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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    De toekomst van hout in de biobased economy
    Annevelink, E. ; Harmsen, P.F.H. ; Spijker, J.H. - \ 2018
    Vakblad Natuur Bos Landschap 15 (2018)141. - ISSN 1572-7610 - p. 7 - 11.
    biobased economy - hout - biobrandstoffen - biomassa - hernieuwbare energie - materialen uit biologische grondstoffen - cellulose - lignine - vezels - biobased economy - wood - biofuels - biomass - renewable energy - biobased materials - cellulose - lignin - fibres
    De laatste jaren is de biobased economy sterk gegroeid door allerlei activiteiten, variërend van fundamenteel onderzoek naar nieuwe biobased toepassingen, tot het op commerciële schaal vervaardigen van biobased producten. Welke kansen biedt dit voor hout en houtige biomassa en wat zijn de verwachte effecten op de houtmarkt?
    Fibrillar structures in mixed systems
    Peng, Jinfeng - \ 2016
    Wageningen University. Promotor(en): Erik van der Linden, co-promotor(en): Paul Venema; K.P. Velikov. - Wageningen : Wageningen University - ISBN 9789462578265 - 284
    cellulose - bacteria - fibres - protein isolates - whey - mixtures - emulsions - mechanical properties - cellulose - bacteriën - vezels - eiwitisolaten - wei - mengsels - emulsies - mechanische eigenschappen

    Fibrillar structures are important structuring elements for food products. Understanding the behaviour of fibrillar structures in complex food systems is essential for successful industrial applications. This thesis presents the behaviour of two different fibrillar structures, i.e. whey protein isolate (WPI) fibrils and bacterial cellulose (BC) microfibrils in mixtures under various conditions. The WPI fibrils are prepared from WPI and the BC microfibrils are extracted from commercial available ‘Nata de Coco’ by high-energy de-agglomeration. In Chapter 1, a general introduction is given, where we introduce two different fibrillar structures that were studied in this thesis. Also, the aim and the outline of the thesis are presented. In Chapter 2, 3, 4 and 5, the behaviour of mixtures containing WPI and BC microfibrils under different conditions are investigated. By varying the concentration ratios, pH, NaCl concentration and further applying heating treatment, their physico-chemical properties in mixed solutions, mixed solutions after heating and further heat-induced mixed gels are investigated and characterized at both pH 2 and pH 7. In general, both mixing WPI and BC microfibrils without heating and subsequently applying heating treatment lead to stable and homogeneous mixtures at pH 7, as long as BC microfibril concentration is above a critical value. Microscopic images showed that the WPI aggregates and BC microfibrils co-existed in the system. WPI denatured and aggregated in the mixture in the same way as when it is heated alone. Upon gelation, the WPI and BC microfibrils form a duplex gel consisting of two independent and homogeneous networks spanning the whole system. At pH 2, the WPI and BC microfibrils also form stable and homogeneous mixtures in the liquid state, both before and after heating. Microscopic images showed two fibrillar structures that are uniformly and independently present. Upon gelation at higher WPI concentration, a bi-fibrillar gel is formed consisting of a WPI fibrilllar gel and BC microfibrillar gel that co-exist. In Chapter 6 and 7, the behaviour of WPI fibrils at pH 2 in dispersions containing spheres, i.e. emulsions and polystyrene latex dispersions are studied. When WPI and spheres are both positively charged (i.e. WPI-stabilized emulsion), we observed depletion flocculation and depletion stabilization when the WPI fibril concentration increases. When WPI and the spheres are oppositely charged (i.e. polystyrene latex dispersions), bridging flocculation and steric/electrostatic stabilization were observed at low WPI fibril concentration, followed by depletion flocculation and depletion stabilization upon increasing WPI fibril concentrations. In Chapter 8 the stability of emulsions at pH 2 in the presence of only BC microfibrils and in the presence of both BC microfibrils and WPI fibrils was studied. When only BC microfibrils added at a sufficiently high concentration, the emulsions are stabilized by the presence of a yield stress as generated by the BC network. When both WPI fibrils and BC microfibrils are added to the emulsions, the networks they form behave in the same way, as when they are added to the emulsions separately. The WPI fibrils induced depletion flocculation and stabilization of the emulsions, despite the presence of the BC microfibrils. However, at high enough BC microfibril concentrations, the emulsions can be stabilized against depletion flocculation as induced by the WPI fibrils. The competition between stabilization and/or de-stabilization induced by the BC microfibrils and the WPI fibrils can lead to emulsions with different microstructures and rheological properties. A general discussion on the results obtained in this thesis is presented in Chapter 9, which includes recommendations for further research and concluding remarks.

