Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Microsphere-based multiplex technology for the simultaneous detection of food allergens
    Smits, N.G.E. ; Hoof, R.A. van; Peters, J. ; Koops, A.J. ; Bovee, T.F.H. ; Ginkel, L.A. van - \ 2019
    Genetics and selective breeding of variation in wing truncation in a flightless aphid control agent
    Lommen, Suzanne T.E. ; Koops, Kees G. ; Cornelder, Bardo A. ; Jong, Peter W. de; Brakefield, Paul M. - \ 2019
    Entomologia Experimentalis et Applicata 167 (2019)7. - ISSN 0013-8703 - p. 636 - 645.
    Adalia bipunctata - artificial selection - augmentative pest control - biological control - Coccinellidae - Coleoptera - cryptic genetic variation - gene-by-environment interaction - ladybird - modifier genes - predator - winglessness

    Augmentative biological control by predaceous ladybird beetles can be improved by using flightless morphs, which have longer residence times on the host plants. The two-spot ladybird beetle, Adalia bipunctata (L.) (Coleoptera: Coccinellidae), is used for the biological control of aphids in greenhouses and on urban trees. Flightlessness due to truncated wings occurs at very low frequency in some natural populations of A. bipunctata. Pure-breeding strains of this 'wingless' genotype of A. bipunctata can easily be obtained in the laboratory. Such strains have not been commercialized yet due to concerns about their reduced fitness compared to wild-type strains, which renders mass production more expensive. Wingless strains exhibit, however, wide intra-population phenotypic variation in the extent of wing truncation which is related to fitness traits. We here use classical quantitative genetic techniques to study the heritability and genetic architecture of variation in wing truncation in a wingless strain of A. bipunctata. Split-families reared at one of two temperatures revealed strong family-by-temperature interaction: heritability was estimated as 0.64 ± 0.09 at 19 °C and 0.29 ± 0.06 at 29 °C. Artificial selection in opposite directions at 21 °C demonstrated that the degree of wing truncation can be altered within a few generations resulting in wingless phenotypes without any wing tissue (realized h2 = 0.72), as well as those with minimal truncations (realized h2 = 0.61) in two replicates. The latter lines produced more than twice as many individuals. This indicates that selective breeding of wing truncation may be exploited to improve mass rearing of flightless strains of A. bipunctata for commercial biological control. Our work illustrates that cryptic variation can also be a source for the selective breeding of natural enemies.

    National approaches to reduce antimicrobial usage in dairy herds – Lessons learned in five European countries
    Borne, Bart van den; Reyher, Kirsten ; Persson, Y. ; Vliegher, S. de; Farre, M. ; Scherpenzeel, C. ; Lam, T. ; Koops, W. ; Hogeveen, H. - \ 2018
    - 1 p.
    Predicting the consequence of natural and chemical dispersion for oil slick size over time
    Zeinstra-Helfrich, Marieke ; Koops, Wierd ; Murk, Albertinka J. - \ 2017
    Journal of Geophysical Research: Oceans 122 (2017)9. - ISSN 2169-9275 - p. 7312 - 7324.
    dispersion - oil slick size - oil spill modeling - oil viscosity - shear spreading - wind speed
    Application of dispersants aims to enhance the natural dispersion process in order to reduce the size of the slick and the amount of oil at the surface. This study presents an approach for modeling the development of the surface oil slick as a function of the wind speed, oil viscosity, and dispersant application. We modeled the oil slick mass distribution across a transect through the slick over time taking into account the continuous entrainment of oil, resurfacing process of the different oil droplet size classes and horizontal transport. Outcomes show distinctively different oil slick features, depending on how favorable conditions are for dispersion. A large comet-shaped slick is formed in the case of suboptimal dispersion. Optimal dispersion yields a small surface oil slick, with a large mass of oil suspended. The benefit of dispersants is limited to in conditions with suboptimal natural dispersion, with the exception of extremely unfavorable conditions in which the slick size would be increased. The oil slick length, fraction of oil still floating, lifetime of the slick, and wind drift are highly influenced by wind speed and related mixing conditions, and to a lesser extent by oil properties. In the newly defined “Dispersibility Factor” (DF) the oil slick properties and environmental conditions can be combined into one value that correlates with the simulation outcomes and therefore can be used as an indicator of favorability of natural dispersion and likelihood of added value of chemical dispersion.
    Oil slick fate in 3D : predicting the influence of (natural and chemical) dispersion on oil slick fate
    Zeinstra-Helfrich, Marieke - \ 2016
    Wageningen University. Promotor(en): Tinka Murk, co-promotor(en): W. Koops. - Wageningen : Wageningen University - ISBN 9789462579279 - 174
    oil spills - pollution - adverse effects - oils - dispersion - models - thickness - olieverontreinigingen - verontreiniging - nadelige gevolgen - oliën - dispersie - modellen - dikte

