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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    Are all eggs equal? : embryonic development and nutrient metabolism in chicken eggs of different origins
    Nangsuay, A. - \ 2016
    Wageningen University. Promotor(en): Bas Kemp, co-promotor(en): Henry van den Brand; R. Meijerhof. - Wageningen : Wageningen University - ISBN 9789462577749 - 213
    eggs - hens - broilers - characteristics - strains - embryonic development - nutrients - metabolism - hatcheries - poultry - nutrition physiology - eieren - hennen - vleeskuikens - karakteristieken - stammen (biologisch) - embryonale ontwikkeling - voedingsstoffen - metabolisme - broedinstallaties - pluimvee - voedingsfysiologie

    Hatching eggs, supplied to hatcheries are originating from different origins varying in breed, strain, and breeder age. These hatching eggs can be different in size, composition and eggshell properties, which might influence nutrient and O2 availability and consequently could affect embryonic development and nutrient metabolism. The aim of this thesis was therefore 1) to investigate effects of egg origin on nutrient and O2 availability, 2) to investigate effects of egg origins on nutrient metabolism and embryonic development and 3) to investigate consequences of different egg origins on the incubation process and hatching characteristics. In five studies, effects of different egg origins on nutrient and O2 availability, nutrient metabolism, embryo development and hatching characteristics were investigated. The first and second study focused on breeder age and egg size. The third study on breed; broilers and layers. The fourth study on broiler strain and the fifth study on breeder age, strain and eggshell temperature (EST). The overall findings in this thesis suggest that hatching eggs from different origins are not equal in availability of nutrients and O2. Nutrient availability is altered through variation in yolk size, especially by the effects of breeder age and breed. O2 availability is altered by differences in eggshell properties, which is influenced by especially breed and broiler strain. The availability of both nutrients and O2 plays a role on nutrient metabolism measured as embryonic heat production (HP) and consequently on embryonic development. Between incubation day (E) E7 and E14, both nutrient and O2 availability might affect nutrient metabolism as shown in the results of the broiler and layer comparison. Between E14 and hatching, the availability of O2 becomes the most determinant factor for nutrient metabolism and consequently for embryonic development. An increase in EST from 37.8 to 38.9°C from E7 onward resulted in an acceleration of nutrient metabolism and embryonic development until E16, but thereafter a high EST resulted in reduced yolk free body mass development. Embryos with an accelerated metabolic speed at an early stage of incubation, caused by an increased EST, might reach limited O2 availability at a higher magnitude than the embryos at a normal EST. As a result, nutrient metabolism is restricted and embryonic development is depressed. It can be concluded that not only the HP, but also the availability of O2 is crucial to be taken into account for developing incubator temperature. The principle is to obtain an optimal EST, which could maintain the balance between O2 requirement (driven by nutrient metabolism) and O2 availability for a continuing optimal nutrient metabolism to generate sufficient energy for embryonic development throughout incubation.

    Targeted and non-targeted effects in cell wall polysaccharides from transgenetically modified potato tubers
    Huang, J.H. - \ 2016
    Wageningen University. Promotor(en): Harry Gruppen; Henk Schols. - Wageningen : Wageningen University - ISBN 9789462576292 - 126
    potatoes - cell walls - polysaccharides - transgenic plants - pectins - tubers - xyloglucans - genetically engineered foods - galactans - characteristics - nontarget effects - effects - aardappelen - celwanden - polysacchariden - transgene planten - pectinen - knollen - xyloglucanen - genetisch gemanipuleerde voedingsmiddelen - galactanen - karakteristieken - onbedoelde effecten - effecten

    The plant cell wall is a chemically complex network composed mainly of polysaccharides. Cell wall polysaccharides surround and protect plant cells and are responsible for the stability and rigidity of plant tissue. Pectin is a major component of primary cell wall and the middle lamella of plants. However, pectin biosynthesis in planta and the mechanisms underlying the influence of structural differences arising from a modified biosynthesis machinery on functional properties remain poorly understood. In our research, the changes in the chemical structures of cell wall polysaccharides after transgenic modification of potato tuber polysaccharides were examined. The cell wall material from potato wild-type varieties, from known and from new potato transgenic lines targeting changes of the homogalacturonan or rhamnogalacturonan I backbone were isolated and characterized. The modified cell wall polysaccharides were examined by determining their individual monosaccharide levels on fresh weight base and their cell wall characteristic parameters, and levels of acetylation and methyl esterification of cell wall pectin. Data for both targeted and non-targeted structures of cell wall polysaccharides from wild-type and transgenic potatoes were obtained. A shorter galactan side chain was found from the buffer soluble pectin and calcium bound pectin of β-galactosidase (β-Gal) transgenic lines. All pectin fractions from rhamnogalacturonan lyase (RGL) transgenic lines had less galactan chains attached to their rhamnogalacturonan I backbones. Two uridine diphosphate-glucose 4-epimerase (UGE) transgenic lines, UGE 45 and UGE 51, had diverse effects on length of the galactan side chain. The xyloglucans from the RGL and UGE transgenic lines retained its XXGG building blocks but differed in the proportion of repeating units compared to the respective wild-type varieties. In contrast, the β-Gal transgenic lines predominantly consisted of XXXG-type xyloglucan in the 4 M alkali extract, but showed XXGG-type building blocks in 1 M alkali extract. In addition, a quick-screening method was validated and used to analyze 31 transgenic lines and their respective wild-type potato varieties. An overall comparison of pectin backbone, pectin side chains, acetylation and methyl-esterification of pectin, pectin content and (hemi)cellulose content of cell wall polysaccharides from these transgenic lines provided a better insight in the frequency, level and combination of both targeted and non-targeted structural changes compared to that of their respective wild-type varieties. The same evaluation method was used to correlate cell wall composition in wild-type and selected transgenic lines and their established gene expression with the texture of corresponding cooked potato cubes. Changed physical properties for the genetically modified tubers could be connected to specific cell wall characteristics. Tubers from transgenic lines containing cell wall pectin with short galactan side chains were less firm after cold processing compared to wild-type tubers. The enhanced understanding of transgenic modifications of potato tubers resulting into significant targeted and non-targeted modifications in cell wall polysaccharides will lead to a better selection of potato lines with tailored cell wall characteristics and desired properties of the tubers during processing.