    Grasraffinage en gebruik van grasvezel in de rundveevoeding
    Klop, A. ; Durksz, D.L. ; Zonderland, A. ; Koopmans, B. - \ 2015
    Wageningen : Wageningen UR, Livestock Research (Livestock Research rapport 790) - 26
    veevoeding - melkveevoeding - kalvervoeding - bioraffinage - grasmaaisel - vezels - eiwit - proeven - melkveehouderij - livestock feeding - dairy cattle nutrition - calf feeding - biorefinery - grass clippings - fibres - protein - trials - dairy farming
    In 2012 is een proef met melkkoeien uitgevoerd met als doel de waarde van grasvezel te onderzoeken. In het rantsoen van de koeien werd een deel van de graskuil vervangen door grasvezel. De grasvezel kwam beschikbaar na de raffinage van gras. De resultaten van de proef vielen tegen. De voeropname van de koeien die grasvezel kregen was namelijk lager dan van de (controle)koeien die het gangbare rantsoen kregen. De melkgift was eveneens lager op het rantsoen met grasvezel. De oorzaak van de lagere voeropname heeft waarschijnlijk te maken met de versheid en daarmee de smakelijkheid van grasvezel. Daarom is in 2013 besloten om eerst te kijken naar de mogelijkheid om grasvezel te conserveren (in te kuilen), waardoor de kwaliteit en de houdbaarheid mogelijk werd verbeterd. In 2012 is eveneens een oriënterend onderzoek gedaan met graseiwit verstrekt aan kalveren. Graseiwit is het eiwit dat gewonnen wordt uit het grassap en in de proef werd het in gelvorm verstrekt. De resultaten van de proef met kalveren waren uitermate positief. De dieren namen het graseiwit graag op. De groei van de kalveren was vergelijkbaar met de controlegroep.
    Hennep in Europa
    Loo, E.N. van - \ 2014
    Wageningen UR, Plant Breeding
    vezelgewassen - hennep - agrarische geschiedenis - vezels - textiel - biobased economy - fibre plants - hemp - agricultural history - fibres - textiles
    Samenvatting van de geschiedenis van de hennepteelt en de hedendaagse mogelijkheden van hennep.
    Dietary carbohydrates and denitrification in recirculating aquaculture systems
    Meriac, A. - \ 2014
    Wageningen University. Promotor(en): Johan Verreth. - Wageningen : Wageningen University - ISBN 9789462570351 - 129
    dieren - vissen - aquacultuur - koolhydraten - denitrificatie - aquacultuur en milieu - feces - vezels - recirculatie aquacultuur systemen - animals - fishes - aquaculture - carbohydrates - denitrification - aquaculture and environment - faeces - fibres - recirculating aquaculture systems

    Due to overfishing of global fish stocks and increasing fish meal prices, plant ingredients are being increasingly used as an alternative source of protein in fish feeds. However, the inclusion of unpurified plant ingredients will also increase the content of fibers in feeds. Fibers are nearly indigestible and will therefore increase solid waste production in aquaculture. This solid waste can be used to as a carbon source for denitrification to control nitrate levels in recirculating aquaculture systems (RAS), thereby reducing both solid and dissolved waste production. Additionally, fibers can change the recovery characteristics and lower the degradability of fecal waste. Therefore, this study investigates how changes in the dietary carbohydrate composition can affect waste production, system performance and denitrification in RAS. Furthermore, ultrasound treatment (to decrease particle size in fecal waste) and enzymatic conditioning (to increase fiber degradability) were tested as possible means to increase the bioavailability of carbon in fecal waste for denitrification.

