The prevalence of anthelmintic resistance in sheep nematodes on the central tablelands of New South Wales     

R. F. WEBB  S. J. OTTAWAY 《Australian veterinary journal》1986,63(1):13-16

A survey was undertaken to assess the prevalence of anthelmintic resistance in sheep nematode populations on 40 commercial farms distributed throughout the central tablelands of New South Wales. Representatives of the 2 major groups of broad spectrum anthelmintics with different modes of action (thiabendazole and levamisole) were used at the manufacturer's recommended dose rates. Efficacy was assessed on the basis of the reduction in faecal strongyle egg counts 7 days after treatment. An efficacy of less than 90% using both anthelmintics was obtained on 4 farms. Thiabendazole had an efficacy of less than 90% on a further 21 farms and levamisole had an efficacy of less than 90% on an additional 4 farms. There was no evidence of anthelmintic resistance on 8 farms, while the remaining 3 had insignificant parasite burdens. Based on larval cultures from faeces, Ostertagia and Trichostrongylus were the most significant species in resistant populations. Haemonchus burdens were sporadic and levels of resistance relatively low. Nematodirus burdens were widespread but no evidence of resistance was detected.  相似文献   

Release of Picloram from Roots*     

WARREN L. WEBB  MICHAEL NEWTON 《Weed Research》1972,12(4):391-394

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OXALATE NEPHROPATHY IN A HORSE     

R. F. WEBB  P. R. KNIGHT 《Australian veterinary journal》1977,53(11):554-555

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Early central andean metalworking from mina perdida, peru     

RL Burger  RB Gordon 《Science (New York, N.Y.)》1998,282(5391):1108-1111

Copper and gold artifacts in contexts dated to approximately 3120 to 3020 carbon-14 years before the present ( approximately 1410 to 1090 calendar years B.C.) recovered in excavations at Mina Perdida, Lurin Valley, Peru, show that artisans hammered native metals into thin foils, in some cases with intermediate anneals. They gilded copper artifacts by attaching gold foil. The artifacts show that fundamental elements of the Andean metallurgical tradition were developed before the Chavin horizon, and that on the Peruvian coast the working of native copper preceded the production of smelted copper objects.  相似文献   

Magnetic microstructure of magnetotactic bacteria by electron holography     

RE Dunin-Borkowski  MR McCartney  RB Frankel  DA Bazylinski  M Posfai  PR Buseck 《Science (New York, N.Y.)》1998,282(5395):1868-1870

Off-axis electron holography in the transmission electron microscope was used to correlate the physical and magnetic microstructure of magnetite nanocrystals in magnetotactic bacteria. The magnetite crystals were all single magnetic domains, and the magnetization directions of small superparamagnetic crystals were constrained by magnetic interactions with larger crystals in the chains. Shape anisotropy was found to dominate magnetocrystalline anisotropy in elongated crystals. A coercive field between 300 and 450 oersted was determined for one chain.  相似文献   

Avian influenza in Australia: a summary of 5 years of wild bird surveillance          下载免费PDF全文

VL Grillo  KE Arzey  PM Hansbro  AC Hurt  S Warner  J Bergfeld  GW Burgess  B Cookson  CJ Dickason  M Ferenczi  T Hollingsworth  MDA Hoque  RB Jackson  M Klaassen  PD Kirkland  NY Kung  S Lisovski  MA O'Dea  K O'Riley  D Roshier  LF Skerratt  JP Tracey  X Wang  R Woods  L Post 《Australian veterinary journal》2015,93(11):387-393

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Vertical Flux of Biogenic Carbon in the Ocean: Is There Food Web Control?     

