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681.
Effects of autumn tillage and residue management on soil respiration in a long‐term field experiment in Sweden
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Several previous field studies in temperate regions have shown decreased soil respiration after conventional tillage compared with reduced or no‐tillage treatments. Whether this decrease is due to differences in plant residue distribution or changes in soil structure following tillage remains an open question. This study investigated (1) the effects of residue management and incorporation depth on soil respiration and (2) biological activity in different post‐tillage aggregates representing the actual size and distribution of aggregates observed in the tilled layer. The study was conducted within a long‐term tillage experiment on a clay soil (Eutric Cambisol) in Uppsala, Sweden. After 38 y, four replicate plots in two long‐term treatments (moldboard plowing (MP) and shallow tillage (ST)) were split into three subplots. These were then used for a short‐term trial in which crop residues were either removed, left on the surface or incorporated to about 6 cm depth (ST) or at 20 cm depth (MP). Soil respiration, soil temperature, and water content were monitored during a 10‐d period after tillage treatment. Respiration from aggregates of different sizes produced by ST and MP was also measured at constant water potential and temperature in the laboratory. The results showed that MP decreased short‐term soil respiration compared with ST or no tillage. Small aggregates (< 16 mm) were biologically most active, irrespective of tillage method, but due to their low proportion of total soil mass they contributed < 1.5% to total respiration from the tilled layer. Differences in respiration between tillage treatments were found to be attributable to indirect effects on soil moisture and temperature profiles and the depth distribution of crop residues, rather than to physical disturbance of the soil. 相似文献
682.
Shawn D. Coyle Siddhartha Dasgupta James H. Tidwell Thomas Beavers Leigh Anne Bright David K. Yasharian 《Journal of the World Aquaculture Society》2005,36(3):282-290
Abstract— The freshwater prawn Macrobrachiurn rosenbergii is a commercially important culture species in the South Central United States. Two major constraints in the commercial culture of the freshwater prawn in the U.S. are poor survival during live transportation of seed‐stock to growout ponds, and live transportation of pond harvested prawn to distant live markets due to the territorial and cannibalistic nature of prawn. The use of anesthetics could possibly improve transport survival; however, to date anesthetic agents have not been evaluated for use with prawn. Two trials were conducted with juvenile freshwater prawn to compare the efficacy of anesthetics commonly used on fish. The first trial was designed to identify the most promising candidates. In Study 1, tricaine methanesulfonate (MS‐222), 2‐phenoxyethanol, quinaldine sulfate (quinaldine), clove oil, and Aqui‐STM were evaluated at 25 and 100 mg/L for 1 h in three replicate 10‐L glass containers, containing five juvenile prawn each. Relative sedation level was determined every 3 min for 1 h, then recovery time and survival were measured. In Study 1, MS‐222 and 2‐phenoxyethanol were determined to be ineffective on prawn at all rates tested. Based on their performance in Study 1, quinaldine, clove oil, and AquiSTM were evaluated at 100, 200, and 300 mg/L in Study 2. Observations were determined as in Study 1. Clove oil and Aqui‐STM induced anesthesia faster and at lower concentrations than quinaldine. At the highest treatment rate (300 mg/L) prawn suffered 60% mortality in the Aqui‐STM treatment, 13% mortality in the quinaldine treatment, and 0% mortality in the clove oil treatment and control following a 1‐h exposure to these concentrations. Based on these data, Aqui‐STM and clove oil applied at 100 mg/L may be suitable anesthetic treatments for prawn. Additional research is needed to determine optimal time and dose relationships to minimize stress during holding, handling, and transportation of prawn. 相似文献
683.
J O Knowles F McArdle S Dawson S D Carter C J Gaskell R M Gaskell 《Veterinary microbiology》1991,27(3-4):205-219
Two groups of cats were inoculated oro-nasally with one of two isolates of feline calicivirus (FCV) from clinical cases of chronic stomatitis. All cats developed signs typical of acute FCV infection; namely, ocular and nasal discharge, conjunctivitis, and marked oral ulceration. None of the cats shed virus beyond 28 days. Seronegative control cats were then infected with a lower dose of one isolate, but again only acute signs were seen and no carriers produced. The original cats were then re-infected with the heterologous isolate. As before, only signs of acute disease were seen, but the range of clinical signs and severity was reduced. Virus shedding patterns in one group were similar to those seen originally, but in the other the duration was reduced. No chronic stomatitis developed over the 10 months of the study. Serum virus neutralising and serum and salivary class specific immunoglobulin responses were investigated. Although long-term carriers were not induced, no relationship between cessation of virus shedding in an individual animal and systemic and local antibody responses was seen. 相似文献
684.
685.