    Comparing a high fiber (HNSP) and low fiber (LNSP) diet in RAS stocked with rainbow trout confirmed that the fibers in the HNSP diet increase fecal waste production. Although the HNSP diet produced more fecal waste than the LNSP diet, both diets produced the same amount of biodegradable fecal carbon. Since feces removal was higher in RAS using the HNSP diet, the load of degradable organic matter on the biofilters was lower with the HNSP diet than with the LNSP diet. Furthermore, fecal waste produced with the HNSP diet contained larger particles than feces of the LNSP diet, which could also improve the recovery of fecal waste with microscreens. Feces produced with the HNSP diet were also less degradable than feces produced with the LNSP diet. By using fecal waste as an internal carbon source for denitrification, solid and dissolved waste emissions from RAS could be reduced by ~50% for the HNSP diet. However, only approximately half of the supplied cellulose and hemicellulose were degraded in the denitrification reactors, whereas lignin was not degraded at all. Thus, the overall degradability of organic carbon in fecal waste was limited by fibers as hemicellulose, cellulose and lignin. Ultrasound and enzymatic conditioning did not sufficiently increase the degradability of fecal waste. Nonetheless, fibers originating from unpurified plant ingredients may also have beneficial effects on RAS performance by increasing fecal recovery. A more selective choice of feed ingredients could be used to increase the recovery and degradability of fecal waste in RAS.

    Fiber fermentation in pigs and poultry : sense and nonsense of its manipulation
    Vries, S. de - \ 2014
    Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Walter Gerrits; Mirjam Kabel. - Wageningen : Wageningen UR - ISBN 9789461739513 - 180
    varkens - pluimvee - vezels - fermentatie - spijsvertering - voer - diervoeding - voedingsfysiologie - pigs - poultry - fibres - fermentation - digestion - feeds - animal nutrition - nutrition physiology

    The increased use of fiber-rich feedstuffs in pig and poultry diets requires an optimal utilization of these feed ingredients. Hence, the animal feed industry explores opportunities to improve degradability of these feedstuffs and maximize their inclusion levels in pig and poultry diets. Processing and enzyme technologies can modify the physicochemical characteristics of fiber fractions from feed ingredients, thereby affecting their degradability. In this way, fermentability of non-starch polysaccharides (NSP) and thus their potential energetic utilization might be enhanced. In addition, technologies can be aimed at alleviation of adverse effects on digestion and absorption of other nutrients, which might be particularly of interest for young pigs and poultry. However, to understand modifications that occur during processing detailed information on the composition of fiber structures is required.

    This thesis aimed at identifying limiting factors in the degradability of fiber fractions in pigs and poultry and at development of technologies to improve their degradation. Focus was on recalcitrant fiber structures as found in in maize dried distillers grain with solubles (DDGS) and rapeseed meal (RSM). Fiber degradation in growing pigs and broilers was studied in detail and limiting structures in the degradation of NSP were identified (Chapter 5 to 7). Effects of processing and enzyme technologies on fiber-rich feedstuffs were evaluated based on literature and in vitro and in vivo studies in growing pigs and broilers (Chapter 2 to 7). In addition, marker methods to study digestibility of fiber-rich diets in broilers were discussed (Chapter 8). Furthermore, interactive effects between specific fermentable fiber sources and the digestive utilization of the diet were investigated (Chapter 9). In the final chapter, results of the thesis were summarized and synthesized. Methods to analyze fiber components and evaluate fiber degradation in vitro and in vivo were discussed, suggestions for future research were given, and implications of the results for feed formulation were addressed (Chapter 10).

    Recalcitrant fiber fractions in DDGS and RSM

    The fiber fraction of maize DDGS was found to consist of complex, highly substituted glucuronoarabinoxylans (GAX) that are cross-linked to or associated with cellulose and lignin within the cell wall matrix. In pigs, total tract degradation of non-glucosyl polysaccharides (NGP) from DDGS was between 51 and 62 %. Coumaric acid and ferulic acid associated (ester)-linkages were found to contribute to the recalcitrance of DDGS fiber to fermentation in the pig.The fiber fraction of RSM consists of pectic polysaccharides, xyloglucan, and cellulose that are linked via ester-linkages or H-bonds, forming a rigid cell wall matrix. This rigid matrix was found to hinder the complete degradation of NSP from RSM. In pigs, total tract degradation of NSP from RSM was ~70 %. Nearly 50 % of the unfermented carbohydrate structures in feces were tightly bound pectins (e.g. rhamnogalacturonan and arabinan), xyloglucan, and cellulose. The other half consisted of smaller uronyl-rich carbohydrates, presumably ester-linked or H-bound. In broilers, total tract degradation of NSP from RSM was ~24 %.