RB Rivkin  L Legendre  D Deibel  JE Tremblay  B Klein  K Crocker  S Roy  N Silverberg  C Lovejoy  F Mesple  N Romero  MR Anderson  P Matthews  C Savenkoff  A Vezina  JC Therriault  J Wesson  C Berube  RG Ingram 《Science (New York, N.Y.)》1996,272(5265):1163-1166

Models of biogenic carbon (BC) flux assume that short herbivorous food chains lead to high export, whereas complex microbial or omnivorous food webs lead to recycling and low export, and that export of BC from the euphotic zone equals new production (NP). In the Gulf of St. Lawrence, particulate organic carbon fluxes were similar during the spring phytoplankton bloom, when herbivory dominated, and during nonbloom conditions, when microbial and omnivorous food webs dominated. In contrast, NP was 1.2 to 161 times greater during the bloom than after it. Thus, neither food web structure nor NP can predict the magnitude or patterns of BC export, particularly on time scales over which the ocean is in nonequilibrium conditions.  相似文献   

1986 survey of upland grassland in England and Wales: changes in age structure and botanical composition since 1970–72 in relation to grassland management and physical features     

A. HOPKINS  JOANNE WAINWRIGHT  P. J. MURRAY  P. J. BOWLING  MORAG WEBB 《Grass and Forage Science》1988,43(2):185-198

A sample of 10000 ha of grassland in seven upland districts originally surveyed in 1970–72 was re-surveyed in 1986. Forty percent of the area was above 240 m elevation, 38% had gradients above 81/2°, 29% had poor or bad drainage and 54% was classified as having difficult or severe limitations to management. Twelve percent had been reseeded within the previous 5 years and 39% within 20 years; 6% was classified as arable grassland (in rotation with crops). Thirty-four percent was usually mown, two-thirds of it for silage. In most years 72% of grassland received fertilizer N (average application 123 kg N ha⁻¹) and 35% received organic manure; nearly 20% received neither. Older swards tended to receive lower rates of fertilizer N than reseeds, hay fields and grazed fields less than silage fields, and fields on beef/sheep farms less than those on dairy farms. The proportion of sown species in swards averaged 35%, of which Lolium perenne accounted for 23%. A good contribution of Trifolium repens was recorded in 15% of the grassland. Herb species were recorded in 30% of the grassland, mostly in situations with low fertilizer N under hay or grazing. Agrostis spp., Poa spp., Holcus lanatus and Festuca rubra were the main unsown grasses. The average contribution of L. perenne had increased since 1970–72; it was also present in two-thirds of the area from which it was absent in 1970–72, whilst the contribution of T. repens had decreased. The incidence of Cirsium arvense and Ranunculus spp. had also decreased, whilst that of Pteridium aquilinum had increased.  相似文献   

A cross-sectional study to show Eperythrozoon ovis infection is prevalent in Western Australian sheep farms   总被引：4，自引：0，他引：4  

MJ KABAY  RB RICHARDS  TE ELLIS 《Australian veterinary journal》1991,68(5):170-173

A serological survey and risk factor study was conducted to estimate the prevalence of Eperythrozoon ovis infection in Western Australian weaner sheep, the prevalence of farms with infected sheep, and to identify factors affecting initiation and maintenance of infection on the farm. The study was conducted on 91 farms, purposively chosen from 41 randomly selected regional shires stratified by sheep number and rainfall zones. Twenty sheep were selected systematically from a mixed-sex flock on each farm and tested for serum antibody to E ovis using an enzyme-linked immunosorbent assay. Information on putative risk factors was collected using an interview questionnaire. Antibody to E ovis was detected in 4.5% of sheep on 47% of the farms sampled. The prevalence of E ovis infection in sheep was estimated at the 95% confidence level to be between 3.6 and 5.5%, and the prevalence of farms with infected sheep was estimated to be between 37.5 and 56.5%. Most farms with serological evidence of infection occurred in the Great Southern agricultural region (79.5%), south-east of Perth through to Albany (latitude 32 to 34 degrees S, longitude 116 to 120 degrees E), and in the Northern region (12.8%) surrounding Geraldton (latitude 29 degrees S, longitude 114 degrees E). There were significantly more farms (P less than 0.05) with evidence of infection in the Great Southern region compared to the Central region between Geraldton and Perth, and on farms in the region south compared to north of latitude 32 degrees S. None of the putative risk factors examined in the questionnaire were associated with serological evidence of infection on the farm.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Surgical management of acquired megacolon in the cat     

SARAH M. WEBB 《The Journal of small animal practice》1985,26(7):399-405

The surgical management of acquired megacolon is described in three cats. The aetiology could not be definitely established in two cats but in the third case megacolon occurred as a result of pelvic narrowing secondary to multiple pelvic fractures. Medical therapy was ineffective and long term resolution was achieved by partial colectomy.  相似文献