Farms In Denmark Research Articles

Very-Short-Term Probabilistic Forecasting of Wind Power With Generalized Logit–Normal Distributions

SummaryVery-short-term probabilistic forecasts, which are essential for an optimal management of wind generation, ought to account for the non-linear and double-bounded nature of that stochastic process. They take here the form of discrete–continuous mixtures of generalized logit–normal distributions and probability masses at the bounds. Both auto-regressive and conditional parametric auto-regressive models are considered for the dynamics of their location and scale parameters. Estimation is performed in a recursive least squares framework with exponential forgetting. The superiority of this proposal over classical assumptions about the shape of predictive densities, e.g. normal and beta, is demonstrated on the basis of 10-min-ahead point and probabilistic forecasting at the Horns Rev wind farm in Denmark.

Population Dynamics of Stable Flies Stomoxys calcitrans (Diptera: Muscidae) at an Organic Dairy Farm in Denmark Based on Mark-recapture With Destructive Sub-sampling

A population of stable flies, Stomoxys calcitrans (L.), was studied on a Danish cattle farm in two successive years. Flies were captured monthly by sweep nettings and marked with fluorescent dust. Absolute population size, dilution rate, loss rate, and adult longevity were estimated by means of a modified version of Bailey's triple catch method. In both years, the abundance of flies peaked in July. Using a statistical model, we were able to explain 86.6% of the variation in the per capita growth rate r as a function of current temperature, precipitation, and population size. Omitting precipitation from the model, it still explained 69.3%. The model predicts that stable flies have a temperature optimum at 21.8°C, and that no development will take place when temperatures inside the stable are below 10.2°C or above 33.5°C. At the optimal temperature the intrinsic rate of natural increase is 0.070 d(-1). The per capita dilution rate increased with temperature and decreased with population size, whereas no effect of these factors on the per capita loss rate could be shown. Mean adult survival time was estimated to 6.3 d with 95% CL ranging from 4.3 to 11.1 d. The study points at the possibility of developing predictive models as tools for achieving better, and more environmentally sound, control of stable flies.

Transient Model Validation of Fixed-Speed Induction Generator Using Wind Farm Measurements

In this paper, an electromagnetic transient model for fixed-speed wind turbines equipped with induction generators is developed and implemented in PSCAD/EMTDC. The model is comprised by: an induction generator, aerodynamic rotor, and a two-mass representation of the shaft system. Model validation is conducted by measurement comparison using recordings obtained from switching operations performed at the Nysted Offshore Wind Farm in Denmark. A sensitivity analysis is performed to determine the impact of different model parameters on the simulated response as compared with measurements. This validated model will be used for assessing induced overvoltage conditions that may arise under switching operations similar to those captured by the measurements used for validation.

Genetic indications of translocated and stocked grey partridges (Perdix perdix): does the indigenous Danish grey partridge still exist?

Non-local population stocking can have adverse genetic effects through loss of genetic diversity and introgressive hybridisation in wild populations exploited by man. The grey partridge (Perdix perdix) has been an important European game species for centuries, widely subject to translocation and stocking. After ca 80 years releasing reared grey partridges into Danish wild partridge areas, this study investigated whether an indigenous Danish grey partridge still existed. We predicted that (i) an indigenous Danish partridge would belong to the western European clade (W1) and (ii) would be more closely related to the historical, indigenous grey partridges than to farm bred partridges. These predictions were tested analysing the variation in the mitochondrial control region (CR1) and microsatellite markers in museum samples representing the ancestral indigenous Danish grey partridge, contemporary (recent) wild grey partridges and farmed grey partridges from the five largest farms in Denmark. Phylogeography- and population structure analyses showed traces of the indigenous Danish grey partridges amongst recent wild partridges in certain areas and significant genetic differences between reared, farmed partridges and historical- and recent partridges. The results also showed that the indigenous Danish grey partridges belonged to the western European clade (W1 haplotype). A foreign stocking effect was detected on the remote island of Bornholm, where the current population originated from introduced Danish and Bohemian grey partridges. The loss of haplotype diversity over time in certain geographical areas probably results from serious declines in wild Danish grey partridge numbers in recent decades. This combined with the 2 observation that hybridisation between released stocked and wild partridges can occur may complicate recovery of partridge populations.