    Processing and enzyme technologies

    Common feed processing technologies may improve degradability of easily solubilizable NSP, but are not sufficient to affect rather recalcitrant fiber fractions, such as those found in DDGS and RSM. Particle size reduction, hydrothermal treatment with or without shear, acid hydrolysis, and cell wall degrading enzymes improved in vitro degradability barley (13-43 % units, P < 0.01), whereas only severe hydrothermal acid treatment increased in vitro degradability of fiber fractions from DDGS (30-60 % units,P < 0.01). In pigs, however, hydrothermal acid treatment did not improve degradability of NSP from DDGS, despite the increased solubility of the fiber fraction. Acid treatment shifted fermentation to more proximal gastrointestinal segments, but total extent of NSP degradation was not affected.Apparently, acid-extrusion accelerated degradation of NSP structures that are not resistant to degradation by microbial enzymes in the pigs’ gastrointestinal tract, whereas the most recalcitrant NSP structures were still not affected.Furthermore, acid treatment reduced feed intake, digestibility of crude protein (CP; 3 % units, P = 0.06) and starch (1 % unit, P = 0.10), and tended to reduce digestibility of crude fat (0.4 % units, P < 0.10). Degradability of NGP from rapeseed meal was found to be successfully improved by addition of pectolytic enzymes (9-20 % units, P < 0.01), due to increased degradation of branched water-soluble arabinans. This coincided with an increased NGP concentration in the ceca (4-7 g/g cobalt, P < 0.01), indicating that more NGP were solubilized such that they could enter the ceca and become available for fermentation. Particle size reduction, through wet milling and extrusion, facilitated solubilization of NSP, but solubilized structures could still not be degraded by the cecal microbiota. No interaction between processing technologies and enzyme addition was found. Apparently, the processing technologies studied were not facilitating accessibility of NSP to pectolytic enzymes added to the feed in vivo.

    In conclusion, both processing and enzyme technologies can be effective in solubilizing NSP from DDGS and RSM, but in vivo research demonstrated the limited potential to improve the degradation, and thus feeding value, of recalcitrant fiber fractions. Future research should aim at targeted degradation of recalcitrant NSP structures only, while minimizing the effects on relatively easy degradable NSP and other nutrients. Enzyme technologies, targeting specific structures, seem to provide more perspective than more rigorous processing technologies.In DDGS and RSM, ester-linkages or H-bonds seem to be involved in the recalcitrance of the fiber fraction to degradation in the animal, presumably due to anchorage of NSP in the rigid cellulose-lignin matrix. Hence, technologies that degrade such linkages, as alkali treatments and especially esterases could be of interest for future research.

    Marker methods

    Digestibility measurements are a crucial tool in the evaluation of the nutritive value of feedstuffs. The marker method, where digestibility is estimated from the ratio between an indigestible marker and the nutrient of interest in feed and digesta or excreta, is commonly used as alternative for the laborious total collection method. In broilers, separation of marker and specific digesta fractions occurs, and especially when degradation of fiber fractions is the matter of interest, the marker method has limitations. When estimating apparent ileal digestibility (AID), separation of marker and digesta resulted in unrealistic high estimates for the digestibility of non-glucosyl polysaccharides (54-66 %), exceeding ATTD values by 16-42 % units. Moreover, the effect of pectolytic enzyme addition on the AID of non-glucosyl polysaccharides was in opposite direction when compared with total collection.These data illustrate that fractionation of digesta, particularly in high-fiber diets, complicates accurate ileal digestibility measurements in broilers, regardless the choice of markers used. It is recommended to add a soluble marker when fiber degradation is of interest, even though it does not allow quantifying fermentative degradation of nutrients.

    Interactions between fiber and digestive utilization of the diet

    In current feed formulation systems interactions between feed ingredients are assumed to be absent. This assumption can be challenged as interactions between specific feed components, such as various types of fiber, and the digestive utilization of the diet exist. Although the effects of fiber inclusion on the digestive utilization of the diet are complex, specific properties can be ascribed to certain fiber types. β-Glucan, a rapidly fermentable, viscous, fiber source, enhanced the degradation of xyloglucan from RSM (ATTD of NGP increased by 6 % units, P < 0.001) but did not seem to affect the recalcitrant fiber fraction of DDGS. Furthermore, β-glucan decreased enzymatic digestion of CP and starch in the small intestine. In contrast, resistant starch (RS), a more slowly, but-well fermentable fiber, decreased degradation of fiber-fractions from DDGS as well as RSM (> 10 % units, P < 0.01). These results clearly show the interactive effects between specific fiber fractions in the diet and the degradation of NSP and other nutrients. It is suggested to include effects of individual feed ingredients on the physicochemical properties of the chyme, such as viscosity and water binding capacity, and retention times in various segments of the gastro-intestinal tract in feed formulation, to more accurately predict the nutritive value of diets.