    Potato cell walls are composed of pectin, hemicellulose and cellulose. Cell wall polysaccharides are responsible for the stability, rigidity and flexibility of plant tissue. Pectin, a major component of primary plant cell walls, primarily consists of homogalacturonan (HG) and rhamnogalacturonan I (RG-I). To understand the structure–function relationships of potato cell wall pectin, this study aimed to identify the characteristics of both pectin and other polysaccharides as present in cell wall material (CWM) and of individual polysaccharide populations from wild-type potato varieties and their respective transgenic potato lines.

    Chapter 1 gives a general introduction to the fine chemical structures of potato cell wall polysaccharides, the main models of cell wall architecture and the cell wall-degrading enzymes, which include pectinases, hemicellulases and cellulases. In addition, transgenic modification of the cell wall through the heterologous expression of various enzymes from fungal or plant origin that could modify potato cell wall polysaccharides in planta is addressed. Transgenic modifications of potato cell wall polysaccharides that targeted pectin structures and cellulose levels are summarised. However, due to unsuccessful starch removal during CWM isolation and incomplete analysis of CWM yield and composition, characteristics regarding the different cell wall polysaccharides from previously-studied transgenic potato lines are hardly available.

    CWMs were extracted from the Karnico (wild-type) potato and its transgenic lines that expressed either β-galactosidase or rhamnogalacturonan lyase (Chapter 2). Improved starch removal procedures proved to be successful. Pectic polysaccharides were fractionated from CWMs of wild-type potato and its transgenic lines β-Gal-14 and RGL-18. Most β-Gal-14 pectin populations had less galactose (Gal) than wild-type, indicating that the transgenic line had shorter galactan side chains, although the side chain length differed for individual pectin populations. The ratio of HG:RG-I was introduced to evaluate the pectin backbone structure. High HG:RG-I ratios were consistently found in RGL-18 pectic polysaccharide populations. A low level of RG-I segments in combination with lower Gal contents indicated the removal of the galactan-rich RG-I segments in all pectin populations of RGL transgenic lines. In addition, RGL-18 transgenic modification increased the methyl-esterification and lowered the acetylation of pectins present in hot buffer extracts, when compared to wild-type. No effect on pectin esterification was found for β-Gal transgenic lines. Side effects of the mutation generated unexpected changes in the various pectin populations.

    The xyloglucan structure was extensively modified after transgenic modification of the pectin structure. Two xyloglucan extracts were obtained from the Karnico and its β-Gal-14 and RGL-18 transgenic lines (Chapter 3). The extracts of the Karnico and RGL-18 lines were mainly comprised of the XXGG-type xyloglucan as represented by XXGG and XSGG as predominant repeating units. In contrast, the XXXG-type xyloglucan was primarily present in the β-Gal-14 4 M alkali extract built up by LLUG repeats, although XXGG type of xyloglucan was present in the 1M alkali extract. Both the RGL and β-Gal transgenic lines had different proportions of xyloglucan building blocks (XSGG/XXGG ratios) than wild-type. After transgenic modification of pectin backbone or pectin side chains, the xyloglucan structures has been biosynthetically modified by plant itself.

    Uridine diphosphate (UDP)-glucose 4-epimerase (UGE) catalyses the conversion of UDP-glucose into UDP-galactose, which hypothetically should lead to more galactose being built into the cell wall polysaccharides. CWMs from the Kardal (wild-type) potato and its UGE45-1 and UGE51-16 transgenic lines were isolated, fractionated and characterised (Chapter 4). Both the UGE45 and UGE51 genes encoded for UGE enzymes, but the corresponding transgenic lines exhibited different modifications of the galactan side chains and of other cell wall structures. The Gal content of CWM from the UGE45-1 transgenic line was 38% higher than that of the wild-type and resulted in longer pectin side chains. The Gal content present in CWM from UGE51-16 was 17% lower than that of wild-type, which resulted in a slightly shorter galactan side chains for most pectin populations. Both UGE transgenic lines showed a decreased acetylation and an increased methyl-esterification of the cell wall pectin. Side effects were found in the xyloglucan structures of the transgenes as reflected by different proportions of XSGG/XXGG repeating units in comparison to wild-type. Pectin side chain biosynthesis had not only a varying level of galactan side chain modification, but also influenced the structure and possibly the interaction of other cell wall polysaccharides.