Exposure to inhalable dust and endotoxin among Danish livestock farmers: results from the SUS cohort study

Studies on personal dust and endotoxin concentrations among animal farmers have been either small or limited to a few sectors in their investigations. The present study aimed to provide comparable information on the levels and variability of exposure to personal dust and endotoxin in different types of animal farmers. 507 personal inhalable dust samples were collected from 327 farmers employed in 54 pig, 26 dairy, 3 poultry, and 3 mink farms in Denmark. Measurements in pig and dairy farmers were full-shift and performed during summer and winter, while poultry and mink farmers were monitored during 4 well-defined production stages. The collected samples were measured for dust gravimetrically and analyzed for endotoxin by the Limulus amebocyte lysate assay. Simple statistics and random-effect analysis were used to describe the levels and the variability in measured dust and endotoxin exposure concentrations. Measured inhalable dust levels had an overall geometric mean of 2.5 mg m(-3) (range <LOD to 47.8) and endotoxin of 988 EU m(-3) (range <LOD to 374,000). The highest dust and endotoxin concentrations were measured among pig and poultry farmers, and were the lowest among dairy and mink farmers, respectively. Exposure among pig and cattle farmers was characterised by a substantial day-to-day variability that increased from the indoor to outdoor working environment. Only mink farmers complied with the Danish occupational exposure limit for total dust (3 mg m(-3)). More than 93% of our measurements exceeded the recently proposed Dutch exposure-limit for endotoxin (90 EU m(-3)). These findings suggest animal farmers to be exposed to high levels of dust and endotoxin consistent with an increased risk of developing respiratory symptoms and diseases. The development of preventive strategies to reduce exposure will require in-depth identification of factors that affect day-to-day variability in exposure.

Persistent spatial clusters of plasmacytosis among Danish mink farms

Aleutian disease (Plasmacytosis) is caused by the Aleutian mink disease virus (AMDV), an autonomous parvovirus and affects many mustelid species, including the American mink ( Neovisonvison). In Denmark, an eradication program reduced the prevalence of test-positive farms from 100% in 1976 to 15% in 1996. Nevertheless, the disease persists in the Vendsyssel district of Northern Jutland, despite the eradication efforts. In this study, we used spatial epidemiological analysis to test for spatial autocorrelation of the distribution of farms positive for the disease. We investigated 2375 farms in Denmark (342 of which were located in the Vendsyssel district), during the period 2000–2008. For the purpose of our study, a farm was considered positive when, on any test conducted in a year, at least three animals were tested positive. To detect spatial clusters, we performed a retrospective analysis with spatial scan statistics. We performed one analysis for each of the nine years (2000–2008). A separate analysis was conducted with only the farms in Vendsyssel included. The spatial cluster analysis revealed a significant cluster throughout the time period studied in Northern Jutland. The only exception was 2002 when an outbreak was detected in the southern part of Jutland, and not in the north. The farm-level prevalence of the disease in Denmark was highest in this year, suggesting that the outbreak in the south could have masked the persistent signal from the north; the northern cluster was still significant when analysing only the Vendsyssel populations. These results confirm that Northern Jutland continues to have a significantly higher number of cases than expected if the disease was randomly distributed.

Sustainability evaluation of automatic and conventional milking systems on organic dairy farms in Denmark