    the role of soluble and insoluble fibers during fermentation of Chicory root pulp
    Ramasamy, U. - \ 2014
    Wageningen University. Promotor(en): Harry Gruppen; Henk Schols. - Wageningen : Wageningen University - ISBN 9789461739650 - 152
    cichorei - pulp - vezels - fermentatie - celwandstoffen - polysacchariden - chicory - pulps - fibres - fermentation - cell wall components - polysaccharides

    This thesis was aimed at understanding the in vitro fermentability of soluble and insoluble fibers in chicory root pulp (CRP). First, CRP and ensiled chicory root pulp (ECRP) were characterized for cell wall polysaccharides (CWPs). Both CRP and ECRP were rich in CWPs (56-58 w/w (%)) and had rather similar sugar compositions. The CWPs consist of 62 % pectin, 11% hemicellulose and 27% cellulose. Pectin and xyloglucan were acetylated and the rhamnogalacturonan-I segments of pectin were branched mostly with arabinan. Compared to CRP, ECRP has four times more soluble pectin.

    In vitrofermentability in a batch model for 24 h using human faecal inoculum, showed that fibers in both CRP (51% carbohydrate utilisation) and ECRP (59% carbohydrate utilisation) were fermentable, especially pectin (80-87%). The increased levels of soluble pectin (arabinan, homogalacturonan and galactan) and the hypothesized open cell wall structure in ECRP contributed to a quicker fermentation and a higher level of carbohydrate utilization compared to CRP. In contrast to batch fermentation, fermentation in the dynamic TNO In vitro model of the colon (TIM-2) was rapid (57% carbohydrate utilisation in 2 h). ECRP carbohydrates (85%) were less fermented in 24 h compared to CRP carbohydrates (92%) due to lower utilisation of ECRP insoluble fibers than CRP insoluble fibers. It was hypothesized that soluble fibers that are readily fermentable and dominantly present in ECRP, programmed the microbiota in TIM-2 to fully adapt to these soluble fibers. After their utilization, the microbiota was not able to adapt towards the fermentation of insoluble fibers.

    Analysis of enzyme activities during batch fermentation of CRP showed increased levels of arabinofuranosidase, β-galactosidase, endo-arabinanase, endo-galactanase, exo-polygalacturonase, pectin de-esterifying enzymes and endo-polygalacturonase. They synergistically contributed to degrading pectin in CRP from 12 to 24 h of fermentation.

    Water holding capacity and enzymatic modification of pressed potato fibres
    Ramasamy, U. - \ 2014
    Wageningen University. Promotor(en): Harry Gruppen, co-promotor(en): Mirjam Kabel. - Wageningen : Wageningen University - ISBN 9789461739643 - 156
    aardappelpulp - aardappelen - vezels - celwandstoffen - polysacchariden - waterbergend vermogen - hydrolyse - enzymen - potato pulp - potatoes - fibres - cell wall components - polysaccharides - water holding capacity - hydrolysis - enzymes

    Cell wall polysaccharides (CWPs) contribute to the water holding capacity (WHC) of fibre rich feeds, such as pressed potato fibres (PPF). However, the role of CWPs on the WHC of PPF was unidentified so far.

    PPF was characterized to be abundant in arabinogalactan (AG) linked rhamnogalacturonan-I (RG-I), homogalacturonan (HG) and cellulose, next to which xyloglucan (XG) contributed the most of the hemicellulosic CWPs. The CWP network in potatoes was loosened upon starch extraction of potatoes and solubilized HG-RG-I-AG.

    Analyses of the WHCs upon enzyme treatments indicated that the WHC of PPF was mainly caused by a network of insoluble, non-cellulosic CWPs such as pectic CWPs (HG-RG-I-AG) and XG. Findings in this thesis showed that AGs were better degraded than xyloglucans (XGs). Since XGs were found to be equally important in contributing to the WHC as AGs, the substantial removal of AGs, as well as XGs, should be advantageous to lower the WHC.

    Other than lowering the WHC, the use of a pectinase-rich preparation improved the recovery of starch from potatoes by the degradation of mainly pectic CWPs, in particular pectic AG side chains and HG. The degradation of arabinan was observed to be inhibited by components in potato juice (PJ).

