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OBJECTIVE: To determine the survival time of Mycobacterium avium subsp paratuberculosis in amitraz-based cattle dip fluid derived from an active dip site in northern New South Wales. PROCEDURE: Following inoculation of triplicate 5 L containers with faeces (0.5 g/L) from a clinical case of bovine paratuberculosis, samples collected up to 8 weeks after inoculation were examined by conventional and radiometric culture. M a paratuberculosis colonies were enumerated on solid media. RESULTS AND CONCLUSIONS: M a paratuberculosis survived in amitraz cattle dip fluid for up to 2 weeks, but not 3 weeks. Where 1% of solids in dip fluid is derived from a clinical case of paratuberculosis, dip fluid may contain viable M a paratuberculosis for at least 2 weeks. These findings have implications for the management of cattle dip sites. 相似文献
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I RIETHMULLER-HAAGE L BASTIAANS C KEMPENAAR† V SMUTNY‡ & MJ KROPFF 《Weed Research》2007,47(5):415-424
To evaluate the effect of pre‐spraying growing conditions on herbicide efficacy, two years of experimentation were conducted in which Persicaria maculosa plants were exposed to different light intensities for 1–4 days before metribuzin treatment. Specific leaf area, rather than plant growth rate or plant size, was the only parameter that correlated well with herbicide efficacy in both years of experimentation. The negative relationship between the ED50 and the specific leaf area indicates that leaf characteristics might be an important determinant of herbicide efficacy, for instance through an effect on herbicide uptake. In the third year of experimentation this hypothesis was further investigated by raising six cohorts of weed plants at a 1‐week interval and thus exposing them to a range of weather conditions. Clear relationships between uptake and herbicide efficacy were found for a combination of four plant species (Solanum nigrum, Senecio vulgaris, Chenopodium album and Brassica napus) and two herbicides (phenmedipham and bentazone). For phenmedipham, uptake was negatively correlated with global radiation and positively correlated with relative humidity. For the herbicide bentazone the opposite was found. These results were not species‐specific. This study shows the importance of the sensitivity of herbicide × species combinations and indicates that pre‐spraying weather information is relevant for the development of reduced dose rate recommendations. 相似文献
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Thirteen of 100 fallow deer, aged between 6 months and 10 years, died over a 5 week period. The deaths occurred in 2 outbreaks 3 weeks apart. Both outbreaks were preceded by at least 3 days of cold wet and windy weather, and were associated with water-logged pastures. Affected animals were usually found dead, with a frothy blood-stained nasal discharge. In the 8 deer necropsied, gross lesions included widespread subserosal petechial haemorrhages, severe pulmonary congestion and oedema with froth-filled airways, and fibrinous pneumonia and pleurisy in 4 deer. Two deer, also, had extensive subcutaneous petechial and ecchymotic haemorrhages and oedema of skeletal musculature. Histologically, the most significant lesions were present in the lungs. Moderate to severe pulmonary congestion and oedema, with fibrinous exudation into alveoli and septal oedema, were present in all deer. In some deer these changes were accompanied by a diffuse infiltration with polymorphonuclear leucocytes. Pasteurella multocida was isolated from a range of tissues from 7 of 8 deer examined. The remaining animal had been treated with antibiotics 8 hours before death. The isolates had identical polyacrylamide gel electrophoresis patterns and were of the same antigenic type-Carter group A, Heddleston type 3,4. 相似文献
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S Caceres G Silvan L Martinez‐Fernandez MJ Illera P Millan B Monsalve L Peña JC Illera 《Reproduction in domestic animals》2014,49(4):611-617
Isoflavones are the most common phytoestrogens found in human diets. However, it is still not clear whether isoflavones have effects on the reproductive and the endocrine systems under normal dietary intake and overdose. The aim of this study was to determine how the most important isoflavones, genistein and daidzein, affect androgen and glucorticoid levels on male prepuberal rats. A hundred and seventy‐five 30‐day‐old male Wistar rats were dosed orally by stomach tube every day for 35 days, with saline solution, low and high doses of genistein, daidzein and a mixture of both. Serum samples were analysed by an enzyme immunoassay for hormone determinations. In control group, there was a peak of testosterone (T) and dihydrotestosterone levels associated to the onset of puberty, at the third week. However, in low‐dose groups, the same peak was found at the fourth week (p < 0.05), indicating a delay in the onset of puberty in these groups. Moreover, high doses groups serum androgen levels were significantly lower (p < 0.05) than the control group from the first week until fifth week. This fact was supported by a epididymal histological analysis that indicate in low doses there were several content of spermatozoa at fourth week and in high doses there were few content of spermatozoa. Besides, corticosterone levels followed the same pattern of androgens in all groups. We can conclude that oral administration of isoflavones in male rats decreased the secretion of androgens and glucocorticoids causing a delay in the onset of puberty and may cause physiological and developmental problems. 相似文献