Organic dairy farmers in Denmark currently are implementing automatic milking systems (AMS) to save labour costs. As organic agriculture aims at sustainable production, the introduction of a new technology such as AMS should be evaluated regarding its economic viability, environmental impact, and social acceptability, i.e., its contribution to sustainable development. The objective of this research, therefore, was to evaluate sustainability of AMS use on organic dairy farms in Denmark, by comparing results of a set of sustainability indicators for nine farms using AMS with nine farms using conventional milking systems (CMS). Sustainability indicators were quantified for economic performance of the farm, on-farm eutrophication, on-farm biodiversity, animal welfare (including health), grazing time, milk composition and labour time. Milk yield per cow per year was higher for AMS farms (9021kg energy corrected milk [ECM] per cow per year) than for CMS farms (7664kg ECM), but did not result in a higher net profit or gross margin per cow for AMS farms. Nitrogen surplus per hectare of available land was higher for AMS farms (110kgNha−1) than for CMS farms (66kgNha−1). This difference was not due to the use of AMS but was caused by a higher export of manure by the CMS farms. The number of veterinary treatments per cow per year was unaffected by AMS use, but culling rate was higher for the AMS farms (38%) than for the CMS farms (32%). There was no difference between the AMS and CMS farms in milk composition indicators such as somatic cell count, clostridium spores, and urea. The acid degree value (ADV), measuring free fatty acids (FFA) in the milk, was higher in the milk from the AMS farms (0.78meql−l) compared with the CMS farms (0.49meql−l). Labour time measured in hours of work per dairy cow per day, was only half for the AMS compared with the CMS users; i.e., 2.3min per cow per day. Grass intake by grazing as percentage of total feed intake was reduced by AMS (5.1kg DM per cow per day for the AMS farms against 6.8kg DM per cow per day for the CMS farms). From this quantification of selected sustainability indicators it can be concluded that organic dairy farms using AMS, in spite of the substantial decrease in grazing time, show the potential of economic and environmental sustainable development within the range of herd sizes investigated (65–157 cows per farm). Even though the lower number of grazing hours per cow per year on the AMS farms did not affect indicator scores for animal health or milk quality, this reduction in grazing hours might be a problem for consumers to accept AMS use.

Economic and environmental evaluation of three goal-vision based scenarios for organic dairy farming in Denmark

The objective of this study was to explore the sustainability of future organic dairy farming systems in Denmark, by evaluating the economic and environmental consequences of three scenarios at the farm level based on different visions of future sustainability leading to different farm-based goals. The future sustainable organic dairy farming systems were deduced from participative sessions with stakeholders, and used to define specific scenarios and related key parameters. Parameterization of the scenarios was based on model simulations and the invoking of expert knowledge. Each scenario was designed to fulfil different aspects of sustainability. The business as usual scenario (BAU) was driven by economic incentives and implemented new technologies and measures to enhance productivity and efficiency. This scenario was expected to be the mainstream strategy of future organic dairy production in Denmark. In the animal welfare scenario (ANW), economic efficiency was subordinate to animal welfare, and measures to improve animal welfare, such as lower milk yield, extra grazing area and a deep-litter barn, were incorporated. The environmental scenario (ENV) was designed to minimize N losses into the environment, reduce emission of greenhouse gases and the use of fossil energy, and was based on self-sufficiency regarding nutrients and feed. The economic evaluation of the scenarios was based on quantification of farm profitability (i.e. net profit), whereas environmental evaluation was based on the quantification of the N-surplus per ha, emission of greenhouse gases, and use of fossil energy per kg energy-corrected milk (ECM). Compared to prolonging the current main stream strategy (BAU), the evaluation of scenarios revealed that investing in animal welfare comprised trade-offs regarding farm profitability, climate change and the use of fossil energy. In ANW, net profit per farm was almost 39 k€ lower than in BAU, whereas emission of greenhouse gases and energy per kg ECM was 8% and 3% higher, respectively. Minimizing environmental impact in ENV reduced local as well as global environmental impact without an economic trade-off. Greenhouse gas emission per kg ECM was 5% lower and fossil energy use was 11% lower than in BAU. The N-surplus of ENV was 80 kg per ha, whereas the N-surplus was approximately 116 in both BAU and ANW. Prolonging the current main stream strategy (BAU) resulted in a high local environmental impact, a moderate global environmental impact and a high economic risk related to changes in milk price or costs.

Inbreeding affects fecundity of American mink (Neovison vison) in Danish farm mink

Inbreeding is an increasing problem in farmed mink, because of limited exchange of individuals between farms. In this study, genetic relatedness within seven American mink (Neovison vison) colour strains originating from 13 different mink farms in Denmark was analysed using 21 polymorphic microsatellite loci. We detected large differences in the level of relatedness (range 0.017-0.520) within colour strains. Moreover, a very strong and highly significant negative correlation between the level of relatedness and fecundity was observed (r = 0.536, P < 0.001) [Correction added after online publication on 9 March 2011: r(2) has been changed to r]. To our knowledge, this is the first time that such a correlation has been demonstrated for commercially farmed mink.

