Losses of adult sheep due to ovine Johne's disease in 12 infected flocks over a 3-year period     

Bush RD  Windsor PA  Toribio JA 《Australian veterinary journal》2006,84(7):246-253

OBJECTIVE: To measure the biological and financial impact of ovine Johne's disease (OJD) mortalities on 12 infected flocks within the endemic area of southern New South Wales over a 3-year period. DESIGN AND POPULATION: An observational study was conducted over a 3-year period from 2002 to 2004 on sheep from 12 OJD-infected flocks from southern NSW. Flocks ranged from between 3,500 and 20,000 sheep. At the start of the study owner estimates of OJD mortality were 5% or greater. METHOD: Annual mortality rates were estimated from farm records provided by owners. The proportion of OJD mortalities was assessed after histological examination of tissues collected from dead and moribund sheep during 5-day necropsy inspections conducted in autumn, winter, spring and summer in 2002. The financial impact was estimated using a gross margin analysis for each of the three study years and by placing a financial value on the necropsied sheep. RESULTS: On the 12 farms, the average OJD mortality rate was 6.2% (range 2.1% to 17.5%) in 2002, 7.8% (range 1.8% to 14.6%) in 2003 and 6.4% (range 2% to 11.9%) in 2004. The average decrease in gross margin due to OJD infection on a farm in 2002 was 6.4% (range 2.2% to 15.4%), 8.5% (range 3.1% to 15.8%) in 2003 and 7.4% (range 1.5% to 15.4%) in 2004. This equates to an average reduction in annual income of $13,715 per farm per year. OJD losses accounted on average for two thirds of the total estimated financial loss associated with sheep deaths. CONCLUSION: This study demonstrates the significant biological and financial impact of OJD on sheep flocks. These findings are of relevance to all Australian sheep flocks infected or at risk of OJD infection.  相似文献   

Sparse pre-Columbian human habitation in western Amazonia     

McMichael CH  Piperno DR  Bush MB  Silman MR  Zimmerman AR  Raczka MF  Lobato LC 《Science (New York, N.Y.)》2012,336(6087):1429-1431

Locally extensive pre-Columbian human occupation and modification occurred in the forests of the central and eastern Amazon Basin, but whether comparable impacts extend westward and into the vast terra firme (interfluvial) zones, remains unclear. We analyzed soils from 55 sites across central and western Amazonia to assess the history of human occupation. Sparse occurrences of charcoal and the lack of phytoliths from agricultural and disturbance species in the soils during pre-Columbian times indicated that human impacts on interfluvial forests were small, infrequent, and highly localized. No human artifacts or modified soils were found at any site surveyed. Riverine bluff areas also appeared less heavily occupied and disturbed than similar settings elsewhere. Our data indicate that human impacts on Amazonian forests were heterogeneous across this vast landscape.  相似文献   

Alterations in serotonin receptor-induced contractility of bovine lateral saphenous vein in cattle grazing endophyte-infected tall fescue     

Klotz JL  Brown KR  Xue Y  Matthews JC  Boling JA  Burris WR  Bush LP  Strickland JR 《Journal of animal science》2012,90(2):682-693

As part of a 2-yr study documenting the physiologic impact of grazing endophyte-infected tall fescue on growing cattle, 2 experiments were conducted to characterize and evaluate effects of grazing 2 levels of toxic endophyte-infected tall fescue pastures on vascular contractility and serotonin receptors. Experiment 1 examined vasoconstrictive activities of 5-hydroxytryptamine (5HT), α-methylserotonin (ME5HT; a 5HT(2) receptor agonist), d-lysergic acid (LSA), and ergovaline (ERV) on lateral saphenous veins collected from steers immediately removed from a high-endophyte-infected tall fescue pasture (HE) or a low-endophyte-infected mixed-grass (LE) pasture. Using the same pastures, Exp. 2 evaluated effects of grazing 2 levels of toxic endophyte-infected tall fescue on vasoconstrictive activities of (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), BW 723C86 (BW7), CGS-12066A (CGS), and 5-carboxamidotryptamine hemiethanolate maleate (5CT), agonists for 5HT(2A),( 2B), 5HT(1B), and 5HT(7) receptors, respectively. One-half of the steers in Exp. 2 were slaughtered immediately after removal from pasture, and the other one-half were fed finishing diets for >91 d before slaughter. For Exp. 1, maximal contractile intensities were greater (P < 0.05) for steers grazing LE pastures than HE pastures for 5HT (73.3 vs. 48.9 ± 2.1%), ME5HT (52.7 vs. 24.9 ± 1.5%), and ERV (65.7 vs. 49.1 ± 2.6%). Onset of contractile response did not differ for 5HT (P = 0.26) and ERV (P = 0.93), but onset of ME5HT contraction was not initiated (P < 0.05) in HE steers until 10(-4) compared with 10(-5) M in LE-grazing steers. For Exp. 2, maximal contractile intensities achieved with DOI were 35% less (P < 0.05), whereas those achieved with 5CT were 37% greater (P < 0.05), in steers grazing HE pastures. Contractile response to CGS did not differ between pasture groups, and there was an absence of contractile response to BW7 in both groups. There were no differences between endophyte content in contractile responses after animals were finished for >91 d. Experiment 1 demonstrated that grazing of HE pastures for 89 to 105 d induces functional alterations in blood vessels, as evidenced by reduced contractile capacity and altered serotonergic receptor activity. Experiment 2 demonstrated that grazing HE pastures alters vascular responses, which may be mediated through altered serotonin receptor activities, and these alterations may be ameliorated by the removal of ergot alkaloid exposure as demonstrated by the absence of differences in finished steers.  相似文献   

Anticipating the species jump: surveillance for emerging viral threats     

Flanagan ML  Parrish CR  Cobey S  Glass GE  Bush RM  Leighton TJ 《Zoonoses and public health》2012,59(3):155-163

Zoonotic disease surveillance is typically triggered after animal pathogens have already infected humans. Are there ways to identify high‐risk viruses before they emerge in humans? If so, then how and where can identifications be made and by what methods? These were the fundamental questions driving a workshop to examine the future of predictive surveillance for viruses that might jump from animals to infect humans. Virologists, ecologists and computational biologists from academia, federal government and non‐governmental organizations discussed opportunities as well as obstacles to the prediction of species jumps using genetic and ecological data from viruses and their hosts, vectors and reservoirs. This workshop marked an important first step towards envisioning both scientific and organizational frameworks for this future capability. Canine parvoviruses as well as seasonal H3N2 and pandemic H1N1 influenza viruses are discussed as exemplars that suggest what to look for in anticipating species jumps. To answer the question of where to look, prospects for discovering emerging viruses among wildlife, bats, rodents, arthropod vectors and occupationally exposed humans are discussed. Finally, opportunities and obstacles are identified and accompanied by suggestions for how to look for species jumps. Taken together, these findings constitute the beginnings of a conceptual framework for achieving a virus surveillance capability that could predict future species jumps.  相似文献   

Diarrhoeal diseases of the calf: Observations on treatment and prevention     

E.W. Jones  D. Hamm  L. Corley  L. Bush 《New Zealand veterinary journal》2013,61(11):312-316