    In Chapter 5, a new screening strategy is introduced to evaluate higher numbers of transgenic potato tubers via CWM yield and sugar composition. A total of four wild-type potato varieties and 31 transgenic lines were evaluated to determine the effects on targeted structures including RG-I or HG pectin backbone elements, galactan or arabinogalactan side chains, acetyl groups of pectin and cellulose levels. Modification of the pectin backbone or pectin side chains in the transgenic lines has either a simultaneous increase or simultaneous decrease of HG:RG-I ratio, side chain length and methyl-esterification of pectin. The pectin esterification transgenic line exhibited only limited side effects. The cellulose level targeted lines had also high HG:RG-I ratios, longer galactan chains and similar pectin content compared to the wild-type, indicative for a less branched pectin backbone with longer side chains. From the monosaccharide composition data, various pectin and cell wall characteristics parameters are suggested as powerful indicators of cell wall polysaccharide structure.

    In Chapter 6, the achievements of this research are summarised and discussed in the context of potato cell wall architecture. The strategy and outcome of a quick screening method for multiple transgenic lines and an in-depth analysis of individual pectin and xyloglucan populations for the evaluation of potato CWMs is discussed. Furthermore, the texture of steam-cooked potatoes and the stability of potato cubes after freeze-thaw cycles are correlated with gene expression and cell wall composition in wild-type and selected transgenetically modified potato tubers. CWMs from transgenetically modified potatoes showed different physical properties during processing. In isolated CWMs, acetylation of cell wall pectin, molar Gal levels and starch content were the main parameters that could be related to the texture or firmness of tubers. Tubers from transgenic lines that resulted in shorter pectin side chains felt apart more easily after several freeze-thaw cycles than wild-type tubers and tubers with an increased length of pectin side chains. The modification of both targeted as well as non-targeted structures have now been shown to occur in many different potato transgenic lines, but precise mechanisms and consequences for the cell wall architecture remain unclear. Research performed so far, as well as research needed for getting a better understanding of plant cell wall architecture, is discussed.

    Fast food in Ghana’s restaurants: prevalence, characteristics, and relevance : an interdisciplinary perspective
    Omari, R. - \ 2014
    Wageningen University. Promotor(en): Han Wiskerke; Guido Ruivenkamp, co-promotor(en): Joost Jongerden. - Wageningen : Wageningen University - ISBN 9789462572584 - 169
    fast foods - consumptie - snelbuffetten - gemaksvoedsel - consumentengedrag - karakteristieken - gezondheid - interdisciplinair onderzoek - ghana - fast foods - consumption - fast food restaurants - convenience foods - consumer behaviour - characteristics - health - interdisciplinary research - ghana


    Fast food has been extensively criticised for its link to health and environments problems and for its tendency to undermine traditional food cultures. Notwithstanding these aspects, this study questioned the assumption that fast food by definition has negative impact on health, environment and traditional food cultures for three main reasons. Firstly, fast-food restaurants are spreading quickly in the Accra Metropolitan Area (AMA) of Ghana and have become an important source of urban food. Secondly, fast food in Ghana is undergoing various changes, such as the introduction of healthier food options, use of environmentally friendly packaging and the incorporation of local cultural features. Thirdly, there has been ambiguity in the definition of fast food in existing literature, which is often exclusively built upon practices in Western, modernised countries and hence has determined how fast food is normatively evaluated. Moreover, evidence shows that some of the characteristics of fast food used in these definitions are changing, as well as being perceived differently in various regions or sociocultural settings. Against this background, this thesis sought to clarify what constitutes fast food in Ghanaian restaurants, assess its prevalence and explore its characteristics and relevance for urban food provisioning, health improvement and tourism development. An interdisciplinary and a combination of qualitative and quantitative approaches were used to gather data for a restaurant study to assess the availability and characteristics of fast food in the AMA using the cuisine concept as an analytical framework. The same approaches were used to gather data for a consumer study to explain how (i) convenience influences fast-food consumption, (ii) identity influences fast-food consumption and (iii) personal responsibility influences fast-food purchase, consumption and waste disposal decisions. Findings indicated that the core food items present in fast-food restaurants are menu items such as foods generally recognised as fast food (FGRAFF), including fried rice, fried chicken, burgers, pizzas and French fries, as well as common Ghanaian foods such as banku and kelewele. Interestingly, the FGRAFFs have been transformed in several ways mainly by the incorporation of aspects of the Ghanaian food culture. Most people eat fast food because of their desire to save time, mental and physical effort, as well as because of the inherent convenience attributes of fast food. Findings also showed that people consume fast food because of its role in identity formation and expression whereby eating in a fast-food restaurant is a way to be connected with what is new and unique, pleasurable and associated with social interaction and sensory and health values. Strikingly, findings showed that fast-food consumers do not only eat fast food for convenience and identity expression, but that they are also reflective about the health and environmental anxieties that might come along with the social practice of consumption. Therefore, consumers may adopt loyalty or exit strategies as a way of reducing the effects of the health and environmental anxieties on themselves and society as a whole. This study has shown that some consumers would prefer to adopt loyalty strategies, implying that fast food provides some major material, social, cultural and behavioural benefits for these consumers and so they may not choose to curtail their fast-food consumption. Therefore, for nutrition and health intervention programmes to be effective, there is a clear need to adopt more holistic approaches by incorporating material, social, cultural and behavioural aspects of food into formal programmes.