Lightning protection of wind turbines – a comparison of measured data with required protection levels

Latest wind turbine lightning protection systems have been refined to the point where lightning damage is now relatively rare. This is increasingly important as wind turbines move offshore where access for maintenance is more difficult than for most land-based wind farms. Manufacturers have been trying to make sure that the lightning protection systems they install comply with the highest protection levels stipulated in the relevant IEC standards. In this study, data from the Nysted Offshore Wind farm in Denmark and that from a large number of other wind turbines worldwide is reviewed to show the range of lightning currents that have been measured on wind turbines currently in operation. These current values are compared with the required protection levels within the standards.

Trend Reversal of Nitrate in Danish Groundwater - a Reflection of Agricultural Practices and Nitrogen Surpluses since 1950

This paper assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. First, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribution, trends, and trend reversals in the groundwater nitrate concentration. Second, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Third, groundwater recharge CFC (chlorofluorocarbon) age determination allows linking of the first two data sets. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater. Regulation and technical improvements in the intensive farming in Denmark have succeeded in decreasing the N surplus by 40% since the mid 1980s, while at the same time maintaining crop yields and increasing the animal production of especially pigs. Trend analyses prove that the youngest (0-15 years old) oxic groundwater shows more pronounced significant downward nitrate trends (44%) than the oldest (25-50 years old) oxic groundwater (9%). This amounts to clear evidence of the effect of reduced nitrate leaching on groundwater nitrate concentrations in Denmark.

Cereal yield and quality as affected by nitrogen availability in organic and conventional arable crop rotations: A combined modeling and experimental approach

The effects of nitrogen (N) availability related to fertilizer type, catch crop management, and rotation composition on cereal yield and grain N were investigated in four organic and one conventional cropping systems in Denmark using the FASSET model. The four-year rotation studied was: spring barley–(faba bean or grass-clover)–potato–winter wheat. Experiments were done at three locations representative of the different soil types and climatic conditions in Denmark. The three organic systems that included faba bean as the N fixing crop comprised a system with manure (stored pig slurry) and undersowing catch crops (OF + C + M), a system with manure but without undersowing catch crops (OF − C + M), and a system without manure and with catch crops (OF + C − M). A grass-clover green manure was used as N fixing crop in the other organic system with catch crops (OG + C + M). Cuttings of grass-clover were removed from the plots and an equivalent amount of total-N in pig slurry was applied to the cropping system. The conventional rotation included mineral fertilizer and catch crops (CF + C + F), although only non-legume catch crops were used. Measurements of cereal dry matter (DM) at harvest and of grain N contents were done in all plots. On average the FASSET model was able to predict the yield and grain N of cereals with a reasonable accuracy for the range of cropping systems and soil types studied, having a particularly good performance on winter wheat. Cereal yields were better on the more loamy soil. DM yield and grain N content were mainly influenced by the type and amount of fertilizer-N at all three locations. Although a catch crop benefit in terms of yield and grain N was observed in most of the cases, a limited N availability affected the cereal production in the four organic systems. Scenario analyses conducted with the FASSET model indicated the possibility of increasing N fertilization without significantly affecting N leaching if there is an adequate catch crop management. This would also improve yields of cereal production of organic farming in Denmark.

Minimizing Collision Risk Between Migrating Raptors and Marine Wind Farms: Development of a Spatial Planning Tool