    Kansen voor de valorisatie van biomassareststromen in de Greenport Betuwse Bloem : valorisatie cases
    Dam, J.E.G. van; Annevelink, E. ; Gogh, J.B. van; Oever, M.J.A. van den - \ 2014
    Wageningen : Wageningen UR - Food & Biobased Research (Rapport 1438) - ISBN 9789461737052 - 50
    biomassa - biomassaconversie - reststromen - plantenresten - champignonmest - snoeiafval - vezels - plantextracten - bouwmaterialen - boomteelt - fruitteelt - glastuinbouw - biobased economy - fermentatie - bio-energie - betuwe - biomass - biomass conversion - residual streams - plant residues - mushroom compost - pruning trash - fibres - plant extracts - building materials - arboriculture - fruit growing - greenhouse horticulture - fermentation - bioenergy
    In opdracht van de Provincie Gelderland werd in het kader van het Ambitieprogramma Betuwse Bloem 2012-2015 door Wageningen UR Food & Biobased Research een verkennende studie uitgevoerd naar de kansen voor valorisatie van bestaande biomassareststromen ter versterking van de economische positie van het regionale tuinbouwcluster. Vijf voorbeeldcases zijn onderzocht: champost – scheiden van fosfaat & andere componenten; houtige reststromen uit de boom- en fruitteelt – hout chips verwerken in vezelboards; reststromen van paprikateelt – stengels verwerken als vezelgrondstof; reststromen van chrysantenteelt – inhoudsstoffen winnen; groenteresten van Veiling Zaltbommel – vergisting.
    Biocomposieten 2012 : natuurlijke vezels en bioharsen in technische toepassingen
    Oever, M.J.A. van den; Molenveld, K. ; Bos, H.L. - \ 2012
    Wageningen : Wageningen UR - Food & Biobased Research - ISBN 9789081911702 - 45
    composieten - materialen uit biologische grondstoffen - harsen - vezels - biobased economy - natuurlijke vezels - composite materials - biobased materials - resins - fibres - natural fibres
    Deze publicatie geeft een overzicht van de mogelijkheden van biocomposieten. Het rapport besteedt aandacht aan zowel bioharsen als aan biologische (natuurlijke) vezels. Met het begrip ‘bio’ wordt bedoeld dat een aanzienlijk deel van het materiaal gebaseerd is op een biobased grondstof. Het aandeel ‘bio’ kan komen van de vezel of de hars of van beide. Dit boekje behandelt al die verschillende combinaties.
    Can diet composition affect behaviour in dogs? : food for thought
    Bosch, G. - \ 2009
    Wageningen University. Promotor(en): Wouter Hendriks; Martin Verstegen, co-promotor(en): Thomas van der Poel; Bonne Beerda. - [S.l. : S.n. - ISBN 9789085853565 - 144
    honden - hondenvoeding - diergedrag - vezels - diëten - voedselsamenstelling - dierfysiologie - dierenwelzijn - voedingsvezels - dogs - dog feeding - animal behaviour - fibres - diets - food composition - animal physiology - animal welfare - dietary fibres
    The consumption of food goes beyond the basic provision of energy and essential nutrients for the maintenance of physical health. Studies in rats, pigs, and human subjects have shown that behaviour and mood can be influenced by specific nutrients consumed. The research described in this thesis aimed to evaluate the impact of dietary composition on two physiological systems involved in the regulation of canine behaviour. In other studies it has been shown that physical activity of pigs can be influenced by dietary fibre type, likely through sustaining satiety after a meal. It appears that the fermentable fibres can stimulate several mechanisms involved in sustaining satiety including the stimulation of the secretion of satiety-related metabolites by the gastrointestinal tract. Furthermore, hunger has been found to influence anxiety in rats. The current study evaluated the potential impact of dietary fibre types for effects on satiety and behaviour in dogs. Two in vitro fermentation studies were conducted to evaluate the microbial fermentation activity in the canine gastrointestinal tract and to screen the fermentability of various fibrous ingredients. Based on these in vitro fermentability data, two diets were formulated expected to differ in fibre fermentability in vivo. The difference in fibre fermentability between diets was confirmed in an in vivo study by evaluation of fibre degradation and concentrations of faecal short-chain fatty acids. In this latter study, the secretion of satiety-related hormones was found not to differ between treatment groups. Feeding dogs a high-fermentable fibre diet did result in a lower motivation to eat 6 hours after their morning meal and a lower activity in their home-kennel compared to dogs fed a low-fermentable fibre diet. Treatment groups did not differ in their responses to short-lasting challenges in a test arena conducted 5 to 7 hours after their morning meal. The second dietary strategy investigated was the use of the essential amino acid tryptophan, the precursor of the neurotransmitter serotonin in the brain. It has been shown that dietary tryptophan supplementation reduces anxiety in rats and increases resilience in dealing with stress in pigs. To investigate if similar effects would occur in dogs, a study was designed and conducted in mildly anxious privately-owned dogs fed diets differing in tryptophan content. Dogs were fed the study diet for 8 weeks using a randomised double-blinded, placebo-controlled design. Intake of the tryptophan supplemented diet increased plasma tryptophan concentrations by 37.4% and its ratio with large neutral amino acids by 31.2% compared to the control diet but the data reported by owners did not show a significant change in the behavioural of the dogs over time that could be attributed to the specific dietary treatment. More controlled behavioural tests conducted on a subset of dogs in both dietary treatment groups failed to show a significant difference of supplementation of the diet with tryptophan. In conclusion, the present work has shown that dietary fibre type can have an impact on canine behaviour through feeding motivation. The measured satiety-related metabolites were not affected by dietary fibre type indicating that other mechanisms were involved in sustaining satiety. Dietary supplementation of tryptophan had no effect on the behaviour of privately-owned dogs.