    A tale too long for a tail too short? : identification of characteristics in pigs related to tail biting and other oral manipulations directed at conspecifics
    Ursinus, W.W. - \ 2014
    Wageningen University. Promotor(en): Bas Kemp, co-promotor(en): Liesbeth Bolhuis; Kees van Reenen. - Wageningen : Wageningen University - ISBN 9789462570023 - 248
    varkens - staartbijten - gedragsstoornissen - karakteristieken - bangheid - dierenwelzijn - genetische effecten - groeitempo - omgevingsverrijking - diergedrag - dierfysiologie - pigs - tail biting - behaviour disorders - characteristics - fearfulness - animal welfare - genetic effects - growth rate - environmental enrichment - animal behaviour - animal physiology

    Ursinus, W.W. (2014). A tale too long for a tail too short? Identification of

    characteristics in pigs related to tail biting and other oral manipulations directed

    at conspecifics. PhD thesis, Wageningen University, The Netherlands.

    Tail biting in pigs, i.e. the chewing on and biting in tails of conspecifics, is a

    multifactorial problem leading to impaired pig welfare and health and economic

    losses in pig farming. In many countries tail docking is used as a preventive

    measure, but there is increased societal concern about this practice. Therefore,

    there is an urgent need to understand, prevent, and reduce tail biting and other

    damaging behaviours directed at pen mates. The main aim of this thesis was to

    identify biological characteristics of barren and enriched housed pigs that relate

    to their tendency to develop these damaging oral manipulative behaviours. Tail

    biting started already early in life and pigs that displayed tail biting post-weaning

    seemed to stem from litters in which tail biting behaviour was already present. The

    onset of tail biting behaviour was different for individual pigs, and many pigs were

    not consistently tail biters throughout different phases of life. It was difficult to

    predict which pigs would develop tail biting based on their individual behaviour.

    Groups of pigs with tail biting problems were, however, more easy to identify by

    increased activity, and increased levels of pig and pen-directed oral manipulative

    behaviours. Subjecting pigs to an individual behavioural test showed that tail

    biters may be more fearful. Fearfulness in pigs appeared related to measures

    of the brain and blood serotonergic system. Moreover, measures of the blood

    serotonergic system seemed temporarily altered in tail biting pigs mainly during

    the phase of life in which they displayed this behaviour. Additionally, (tail) biting

    behaviour may be associated with higher (phenotypic and genotypic) production,

    such as higher growth. Growth of individual pigs can be affected by the other

    pigs in a pen. The heritable effect of one pig on the growth of another group

    member is referred to as an indirect genetic effect. Pigs with a relatively negative

    indirect genetic effect for growth displayed more biting behaviours, caused more

    tail damage and destroyed more of the available jute sacks. The presence of strawbedding

    or jute sacks as enrichment materials for rooting and chewing largely

    reduced damaging biting behaviours and, consequently, tail damage. Pigs that

    still develop tail biting behaviour in an enriched environment likely do so due to

    a (temporary) physiological problem, whereas in barren housed pigs the lack of

    suitable rooting and chewing material plays a large role. Tail biting behaviour

    in pigs thus seems to be caused by a variety of temporary states and more

    stable traits that influence their motivation to display foraging and exploratory

    behaviours. Therefore, the tale of (tail) biting behaviours in pigs needs a better

    understanding of underlying physiological processes. Preventing and reducing

    damaging biting behaviours in pigs requires a joint effort of science, industry

    and society to optimize housing conditions, feeding, management and breeding

    of pigs.

    Offspring sex ratio bias and sex related characteristics of eggs in chicken
    Aslam, M.A. - \ 2014
    Wageningen University. Promotor(en): Mari Smits; T.G.G. Groothuis, co-promotor(en): Henri Woelders. - Wageningen : Wageningen University - ISBN 9789462570757 - 192
    kippen - eieren - geslachtsverhouding - karakteristieken - nageslacht - toewijzing - polymerase-kettingreactie - hormonen - voedselbeperking - dierveredeling - fowls - eggs - sex ratio - characteristics - progeny - allocation - polymerase chain reaction - hormones - food restriction - animal breeding