An increased focus on renewable energy has led to the planning and construction of marine wind farms in Europe. Since several terrestrial studies indicate that raptors are especially susceptible to wind turbine related mortality, a Spatial Planning Tool is needed so that wind farms can be sited, in an optimal way, to minimize risk of collisions. Here we use measurements of body mass, wingspan and wing area of eight European raptor species, to calculate their Best Glide Ratio (BGR). The BGR was used to construct a linear equation, which, by the use of initial take-off altitude, could be used to calculate a Theoretical Maximum Distance (TMD) from the coast, attained by these soaring-gliding raptor species. If the nearest turbine, of future marine wind farms, is placed farther away from the coast than the estimated TMD, the collision risk between the turbine blades and these gliding raptors will be minimized. The tool was demonstrated in a case study at the Rødsand II wind farm in Denmark. Data on raptor migration altitude were gathered by radar. From the TMD attained by registered soaring-gliding raptors in the area, we concluded that the Rødsand II wind farm is not sited ideally, from an ornithological point of view, as potentially all three registered species are at risk of gliding through the area swept by the turbine rotor blades, and thereby at risk of colliding with the wind turbines.

Changes in the use of antimicrobials and the effects on productivity of swine farms in Denmark

To evaluate changes in antimicrobial consumption and productivity by Danish swine farms during 1992 to 2008. All Danish swine farms for antimicrobial consumption data and a representative sample of Danish swine herds for productivity data. Antimicrobial consumption by Danish swine farms from 1992 to 2008 was determined and evaluated in light of policies to regulate antimicrobial consumption, changes in disease patterns, and productivity data. Trend analyses of productivity data were conducted before and after a ban on use of antimicrobial growth promoters (AGPs). Results-Antimicrobial consumption peaked at 100 mg/kg of swine produced in 1992, decreased to 31 mg/kg in 1999, and increased to 49 mg/kg in 2008. Key factors for changes were regulations banning subtherapeutic use of antimicrobials and veterinary profits from the prescription and sale of antimicrobials in 1994 and termination of AGP use by January 2000. Pig production increased from 18.4 to 271 million pigs, and the mean number of pigs per sow per year raised for slaughter increased from 21 in 1992 to 25 in 2007 Average daily gain for weaning (< 35 kg) and finishing (> 35 kg) pigs was higher in 2008 than in 1992, but mortality rates for weaning and finishing pigs were similar in 1992 and 2008. From 1992 to 2008, antimicrobial consumption per kilogram of pig produced in Denmark decreased by > 50%. Furthermore, there was improvement in productivity, suggesting that long-term swine productivity was not negatively impacted by a ban on AGP use.

Offshore wind power policy and planning in Sweden

The main objective of this paper is to analyze the role of policy support schemes and planning systems for inducing offshore wind power development in Sweden. Specifically, it highlights the different types of economic, political and planning-related conditions that face offshore wind power investors in Sweden, and provides brief comparisons to the corresponding investment conditions in Denmark, Norway and the UK. The analysis shows that in Sweden existing policy incentives are generally too weak to promote a significant development of offshore wind power, and the paper provides a discussion about a number of political and economic aspects on the choice between different support schemes for offshore wind in the country. Swedish permitting and planning procedures, though, appear favorable to such a development, not the least in comparison to the corresponding processes in the other major offshore wind countries in Europe (e.g., the UK). On a general level the paper illustrates that the success and failure stories of national offshore wind policies and institutions cannot be easily transferred across country borders, and the analysis shows that both the political and the legal frameworks governing the investment situation for offshore wind farms in Denmark, Norway, Sweden and the UK differ significantly.

Generating Policy Capacity in Emerging Green Industries: The Development of Organic Farming in Denmark and Australia

In many cases, when governments commit themselves to green policy targets, they also imply the development of ‘green’ industries to reach those targets. But, how do governments foster the development of such industries? This is particularly relevant because such industries are often in a very early stage of their evolution. Taking the case of organic farming, we argue that the state's ability to foster ‘policy capacity’ is critical to the emerging development trajectories of such industries. Focussing on the state's ability to generate policy capacity in the Danish and Australian organic food sector, this article suggests that policy capacity develops as a result of high levels of state and associative capacity and the ability to create conditions favourable for corporatist deliberation. The comparative study undertaken demonstrates that these conditions are met in the Danish case, resulting in a high level of policy capacity. By contrast, Australia suffers from a low level of policy capacity as a result of low state and associative capacity and lack of corporatist deliberation.