    In certain conditions, (part of) an oil spill can disappear from the water surface through a process called natural dispersion. One available oil spill response option is to enhance this process by addition of dispersants (chemical dispersion). An informed decision for such response requires insight in the oil slick size WITH and WITHOUT treatment. This thesis aims to enable such assessment of net effectiveness, by providing a strategy for modelling the dispersion process.

    A plunging jet test was developed for investigating entrainment and droplet breakup. Using this set up the relevance of oil layer thickness was proven and an algorithm to model droplet sizes of dispersed oil was defined. The findings were applied in a model simulating dispersion and resurfacing as well as the wind-driven differential transport between the floating slick and suspended droplets. The simulation outputs help assess the added value (or not) of dispersant application in reducing the surface oil slick size for different oil types and conditions.

     

    How oil properties and layer thickness determine the entrainment of spilled surface oil
    Zeinstra-Helfrich, Marieke ; Koops, Wierd ; Murk, Albertinka J. - \ 2016
    Marine Pollution Bulletin 110 (2016)1. - ISSN 0025-326X - p. 184 - 193.
    Chemical dispersion - Entrainment - Natural dispersion - Oil properties - Oil spill response

    Viscosity plays an important role in dispersion of spilled surface oil, so does adding chemical dispersants. For seven different oil grades, entrainment rate and initial droplet size distribution were investigated using a plunging jet apparatus with coupled camera equipment and subsequent image analysis. We found that amount of oil entrained is proportional to layer thickness and largely independent of oil properties: A dispersant dose of 1:200 did not result in a significantly different entrainment rate compared to no dispersants. Oil viscosity had a minor to no influence on entrainment rate, until a certain threshold above which entrainment was impeded. The mean droplet size scales with the modified Weber number as described by Johansen. The obtained results can help improve dispersion algorithms in oil spill fate and transport models, to aid making an informed decision about application of dispersants.

    New skills for entrepreneurial researchers
    Leloux, Mirjam ; Popescu, Florentin ; Koops, Andries - \ 2016
    In: Advances in Intelligent Systems and Computing. - Springer Verlag (Advances in Intelligent Systems and Computing ) - ISBN 9783319420691 - p. 1251 - 1263.
    Academic researcher - Entrepreneurial skills - Exploitation of research - Valorization

    Knowledge exchange between universities and business in collaborative/ contractual research and public-private partnerships has become far more significant. These developments instigate new mind-sets and skills for academic researchers, that should be able to translate their new technological concepts into new (business) developments. Using the two entrepreneurial functions—identification and exploitation— Park (Technovation 25: 739-752, 2005); Wright et al. (J. Technol. Transfer 29: 235-246, 2004) as well as the Vitae Researcher Development Framework (www.vitae.ac.uk) and Entrepreneurial competency framework (Int. J. Entrepreneur. Behav. Res. 6(2): 92-111, 2010), this chapter looks at the new, entrepreneurial skills that any academic researcher needs to make commercial exploitation of research a success. The purpose of this article is to investigate which (i.e. entrepreneurial) skills academic researchers need to facilitate to be more effective in exploiting their research. We especially focus on the academic researcher with a beta-scientific background.