    Understanding the factors influencing sex of egg and sex ratio in laying chicken may lead to finding potential solutions for the problem of killing of day old male chicks, which is the current practice in breeding of laying hens. In studies described in this thesis, it was investigated if the sex of the chicken egg can be predicted by measurable differences in male and female eggs at unincubated stage and if the female primary sex ratio can be induced in laying chicken using different experimental conditions such as feed restriction and corticosterone feeding. The method of sex determination in unincubated chicken eggs using PCR targeted to CHD1 gene was first developed. This method was subsequently used to study the primary sex ratio bias as well as relationship between egg sex and yolk hormones. No significant relationship of the sex of egg with concentrations of several hormones (testosterone, estradiol, androstenedione, progesterone, dihydrotestosterone) and glucose in yolk as well as of egg parameters (mass, width and length) was found. Effect of feed availability on sex ratio was tested in two separate studies. In one study, the rate of change of hen body mass between day of laying and day of laying minus 2 days (encompass time of meiosis completion) was a significant predictor for the sex of that egg, suggesting meiotic drive as mechanism of sex ratio bias. This relationship was not found in the later study. The difference in results could be due to the reason that hens decreased in body mass much less in the later study as compared to earlier study. Blood corticosterone concentrations were associated with sex ratio per hen in the earlier study. Effect of egg mass on egg sex was studied during the later experiment of feed restriction. The egg sex ratio per hen was negatively associated with the average egg mass per hen in the feed restriction group. Two groups of hens were selected from the feed restriction group i.e. male biased hens with low egg mass and female biased hens with high egg mass for microarray analysis of gene expression in the germinal disc of collected F1 follicle. The results did not show differential expression of genes between the groups. However, gene set enrichment analysis showed that a number of processes related to cell cycle progression, mitotic/meiotic apparatus and chromosomal movement were differently enriched between the groups, supporting meiotic drive as potential mechanisms underlying sex ratio determination. In another experiment, blood circulating levels of corticosterone in hens were increased by feeding corticosterone mixed feed under ad libitum. The blood levels of corticosterone were significantly higher in treated hens but these levels were not associated with sex ratio. Treatment did not affect the overall sex ratio, but affected the sex ratio in interaction with hen body mass. In the corticosterone group, sex ratio, laying rate, and fertility rate per hen were decreased in heavy hens. These results suggest that three parameters (sex ratio, laying rate and fertility rate) are connected at the level of ovarian physiology. Interference with meiosis have been shown to affect these three parameters, suggesting the involvement of meiotic drive as mechanism of sex ratio bias.

