A farming systems study of abortion in dairy cattle on the Atherton Tableland: 3. Metabolic factors     

J H Norton  W P Tranter  R S Campbell  R K Shepherd 《Australian veterinary journal》1989,66(6):167-170

An association with a rank correlation of 0.55 (p = 0.06) was obtained between monthly rainfall and monthly abortions for a group of 24 farms in tropical Australia where cows grazed predominantly summer rain-dependent pasture. A similar association was found among cows grazing nitrogen-fertilised, irrigated pasture in winter in the same area. On farms with irrigated pasture the first service conception and abortion rates in herds which grazed intensively during the night (abortion 8.9%; first service conception 42.9%) differed significantly from those which grazed during the day (abortion 6.4%; first service conception 52.9%), and this suggested that increased abortion rates and decreased first conception rates may be part of the one syndrome. An hypothesis was developed that the feeding of immature nitrogen-fertilised pasture, rich in protein and stimulated by rain or irrigation, is associated with an increased abortion rate and a depressed conception rate. Other evidence included an increased susceptibility of first lactation cows to abortion, a lower abortion rate in late pregnant dry cows fed more mature pasture, a 20% repeat abortion rate in the population sampled and the lack of conclusive evidence for infectious and selected non-infectious agents. There were no other observed clinical signs in most aborting cows.  相似文献   

A decision-analysis approach to integrated pest control     

G.A. Norton 《Crop Protection》1982,1(2):147-164

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New decontamination efforts and techniques for elimination of Salmonella from animal protein rendering plants     

G W Hess  J I Moulthrop  H R Norton 《Journal of the American Veterinary Medical Association》1970,157(11):1975-1980

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OEDEMA DISEASE IN CHICKENS CAUSED BY MEXICAN POPPY (ARGEMONE MEXICANA) SEED     

J. H. Norton  P. K. O'Rourke 《Australian veterinary journal》1980,56(4):187-189

Ground Mexican poppy (Argemone mexicana) seed produced growth depression, oedema and death when fed at 1% and 3% of a basal ration to day-old, layer strain, cockerel chickens. The mortality rate was increased by raising the sodium chloride content of the basal ration from 0.18% to 1.68%.
Clinical signs consisted of subcutaneous oedema, a high pitched chirp and terminal gasping. Hydropericardium, oedema of the lungs, and subcutaneous oedema of the thorax, abdomen, wings, neck and throat were the major lesions. Foci of calcification were present in the ventricular myocardium of some chickens fed 3% A. mexicana.  相似文献   

Relationships between the thyroid and somatotropic axes in steers I: Effects of propylthiouracil-induced hypothyroidism on growth hormone, thyroid stimulating hormone and insulin-like growth factor I     

T. H. Elsasser  T. S. Rumsey  S. A. Norton 《Domestic animal endocrinology》1992,9(4):261-271

The effects of propylthiouracil (PTU)-induced thyroid hormone imbalance on GH, TSH and IGF-I status in cattle were examined. In the first study, four crossbred steers (avg wt 350 kg) were fed a diet dressed with PTU (0, 1, 2 or 4 mg/kg/d BW) in a Latin square design with four 35-d periods. On day 29 in each period, steers were challenged with an intrajugular bolus of thyrotropin releasing hormone (TRH, 1.0 μg/kg). Blood samples were obtained to assess the change in plasma GH and TSH as affected by PTU. Plasma IGF-I was measured from blood samples obtained before and after (every 6 hr for 24 hr) intramuscular injection of bovine GH (0.1 mg/kg, day 31). Doses of 1 and 2 mg/kg PTU increased plasma T₄ (P<.01). At 4 mg/kg, PTU depressed T₄ concentrations to 30% of control (P<.01). Plasma T₃ linearly decreased with increasing doses of PTU (P<.01). Plasma TSH increased when PTU was fed at 4 mg/kg (P<.05) while the TSH response to TRH declined with increasing PTU (P<.02). Neither basal nor TRH-stimulated plasma concentration of GH was affected by PTU; the IGF-I response to GH tended to increase at the 1 and 2 mg/kg PTU (P<.01). In a second study 24 crossbred steers were fed PTU (1.5 mg/kg) for 119 d in a 2 × 2 factorial design with implantation of the steroid growth effector, Synovex-S (200 mg progesterone + 20 mg estradiol), as the other main effect. Basal plasma GH and IGF-I were not affected by PTU treatment. Synovex increased plasma concentration (P<.01) of IGF-I without an effect on plasma GH. The data suggest that mild changes in thyroid status associated with PTU affects regulation of T₃, T₄ and TSH more than GH or IGF-I in steers.  相似文献   

Sampling to characterize landscape pattern   总被引：8，自引：0，他引：8  

Carolyn T. Hunsaker  Robert V. O'Neill  Barbara L. Jackson  S. P. Timmins  Daniel A. Levine  Douglas J. Norton 《Landscape Ecology》1994,9(3):207-226