    Antibiotic use in dairy herds in the Netherlands from 2005 to 2012
    Kuipers, A. ; Koops, W.J. ; Wemmenhove, H. - \ 2016
    Journal of Dairy Science 99 (2016)2. - ISSN 0022-0302 - p. 1632 - 1648.
    Antibiotic use - Dairy farmer group - Treatment category - Variation and trend

    The aim of this study was to examine the variation in antibiotic use and the effects of external factors on trends in antibiotic use at the herd level by using the number of daily dosages as an indicator for antibiotic use. For this purpose, antibiotic use was analyzed in 94 dairy herds in the Netherlands from 2005 to 2012. The herds were divided into 3 groups of farmers: one group was guided in their antibiotic use from 2008 to 2010 as part of the project, whereas the other 2 groups were not actively guided. The farms were located in 10 of the 12 provinces and were clients of 32 of the 300 veterinary practices that treat cattle. Sales invoices from the veterinary practices provided the antibiotic and cost data for the participating farmers. The number of animal-defined daily dosages (ADDD) indicates the number of days per year that the average cow in a herd is given antibiotic treatment. The average ADDD for all farms from 2005 to 2012 was 5.86 (standard deviation. = 2.14); 68% of ADDD were used for udder health, 24% for clinical mastitis and 44% for dry-cow therapy. Variation in ADDD among herds decreased during the study period. The trend in ADDD can be described as having 3 phases: (1) a period of increasing use coinciding with little public concern about antibiotic use (2005-2007), (2) a period of growing awareness and stabilization of use (2007-2010), and (3) a period of decreasing use coinciding with increasing societal concerns (2010-2012). The greatest reduction in use was for drugs other than those used to treat the udder. Drug use for mastitis treatment fell considerably in the final year of the study period, whereas farmers were reluctant to reduce use for dry-cow therapy. Almost 40% of the herds were given less than 2.5 ADDD for dry-cow therapy, which is equivalent to 2.5 tubes per average cow in the herd, and 20% used more than 3 tubes per cow. Use of third- and fourth-generation cephalosporins and fluoroquinolones dropped from 18% of ADDD during 2005 to 2010 to 1% in 2012, with a shift toward penicillins and broad spectrum drugs. The ADDD was 22% lower in 2012 than 2007, the year of the highest usage. The decrease in ADDD over time varied between the 3 groups of farmers. During the second phase of the study, the guided group began to display a reduction in use, whereas the other groups only displayed a significant reduction in the third phase. The reduction in antibiotic use has resulted in lower veterinary costs per cow in recent years.

    The NET effect of dispersants - a critical review of testing and modelling of surface oil dispersion
    Zeinstra-Helfrich, Marieke ; Koops, Wierd ; Murk, A.J. - \ 2015
    Marine Pollution Bulletin 100 (2015)1. - ISSN 0025-326X - p. 102 - 111.
    Chemical dispersion - Natural dispersion - Oil properties - Oil spill modelling - Response decision

    Application of chemical dispersants or mechanical dispersion on surface oil is a trade-off between surface effects (impact of floating oil) and sub-surface effects (impact of suspended oil). Making an informed decision regarding such response, requires insight in the induced change in fate and transport of the oil.We aim to identify how natural, chemical and mechanical dispersion could be quantified in oil spill models. For each step in the dispersion process, we review available experimental data in order to identify overall trends and propose an algorithm or calculation method. Additionally, the conditions for successful mechanical and chemical dispersion are defined.Two commonly identified key parameters in surface oil dispersion are: oil properties (viscosity and presence of dispersants) and mixing energy (often wind speed). Strikingly, these parameters play a different role in several of the dispersion sub-processes. This may explain difficulties in simply relating overall dispersion effectiveness to the individual parameters.