Abstract

Extract

During the past two decades intestinal absorptive and secretory functions and the intestinal flora have been significantly clarified. Important concepts of intestinal dysfunction have emerged which have proved of immense clinical value(32) Moon, H. W. 1974. Pathogenesis of Enteric Diseases Caused by Escherichia coli. Adv. Vet. Sci. Comp. Med, 18: 179–211. [PubMed] , [Google Scholar] (39) Phillips, S. F. 1972. Diarrhoea: A Current View of the Pathophysiology. Gastroenterology, 63: 495–518.  [Google Scholar] (46) Smith, H. W. 1965. Observations on the Flora of the Alimentary Tract of Animals and Factors Affecting its Composition. J. Pathol, 89: 95–122.  [Google Scholar] (47) Smith, H. W. 1971. The Bacteriology of the Alimentary Tract of Domestic Animals Suffering from E. coli Infection. Ann. N. Y. Acad Set, 176: 110–125.  [Google Scholar] (51) Soergel, K. H. 1973. New Concepts of Intestinal Function. Hepatogaslroenterol, 20: 351–358.  [Google Scholar]. Despite this, the medical and economic consequences of diarrhoea continue to beset the cattle industry(1) Barnum, D. A., Glantz, P. J. and Moon, H. W. 1967. Colibacillosis. CI_RV_eterinary Monograph Series/Two, : 5–44.  [Google Scholar] (18) Hubbert, W. T. 1974. Factors Affecting Survival of the Bovine Fetus and Neonate. Theriogenology, 1: 15–34.  [Google Scholar] (30) Marsh, H. 1968. Prenatal and Postnatal Mortality in Cattle. National Academy of Science. Pub. No. 1685,, : 1–6.  [Google Scholar] (56) Vollmar, R. E. 1974. Diarrhoea Control in a Dairy Operation. Mod Vet. Pract., 55: 509–512.  [Google Scholar] (57) White, R. G. Scours-The Calf Killer. Presented at the California Livestock Symposium. An. Nut. Health, pp.14–18.  [Google Scholar]. Diarrhoeal disease of the calf occurs at a time of complex developmental, environmental and functional change. The surface defences and enzyme systems of the neonatal gut are maturing in a protective film of maternal antibody, while undergoing increasing stimulation from environmental microbial challenge. The precarious nature of this defence system is not surprising. It is contingent upon a balance of such changing conditions as maternal antibody quantity, quality and delivery(5) Bush, L. J., Aguilera, M. A., Adams, G. D. and Jones, E. W. 1971. Absorption of Colostral Immunoglobulins by Newborn Dairy Calves. J. Dairy Sci., 54: 1547–1549.  [Google Scholar], environmental microbial challenge(46) Smith, H. W. 1965. Observations on the Flora of the Alimentary Tract of Animals and Factors Affecting its Composition. J. Pathol, 89: 95–122.  [Google Scholar] (47) Smith, H. W. 1971. The Bacteriology of the Alimentary Tract of Domestic Animals Suffering from E. coli Infection. Ann. N. Y. Acad Set, 176: 110–125.  [Google Scholar] and neonatal immunological and intestinal epithelial maturation(7) Corley, L. D., Staley, T. E., Bush, L. J. and Jones, E. W. 1977. Influence of Colostrum on Transepithelial Movement of E. coli 055. J. Dairy Sci., in press [Google Scholar] (52) Staley, T. E., Corley, L. D., Bush, L. J. and Jones, E. W. 1972. The Ultra-structure of Neonatal Calf Intestine and Absorption of Heterologous Proteins. A rial. Rec, 172: 559–579. [Crossref], [PubMed] , [Google Scholar]. While both infectious and non-infectious etiologic factors are involved(1) Barnum, D. A., Glantz, P. J. and Moon, H. W. 1967. Colibacillosis. CI_RV_eterinary Monograph Series/Two, : 5–44.  [Google Scholar] the former (Escherichia coli, Saltiionsllci and Shigella spp., and reo and corona viruses) is the more significant. Enteropathogenic E. coli (EPEC), a major contributor to neonatal diarrhoeal disease, will be discussed primarily. Four syndromes, septicaemia, enteric-toxaemia, local invasive and enterotoxic have been described(32) Moon, H. W. 1974. Pathogenesis of Enteric Diseases Caused by Escherichia coli. Adv. Vet. Sci. Comp. Med, 18: 179–211. [PubMed] , [Google Scholar] and ad verseoutcomes may result from endotoxic shock and/or hypovolemic shock, from systemic infection and from malnutrition. The clinician is thus faced with the selection of a multi-faceted approach to the problem. Avenues of attack, in addition to prophylactic husbandry, include: passive and active immunization, reduction of challenge, specific antimicrobial therapy, and resolution of fluid and electrolyte loss and shock. This presentation includes a resumé of the calf scour syndrome, together with observations concerning treatment and control. These observations include active and passive immunization, antimicrobial therapy, and modification of intestinal fluid loss.  相似文献   

