine International , 2012, DOI: 10.1155/2012/796527
Abstract: Multiple determinants have been hypothesized to cause or favor disease outbreaks among free-ranging bighorn sheep (Ovis canadensis) populations. This paper considered direct and indirect causes of mortality, as well as potential interactions among proposed environmental, host, and agent determinants of disease. A clear, invariant relationship between a single agent and field outbreaks has not yet been documented, in part due to methodological limitations and practical challenges associated with developing rigorous study designs. Therefore, although there is a need to develop predictive models for outbreaks and validated mitigation strategies, uncertainty remains as to whether outbreaks are due to endemic or recently introduced agents. Consequently, absence of established and universal explanations for outbreaks contributes to conflict among wildlife and livestock stakeholders over land use and management practices. This example illustrates the challenge of developing comprehensive models for understanding and managing wildlife diseases in complex biological and sociological environments. 1. Introduction Effective management and conservation of wildlife populations can be undermined by multiple causes. These include decreased and altered habitat and other direct anthropogenic effects, climate change, competition and predation from nonnative wildlife and domestic species, demographic challenges associated with small populations, multiple, incompatible management objectives for sympatric species or their habitat, and exposure to native and exotic infectious agents [1–4]. The consequences and interactions of these variables are difficult to understand and predict, and may vary by circumstances. This uncertainty, particularly when it occurs in complex sociological environments where stakeholders have differing values and objectives, presents substantial challenges for decision makers. In such uncertain environments, the absence of data and differing values can result in polarized debate among stakeholders. It can also serve as an impediment to the acquisition of data that would contribute to effective management. Respiratory disease outbreaks in bighorn sheep (Ovis canadensis) illustrate the challenge of identifying and managing disease in valued wildlife populations, where stakeholder perceptions and values clash [5]. Bighorn sheep are highly valued for recreational, ecological, philosophical, spiritual, and other reasons [6]. Bighorns have experienced a population decline of two orders of magnitude subsequent to 19th century settlement of western North
Disease and Predation: Sorting out Causes of a Bighorn Sheep (Ovis canadensis) Decline  [PDF]
Joshua B. Smith, Jonathan A. Jenks, Troy W. Grovenburg, Robert W. Klaver
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0088271
Abstract: Estimating survival and documenting causes and timing of mortality events in neonate bighorn sheep (Ovis canadensis) improves understanding of population ecology and factors influencing recruitment. During 2010–2012, we captured and radiocollared 74 neonates in the Black Hills, South Dakota, of which 95% (70) died before 52 weeks of age. Pneumonia (36%) was the leading cause of mortality followed by predation (30%). We used known fate analysis in Program MARK to estimate weekly survival rates and investigate the influence of intrinsic variables on 52-week survival. Model {S1 wk, 2–8 wks, >8 wks} had the lowest AICc (Akaike’s Information Criterion corrected for small sample size) value, indicating that age (3-stage age-interval: 1 week, 2–8 weeks, and >8 weeks) best explained survival. Weekly survival estimates for 1 week, 2–8 weeks, and >8 weeks were 0.81 (95% CI = 0.70–0.88), 0.86 (95% CI = 0.81–0.90), and 0.94 (95% CI = 0.91–0.96), respectively. Overall probability of surviving 52 weeks was 0.02 (95% CI = 0.01–0.07). Of 70 documented mortalities, 21% occurred during the first week, 55% during weeks 2–8, and 23% occurred >8 weeks of age. We found pneumonia and predation were temporally heterogeneous with lambs most susceptible to predation during the first 2–3 weeks of life, while the greatest risk from pneumonia occurred from weeks 4–8. Our results indicated pneumonia was the major factor limiting recruitment followed by predation. Mortality from predation may have been partly compensatory to pneumonia and its effects were less pronounced as alternative prey became available. Given the high rates of pneumonia-caused mortality we observed, and the apparent lack of pneumonia-causing pathogens in bighorn populations in the western Black Hills, management activities should be geared towards eliminating contact between diseased and healthy populations.
Resistance of gastrointestinal nematodes to anthelmintics in sheep (Ovis aries)
Thomaz-Soccol, Vanete;Souza, Felipe Pohl de;Sotomaior, Cristina;Castro, Edilene Alcantara;Milczewski, Viviane;Mocelin, Giovani;Silva, Maria do Carmo Pessoa e;
Brazilian Archives of Biology and Technology , 2004, DOI: 10.1590/S1516-89132004000100006
Abstract: the fecal egg count reduction test (fecrt) was used in a survey for anthelmintic resistance in 42 sheep farms, in five different regions in paraná state, brazil between july 1996 - july 2000. animals with natural infection were tested. five drugs were used individually or in combination - benzimidazole, imidazothiazole, ivermectin, milbemicina and closantel. results showed that the prevalence of resistance to all anthelmintic was as high as 88.1% for benzimidazoles (oxfendazole), 78.6% for ivermectin, 56.4% for closantel, 38.7% for closantel + oxfendazole, 38% for levamisole, and 23.6% for moxidectin. there was multiple resistance in all tested farms. the most important infective larvae recovered from culture were haemonchus contortus and trichostrongylus colubriformis. the failure of the existing drugs in the state of paraná is considered an important issue. some proposals to improve the situation are suggested which include a change of attitude on anthelmintic use by sheepherders, veterinarians and sanitary authorities.