    The Emerging Concept of Responsible Innovation. Three Reasons Why It Is Questionable and Calls for a Radical Transformation of the Concept of Innovation
    Blok, V. ; Lemmens, P. - \ 2015
    In: Responsible Innovation 2: Concepts, Approaches, and Appplications / Koops, B.J., Oosterlaken, I., Romijn, H., Swierstra, T., van den Hoven, J., Dordrecht : Springer - ISBN 9783319173078 - p. 19 - 35.
    In this chapter, we challenge the presupposed concept of innovation in the responsible innovation literature. As a first step, we raise several questions with regard to the possibility of ‘responsible’ innovation and point at several difficulties which undermine the supposedly responsible character of innovation processes, based on an analysis of the input, throughput and output of innovation processes. It becomes clear that the practical applicability of the concept of responsible innovation is highly problematic and that a more thorough inquiry of the concept is required. As a second step, we analyze the concept of innovation which is self-evidently presupposed in current literature on responsible innovation. It becomes clear that innovation is self-evidently seen as (1) technological innovation, (2) is primarily perceived from an economic perspective, (3) is inherently good and (4) presupposes a symmetry between moral agents and moral addressees. By challenging this narrow and uncritical concept of innovation, we contribute to a second round of theorizing about the concept and provide a research agenda for future research in order to enhance a less naïve concept of responsible innovation.
    Quantification of the effect of oil layer thickness on entrainment of surface oil
    Zeinstra-Helfrich, M. ; Koops, W. ; Dijkstra, K. ; Murk, A.J. - \ 2015
    Marine Pollution Bulletin 96 (2015)1-2. - ISSN 0025-326X - p. 401 - 409.
    air entrainment - plunging jet - breakers
    This study quantifies the effect of oil layer thickness on entrainment and dispersion of oil into seawater, using a plunging jet with a camera system. In contrast to what is generally assumed, we revealed that for the low viscosity “surrogate MC252 oil” we used, entrainment rate is directly proportional to layer thickness. Furthermore, the volume of stably suspended small oil droplets increases with energy input (plunge height) and is mostly proportional to layer thickness. Oil pre-treated with dispersants (dispersant-oil ratio ranges from 1:50 to 1:300) is greatly entrained in such large amounts of small droplets that quantification was impossible with the camera system. Very low interfacial tension causes entrainment by even minor secondary surface disturbances. Our results indicate that the effect of oil layer thickness should be included in oil entrainment and dispersion modelling.
    Natural Food: Organizing ‘responsiveness’ in responsible innovation of food technology
    Haen, D. ; Sneijder, P.W.J. ; Molder, H. te; Swierstra, T. - \ 2015
    In: Responsible Innovation 2. Concepts, approaches, and applications / Koops, B.J., Oosterlaken, I., Romijn, H., Swierstra, T., Van den Hoven, J., Springer International Publishing Switzerland - ISBN 9783319173078 - p. 161 - 181.
    Responsible innovation requires mutual responsiveness between various stakeholders around technological innovation. But in public engagement exercises, concerns about ethical, cultural and political impacts are too easily set aside, so that no one is actually encouraged to discuss responsibilities for these impacts. A typical example in the field of food innovation is the consumer’s recurring concern for natural food. In discussions, both consumers and engineers tend to consider the meaning of naturalness as subjective and private. In this chapter, we present an interdisciplinary design tool for public engagement that is more hospitable to such concerns, based on the Discursive Action Method and Techno- Ethical Imagination. We describe the advancements we made and the obstacles we faced when applying this tool in two dialogue workshops on novel foods and naturalness.
    Fructan Biosynthesis Regulation and the Production of Tailor-Made Fructan in Plants
    Arkel, J. van; Sévenier, R. ; Hakkert, J.C. ; Bouwmeester, H.J. ; Koops, A.J. ; Meer, I.M. van der - \ 2014
    In: Polysaccharides : Natural Fibers in Food and Nutrition / Benkeblia, N., CRC Press - ISBN 9781466571815 - p. 1 - 1.