Current reseach suggests that metrics of landscape pattern may reflect ecological processes operating at different scales and may provide an appropriate indicator for monitoring regional ecological changes. This paper examines the extent to which a 1/16 areal subset of the landscape using equally spaced 40-km² hexagons can characterize the spatial extent of land cover types and landscape pattern (number of types of edges, patch shape complexity, dominance, and contagion). For 200-m resolution data the hexagon subset gives a reasonable estimate of overall landscape cover but may not be adequate for monitoring uncommon land cover types such as wetlands. For agriculture and forest, their proportion of the full landscape units is only outside the 95% confidence interval of the hexagon estimate 4–8% of the time, whereas the proportions for wetland and barren areas are outside the confidence interval 11–34% of the time. The hexagon subset also does not appear to be adequate as the sole basis for monitoring landscape pattern. The values for contagion, dominance, and shape complexity calculated on the full landscape units are outside the 95% confidence interval of the hexagon estimate 27–76% of the time. Other statistical analyses include regressions between full landscape and hexagon subsets, mean differences and standard errors along with tests on number of positive and negative values, and percent relative error of hexagon estimates.Although the research described in this article has been funded in part by the U.S. Environmental Protection Agency, under Interagency Agreement DW89934921-01-0 with the U.S. Department of Energy under Contract DE-AC05-84OR21400 with Martin Marietta Energy Systems, Inc., it has not been subjected to Agency review. Therefore, it does not necessarily reflect the views of the Agency. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.Research supported by the Landscape Characterization Project, Environmental Monitoring and Assessment Program, U.S. Environmental Protection Agency, under Interagency Agreement DW89934921-01-0 with the U.S. Department of Energy under Contract DE-AC05-84OR21400 with Martin Marietta Energy Systems, Inc., Environmental Sciences Division Publication No. 4090.  相似文献   

Comparison and standardisation of serological methods for the diagnosis of Neospora caninum infection in bovines     

von Blumröder D  Schares G  Norton R  Williams DJ  Esteban-Redondo I  Wright S  Björkman C  Frössling J  Risco-Castillo V  Fernández-García A  Ortega-Mora LM  Sager H  Hemphill A  van Maanen C  Wouda W  Conraths FJ 《Veterinary parasitology》2004,120(1-2):11-22

Various existing serological tests were compared with a standard panel of 523 sera in a multicentred study across Europe. Well characterised sera from animals that were experimentally or naturally infected with Neospora caninum as well as sera from cattle deemed uninfected with N. caninum were provided by the participants of the study and analysed in several commercial (CHEKIT Dr. Bommeli/Intervet, CIVTEST BOVIS NEOSPORA Hipra, Cypress Diagnostics C.V., Herd Check IDEXX, Mastazyme MAST Diagnostics, P38-ELISA Animal Welfare and Food Safety GmbH (AFOSA)) as well as in-house assays (five ELISAs and one IFAT). Most tests showed a high level of agreement in the interpretation of the test results (positive or negative). A further distinct increase in agreement between tests was obtained after the application of standardised cut-offs offered by a two-graph receiver operating characteristic analysis. This procedure allows a standardised interpretation of results obtained with different tests used in independent, parallel seroepidemiological studies.  相似文献   

Selecting for scrapie-resistant sheep     

Norton AM 《The Veterinary record》2004,155(15):467

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Evaluation of cognitive learning, memory, psychomotor, immunologic, and retinal functions in healthy puppies fed foods fortified with docosahexaenoic acid-rich fish oil from 8 to 52 weeks of age     

SC Zicker  DE Jewell  RM Yamka  NW Milgram 《Journal of the American Veterinary Medical Association》2012,241(5):583-594

Objective-To assess effects of foods fortified with docosahexaenoic acid (DHA)-rich fish oil on cognitive, memory, psychomotor, immunologic, and retinal function and other measures of development in healthy puppies. Design-Evaluation study. Animals-48 Beagle puppies. Procedures-Puppies were assigned to 3 groups after weaning (n = 16/group) and received 1 of 3 foods (low-DHA, moderate-DHA, or high-DHA food) as their sole source of nutrition until 1 year of age. Visual discrimination learning and memory tasks, psychomotor performance tasks, and physiologic tests including blood and serum analysis, electroretinography, and dual-energy x-ray absorptiometry were performed at various time points. Anti-rabies virus antibody titers were evaluated 1, 2, 4, and 8 weeks after vaccination at 16 weeks of age. Results-Foods had similar proximate analysis results but varied in concentration of DHA from fish oil; the high-DHA food also contained higher concentrations of vitamin E, taurine, choline, and l-carnitine than did other foods. The high-DHA group had significantly better results for reversal task learning, visual contrast discrimination, and early psychomotor performance in side-to-side navigation through an obstacle-containing maze than did the moderate-DHA and low-DHA groups. The high-DHA group had significantly higher anti-rabies antibody titers 1 and 2 weeks after vaccination than did other groups. Peak b-wave amplitudes during scotopic electroretinography were positively correlated with serum DHA concentrations at all evaluated time points. Conclusions and Clinical Relevance-Dietary fortification with fish oils rich in DHA and possibly other nutrients implicated in neurocognitive development following weaning improved cognitive, memory, psychomotor, immunologic, and retinal functions in growing dogs.  相似文献   

Concurrent Ivermectin and Solanum spp. Toxicosis in a Herd of Horses     

T.E. Norman  M.K. Chaffin  P.L. Norton  M.C. Coleman  W.B. Stoughton  T. Mays 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2012,26(6):1439-1442

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