Safety and Immunogenicity of a Mycoplasma ovipneumoniae Bacterin for Domestic Sheep (Ovis aries)  [PDF]
Jessie C. Ziegler, Kevin K. Lahmers, George M. Barrington, Steven M. Parish, Katherine Kilzer, Katherine Baker, Thomas E. Besser
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0095698
Abstract: Background Mortality from epizootic pneumonia is hindering re-establishment of bighorn sheep populations in western North America. Mycoplasma ovipneumoniae, a primary agent of this disease, is frequently carried asymptomatically by the domestic sheep and goats that constitute the reservoir of this agent for transmission to bighorn sheep. Our long-term objective is to reduce the risk of M. ovipneumoniae infection of bighorn sheep; one approach to this objective is to control the pathogen in its reservoir hosts. Methods The safety and immunogenicity of M. ovipneumoniae for domestic sheep was evaluated in three experimental immunization protocols: 1) live M. ovipneumoniae (50 ug protein); 2) killed M. ovipneumoniae (50 ug whole cell protein) in oil adjuvant; and 3) killed M. ovipneumoniae (250 ug whole cell protein) in oil adjuvant. Immunogenicity was assessed by two serum antibody measures: competitive enzyme-linked immunosorbent assay (cELISA) (experiments 1–3) and serum growth inhibition (Experiment 3). Passive immunogenicity was also assessed in the third experiment using the same assays applied to blood samples obtained from the lambs of immunized ewes. Results and Conclusions Adverse reactions to immunization were generally minor, but local reactions were regularly observed at immunization sites with bacterins in oil adjuvants. No evidence of M. ovipneumoniae specific antibody responses were observed in the first or second experiments and no resistance to colonization was observed in the first experiment. However, the ewes in the third experiment developed strong cELISA serum antibody responses and significant serum M. ovipneumoniae inhibition activity, and these responses were passively transferred to their lambs. The results of these trials indicate that immunization with relatively large antigenic mass combined with an adjuvant is capable of inducing strong active antibody responses in ewes and passively immunizing lambs.
Phylogenetic Position of a Copper Age Sheep (Ovis aries) Mitochondrial DNA  [PDF]
Cristina Olivieri, Luca Ermini, Ermanno Rizzi, Giorgio Corti, Stefania Luciani, Isolina Marota, Gianluca De Bellis, Franco Rollo
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033792
Abstract: Background Sheep (Ovis aries) were domesticated in the Fertile Crescent region about 9,000-8,000 years ago. Currently, few mitochondrial (mt) DNA studies are available on archaeological sheep. In particular, no data on archaeological European sheep are available. Methodology/Principal Findings Here we describe the first portion of mtDNA sequence of a Copper Age European sheep. DNA was extracted from hair shafts which were part of the clothes of the so-called Tyrolean Iceman or ?tzi (5,350 - 5,100 years before present). Mitochondrial DNA (a total of 2,429 base pairs, encompassing a portion of the control region, tRNAPhe, a portion of the 12S rRNA gene, and the whole cytochrome B gene) was sequenced using a mixed sequencing procedure based on PCR amplification and 454 sequencing of pooled amplification products. We have compared the sequence with the corresponding sequence of 334 extant lineages. Conclusions/Significance A phylogenetic network based on a new cladistic notation for the mitochondrial diversity of domestic sheep shows that the ?tzi's sheep falls within haplogroup B, thus demonstrating that sheep belonging to this haplogroup were already present in the Alps more than 5,000 years ago. On the other hand, the lineage of the ?tzi's sheep is defined by two transitions (16147, and 16440) which, assembled together, define a motif that has not yet been identified in modern sheep populations.
