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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Human Milk Oligosaccharides in Colostrum and Mature Milk of Chinese Mothers : Lewis Positive Secretor Subgroups
Elwakiel, M. ; Hageman, J.A. ; Wang, W. ; Szeto, I.M. ; Goudoever, J.B. van; Hettinga, K.A. ; Schols, H.A. - \ 2018
Journal of Agricultural and Food Chemistry 66 (2018)27. - ISSN 0021-8561 - p. 7036 - 7043.
carbohydrates - genetic polymorphisms - lactation stage - variability

To study the variability in human milk oligosaccharide (HMO) composition of Chinese human milk over a 20-wk lactation period, HMO profiles of 30 mothers were analyzed using CE-LIF. This study showed that total HMO concentrations in Chinese human milk decreased significantly over a 20-wk lactation period, independent of the mother's SeLe status, although with individual variations. In addition, total acidic and neutral HMO concentrations in Chinese human milk decreased over lactation, and levels are driven by their mother's SeLe status. