Integrating socio‐economic and biophysical models: revision of a land‐use allocation model

Integration of large‐area, economically driven macro‐models and small‐area, biophysically based models in the Canadian agricultural sector was described recently in the development of a land‐use allocation model (LUAM). We have since developed and integrated an improved methodology for allocating crop area changes generated for large areas by the Canadian Regional Agricultural Model (CRAM) to much smaller Soil Landscapes of Canada (SLC) polygons. Validation of outputs showed considerable improvement. The new coefficients of determination (R²) between simulated and actual data, with previous values in brackets, were 0.69 for fodder corn (0.54), 0.88 for wheat (0.62), 0.77 for hay (0.26), 0.54 for alfalfa (not previously reported), 0.88 for soya bean (0.26) and 0.86 for grain corn (0.22). The best result was obtained for soya bean, with a normalized root mean square error (NRMSE) of 0.31%, and the poorest for alfalfa, with NRMSE = 17.34%.     

Husking stations provide evidence of seed predation by introduced rodents in Tongan rain forests

The islands of Tonga, in Western Polynesia, lacked rodents prior to human colonization. During the past 3000 years, people have introduced three species of rats (Rattus). Seed predation by rodents structures plant communities in many parts of the world. Therefore, there is the potential for rats to have a significant impact on the regeneration of plant communities in Tonga. We found 53 husking stations—sheltered sites used by rats to strip inedible protective structures (husks) from the seeds they eat—on eight islands in Tonga. The stations contained 13,555 empty husks from at least 18 plant species, but only 165 viable seeds and seedlings. These husking stations provide evidence of seed predation by rats. Determining the extent to which seed predation threatens plant regeneration will be important for conservation of native forest remnants.     

Inter-laboratory comparison of radiometric culture for Mycobacterium avium subsp. paratuberculosis using raw milk from known infected herds and individual dairy cattle in Victoria

Objective To compare the results of radiometric culture conducted in three Australian laboratories for Mycobacterium avium subsp. paratuberculosis (Mptb) using bulk vat and individual animal milk samples. Procedure Milk samples were collected from 15 cows exhibiting clinical signs of Johne's disease, and subsequently confirmed as infected with Mptb, and from the bulk milk vats on 91 farms running herds known to be infected with Mptb. Each milk sample was divided into three equivalent samples and one of each of the replicates was forwarded to the three participating laboratories. The identity and nature of the samples was protected from the study collaborators. The laboratories processed the samples and undertook radiometric culture for Mptb using their standard method. Results of testing were provided to the principal investigator for collation and analysis. Results In total, 2 (2.2%) of 91 vat-milk samples and 8 (53.3%) of 15 individual cows' milk samples returned positive radiometric milk culture results. Only one sample, from a clinical case of Johne's disease, was identified as positive by more than one laboratory. There were differences in the absolute frequency with which Mptb was identified in the milk samples by the collaborating laboratories. Conclusions Mptb was cultured from a very small percentage of Australian raw bulk milk samples sourced from known infected herds. By contrast, Mptb was successfully cultured from half of the milk samples collected from clinically affected cows. There was no statistical difference between laboratories in the proportion of vat samples or individual animal milk samples in which Mptb was detected.     

Converting from no-tillage to pre-seeding tillage: Influence on weeds, spring wheat grain yields and N, and soil quality

