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Bemestingsschema’s voor Nieuw Nederlands Weiden
No full textNieuw Nederlands Weiden is de oplossing voor melkveehouders die meer vers gras willen omzetten naar melk, maar wel met een eenvoudig en goed inpasbaar systeem. Nieuw Nederlands Weiden is overzichtelijk voor zowel de melkveehouder en de koe, omdat voor beiden, elke dag, duidelijk is waar ze aan toe zijn
Supplementation of lamb diets with vitamin E and rosemary extracts on meat quality parameters
No full textBACKGROUND: Supranutritional supplementation of lamb diets with α-tocopherol is an effective method to reduce lipid oxidation and colour deterioration in meat products. However, alternative antioxidant sources have been proposed to replace the supranutritional vitamin E applications. RESULTS: Indoor concentrate-fed Rasa Aragonesa male lambs (n = 480) were supplemented with increasing levels of all-rac-α-tocopheryl acetate (0.25, 0.5, 1.0 g kg−1 compound feed), rosemary extract (0.20, 0.40, or 0.80 g kg−1 compound feed), or rosemary extract embedded in a fat matrix (0.20, 0.40, or 0.80 g kg−1 compound feed) for 14 days before slaughter. The longissimus thoracis et lumborum muscle from three lambs per pen (18 lambs per treatment) were modified-atmosphere packaged (70% O2 + 30% CO2) and maintained under retail conditions for 14 days. Supranutritional supplementation with antioxidants had no effect (P > 0.05) on average daily weight gain, feed intake, and feed efficiency. Rosemary extract supplementation (with or without fat embedment) had no effect on lipid oxidation, myoglobin forms, or colour stability parameters, regardless of the dose. All vitamin E supplementation levels significantly affected lipid oxidation, colour stability (L*, C*, and h), myoglobin forms, and meat discoloration parameters compared with non-supplemented lambs. CONCLUSIONS: This study demonstrates that, unlike vitamin E, neither dose nor protection of the rosemary extract had an effect on lipid oxidation or meat colour stability of lambs during the 14 days of storage under retail conditions.</p
Mobility and redox transformation of arsenic during treatment of artificially recharged groundwater for drinking water production
No full textIn this study we investigate opportunities for reducing arsenic (As) to low levels, below 1 μg/L in produced drinking water from artificially infiltrated groundwater. We observe that rapid sand filtration is the most important treatment step for the oxidation and removal of As at water treatment plants which use artificially recharged groundwater as source. Removal of As is mainly due to As co-precipitation with Fe(III)(oxyhydr)oxides, which shows higher efficiency in rapid sand filter beds compared to aeration and supernatant storage. This is due to an accelerated oxidation of As(III) to As(V) in the filter bed which may be caused by the manganese oxides and/or As(III) oxidizing bacteria, as both are found in the coating of rapid sand filter media grains by chemical analysis and taxonomic profiling of the bacterial communities. Arsenic removal does not take place in treatment steps such as granular activated carbon filtration, ultrafiltration or slow sand filtration, due to a lack of hydrolyzing iron in their influent and a lack of adsorption affinity between As and the filtration surfaces. Further, we found that As reduction to below 1 μg/L can be effectively achieved at water treatment plants either by treating the influent of rapid sand filters by dosing potassium permanganate in combination with ferric chloride or by treating the effluent of rapid sand filters with ferric chloride dosing only. Finally, we observe that reducing the pH is an effective measure for increasing As co-precipitation with Fe(III)(oxyhydr)oxides, but only when the oxidized arsenic, As(V), is the predominant species in water.</p
Variability in lag-duration of Campylobacter spp. during enrichment after cold and oxidative stress and its impact on growth kinetics and reliable detection
No full textCampylobacter jejuni and Campylobacter coli continue to be the leading cause of zoonotic gastroenteritis in the European Union, making reliable detection in food important. Low storage temperatures and atmospheric oxygen concentrations during food production can cause sub-lethal damage or transient non-culturability which is why ISO 10272-1:2017 includes an enrichment step to repair cell damage and increase cell concentrations, thereby supporting detection of campylobacters from foods. The aim of this study was to assess the variability in lag-duration of C. jejuni and C. coli during enrichment after different food-relevant stress treatments and evaluate its impact on growth kinetics and reliability of detection outcomes. Therefore, 13 C. jejuni and 10 C. coli strains were subjected to cold stress during refrigerated and frozen storage. Refrigerated storage did not significantly reduce culturability, but frozen storage reduced cell concentrations by 1.6 ± 0.1 log10cfu/ml for both species. Subsequently, cells were enriched following ISO 10272-1:2017-A and cell concentrations were determined over time and lag-duration and growth rate were determined by fitting the Baranyi-model. Without prior stress treatment, mean lag-duration for C. jejuni and C. coli was 2.5 ± 0.2 h and 2.2 ± 0.3 h, respectively. Refrigerated storage increased lag-duration for C. jejuni to 4.6 ± 0.4 h and for C. coli to 5.0 ± 0.4 h and frozen storage increased lag-duration to 5.0 ± 0.3 h and 6.1 ± 0.4 h for C. jejuni and C. coli, respectively. Comparison of strain- and biological variability showed that differences in recovery after cold stress can be attributed mainly to strain variability since strain variability after refrigeration and freeze stress increased respectively 3-fold and 4-fold while biological variability remained constant. A subset of strains was also subjected to oxidative stress that reduced cell concentrations by 0.7 ± 0.2 log10 cfu/ml and comparison of recovery patterns after oxidative and freeze stress indicated that recovery behaviour was also dependent on the stress applied. A scenario analysis was conducted to evaluate the impact of heterogeneity in outgrowth kinetics of single cells on the reliability of detection outcomes following ISO protocol 10272-1:2017. This revealed that a ‘worst-case’-scenario for successful detection by a combination of the longest lag-duration of 7.6 h and lowest growth rate of 0.47 h−1 still resulted in positive detection outcomes since the detection limit was reached within 32.5 h. This suggests that other factors such as competitive microbiota can act as a causative factor in false-negative outcomes of tested food samples.</p