    Research news : pulping and bleaching activities
    Keijsers, E.R.P. - \ 2008
    pulpbereiding - papier - bleking - vezels - karton - wetenschappelijk onderzoek - pulping - paper - bleaching - fibres - paperboard - scientific research
    Agrotechnology & Food Sciences Group is an organisation for fundamental and applied scientific research. The research department Fibre and Paper Technology is actively involved in pulping and bleaching research with a wide range of raw materials, including wood, non- wood and recycled fibres.
    Facilities and services : testing facilities, Paper and Board Research at Wageningen UR
    Kamp, R.G.M. op den - \ 2008
    vezels - pulp - papier - karton - testen - technieken - biobased economy - fibres - pulps - paper - paperboard - testing - techniques
    Fibres, pulp, paper and board are analysed for different purposes by standard or specially developed methods.
    Research news : Paper and Board Research
    Yilmaz, G. - \ 2008
    papier - karton - onderzoek - vezels - ruwe grondstoffen - kwaliteit - afvalhergebruik - biobased economy - energiebesparing - proceskunde - paper - paperboard - research - fibres - raw materials - quality - waste utilization - energy saving - process engineering
    Wageningen UR Paper and Board conducts fundamental and applied research to develop new sustainable processes and products in the paper and board area. Our expertise enables us to contribute towards improved process efficiency by more effective use of fibre raw materials, introduction of new chemicals, control of stock preparation and product quality and by reduction of energy and waste formation.
    Microbial enrichment of torrefied grass fibers : a novel ingredient of potting soil
    Trifonova, R.D. - \ 2008
    University of Groningen. Promotor(en): J.D. van Elsas, co-promotor(en): Joeke Postma. - [S.l.] : S.n. - ISBN 9789036736695 - 146
    groeimedia - vezels - hooi - grassen - microbiële flora - verrijking - verbeteraars - fytotoxiciteit - growing media - fibres - hay - grasses - microbial flora - enrichment - amendments - phytotoxicity
    Protein fibrillization: preparation, mechanism and application
    Akkermans, C. - \ 2008
    Wageningen University. Promotor(en): Remko Boom; Erik van der Linden, co-promotor(en): Atze Jan van der Goot; Paul Venema. - [S.l.] : S.n. - ISBN 9789085048794 - 162
    bèta-lactoglobuline - wei-eiwit - structuur - ingrediënten - voedingsmiddelen - vezels - fysische toestand - levensmiddelenfysica - beta-lactoglobulin - whey protein - structure - ingredients - foods - fibres - physical state - food physics
    The development of new functional ingredients is important for future food products. This PhD research aimed at the development of protein based structuring agents. Structuring agents are ingredrients that can be used to tailor the texture (and the mouth-feel) of products. Proteins were transferred into protein fibres (fibrils) that are long (1 micrometer) and very thin (few nanometers). Due to their special properties, protein fibrils offer unique possibilities to mimick meat structures and make products like yoghurt more creamy. This research shows that protein fibrils can be made from different protein sources (whey protein of milk, soy protein, potato protein) by heating an acidic protein solution. Furthermore, the mechanism of fibril formation was clarified. As a result, it was possible to optimize the fibril production and control the fibril properties. Finally, an important step was made towards the application of these fibrils in food products by studying the behaviour of fibrils in a model system for food products.
    Hennep voor textiel : de Agro-industriële productieketen
    Dam, J.E.G. van; Heugten, W.G.N. van - \ 2006
    textiel - hennep - vezels - kwaliteit - biobased economy - agro-industriële ketens - ketenmanagement - textiles - hemp - fibres - quality - agro-industrial chains - supply chain management
    Poster met informatie over de productie van textiel uit hennepvezels.
    Dietary Fibre
    Kamp, J.W. van der; Asp, N.G. ; Miller Jones, J. ; Schaafsma, G. - \ 2004
    Wageningen : Wageningen Academic Publishers - ISBN 9789076998329 - 357
    vezel - vezels - voeding - diervoeding - gezondheid - voedingsvezels - fibre - fibres - nutrition - animal nutrition - health - dietary fibres
    In this book invited expert scientists of leading research groups all over the world will address the following issues: Definitions, health claims and new challenges, Analytical tools, technological aspects and applications, Health Benefits of dietary fibre, including both authoritative generic reviews and papers describing the impact on health of specific types of fibre and Health aspects for target groups, with broad overviews on issues related to dietary fibre in clinical nutrition and in food for pets.
    Energetic utilization of dietary fiber in pigs
    Rijnen, M.M.J.A. - \ 2003
    Wageningen University. Promotor(en): Martin Verstegen, co-promotor(en): Johan Schrama. - Wageningen : S.n. - ISBN 9789058088666 - 159
    varkens - vezels - varkensvoeding - diervoeding - energiemetabolisme - energiegebruik - lichamelijke activiteit - warmteproductie - fermentatie - varkensstallen - voedingsfysiologie - voedingsvezels - pigs - fibres - pig feeding - animal nutrition - energy metabolism - energy consumption - physical activity - heat production - fermentation - pig housing - nutrition physiology - dietary fibres