    De opmars van de academische entrepeneur
    Leloux, M. ; Popescu, F. ; Koops, A.J. - \ 2014
    TH&MA : tijdschrift voor hoger onderwijs & management 2014 (2014)5. - ISSN 1380-7110 - p. 76 - 82.
    Onze kenniseconomie vraagt in toenemende mate dat universiteiten, als nieuwe aanjagers van regionale innovatie, hun kennis valoriseren: de entrepreneurial university ontstaat (Etzkovitz, 2003). Valorisatieactiviteiten van ondernemende universiteiten omvatten de volgende activiteiten (Tijsen, 2006): kennisoverdracht (bijvoorbeeld in consultancy of contractonderzoek), technologieoverdracht (bijvoorbeeld het uitgeven van octrooien), en overdracht van producten en diensten via spin-offs.
    Exploring genetic variation in the tomato (Solanum section Lycopersicon) clade by whole-genome sequencing
    Aflitos, S.A. ; Schijlen, E.G.W.M. ; Jong, J.H.S.G.M. de; Ridder, D. de; Smit, S. ; Finkers, H.J. ; Bakker, F.T. ; Geest, H.C. van de; Lintel Hekkert, B. te; Haarst, J.C. van; Smits, L.W.M. ; Koops, A.J. ; Sanchez-Perez, M.J. ; Heusden, A.W. van; Visser, R.G.F. ; Schranz, M.E. ; Peters, S.A. - \ 2014
    The Plant Journal 80 (2014)1. - ISSN 0960-7412 - p. 136 - 148.
    single-nucleotide polymorphisms - burrows-wheeler transform - wild tomatoes - genus lycopersicon - read alignment - fruit size - evolution - domestication - solanaceae - plant
    We explored genetic variation by sequencing a selection of 84 tomato accessions and related wild species representative for the Lycopersicon, Arcanum, Eriopersicon, and Neolycopersicon groups which has yielded a huge amount of precious data on sequence diversity in the tomato clade. Three new reference genomes were reconstructed to support our comparative genome analyses. Comparative sequence alignment reveals group-, species-, and accession-specific polymorphisms, which explains characteristic fruit traits and growth habits in the different cultivars. Using gene models from the annotated Heinz 1706 reference genome, we observed differences dN/dS ratio in fruit and growth diversification genes compared to a random set of genes, pointing to positive selection and to differences in selection pressure between crop accessions and wild species. In wild species SNPs are found in excess of 10 million, i.e. 20 fold higher than found in most of the crop accessions, indicating dramatic genetic erosion of crop and heirloom tomatoes. In addition, highest levels of heterozygosity were found for allogamous SI wild species, while facultative and autogamous SC species display a lower heterozygosity level. Using whole genome SNP information for Maximum Likelihood analysis we achieved complete tree resolution, whereas ML trees based on SNPs from 10 fruit and growth genes show incomplete resolution for the crop accessions, partly due to the effect of heterozygous SNPs. Finally, results suggest that phylogenetic relationships are correlated with habitat pointing at the occurrence of geographical races within these groups, which is of practical importance for Solanum genome evolution studies.
    Study of development paths of dairy farmers in Slovenia
    Klopcic, M. ; Verhees, F.J.H.M. ; Kuipers, A. ; Koops, W.J. - \ 2014
    In: Cattle husbandry in Eastern Europe and China. Structure, development paths and optimisation / Kuipers, A., Rozstalnyy, A., Keane, G., Wageningen : Wageningen Academic Publishers (EAAP publication 135) - ISBN 9789086862320 - p. 85 - 98.
    As part of the Central and Eastern European project of Wageningen UR (Wageningen, the Netherlands) combined with a Leonardo da Vinci project coordinated by Warsaw University of Life Sciences (Warsaw, Poland), an analysis was performed in year 2012 of future development paths of dairy farmers in three countries: Lithuania, Poland and Slovenia. In a previous EU-twinning project in 2005-2007, future plans of Slovenian farmers were also studied. In this chapter the status of Slovenian agriculture, especially of the dairy sector is described as well as the studies mentioned looking to future plans and strategies from a farmers’ viewpoint. The Slovene dairy sector can be characterised by a rather large variation in size, but is on average small due to historical reasons and less favourable (e.g. hilly/mountainous) land conditions. As a tool for the studies, two questionnaires were used. In the 2006 study, 1,114 questionnaires from dairy farmers, 121 from suckler cow farmers and 111 from