Approaches to identify the value of seminatural habitats for conservation biological control
No full textInvertebrates perform many vital functions in agricultural production, but many taxa are in decline, including pest natural enemies. Action is needed to increase their abundance if more sustainable agricultural systems are to be achieved. Conservation biological control (CBC) is a key component of integrated pest management yet has failed to be widely adopted in mainstream agriculture. Approaches to improving conservation biological control have been largely ad hoc. Two approaches are described to improve this process, one based upon pest natural enemy ecology and resource provision while the other focusses on the ecosystem service delivery using the QuESSA (Quantification of Ecological Services for Sustainable Agriculture) project as an example. In this project, a predictive scoring system was developed to show the potential of five seminatural habitat categories to provide biological control, from which predictive maps were generated for Europe. Actual biological control was measured in a series of case studies using sentinel systems (insect or seed prey), trade-offs between ecosystem services were explored, and heatmaps of biological control were generated. The overall conclusion from the QuESSA project was that results were context specific, indicating that more targeted approaches to CBC are needed. This may include designing new habitats or modifying existing habitats to support the types of natural enemies required for specific crops or pests.</p
Goose parents lead migration V
No full textMany migratory animals travel in large social groups. Large, avian migrants that fly in V-formations were proposed do so for energy saving by the use of up-wash by following individuals and regularly change leadership. As groups have been rather homogeneous in previous work, we aimed to explore leadership and its flight mechanics consequences in an extremely heterogeneous case of social migration, namely in spring migration of goose families. In families the experience of group members differs strongly and inclusive fitness may be important. We successfully collected overlapping spring migration tracking data of a complete family of greater white-fronted geese Anser a. albifrons and extracted leadership, flapping frequency and wind conditions in flight. Our data revealed V-formations where one parent was flying in front at all times. Although the father led the family group most of the time, he did not flap at higher frequency while doing so. In contrast, the mother flapped faster when leading, possibly because she experienced less supportive wind conditions than when the father led. We argue that in heterogeneous, social groups leadership might be fixed and not costly if supportive environmental conditions like wind can be used.</p
Practical implementation and evaluation of optimal carbon dioxide supply control
No full textIn state-of-the-art production of greenhouse crops, the air is enriched to higher than atmospheric carbon dioxide levels to increase photosynthesis and final yield. When there is ventilation, this means that some of the supplied carbon dioxide will be lost. Especially when the available carbon dioxide is not a by-product of heat production (e.g. pure liquid carbon dioxide), the enrichment has a significant cost. Commonly, controlling carbon dioxide level is a simple on/off control depending on the windows opening. Experienced growers try to increase the benefit-cost ratio by using more complicated strategies based on influences of climatic factors, e.g. sun irradiation and wind speed. The settings for the influences are made intuitively and it is hardly possible to get any feedback on the applied strategy; therefore they do not warrant optimal use of carbon dioxide. This study demonstrates as alternative a model-based optimization algorithm. This algorithm estimates the carbon dioxide concentration where the difference between benefits and costs of carbon dioxide dosing is maximized. The greenhouse ventilation rate, as the major determinant of the costs, is estimated from the energy and vapor balance of the greenhouse. The photosynthesis, as the major determinant of the benefits, is simulated as a function of solar radiation and carbon dioxide. The model is implemented in the process computer of a commercial tomato greenhouse. The method gives a reasonable estimation of optimum carbon dioxide concentration in varying conditions. The estimated increase in weekly margin compared to the strategy of the grower could be over 200 € ha-1 </p
Valuation of Wetland Ecosystem Services in National Nature Reserves in China’s Coastal Zones
No full textWetlands provide ecosystem services for regional development, and, thus, have considerable economic value. In this study, a combination of evaluation methods was carried out to evaluate the wetland ecosystem services provided by national nature reserves in 11 coastal provinces/municipalities in China. We constructed a literature database containing 808observations (over 170 papers) on field-scale research for wetlands in China’s coastal zones. Using this literature database, as well as land use (LU) data, net primary productivity (NPP), and statistical data, and digital elevation model (DEM) data, we established a valuation framework and database for nine important ecosystem services of the 13 wetland types in the study area. After the large-scale academic literature review, the ordinary kriging offered by Geostatistical Analyst tools was used to interpolate the physical dimensions of the unmeasured locations. The results showed that: 1) the wetland ecosystem services in 35 national nature reserves have a total value of 33.168billion USD/year; 2) the values of wetland ecosystem services revealed considerable spatial variability along China’s coastal zones; and 3) assessments provide additional insights into the trade-offs between different ecosystem services and wetland types. The valuation framework and database established in this study can contribute to the mapping of wetland ecosystem services in coastal zones
