Modelling nitrogen fixation of pea ( Pisum sativum L.)     

Henrik Eckersten  Linda AF Geijersstam  Bengt Torssell 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(2):129-137

Abstract

Nitrogen fixation was simulated for a leafless variety (Delta) of pea (Pisum sativum L.) in central Sweden. It is assumed that N₂ fixation is basically proportional to root biomass, but limited by high root N or low substrate carbon concentrations. Input data on root carbon and nitrogen were estimated from observations of above-ground biomass and nitrogen. The simulated N₂ fixation was compared with estimated values from observations using the ¹⁵N labelling technique. Test data were taken from pea monocultures and pea-oat mixtures with varying pea biomass levels during 1999. Simulated within-season accumulated N₂ fixation correlated to the estimated N₂ fixation with a correlation coefficient (R ²) of 0.74. For seasonal simulations, the predictability was higher (R ²=0.93). Two alternative non-dynamic models, estimating seasonal N₂ fixation as proportional to above-ground biomass and above-ground N, respectively, gave lower predictability (R ²=0.83 and 0.80, respectively). The models were also applied to a second year (1998) and two other sites by comparison with accumulated N₂ fixation estimated by the Difference method. A halved specific N₂ fixation rate (expressed per unit of root biomass) in 1999, compared with 1998, corresponded to essentially dryer and warmer soil conditions during 1999. It was indicated that the variations in soil moisture were more important than soil temperature. It was concluded that the abiotic responses might be of great importance for modelling N₂ fixation rate under different soil conditions.  相似文献   

A survey of the prevalence of emerging macrocyclic lactone resistance and of benzimidazole resistance in sheep nematodes in the lower North Island of New Zealand     

PL Hughes  PB McKenna  AF Dowling 《New Zealand veterinary journal》2013,61(1):87-90

AIM: To investigate the occurrence of emerging macrocyclic lactone (ML) resistance and of resistance to benzimidazole anthelmintics on a number of sheep farms in the North Island of New Zealand.

METHODS: On commercial sheep farms (n=30) in the Taihape district in the North Island of New Zealand, 30 animals were randomly allocated to one of two equal-sized groups and treated with either half of the recommended dose rate of ivermectin (half of 0.2 mg/kg), or with the full recommended dose rate of oxfendazole (4.5 mg/kg). The ivermectin treatment only was used on a further six properties. Faecal egg counts, accompanied by pooled larval cultures, were conducted on all samples at the time of treatment and 7–10 days later.

RESULTS: Resistance, as indicated by a <95% faecal egg count reduction (FECR) in both instances, was found to oxfendazole on 13/30 (43%) farms and to a half dose of ivermectin on 12/36 (33%) properties. For oxfendazole, such resistance was found to involve all six nematode genera whereas for ivermectin it was almost entirely restricted to Ostertagia and Cooperia infections.

CONCLUSIONS: These results indicate that emerging ML resistance may be more common on sheep farms in New Zealand than is generally realised. They also suggest that the half-dose ivermectin faecal egg count reduction test (FECRT) may offer some very practical benefits for parasite control by providing early warning of developing resistance to ML drenches and by signalling the possible imminent failure of these at their therapeutic dose rates. The sensitivity and reliability of this procedure may be further enhanced by the inclusion of larval cultures.  相似文献   

Cerebral phaeohyphomycosis in a Birman kitten     

AF Julian 《New Zealand veterinary journal》2013,61(1)

Extract

A 6-month-old female Birman kitten was presented for long-lasting and repeated seizures. It initially had some response to treatment but deteriorated and was euthanised. At necropsy, the brain was swollen and some of the caudal cerebellum was compressed into the foramen magnum. The right cerebral hemisphere was enlarged and had a round, dark, 5 mm-diameter focus on the dorsal surface of the rostral sigmoid gyrus of the frontal cerebrum. There were smaller dark areas extending caudally into the endomarginal gyrus. When the fixed brain was sliced transversely, the lesions were grey-coloured or translucent and involved most of the rostral half of the right cerebral hemisphere. Histologically, there was severe, extensive pyogranulomatous inflammation with some interspersed areas of spongiosus and oedema. Within the granulomas were variable numbers of branching, pigmented, thin-walled, septate fungal hyphae. Cladosporium bantianum (trichoides) was isolated from the brain. This is the most frequent agent reported from cases of cerebral phaeohyphomycosis.  相似文献   