Cika cow farmers were collected. Dairy farmers appeared to be more efficiency oriented, while Cika farmers were more nature oriented. About 40% of the dairy farmers had some interest in diversification. Dairy farmers more often had plans to develop the farm than the suckler cow and Cika farmers. For the recent study in 2012, a questionnaire was constructed with 49 main questions. In total, 365 questionnaires were received in Slovenia. With factor analysis we reduced number of questions and with cluster analysis we formed various farmer segments. On a base of 10 strategies, farmers indicated their 1st, 2nd and 3rd most important strategies for development of their farms in the next 5 years. Farmers’ segments identified were: independent specialisers, cooperating specialisers, independent diversifiers, cooperating diversifiers, chain integrating farmers, new starters and wait-and-see farmers. The wait-and-see segment had smaller farms. Compared to the other two countries, farmers in Slovenia look more for cooperation to develop the farm structure (28% of farmers) and consider diversification as a viable option (22% of farmers). Also, farmers indicated how important farming goals were on a 7-point Likert scale. Factors identified were: sustainable quality, succession, enjoying work, good management and financial management. Significantly lower scores for farmers’ goals were given by the wait-and-see and cooperating diversifying segments of farmers. The data were also analysed for resources, and opportunities and threats. Concerning resources, land and labour availability are the biggest problems for all farmers’ segments. In relation to perceived opportunities and threats farmers consider the common agricultural policy, EU agricultural policy after 2015 and the milk market as threats, while new technologies, services, interaction in the chain and EU membership are seen as opportunities.
    Expression of the Aspergillus terreus itaconic acid biosynthesis cluster in Aspergillus niger
    Straat, L. van der; Vernooij, M. ; Lammers, M. ; Berg, W.A.M. van den; Schonewille, T. ; Cordewener, J. ; Meer, I. van der; Koops, A.J. ; Graaff, L.H. de - \ 2014
    Microbial Cell Factories 13 (2014). - ISSN 1475-2859 - 9 p.
    gene
    BACKGROUND: Aspergillus terreus is a natural producer of itaconic acid and is currently used to produce itaconic acid on an industrial scale. The metabolic process for itaconic acid biosynthesis is very similar to the production of citric acid in Aspergillus niger. However, a key enzyme in A. niger, cis-aconitate decarboxylase, is missing. The introduction of the A. terreus cadA gene in A. niger exploits the high level of citric acid production (over 200 g per liter) and theoretically can lead to production levels of over 135 g per liter of itaconic acid in A. niger. Given the potential for higher production levels in A. niger, production of itaconic acid in this host was investigated. RESULTS: Expression of Aspergillus terreus cis-aconitate decarboxylase in Aspergillus niger resulted in the production of a low concentration (0.05 g/L) of itaconic acid. Overexpression of codon-optimized genes for cis-aconitate decarboxylase, a mitochondrial transporter and a plasma membrane transporter in an oxaloacetate hydrolase and glucose oxidase deficient A. niger strain led to highly increased yields and itaconic acid production titers. At these higher production titers, the effect of the mitochondrial and plasma membrane transporters was much more pronounced, with levels being 5-8 times higher than previously described. CONCLUSIONS: Itaconic acid can be produced in A. niger by the introduction of the A. terreus cis-aconitate decarboxylase encoding cadA gene. This results in a low itaconic acid production level, which can be increased by codon-optimization of the cadA gene for A. niger. A second crucial requirement for efficient production of itaconic acid is the expression of the A. terreus mttA gene, encoding a putative mitochondrial transporter. Expression of this transporter results in a twenty-fold increase in the secretion of itaconic acid. Expression of the A. terreus itaconic acid cluster consisting of the cadA gene, the mttA gene and the mfsA gene results in A. niger strains that produce over twenty five-fold higher levels of itaconic acid and show a twenty-fold increase in yield compared to a strain expressing only CadA