Effects of allopurinol on plasma uric acid levels in normouricaemic and hyperuricaemic green iguanas (Iguana iguana)     

Hernandez-Divers SJ  Martinez-Jimenez D  Bush S  Latimer KS  Zwart P  Kroeze EJ 《The Veterinary record》2008,162(4):112-115

A two-phase cross-over therapeutic study was performed with 19 green iguanas (Iguana iguana) maintained within a preferred optimum temperature range of 26 to 37 degrees C. During phase 1, they were fed a normal vegetarian diet and medicated orally with either allopurinol or a placebo control once a day for seven days. Uric acid concentrations, total protein, packed-cell volumes (pcv) and bodyweights were recorded from each lizard before and after treatment to determine the effects of allopurinol. In phase 2, after a 10-day washout period, the iguanas were fed a high protein diet to induce hyperuricaemia. Normo- and hyperuricaemic iguanas that received 24.2 (3.2) mg/kg allopurinol had significantly lower mean (sd) uric acid concentrations (100.3 [53.1] micromol/l) than the controls (159.3 [100.3] micromol/l). There were no detectable interactions between the doses of allopurinol or placebo, and the iguanas' diet, weight, pcv or total protein. The allopurinol was well tolerated, and there was no significant clinical, gross or histological evidence of hepatic or renal toxicity in the iguanas that received the drug. However, in the kidneys of the hyperuricaemic iguanas that did not receive allopurinol there were proliferative changes in the glomeruli and degeneration of tubular epithelia. Allopurinol given orally at 25 mg/kg daily is able to reduce plasma uric acid levels by 41 to 45 per cent, and is therefore recommended for the treatment of hyperuricaemia in the green iguana.  相似文献   

Effects of selected combinations of tall fescue alkaloids on the vasoconstrictive capacity of fescue-naive bovine lateral saphenous veins     

Klotz JL  Kirch BH  Aiken GE  Bush LP  Strickland JR 《Journal of animal science》2008,86(4):1021-1028

Vasoconstriction is a response associated with consumption of toxic endophyte-infected tall fescue. It is not known if endophyte-produced alkaloids act alone or collectively in mediating the response. Therefore, the objective of this study was to examine the vasoconstrictive potentials of selected ergot alkaloids, individually or in paired combinations, using bovine lateral saphenous veins biopsied from fescue-na?ve cattle. Segments (2 to 3 cm) of vein were surgically biopsied from healthy crossbred yearling heifers (n = 22; 330 +/- 8 kg of BW). Veins were trimmed of excess fat and connective tissue, sliced into 2- to 3-mm sections, and suspended in a myograph chamber containing 5 mL of oxygenated Krebs-Henseleit buffer (95% O(2)/5% CO(2); pH = 7.4; 37 degrees C). Increasing doses of ergovaline, lysergic acid, and N-acetylloline individually or in combination were evaluated. Contractile data were normalized as a percentage of the contractile response induced by a reference dose of norepinephrine (1 x 10(- 4) M). Increasing concentrations of lysergic acid did not result in an appreciable contractile response until the addition of 1 x 10(- 4) M lysergic acid. In contrast, the vascular response to increasing concentrations of ergovaline was apparent at 1 x 10(- 8) M and increased to a maximum of 104.2 +/- 6.0% with the addition of 1 x 10(- 4) M ergovaline. The presence of N-acetylloline did not alter the onset or magnitude of vascular response to either lysergic acid or ergovaline. The presence of 1 x 10(- 5) M lysergic acid with increasing concentrations of N-acetylloline and ergovaline generated an increased contractile response during the initial additions compared with the responses of N-acetylloline and ergovaline alone. In the presence of 1 x 10(- 7) M ergovaline, the contractile response increased with increasing concentrations of N-acetylloline and lysergic acid. Neither N-acetylloline nor lysergic acid elicited an intense contractile response individually (maximum contractile responses of 1.9 +/- 0.3% and 22.6 +/- 4.1%, respectively), suggesting that this was the result of the repetitive addition of 1 x 10(- 7) M ergovaline. These data indicate that ergovaline is a more potent vascular toxicant than lysergic acid or N-acetylloline. The contractile responses of the ergovaline and lysergic acid combinations appeared to differ from the individual dose responses. These data support the possibility that an additive alkaloid exposure effect may exist and should be considered during evaluations of ergot alkaloids.  相似文献   