    The energetic utilization of fermentable dietary fiber (fDF) of different fiber sources and its relation to physical activity and housing conditions was studied in three experiments. In all experiments the daily intake of digestible nutrients, nitrogen and energy balances, heat production, and activity-related heat production was measured in climatically controlled respiration chambers. The energetic utilization of fDF was estimated from the linear relationship between heat production and the intake of fDF, after correcting heat production data for other nutrients and methane production. It was found that the energetic utilization of fDF from sugar beet pulp silage (SBPS) was 14.7 kJ/g in group-housed sows. This was slightly higher than for group-housed growing pigs (14.1 kJ/g). The relatively high energetic utilization of fDF from SBPS was related to the decreased activity-related heat production (AHP) with fDF intake. In group-housed growing pigs, the energetic utilization of fDF from solvent-extracted coconut meal and soybean hulls was similar; on average 10.6 kJ/g. There was no relationship between the intake of fDF and AHP. Increased dietary bulkiness and fermentation in the gastrointestinal tract increased the empty weight of the gastrointestinal tract by increased empty weights of the stomach and large intestine, respectively. Digestibility and metabolizability of dietary energy was higher for individually housed growing pigs than for group-housed growing pigs. The energetic utilization of fDF was only numerically higher for individually housed pigs than for group-housed pigs. Individually housed pigs were able to decrease their AHP with the same magnitude as group-housed pigs. It was concluded that there are differences in the energetic utilization of fDF from different origin. Differences in energy expenditure on physical activity play an important role. The rate of fermentation may be of importance. Possible mechanism should be further investigated.

    Praktijktest antifouling op touwen
    Kamermans, P. ; Gool, A.C.M. van; Perdon, K.J. - \ 2003
    IJmuiden : RIVO (RIVO rapport C049/03) - 12
    vistuig - netten - aangroeiwerende middelen - vezels - proeven - fishing gear - nets - antifouling agents - fibres - trials
    In een bassin op het RIVO is een praktijktest van 6 weken uitgevoerd ten behoeve van een kwantitatieve onderbouwing van de effectiviteit van antifouling op vezels voor viskooien. Er zijn twee typen antifouling (Netrex en Lago) en drie typen vezels getest. Gedurende de gehele proef vond geen aangroei op de netten plaats. Dit kan betekenen dat beide antifoulings even goed werken, of dat het bassin niet geschikt is voor het verkrijgen van aangroei. Omdat wel aangroei werd gevonden op de wanden en op ander materiaal in het bassin lijkt de eerste conclusie het meest waarschijnlijk. Netrex antifouling lijkt sterker uit te logen dan Lago antifouling.
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