    Technical note: a mathematical function to predict daily milk yield of dairy cows in relation to the interval between milkings
    Klopcic, M. ; Koops, W.J. ; Kuipers, A. - \ 2013
    Journal of Dairy Science 96 (2013)9. - ISSN 0022-0302 - p. 6084 - 6090.
    testing schemes - single milking - lactation - cattle - protein - model - bias - fat
    The milk production of a dairy cow is characterized by lactation production, which is calculated from daily milk yields (DMY) during lactation. The DMY is calculated from one or more milkings a day collected at the farm. Various milking systems are in use today, resulting in one or many recorded milk yields a day, from which different calculations are used to determine DMY. The primary objective of this study was to develop a mathematical function that described milk production of a dairy cow in relation to the interval between 2 milkings. The function was partly based on the biology of the milk production process. This function, called the 3K-function, was able to predict milk production over an interval of 12 h, so DMY was twice this estimate. No external information is needed to incorporate this function in methods to predict DMY. Application of the function on data from different milking systems showed a good fit. This function could be a universal tool to predict DMY for a variety of milking systems, and it seems especially useful for data from robotic milking systems. Further study is needed to evaluate the function under a wide range of circumstances, and to see how it can be incorporated in existing milk recording systems. A secondary objective of using the 3K-function was to compare how much DMY based on different milking systems differed from that based on a twice-a-day milking. Differences were consistent with findings in the literature.
    Antibioticagebruik hangt samen met veehouder en bedrijfsvoering
    Kuipers, A. ; Wemmenhove, H. ; Koops, W. - \ 2013
    V-focus 10 (2013)1. - ISSN 1574-1575 - p. 36 - 38.
    melkveehouderij - antibiotica - dosering - antibioticaresistentie - milieueffect - milieuhygiëne - agrarische bedrijfsvoering - dairy farming - antibiotics - dosage - antibiotic resistance - environmental impact - environmental hygiene - farm management
    Het antibioticagebruik werd in de periode 2005 t/m 2011 in kaart gebracht. Er is veel variatie tussen bedrijven. Vanaf 2009 is een lichte daling te zien, met name voor toepassing tegen aandoeningen anders dan mastitis. De melkveehouder met een wat groter quotum, lager celgetal en hogere diergezondheidsstatus gebruikte meer. Deze melkveehouder heeft een goede band met de dierenarts, onderneemt snel actie qua diergezondheid, zoemt in op de omgeving, maar is niet zo bezig met regelgeving. Conclusie: de veehouder, die als ‘succesvol en ondernemend’ wordt gezien, gebruikte meer antibiotica.
    Tailor-made fructan synthesis in plants: A review
    Arkel, J. van; Sévenier, R. ; Hakkert, J.C. ; Bouwmeester, H.J. ; Koops, A.J. ; Meer, I.M. van der - \ 2013
    Carbohydrate Polymers 93 (2013)1. - ISSN 0144-8617 - p. 48 - 56.
    sucrose sucrose 1-fructosyltransferase - helianthus-tuberosus colombia - transgenic potato plants - cichorium-intybus - sugar-beet - fructosyltransferase genes - fructosyl transferase - perennial ryegrass - tobacco plants - lactuca-sativa
    Fructan, a fructose polymer, is produced by many bacteria and plants. Fructan is used as carbohydrate reserve, and in bacteria also as protective outside layer. Chicory is a commercial fructan producing crop. The disadvantage of this crop is its fructan breakdown before harvest. Studies using genetically modification showed that fructan biosynthesis is difficult to steer in chicory. Alternatives for production of tailor-made fructan, fructan with a desired polymer length and linkage type, are originally non-fructan-accumulating plants expressing introduced fructosyltransferase genes. The usage of bacterial fructosyltransferases hindered plant performance, whereas plant-derived fructan genes can successfully be used for this purpose. The polymer length distribution and the yield are dependent on the origin of the fructan genes and the availability of sucrose in the host. Limitations seen in chicory for the production of tailor-made fructan are lacking in putative new platform crops like sugar beet and sugarcane and rice
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