    Buffercapaciteit : bedrijfsstijlen in de melkveehouderij, volatiele markten en kengetallen
    Oostindië, H.A. ; Ploeg, J.D. van der; Broekhuizen, R.E. van - \ 2013
    Wageningen : Wageningen UR etc. - 50
    melkveehouderij - melkprijzen - agrarische bedrijfsvoering - bedrijfssystemen - karakteristieken - veehouders - indexen - buffercapaciteit - dairy farming - milk prices - farm management - farming systems - characteristics - stockmen - indexes - buffering capacity
    Dit rapport doet verslag van een statistische analyse uitgevoerd op een bestand van Nederlandse melkveehouderijbedrijven. Het doel van deze analyse was na te gaan wat de effecten waren van de melkprijsdaling, die zich voordeed in de tweede helft van 2008 en de eerste helft van 2009. De toenmalige prijsdaling beschouwen we als een voorbode van de situatie die steeds meer de zuivelmarkt zal typeren: een volatiele markt met scherpe prijswisselingen. Het onderzoek toont aan dat de effecten van een melkprijsdaling differentieel van aard zijn, ze variëren al naar gelang het type bedrijf. Om deze verschillen te vatten is een bedrijfsstijlenanalyse uitgevoerd die 4 strategische grondpatronen naar voren brengt: schaalvergroting, fijnregulering, kostenreductie en arbeidsbesparing. In ‘normale’ jaren kan via elk strategisch grondpatroon een goed inkomen worden verworven. Naarmate men meer ‘stijlspecifiek’ is, is het inkomen beter. In ‘slechte’ jaren ligt dit anders: dan blijken strategieën, die draaien om kostenreductie en fijnregulering, tot de beste resultaten te leiden. Ook de balans van vreemd en eigen vermogen speelt in slechte jaren een grote rol. Op haar beurt hangt die balans ook weer op significante wijze samen met de verschillende stijlen. Daarmee brengt de analyse een verschil naar voren dat in de komende jaren wellicht van groot belang zal worden: dat is het verschil tussen boerenlandbouw en ondernemerslandbouw. Met dit onderscheid wordt hier geen moreel of maatschappelijk oordeel gegeven. Waar het om gaat is de vraag welke vorm van landbouwbeoefening het best moeilijke marktomstandigheden weet te weerstaan. In de tweede helft van dit verslag staat de vraag centraal: welk kengetal biedt de melkveehouder het meeste houvast om na te gaan of zijn bedrijf over voldoende veerkracht beschikt om periodes van lage prijzen het hoofd te bieden? Er wordt een nieuw kengetal voorgesteld: buffercapaciteit. Daarnaast kijken we bij welke bedrijfsopzet (stijl) de buffercapaciteit het hoogst is en hoe deze verder is op te voeren
    DNA technieken voor de boomkwekerij
    Hop, M.E.C.M. - \ 2012
    Bomen, het vakblad voor de boomverzorging (2012)21. - p. 8 - 13.
    bomen - rassen (planten) - uitwendige kenmerken - karakteristieken - dna - technieken - vergelijkingen - soorten - plantenveredeling - trees - varieties - external traits - characteristics - dna - techniques - comparisons - species - plant breeding
    Bij het gebruik van DNA-technieken bij planten denken de meeste mensen meteen aan genetische modificatie. Deze speelt bij boomkwekerijgewassen echter nog niet of nauwelijks een rol. Maar er bestaan wel degelijk bruikbare en betaalbare DNA-technieken voor deze branche. Het gaat dan niet om het veranderen van eigenschappen van planten, maar alleen om het meten ervan, bijvoorbeeld voor identificatie van planten en ter ondersteuning van klassieke kruisingsveredeling. Dit type DNA-technieken is bekend uit politieseries als CSI, of van nieuwsberichten over het opsporen van biologische vaders. Maar wat kunnen ze betekenen voor boomkwekerijgewassen?
    Potentilla fruticosa, sortimentsonderzoek en keuringsrapport
    Hoffman, M.H.A. - \ 2011
    Dendroflora 2011 (2011)48. - ISSN 0374-7247 - p. 103 - 146.
    houtachtige planten als sierplanten - struiken - potentilla fruticosa - rassen (planten) - cultivars - gebruikswaarde - openbaar groen - classificatie van rassen - karakteristieken - ornamental woody plants - shrubs - potentilla fruticosa - varieties - cultivars - use value - public green areas - variety classification - characteristics
    Potentilla fruticosa L. (Struikganzerik) is een heester die veel wordt gebruikt in het openbaar groen en op beperkte schaal in particuliere tuinen. Van nature is het een gemakkelijke plant, die vooral opvalt door zijn lange bloeitijd, vaak van het late voorjaar tot in de nazomer of herfst. Naast de natuurlijke gele en witte bloemkleur, zijn er in de loop van de jaren nieuwe cultivars ontwikkeld met rode, roze en oranje bloemen. Ook de gezondheid is flink verbeterd. Dit heeft het gewas een enorme impuls gegeven. Inmiddels zijn er ruim 150 verschillende cultivars bekend. Ongeveer 80 cultivars zijn op twee verschillende locaties getest. De planten zijn door PPO beschreven en beoordeeld op gebruikswaarde. De KVBC voerde een sterrenkeuring uit.
    Drentse Paosbloem, een Meertbleuier in april
    Dijkhuis, E. ; Slikke, W. van der - \ 2010
    Nature Today 2010 (2010)05-04.
    narcissus pseudonarcissus - habitats - karakteristieken - inventarisaties - drenthe - groeiplaatsen - narcissus pseudonarcissus - habitats - characteristics - inventories - drenthe - sites
    De Narcis is een veel gekweekt bolgewas waarvan allerlei soorten en cultivars verkrijgbaar zijn. De Trompetnarcis is daarbij van oudsher de bekendste een meest gekweekte vorm. Minder bekend is dat de Narcis oorspronkelijk inheems is in ons land.
    Aronskelk, geurkaars en insectenval ineen, bloeit weer
    Beringen, R. - \ 2010
    Nature Today 2010 (2010)10-05.
    arum - bloeiwijzen - karakteristieken - plant-dier interacties - arum - inflorescences - characteristics - plant-animal interactions
    Eind april begin mei is de bloeitijd van de Gevlekte aronskelk. De bloeiwijze van de Gevlekte aronskelk is in meerdere opzichten bijzonder. Wanneer de plant in bloei staat is bijvoorbeeld niet direct te zien, maar te voelen. Ook werden mogmugjes een dag lang in de val gelokt om zo te helpen met de bestuiving van de planten.
    Vleeskleurige orchis, ambassadeur van duinvalleien
    Beringen, R. - \ 2010
    Nature Today 2010 (2010)17-05.
    orchis - biotopen - soortenrijkdom - karakteristieken - kustgebieden - orchis - biotopes - species richness - characteristics - coastal areas