ARIMA-Based Time Series Model of Stochastic Wind Power Generation

This paper proposes a stochastic wind power model based on an autoregressive integrated moving average (ARIMA) process. The model takes into account the nonstationarity and physical limits of stochastic wind power generation. The model is constructed based on wind power measurement of one year from the Nysted offshore wind farm in Denmark. The proposed limited-ARIMA (LARIMA) model introduces a limiter and characterizes the stochastic wind power generation by mean level, temporal correlation and driving noise. The model is validated against the measurement in terms of temporal correlation and probability distribution. The LARIMA model outperforms a first-order transition matrix based discrete Markov model in terms of temporal correlation, probability distribution and model parameter number. The proposed LARIMA model is further extended to include the monthly variation of the stochastic wind power generation.

Automatische Fütterungssysteme (AFS) - Optimierungspotenzial im Milchviehstall

A survey carried out on farms in Denmark, Germany, the Netherlands and Switzerland indicates current trends in cattle feeding. The survey indicates that automatic feeding systems ease the workload of dairy farmers, save time, and increase fl exibility. The investigated farms differ both in the number of feed rations and feed components. The working time, required by the automatic feeding systems (AFS), depends mainly on the time for feed handling, such as the used collection technology, the type and distance to the feed storage. In some systems feed pushing can be omitted completely.

Decreased susceptibility to zinc chloride is associated with methicillin resistant Staphylococcus aureus CC398 in Danish swine

A total of 31 MRSA and 60 MSSA isolated from different swine farms in Denmark were examined for their susceptibility to zinc chloride, erythromycin, penicillin and tetracycline, as well as their spa-type. mecA positive isolates were examined for their SCCmec type. The isolates were assigned to a CC-type based on their spa-type and supportive multi-locus sequence typing (MLST). No difference in susceptibility to erythromycin, penicillin or tetracycline could be observed between methicillin resistant and susceptible isolates of CC398. Twenty-three (74%) of the MRSA CC398 isolates had reduced susceptibility to ZnCl2 (MIC 4–12mM), whereas all MSSA had MICs from 0.5 to 2mM. Thirty MRSA, including all 23 zinc resistant isolates harboured SCCmec type V. This provides biological evidence to suggest that the use of zinc compounds may be partly implicated in the emergence of some MRSA clones among swine in Denmark.

Potentials to differentiate milk composition by different feeding strategies

To investigate the effect of the dietary intake of the cow on milk composition, bulk-tank milk was collected on 5 occasions from conventional (n=15) and organic (n=10) farms in Denmark and on 4 occasions from low-input nonorganic farms in the United Kingdom, along with management and production parameters. Production of milk based on feeding a high intake of cereals, pasture, and grass silage resulted in milk with a high concentration of α-linolenic acid (9.4±0.2 mg/kg of fatty acids), polyunsaturated fatty acids (3.66±0.07 mg/kg of fatty acids), and natural stereoisomer of α-tocopherol (RRR-α-tocopherol, 18.6±0.5 mg/kg of milk fat). A milk production system using a high proportion of maize silage, by-products, and commercial concentrate mix was associated with milk with high concentrations of linoleic acid (LA; 19.7±0.4 g/kg of fatty acids), monounsaturated fatty acids (27.5±0.3 mg/kg of fatty acids), and a high ratio between LA and α-linolenic acid (4.7±0.2). Comparing these 2 production systems with a very extensive nonorganic milk production system relying on pasture as almost the sole feed (95±4% dry matter intake), it was found that the concentrations of conjugated LA (cis-9,trans-11; 17.5±0.7 g/kg of fatty acids), trans-11-vaccenic acid (37±2 g/kg of fatty acids), and monounsaturated fatty acids (30.4±0.6 g/kg of fatty acids) were higher in the extensively produced milk together with the concentration of antioxidants; total α-tocopherol (32.0±0.8 mg/kg of milk fat), RRR-α-tocopherol (30.2±0.8 mg/kg of milk fat), and β-carotene (9.3±0.5 mg/kg of milk fat) compared with the organic and conventional milk. Moreover, the concentration of LA (9.2±0.7 g/kg of fatty acids) in milk from the extensive milk production system was found to approach the recommended unity ratio between n-6 and n-3, although extensive milk production also resulted in a lower daily milk yield.