Microarchitecture of the Palatine Tonsil in Sheep (Ovis aries) Microarquitectura de la Tonsila Palatina en Oveja (Ovis aries)  [cached]
N. K. B Raju,Geetha Ramesh,Sabiha Hayath Basha,S Ushakumary
International Journal of Morphology , 2012,
Abstract: The tissue pieces of palatine tonsil were collected from different postnatal age groups of sheep from the Corporation Slaughter House, Perambur, Chennai. The palatine tonsil consisted of a surface epithelium, capsule, tonsillar lobes, crypts, crypt epithelium and tonsillar follicles. The surface epithelium over the palatine tonsil was made up of non-keratinized stratified squamous epithelium in all the postnatal age groups studied. The palatine tonsil was clearly demarcated from the surrounding structures by a distinct connective tissue capsule and one septa dividing the tonsil into two lobes. The surface epithelium was invaginated into the substance of the tonsil to form primary and secondary crypts in each lobe. The crypt epithelium covered the regions of lymphoid follicles became lymphoepithelium. The macrophages were also observed in the epithelium. In the areas of lymphoepithelium the basement membrane was interrupted since lymphocytic infiltration was heavy into the epithelium. Numerous secondary tonsillar follicles with germinal centers separated by interfollicular areas were observed in the palatine tonsil. The tonsillar follicles consisted of a mantle zone, which was heavily populated with small darkly stained lymphocytes. These mantle zones were always oriented towards the crypts. The tonsillar follicles of young sheep showed many medium and small sized lymphocytes, lymphoblasts and also reticulocytes. The reticular cells usually appeared larger than lymphocytes and had a more abundant and organized cytoplasm with vacuoles. Fueron recolectadas piezas de tejido desde la tonsila palatina de ovejas con diferentes edades postnatales, desde la Corporación Slaughter House, Perambur, Chennai. La tonsila palatina consistía en un epitelio de superficie, cápsula, lóbulos de las tonsilas, criptas, epitelio de las criptas tonsilares y folículos. El epitelio superficial sobre la tonsila palatina estaba compuesto, en todos los grupos estudiados, de epitelio escamoso estratificado no-queratinizado. La tonsila palatina se delimitó claramente de las estructuras circundantes por un tejido conectivo capsular y un septo dividiendo la tonsila en dos lóbulos. El epitelio superficial se invaginó dentro de de la tonsila para formar criptas primarias y secundarias en cada lóbulo. El epitelio de las criptas cubrió las regiones de folículos linfoides transfomándose en linfoepitelo. También se observaron macrófagos en el epitelio. En las áreas de linfoepitelo la membrana basal estaba interrumpida por la infiltración linfocitaria y fue mayor en el epitelio. Fueron observa
Biochemical Analysis of Sheep (Ovis Aries) Urine in Relation to Estrous Cycle  [PDF]
Rameshkumar. K,Renuka. R,Prabu. T,Sangeetha. P
Advanced Biotech , 2013,
Abstract: Sheep (Ovis aries) have been domesticated for over 10,000 years. They have also been the subject of considerable research from the viewpoint of physiological function and animal production, are now regarded as one of the most studied non-human, non-rodent species. The social relationships that an animal has with others of the same species can affect many aspects of the reproductive process. Urine is known to be a major source of mammalian chemosignals which involved in this pheromonal communication. Based on the above information, the present study was designed to estimate the biochemical constituents of sheep urine during various phases. The samples were collected from six sheep at four different phases such as prepubertal, estrus, pregnant and lactation. The estimation of protein, carbohydrates, lipids and also hormonal analysis were carried out with standard procedure at different phases of sheep urine. The result of this study showed that carbohydrate was found to be significantly higher in all phases, when compared to proteins and lipids. Further, the level of carbohydrate is found to be prepubertal stage when compared to other stages. The present results showed that the level of protein is higher in estrus period followed by pregnant, lactation and prepubertal. Similarly, the level of lipid is also higher in estrus followed by prepubertal, lactation and pregnant. The level of estrogen is higher in estrus period and level of progesterone is higher in pregnant period. The present study concluded that the estrus urine contain more amount of protein, lipid and hormone of estrogen and progesterone than the other phases.
Experimental infection of reindeer, sheep and goats with Elaphostrongylus spp. (Nematoda, Protostrongylidae) from moose and reindeer
Margarets Stéen,Ibrahim Warsame,Arne Skorping
Rangifer , 1998,
Abstract: Six reindeer (Rangifer tarandus), five sheep and six goats (Ovis ovis and Capra hircus) were experimentally infected with the nematode Elaphostrongylus alces. Additionally, one sheep was infected with E. rangiferi. Reindeer infected with E. alces showed no neurological signs. Sheep and goats infected with the same parasite also remained clinically healthy; however, the sheep infected with E. rangiferi showed severe neurological signs and became paralysed. Pathological lesions were minimal in reindeer and domestic ruminants infected with E. alces, but were prominent in the lamb infected with E. rangiferi. Our results indicate that keeping and transferring sheep and goats into ateas inhabited by moose, which is a natural host of E. alces may not harm the livestock, while keeping sheep in areas inhabited by reindeer infected with E. rangiferi may result in petiodic outbreaks of cerebrospinal elaphostrongylosis in sheep.
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