Bovine γδ T cells: cells with multiple functions and important roles in immunity     

Guzman E  Price S  Poulsom H  Hope J 《Veterinary immunology and immunopathology》2012,148(1-2):161-167

The γδ T-cell receptor (TCR)-positive lymphocytes are a major circulating lymphocyte population in cattle, especially in young calves. In contrast, human and mice have low levels of circulating γδ TCR(+) T cells (γδ T cells). The majority of the circulating γδ T cells in ruminants express the workshop cluster 1 (WC1) molecule and are of the phenotype WC1(+) CD2(-) CD4(-) CD8(-). WC1 is a 220000 molecular weight glycoprotein with homology to the scavenger receptor cysteine-rich (SRCR) family, closely related to CD163. The existence of 13 members in the bovine WC1 gene family has recently been demonstrated and although murine and human orthologues to WC1 genes exist, functional gene products have not been identified in species other than ruminants and pigs. Highly diverse TCRδ usage has been reported, with expanded variable genes in cattle compared to humans and mice. Differential γ chain usage is evident between populations of bovine γδ T cells, this may have implications for functionality. There is a growing body of evidence that WC1(+) γδ T cells are important in immune responses to mycobacteria and may have important roles in T cell regulation and antigen presentation. In this review, we will summarize recent observations in γδ T cell biology and the importance of γδ T cells in immune responses to mycobacterial infections in cattle.  相似文献   

Natural scrapie in British sheep: breeds, ages and PrP gene polymorphisms.     

N Hunter  J D Foster  J Hope 《The Veterinary record》1992,130(18):389-392

One hundred and sixty-seven sheep of 32 breeds and crossbreeds affected by natural scrapie throughout Britain were tested for the presence of restriction fragment length polymorphisms of the PrP gene observed when their DNA was digested with EcoRI or HindIII. These polymorphisms have already been associated with different susceptibilities to experimental scrapie (controlled by alleles of the Sip gene) in a flock of Cheviot sheep. In two studies 86 to 92 per cent of the sheep were found to carry the PrP gene EcoRI fragment e1 which is associated with high susceptibility (or the sA allele of Sip) to experimental scrapie. The PrP gene HindIII genotypes of the natural scrapie sheep were not apparently associated with differences in susceptibility to scrapie. There was no link between the polymorphisms and the age or breed of the affected sheep.  相似文献   

Role of bovine chemokines produced by dendritic cells in respiratory syncytial virus-induced T cell proliferation     

Werling D  Koss M  Howard CJ  Taylor G  Langhans W  Hope JC 《Veterinary immunology and immunopathology》2002,87(3-4):225-233

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Clinical challenge. An enlarged urinary bladder.     

Katharine Hope  Carlos Sanchez  Suzan Murray 《Journal of zoo and wildlife medicine》2005,36(3):550-552

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The Application of Reproductive Technologies to Natural Populations of Red Deer   总被引：1，自引：0，他引：1  

JJ Garde  F Martínez-Pastor  M Gomendio  AF Malo  AJ Soler  MR Fernández-Santos  MC Esteso  AJ García  L Anel  ERS Roldán 《Reproduction in domestic animals》2006,41(S2):93-102

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Clinical and clinicopathological features and outcomes of cats with suspected dietary induced pancytopenia     

Barbara Glanemann  Karen Humm  Mariana Abreu  Sophie Aspinall  David Buckeridge  Hope Carveth  Hannah Darcy  Jessica Florey  Polly Frowde  Isuru Gajanayake  Kate Green  Emma Holmes  Alenka Hrovat  Anne-Katherine Jasensky  Bryn A Jones  Vasiliki Lantzaki  Eve JY Lo  Kirsty MacDonald  Kevin O'Brien  Alejandro Suárez-Bonnet  Nele Van den Steen  Balazs Szladovits  Annelies Willems  Helen Wilson 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2023,37(1):126-132

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Long‐Term Outcome,Complications and Disease Progression in 23 Dogs After Placement of Tracheal Ring Prostheses for Treatment of Extrathoracic Tracheal Collapse          下载免费PDF全文

Hope K. Chisnell DVM  Anthony D. Pardo MS  DVM  Diplomate ACVS 《Veterinary surgery : VS》2015,44(1):103-113

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