    Nederlandse biotopen kennen vaak heel kenmerkende soorten planten. Lamsoor op schorren, blauwe zeedistel aan de zeereep en eenbes in de hellingbossen van Zuid-Limburg zijn enkele voorbeelden. Als die planten ergens groeien weet je ook dat er andere karakteristieke en bijzondere soorten te vinden zijn. In natte duinvalleien is vleeskleurige orchis zo'n ambassadeur.
    Aardkastanje, onopvallend en te weinig om te eten
    Spruijt, T. - \ 2010
    Nature Today 2010 (2010)05-07.
    bunium bulbocastanum - apiaceae - wilde planten - karakteristieken - identificatie - duinen - noord-holland - bunium bulbocastanum - apiaceae - wild plants - characteristics - identification - dunes - noord-holland
    Hij staat vanaf half juni volop in bloei, maar wordt door weinigen gezien. Hoewel een zoektocht op Google anders doet vermoeden, wordt hij niet meer gegeten. De Aardkastanje is daarvoor te onopvallend en te zeldzaam in Nederland. Toch is het een bijzondere schermbloem.
    Molecular characterization of beet necrotic yellow vein virus in Greece and transgenic approaches towards enhancing rhizomania disease resistance
    Pavli, O.I. - \ 2010
    Wageningen University. Promotor(en): Just Vlak; G.N. Skaracis, co-promotor(en): M. Prins; N.J. Panopoulos. - [S.l. : S.n. - ISBN 9789085855477 - 166
    beta vulgaris - suikerbieten - bietenrhizomanievirus - stammen (biologisch) - karakteristieken - pathogeniteit - plantenvirussen - ziekteresistentie - resistentie van variëteiten - transgene planten - genexpressie - griekenland - beta vulgaris - sugarbeet - beet necrotic yellow vein virus - strains - characteristics - pathogenicity - plant viruses - disease resistance - varietal resistance - transgenic plants - gene expression - greece
    Rhizomania disease of sugar beet, caused by Beet necrotic yellow vein virus (BNYVV), is responsible for severe economic losses. Due to the widespread occurrence of BNYVV and the absence of other practical and efficient control measures, economic viability of the crop is to the largest extent dependent on the use of varieties genetically resistant to the disease. Recent reports on the emergence of virus strains capable of compromising the Rz1-based resistance as well as on the spread of highly pathogenic RNA 5-containing BNYVV isolates have necessitated a detailed investigation of the situation as it evolves in Greece. The study revealed the widespread occurrence of BNYVV throughout the country as well as the prevalence of pathotype A isolates in all sugar beet growing regions. Sequence determination of the p25 protein, responsible for symptom development, pointed to the amino acid motifs ACHG/VCHG in the hypervariable amino acid region 67-70. However, the presence of valine (V) in position 67 was not associated with increased pathogenicity and resistance breaking properties. Disease severity appeared mostly dependent on agroclimatic conditions influencing the progress of the disease. A survey for a possible occurrence of Beet Soilborne Virus (BSBV) and Beet Virus Q (BVQ) in rhizomania infested fields revealed the co-existence of both viruses, with BVQ being systematically found in co-infections with BNYVV, while BSBV was in all cases only found in triple infections. Towards the exploitation of the antiviral properties of RNA silencing, three intron hairpin constructs carrying parts of the BNYVV replicase gene, were evaluated for their potential to confer rhizomania resistance in Ri T-DNA-transformed sugar beet roots. The results show that transgenic hairy roots were effectively protected against the virus disease and further indicate that the developed methodology for Agrobacterium rhizogenes-mediated transformation can be employed as a suitable platform to study transgene expression in sugar beet and other transformation recalcitrant crop species. In parallel, the potential to exploit the HrpZPsph protein from Pseudomonas syringae pv. phaseolicola for engineering rhizomania resistance in sugar beet against BNYVV was demonstrated by the successful engineering and protection against BNYVV in the model plant Nicotiana benthamiana
    Kwaliteiten werkgebieden op zorgboerderijen
    Hassink, J. - \ 2009
    Wageningen : Plant Research International (Rapport / Plant Research International 298) - 20
    landbouw - doelgroepen - agrarische bedrijfsvoering - werkzaamheden - karakteristieken - zorgboerderijen - multifunctionele landbouw - agriculture - target groups - farm management - manipulations - characteristics - social care farms - multifunctional agriculture
    Er is een grote diversiteit aan zorgboerderijen. Op een zorgboerderij kunnen verschillende werkgebieden ontwikkeld worden. Elk werkgebied heeft specifieke werkzaamheden en kwaliteiten. Voor een zorgboerderij is het van belang voldoende variatie in werkzaamheden en kwaliteiten te ontwikkelen. In deze notitie worden de werkzaamheden beschreven die bij verschillende werkgebieden horen, specifieke kenmerken van elk werkgebied en voorbeelden van doelstellingen waaraan werkgebieden aan kunnen bijdragen
    Dynamiek en Robuustheid van Multifunctionele Landbouw, Rapportage fase 1: stand van zaken
    Oostindië, H.A. ; Broekhuizen, R.E. van; Seuneke, P.L.M. ; Wiskerke, J.S.C. - \ 2009
    Wageningen : Leerstoelgroep Rurale Sociologie, Wageningen University - 35
    landbouw - nevenactiviteiten - diversificatie - karakteristieken - multifunctionele landbouw - sociale zorg - toekomst - sociale factoren - agriculture - ancillary enterprises - diversification - characteristics - multifunctional agriculture - social care - future - social factors
    Op 1 maart 2009 is het project ‘Dynamiek en Robuustheid van Multifunctionele Landbouw’ van start gegaan. Het project heeft een looptijd van twee jaar en wordt gefinancierd door het Ministerie van Landbouw, Natuur en Voedselkwaliteit. Inhoudelijk is het project ondersteunend aan de activiteiten van de Taskforce Multifunctionele Landbouw. De hoofdvraag van het project luidt: Welke factoren zijn van invloed op de dynamiek en robuustheid van multifunctionele landbouw? In dit rapport wordt een eerste aanzet gegeven tot een antwoord op deze hoofdvraag
    Methodiek voor het karakteriseren van fosfaatlekkende gronden : beschrijving van het instrumentarium PLEASE
    Schoumans, O.F. ; Groenendijk, P. ; Salm, C. van der; Pleijter, M. - \ 2008
    Wageningen : Alterra (Alterra-rapport 1724) - 76
