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The presentation of approximately 40 dairy cows affected with left-side displacement of the abomasum (LDA) per annum in a cattle practice in East Gippsland, Victoria provided an opportunity to conduct a survey and case-control study of the disease in a grazing environment. The study, involving 37 dairy cows at pasture, revealed significant differences from the pattern of the disease occurring in the northern hemisphere where cows in older age groups, of larger frame size, higher production and fed high grain rations are at increased risk. Affected cows were diagnosed over a 10-month period and represented approximately 0.06% of the dairy cow population. Most cases were diagnosed in the early lactation period. Evidence for a genetic predisposition was suggested by the discovery that one sire generated a disproportionately large number (9) of the cows with LDA. Although affected cows were average producers in their herds, being a member of a high-producing herd was a significant risk factor. 相似文献
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SUMMARY Two field trials using an injectable vitamin A, D and E solution conducted in the pastoral environment of northern Australia are described. It was found that treatment of lighter (< 150 kg) or heavier (> 372 kg) weight cattle did not reduce weight loss during road transport. These findings contradict anecdotal evidence of reduced weight loss during transport with the use of vitamins A, D and E. The lack of scientific basis for their use is discussed. 相似文献
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Use of enzyme-linked immunoassays for antibody to types C and D botulinum toxins for investigations of botulism in cattle 总被引:3,自引:0,他引:3
The development of specific enzyme-linked immunosorbent assays (ELISA) for antibody to types C and D Clostridium botulinum toxins for investigation of botulism in cattle is described. Partially purified type C and D toxins were used as antigens to develop these ELISAs. Specificity of the ELISAs was evaluated on sera from 333 adult beef and dairy cattle from areas with no history or evidence of botulism in animals or water birds. The test was also evaluated on sera from 41 herds that included herds vaccinated against botulism, confirmed botulism cases and herds from areas where the disease is considered endemic. The ELISAs detected the presence of antibody to botulinum toxins in samples from vaccinated cattle and both convalescent and clinically normal animals from unvaccinated herds with outbreaks of botulism. Antibody was also found in unvaccinated animals from herds in which there had been no diagnosed botulism cases in areas where botulism was considered endemic. Sera from some unvaccinated cattle with high ELISA reactivity was shown to be protective for mice in botulinum toxin neutralisation tests. The use of these tests in investigations of botulism in cattle is discussed. 相似文献
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From 2004 till 2008, Diplura were sampled at 96 localities in Belgium. Nine different species of Campodea were collected: Campodea fragilis Meinert 1865, Campodea lankesteri Silvestri 1912, Campodea lubbocki Silvestri 1912, Campodea meinerti Bagnall 1918, Campodea plusiochaeta Silvestri 1912, Campodea remyi Denis 1930, Campodea rhopalota Denis 1930, Campodea staphylinus Westwood 1842 and Campodea wallacei Bagnall 1918. The ordination technique non-metric multidimensional scaling indicated that pH and temperature/humidity were probably the most important variables determining species composition. However, it was remarkable that almost all combinations of species were encountered in the field, often even under the same stone. As no temporal segregations seem to take place, it remains unknown how these very similar species can occur together. 相似文献
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Steffen Gebhardt Jürgen Schellberg Reiner Lock Walter Kühbauch 《Precision Agriculture》2006,7(3):165-178
Digital image processing has the potential to support the identification of plant species required for site-specific weed control in grassland swards. The present study focuses on the identification of one of the most invasive and persistent weed species on European grassland, the broad-leaved dock (Rumex obtusifolius L., R.o.), in complex mixtures of perennial ryegrass with R.o. and other herbs.A total of 108 digital photographs were obtained from a field experiment under constant recording geometry and illumination conditions. An object-oriented image classification was performed. Image segmentation was done by transforming the red, green, blue (RGB) colour images to greyscale intensity images. Based on that, local homogeneity images were calculated and a homogeneity threshold (0.97) was applied to derive binary images. Finally, morphological opening was performed. The remaining contiguous regions were considered to be objects. Features describing shape, colour and texture were calculated for each of these objects. A Maximum-likelihood classification was done to discriminate between the weed species. In addition, rank analysis was used to test how combinations of features influenced the classification result.The detection rate of R.o. varied with the training dataset used for classification. Average R.o. detection rates ranged from 71 to 95% for the 108 images, which included more than 3,600 objects. Misclassifications of R.o. occurred mainly with Plantago major (P.m.). Between 9 and 16% R.o. objects were classified incorrectly as P.m. and 17–24% P.m. objects were misclassified as R.o. The classification result was influenced by the defined object classes (R.o., P.m., T.o., soil, residue vs. R.o., residue). For instance, classification rates were 86–91% and 65–82% for R.o. exclusively and R.o. against the remaining herb species, respectively. 相似文献