Dogs with canine rheumatoid arthritis had significantly elevated levels of antibodies to canine distemper virus. This increase was particularly seen in the synovial fluids, compared with paired sera, and was not found in dogs with infective arthropathies, osteoarthritis or in osteoarthritis secondary to rupture of the cranial cruciate ligament. Analysis of the immune complexes precipitated from synovial fluids showed immunoglobulins in all types of arthropathy. Western blotting analyses showed reactivity with anti-distemper antisera in immune complexes from dogs with rheumatoid arthritis, but not in immune complexes from dogs with other joint diseases. These results suggest that there are increased immune responses to distemper in canine arthritis and that these may be due to the presence of this paramyxovirus in affected joints. The implications for the role of a possible infectious agent in rheumatoid arthritis in the dog are considerable. 相似文献
686.
A study was conducted with the objective of obtaining a profile of farmers who have participated in the Farm Partnership Scheme
in Ireland. This scheme is a joint venture between Coillte (The Irish Forestry Board) and farmers. Under the terms of the
scheme, Coillte is responsible for the establishment, management and harvesting of the forest plantation on the farmer’s land.
The farmer retains ownership of the land, receives premium payments and shares in the harvesting profits. Fifty farmers who
joined the Farm Partnership Scheme between 1993–1997 were interviewed in 1999 and a detailed questionnaire was completed.
Survey results indicate that the typical farm partner was male, married and aged 50 years or older. Over half of those surveyed
had an off-farm job. The most popular reason for farmers opting to participate in the Farm Partnership Scheme was that they
did not have sufficient time to undertake the establishment and management of a forest plantation themselves. The average
size of forest established under the scheme was 23.7 ha, with Sitka spruce the most popular species planted. The average annual
payment under the scheme was €8077. For 46% of those surveyed, the returns from the Farm Partnership Scheme comprised all
of their farm income. 相似文献
687.
Thomas G. Nyland DVM Paul Y. Barthez DVM Theresa M. Ortega DVM Corrine R. Davis DVM 《Veterinary radiology & ultrasound》1996,37(3):200-205
A unique, "honeycomb" pattern was found on ultrasonographic evaluation of the liver of 5 dogs with canine superficial necrolytic dermatitis (hepatocutaneous syndrome). This pattern consisted of variably-sized, hypoechoic regions measuring 0.5–1.5 cm in diameter surrounded by highly echogenic borders. Histologically, the hypoechoic regions corresponded to distinct regenerative nodules bounded by severely vacuolated (fat-laden) hepatocytes, numerous bile ductules, and a network of reticulin and fine collagen fibers representing remnants of collapsed hepatic lobules. While certain features of the architectural disruption were characteristic of cirrhosis, the lesion lacked the extensive fibrosis and reduced liver size usually associated with chronic cirrhosis. To our knowledge, this hepatic ultrasonographic pattern has only been seen with canine superficial necrolytic dermatitis. Therefore, it appears to be pathognomonic in a dog with questinable skin lesions. A liver biopsy is required to confirm the unique histopathologic features of the hepatopathy found in this syndrome. 相似文献
688.
R M Dabareiner J P Watkins G K Carter C M Honnas T Eastman 《Journal of the American Veterinary Medical Association》2001,219(1):82-86
OBJECTIVE: To determine clinical, radiographic, and scintigraphic abnormalities in and outcome of horses with septic or nonseptic osteitis of the axial border of the proximal sesamoid bones. DESIGN: Retrospective study. ANIMALS: 8 horses. PROCEDURE: Data collected from medical records included signalment; history; horse use; severity and duration of lameness; results of perineural anesthesia, radiography, ultrasonography, and scintigraphy; and outcome following surgery. RESULTS: Five horses did not have any evidence of sepsis; the other 3 had sepsis of the metacarpophalangeal or metatarsophalangeal joint or the digital synovial sheath. All horses had a history of chronic unilateral lameness. Three of 5 horses improved after diagnostic anesthesia of the metacarpophalangeal or metatarsophalangeal joint; the other 2 improved only after diagnostic anesthesia of the digital synovial sheath. Nuclear scintigraphy was beneficial in localizing the source of the lameness to the proximal sesamoid bones in 4 horses. Arthroscopy of the palmar or plantar pouch of the joint or of the digital synovial sheath revealed intersesamoidean ligament damage and osteomalacia of the axial border of the proximal sesamoid bones in all horses. All 5 horses without sepsis and 1 horse with sepsis returned to their previous uses. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that osteitis of the axial border of the proximal sesamoid bones is a distinct entity in horses that typically is associated with inflammation of the associated metacarpointersesamoidean or metatarsointersesamoidean ligament and may be a result of sepsis or nonseptic inflammation. Arthroscopic debridement may allow horses without evidence of sepsis to return to their previous level of performance. 相似文献
689.
690.