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Westerau, Germany

Larsen T.,University of Aarhus | Aulrich K.,Institute of Organic Farming
Journal of Dairy Research | Year: 2012

Activity of the enzyme β-glucuronidase (EC is found in milk from ruminants with mastitis. However, the use of this enzymic activity as an indicator of mastitis has gained little attention possibly because of its low activity when compared with other mastitis indicators. The determination may therefore be less precise and the analytical procedure very time consuming and labour intensive. The present study optimized the fluorometric determination of the β-glucuronidase activity with respect to substrate concentration, pH, incubation time etc., validated the assay, and developed it into large scale analyses. The assay performance is satisfactory regarding precision, linearity etc., and it appears comparable to analogous fluorometric assays for mastitis indicators in milk. From a local dairy herd, 825 milk samples were analysed for potential mastitis indicators, i.e. β-glucuronidase, lactate dehydrogenase (LDH), alkaline phosphatase (AP), and N-acetyl-β-d-glucosaminidase (NAGase) activity, and for somatic cell counts (SCC) and the variables were compared. Activity of β-glucuronidase was moderately but significantly correlated to SCC (r=0·21; n=768) as well as the other mentioned variables (r=0·25-0·43; n=825). Simple indices based on β-glucuronidase and LDH or NAGase activity were tested as indicators of mastitis (SCC), but were not found to improve the diagnostic value. Future studies may further verify whether β-glucuronidase can compete with well-established indicators of mastitis in cows such as LDH or NAGase as well as determine whether β-glucuronidase activity, in combination with other indicators of mastitis, has an advantage. Nineteen milk samples from subclinical and latent cases of mastitis (individual quarters) were identified for specific pathogens (PCR method) and measured for β-glucuronidase activity. The activity was tested at four different pH levels (5·5, 6·0, 6·5 and 7·0) in order to investigate the possibility of discrimination between pathogens. However, all milk samples (strains of pathogens) had the same pH optimum for β-glucuronidase activity; this may indicate that enzymic activity from mammary tissue and leucocytes dominates over enzyme activity from bacterial cells. © 2011 Proprietors of Journal of Dairy Research. Source

Ashour T.,Benha University | Wieland H.,Dipl Biol Institute Of Production Engineering And Building Research | Georg H.,Institute of Organic Farming | Bockisch F.-J.,Institute of Production Engineering and Building Research | Wu W.,University of Natural Resources and Life Sciences, Vienna
Materials and Design | Year: 2010

This work aimed to measure the thermal conductivity of some natural plaster materials that could be used for straw bale buildings. Thermal conductivity is very important to determine the insulation value and other thermal parameters for natural plaster materials. Plaster materials consisted of soil, sand and straw. Straw is used as a reinforcement fibre for plaster. Three types of fibres were used such as wheat straw, barley straw and wood shavings. The results indicated that the thermal conductivity of all materials decreased with increasing straw fibre content and decreased with increasing sand content. The straw fibres have greater effect on the change of thermal conductivity than the effect of sand. The results also revealed that plaster reinforced by barley straw fibres has the highest values of thermal insulation. © 2010 Elsevier Ltd. Source

Koesling M.,Norwegian Institute for Agricultural And Environmental Research Bioforsk | Koesling M.,Institute of Organic Farming | Loes A.-K.,Norwegian Institute for Agricultural And Environmental Research Bioforsk | Flaten O.,Norwegian Agricultural Economics Research Institute | And 2 more authors.
Organic Agriculture | Year: 2012

Every year since 2002, 150 to 200 farmers in Norway have deregistered from certified organic production. The aim of this study was to get behind these figures and improve our understanding of the reasoning leading to decisions to opt out. Four cases of deregistered organic farmers with grain, sheep, dairy or vegetable production were selected for in-depth studies. The cases were analysed from the perspective of individual competencies and the competencies available in the networks of the selected organic farmers. Besides the conspicuous reasons to opt out of certified organic farming, such as regulations getting stricter over time and low income, personal reasons such as disappointment and need for acceptance were also important. This shows that hard mechanisms, such as economic support and premium prices, are not sufficient to motivate farmers for sustained organic management. Support and encouragement, for example from people in the local community, politicians and other spokespersons, would likely contribute to increase farmers' motivation. © 2012 Springer Science & Business Media BV. Source

Ashour T.,Benha University | Georg H.,Institute of Organic Farming | Wu W.,University of Vienna
Energy and Buildings | Year: 2011

This research aimed to evaluate a straw bale house located in Bavaria, Germany. An extensive test program was carried out. The experimental work includes compression tests, moisture content, thermal stability of bales and pH. The in situ work includes temperature and relative humidity inside the straw bale wall. The stress-strain behavior of straw bales was investigated including nonlinearity and anisotropy. Thermal stability of bales under constant temperature and relative humidity was studied considering time dependence. The moisture content of straw bale was about 11%, while pH value inside the bale was about 7.29. Moreover, the temperature and the relative humidity between the interior (inside straw bale wall) and the exterior were investigated. © 2011 Elsevier B.V. All rights reserved. Source

Ashour T.,Benha University | Ashour T.,University of Natural Resources and Life Sciences, Vienna | Georg H.,Institute of Organic Farming | Wu W.,University of Natural Resources and Life Sciences, Vienna
Applied Thermal Engineering | Year: 2011

This work focuses on the determination of equilibrium moisture content (EMC) of natural plaster materials for straw bale buildings. Earth plasters of four different compositions of cohesive soil and sand combined with reinforcement of three different natural fibre types, wheat straw, barley straw and wood shavings, were investigated. The plaster materials were treated under different temperature (10-40 °C) and relative humidity (43-95%). The moisture content is in dynamic equilibrium with environmental condition. The effect of relative humidity is more pronounced than temperature. The test results are discussed with reference to the relevance of the earth plasters as rendering for straw bale buildings. Guggenheim-Anderson-de Boer (GAB) model is used to fit the experimental data. © 2010 Elsevier Ltd. All rights reserved. Source

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