Equine osteosarcoma: a series of 8 cases     

Bush JM  Fredrickson RL  Ehrhart EJ 《Veterinary pathology》2007,44(2):247-249

In horses, osteosarcoma is a rare tumor, with the majority of reported cases occurring in the head, and, more specifically, in the mandible of young horses. The following report documents 8 cases of equine osteosarcoma, the majority occurring in male horses aged 7 years or older with a lack of metastasis identified in any horse. Six arose in the maxilla or mandible and one in the proximal tibia. The predominant subtype was fibroblastic osteosarcoma with fewer osteoblastic type tumors. All had osteoid and most had a chondromucinous matrix. Surgical excision was attempted in the majority of cases. An inability to completely excise the tumor and progressive disease typically resulted in euthanasia. To the authors' knowledge, this case series also documents the first report of an equine extraosseous osteosarcoma within the subcutaneous tissue caudal to the shoulder. Surgical excision appears successful with no recurrence of disease 14 months later. Further investigations of equine osteosarcoma and various chemotherapeutic agents are warranted to present additional treatment options.  相似文献   

Synthesis of large arrays of well-aligned carbon nanotubes on glass     

ZF Ren  ZP Huang  JW Xu  JH Wang  P Bush  MP Siegal  PN Provencio 《Science (New York, N.Y.)》1998,282(5391):1105-1107

Free-standing aligned carbon nanotubes have previously been grown above 700 degreesC on mesoporous silica embedded with iron nanoparticles. Here, carbon nanotubes aligned over areas up to several square centimeters were grown on nickel-coated glass below 666 degreesC by plasma-enhanced hot filament chemical vapor deposition. Acetylene gas was used as the carbon source and ammonia gas was used as a catalyst and dilution gas. Nanotubes with controllable diameters from 20 to 400 nanometers and lengths from 0. 1 to 50 micrometers were obtained. Using this method, large panels of aligned carbon nanotubes can be made under conditions that are suitable for device fabrication.  相似文献   

Are tree breeders properly predicting genetic gain? A case study involving <Emphasis Type="Italic">Corymbia</Emphasis> species     

Evandro Vagner Tambarussi  Fernanda Bortolanza Pereira  Paulo Henrique Müller da Silva  David Lee  David Bush 《Euphytica》2018,214(8):150

The estimation of quantitative genetic parameters in breeding programs is important to ensure efficient selection. In this context, knowledge of the mating system is critical, as it underpins assumptions about inter-relatedness on which variance component estimation depends. However, proper account of the breeding system is not always taken, either because it is unknown and/or because it is ignored. That eucalypts have a mixed-mating system is well-established, however many breeders use models that assume outcrossed mating with an infinite number of male parents (i.e. allogamous mating), from which genetic parameter estimates are then used to predict genetic gains. First-generation, open-pollinated progeny tests of Corymbia citriodora subsp. citriodora and C. citriodora subsp. variegata, being managed for seed production, were used to investigate the likely bias, resulting in overestimation of genetic parameters under the assumption of allogamous mating. When we assumed allogamous mating, we observed inflated predictions of additive variance and narrow-sense heritability (\(\hat{h}_{a}^{2}\)) of diameter at breast height and height. The overestimate of \(\hat{h}_{a}^{2}\) was approximately 32% for C. citriodora subsp. citriodora and 21% for C. citriodora subsp. variegata. Inappropriate modelling of relatedness in eucalypts that assumes panmictic outcrossing when in fact these species have a mixed-mating system results in overestimates of the population genetic gain with selection.  相似文献