173 research outputs found

    Economic impact of FMDV carriers

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    Development of nature-oriented dairy farm systems with an optimization model: the case of ‘Farming for Nature’ in ‘de Langstraat’, the Netherlands

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    ‘Farming for Nature’, a relatively new policy instrument being tried out in the Netherlands, is evaluated. The concept has been designed to allow dairy farmers to improve nature conservation on their farms. Under the scheme, no manure, fertilizer, or feed – concentrates or roughage - may be imported into farm systems from external sources. The feasibility of such a self-sustaining system and the conditions required for it to deliver the desired results, are explored with a farm-based linear programming model known as FIONA (Farm based Integrated Optimization Model for Nature and Agriculture). The model is explained and applied to ‘de Langstraat’, a region in southern Netherlands. The results show that levels of production under the ‘Farming for Nature’ regime are dependent upon soil fertility and the proportion of land that is suitable for growing arable crops. If all available land on a dairy farm in the scheme is arable land, then high production levels of up to 7,500 kg milk per hectare can be realized. If only 30% of the farm area is suitable for arable crops, then only lower production levels, of about 6,600 kg milk per hectare can be realized. The scheme has positive ecological effects. Both nature and cultural landscape values may benefit significantly from the concept. Improvement in ecological terms however, carries a price in terms of agricultural income. An average dairy farm adopting the concept of ‘Farming for Nature’ experiences an income loss of approximately € 840 per hectare in the short-run (5-10 years). More important is the observation that the scale of such farms in the short-run might be too small to earn an attractive income for its workers, even when fully compensated according to European Union regulations.nature management, dairy farming system, linear programming, farm-economics, Farm Management, Land Economics/Use,

    Derivation of a Floquet Formalism within a Natural Framework

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    Many biological systems experience a periodic environment. Floquet theory is a mathematical tool to deal with such time periodic systems. It is not often applied in biology, because linkage between the mathematics and the biology is not available. To create this linkage, we derive the Floquet theory for natural systems. We construct a framework, where the rotation of the Earth is causing the periodicity. Within this framework the angular momentum operator is introduced to describe the Earth’s rotation. The Fourier operators and the Fourier states are defined to link the rotation to the biological system. Using these operators, the biological system can be transformed into a rotating frame in which the environment becomes static. In this rotating frame the Floquet solution can be derived. Two examples demonstrate how to apply this natural framework

    Quantitative analysis of transmission parameters for bluetongue virus serotype 8 in Western Europe in 2006

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    The recent bluetongue virus serotype 8 (BTV-8) epidemic in Western Europe struck hard. Controlling the infection was difficult and a good and safe vaccine was not available until the spring of 2008. Little was known regarding BTV transmission in Western Europe or the efficacy of control measures. Quantitative details on transmission are essential to assess the potential and efficacy of such measures

    Quick scan economische aspecten van het mestbeleid : evaluatie Meststoffenwet 2012: deelrapport ex post

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    Dit rapport beschrijft voor de Evaluatie Meststoffenwet 2012 op basis van een quick scan de ontwikkelingen op de mestmarkt en de mate waarin deze worden beïnvloed door het gevoerde mineralenbeleid. Vervolgens gaat het rapport in op de effecten van het mineralenbeleid op de economische prestaties van de ondernemers en op de concurrentiepositie van de sector

    Quantification of within- and between-pen transmission of Fouth-and-Mouth disease virus in pigs

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    Quantified transmission parameters of Foot-and-Mouth Disease Virus (FMDV) are needed for epidemic models used for control and surveillance. In this study, we quantified the within- and between-pen transmission of FMDV in groups of pigs by estimating the daily transmission rate , i.e. the number of secondary infections caused by one infectious pig during one day, using an SIR (susceptible-infectious-removed) model. Within-pen transmission was studied in four groups of ten pigs in which 5 infected and 5 susceptible pigs had direct contact; between-pen transmission was studied in one group of ten pigs in which 5 infected and 5 susceptible pigs had indirect contact. Daily results of virus isolation of oropharyngeal fluid were used to quantify the transmission rate , using Generalised Linear Modelling (GLM) and a maximum likelihood method. In addition, we estimated the expected time to infection of the first pig within a pen Tw and in the indirect-contact pen Tb. The between-pen transmission rate b was estimated to be 0.59 (0.083-4.18) per day, which was significantly lower than the within-pen transmission rate w of 6.14 (3.75-10.06). Tw was 1.6 h, and Tb was 16 h. Our results show that the transmission rate is influenced by contact structure between pigs
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