    landbouwgrond - bodemchemie - fosfor - uitspoelen - karakteristieken - grondwaterstand - bodemkwaliteit - agricultural land - soil chemistry - phosphorus - leaching - characteristics - groundwater level - soil quality
    Een eenvoudige methode, genaamd PLEASE, is ontwikkeld om op lokale schaal de fosfaatuit- en afspoeling vanuit een perceel naar het oppervlaktewater te kwantificeren. De methode is gebaseerd op het fosfaatconcentratieprofiel in de bodem, de drainage van water uit de verschillende bodemlagen van het perceel, en de afvoer van water via runoff naar het oppervlaktewater. Tevens wordt rekening gehouden met de connectiviteit tussen het perceel en het nabij gelegen oppervlaktewater. Voor een specifieke regio is op basis van een bestaande dataset een oriënterende berekening met de methode uitgevoerd. Deze is bedoeld als eerste test om een gevoel te krijgen van de bruikbaarheid van het instrument. Aanbevolen wordt om in de nabije toekomst een gerichte test uit te voeren op perceelsschaal, waarvoor de methode ook ontwikkeld is.
    Robustness in laying hens
    Star, L. - \ 2008
    Wageningen University. Promotor(en): Bas Kemp; Johan van Arendonk, co-promotor(en): Henk Parmentier; Jan van der Poel. - [S.l.] : S.n. - ISBN 9789085049708 - 196
    hennen - pluimvee - adequate immuniteit - humorale immuniteit - overleving - genetische factoren - milieufactoren - stressreactie - ontogenie - karakteristieken - dierveredeling - hens - poultry - immune competence - humoral immunity - survival - genetic factors - environmental factors - stress response - ontogeny - characteristics - animal breeding
    The aim of the project ‘The genetics of robustness in laying hens’ was to investigate nature and regulation of robustness in laying hens under sub-optimal conditions and the possibility to increase robustness by using animal breeding without loss of production. At the start of the project, a robust animal was defined as ‘an animal under a normal physical condition that has the potential to keep functioning and take short periods to recover under varying environmental conditions’. Next, parameters or traits were selected that could give an indication of robustness, and that could be implemented into a breeding goal for robustness. The experiments described in this thesis investigated parameters of interest for robustness in laying hens, where the influence of genetic background, environmental conditions, and early-life experiences was used as framework. The first experiment aimed at genetic differences in innate (natural) humoral immune components between 12 purebred layer Lines. Levels of innate and specific immune competence depended on genotype. Within layer lines, however, innate immune competence was related with survival. The second experiment aimed at influence of, or response to, environmental conditions, i.e., climatic stress (high temperature) and microbial challenge (lipopolysaccharide). Comparable response patterns to climatic stress and microbial challenge were found within lines, but lines differed in response levels towards these stressors. The third experiment aimed at improvement of robustness by early-life experiences to climatic stress and microbial challenge. The data did not reveal improvement of robustness by early-life experiences. Results from these studies indicate that robustness mainly depends on genetic background and environmental circumstances and to a minor extent on early-life experiences. The basic elements for robustness are survival, reproduction, and responsiveness towards environmental stressors, where a robust laying hen is a hen with a high survival rate, high production level, and low responsiveness towards environmental stressors. We have established a predictive value for the level of NAb binding to KLH for survival of the laying period of laying hens. Besides, NAb have a moderate heritability, giving opportunity for selection towards this trait. Performance parameters and innate immune parameters are most likely not related and selection on innate immune parameters will probably not be on the expense of hen-day egg production. Implementation of selection for NAb into a breeding goal might, therefore, improve robustness of laying hens.
    Karaktertests voor paarden: dier en welzijn
    Visser, E.K. - \ 2008
    V-focus 5 (2008)2. - ISSN 1574-1575 - p. 42 - 43.
    paarden - paardenfokkerij - karakteristieken - tests - sporten met dieren - horses - horse breeding - characteristics - tests - animal sports
    Wageningen UR ontwikkelde verschillende tests om zicht te krijgen op karakters van paarden. Thans onderzoekt Wageningen UR samen met het KWPN of, en in hoeverre, karaktertests bij de fokkerij onderdeel kunnen zijn voor aanlegtests voor jonge paarden in de topsport
    Aberlour Environmental Seabed Survey, UK 2007
    Dalfsen, J. van; Witbaard, R. - \ 2008
    Den Helder : IMARES (Report / Wageningen IMARES C016/08) - 33
    milieutoets - karteringen - verenigd koninkrijk - karakteristieken - fysicochemische eigenschappen - milieu-analyse - biologische processen - environmental assessment - surveys - uk - characteristics - physicochemical properties - environmental analysis - biological processes
    In July 2007 Geolab Nor AS carried out an environmental survey for Chevron North Sea Limited / Chevron Upstream Europe at the Aberlour prospect at UKCS block 213/28 in the Faroe Shetland Channel. The objective of trhe survey was to describe the physico-chemical and biological characteristics in the Aberlour prospect area.
    Mooi zonder blad
    Hoffman, M.H.A. - \ 2008
    Tuin en Landschap 30 (2008)1. - ISSN 0165-3350 - p. 10 - 13.
    houtachtige planten als sierplanten - struiken - aantrekkelijke bomen - ornamentele waarde - karakteristieken - kleur - boomvorm - ornamental woody plants - shrubs - amenity trees - ornamental value - characteristics - colour - tree architecture
    De meeste gewassen zijn aantrekkelijk door hun blad of bloemen in voorjaar, zomer of herfst. Maar er zijn ook heesters en kleine bomen die juist in hun kale winterse staat hun schoonheid tonen, vanwege de kleur of vorm van hun takken. PPO bracht ze in kaart. Een uitgebreid overzichtsartikel is gepubliceerd in Dendroflora 43(2006)
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