On the Canadian prairies there has been a steady increase in no-till seeding coupled with more frequent cropping, facilitated by the greater use of snow management to increase stored soil water. Although no-till seeding can gradually improve soil conservation and soil quality, it may also increase the incidence of grassy weed infestations and thus cause more frequent use of costly herbicides, such as glyphosate. Our objective was to determine if no-till producers experiencing grassy weed problems could introduce pre-seeding tillage for a few years to more economically control perennial weeds, without adversely affecting grain yield and quality, and soil quality. An experiment in which spring wheat (Triticum aestivum L.) was grown for 9 years with no-tillage management on an Orthic Brown Chernozem (Typic Haplobroll) with treatments involving snow management and N rate, placement and timing, was converted to a study of pre-seeding shallow (5–7.5 cm) tillage with a cultivator, versus no-tillage, by replacing the N timing treatment in the tenth year. The experiment was then continued for three more years, during which we assessed the effect of tillage on weed populations, grain yield and N content, and on soil quality. Soil quality was also assessed following one more year during which the entire study site was summerfallowed and subjected to four tillage operations. Weed populations generally were not affected by tillage or snow management treatments, but differed among N rate and placement treatments, though not in a way that could be easily interpreted. Tillage had no effect on yield or grain N content. It increased the erodible fraction of soil (dry sieving), but did not affect wet aggregate stability. Neither microbial biomass C, nor C and N mineralization were affected by the change in tillage method. We conclude that the judicious use of shallow pre-seeding tillage in an otherwise no-till cropping system can be tolerated to manage persistent grassy weed problems without deleteriously influencing soil quality, grain yield or protein.     

Extramedullary plasmacytoma in a horse with ptyalism and dysphagia.

A Clydesdale mare was examined for weight loss, inappetence, ptyalism, and dysphagia. The main abnormality revealed by serum biochemistry was a marked hyperglobulinemia, and protein electrophoresis revealed a monoclonal gammopathy in the gamma region. The urine was positive for Bence Jones proteins. These findings suggested a plasma cell tumor. The neoplasm could not be located with extensive antemortem examination. At postmortem, neoplastic cells morphologically compatible with plasma cells and positive for equine IgG with imunoperoxidase staining infiltrated the pericardium, mediastinal stromal tissues, adrenal glands, meninges, atrioventricular valves, aorta, abdominal and thoracic fat, and nerves, including the trigeminal nerve. The neoplastic cells invading the cranial nerves were responsible for many of the presenting signs.     

Outcomes of thoracic surgery in dogs and cats

Summary: Records of 146 dogs and 41 cats that underwent thoracic surgery at The University of Sydney Veterinary Teaching Hospital were reviewed for age, sex, breed, disease, operation date, periods of pre- and post-operative hospitalisation, use of surgical drains and outcome. Animals were assigned to 16 disease categories, the most common being patent ductus arteriosus, traumatic diaphragmatic hernia and oesophageal foreign body in dogs and traumatic diaphragmatic hernia in cats. Differences were observed between disease categories in all the criteria examined. There were almost equal numbers of male (72) and female (74) dogs, the median (range) age was 2.0 (0.2 to 14.0) years, the median pre-operative stay was 1 (0 to 14) days, the median post-operative stay was 4 (0 to 28) days and the overall survival to discharge rate was 78%.
There were 24 male and 15 female cats (sex not recorded in 2 cats). The median (range) age was 3 (0.1 to 12) years, pre-operative stay 1 (0 to 6) days, post-operative stay 5 (0 to 15) days and the overall survival to discharge rate was 85%. Causes of post-operative deaths among animals in the most common categories are recorded and discussed.     

Association of phytoplasmas with the decline of European hazel in southern Italy

In the Campania region of southern ltaly. commercial orchards of European hazel ( Corylus avellana ) are severely affected by yellowing and decline. To determine whether phytoplasmas are associated with the disorder, stem samples from diseased trees were examined using polymerase chain reaction assays. No visible products were obtained by amplification of sample DNA with universal and group-specific phytoplasma primers. However, when the products obtained with universal primers were re-amplified with nested primers that were specific for the fruit tree phytoplasmas of the apple proliferation group, most samples tested positively. Restriction site analysis revealed that the trees were infected with the apple proliferation, pear decline, and European stone fruit yellows phytoplasmas in about the same proportion. Some of the trees were doubly infected with one of the fruit tree phytoplasmas and the aster yellows agent. Most of the infected trees were also identified by hybridization of the products obtained in the initial amplification with suitable oligonucleotide probes.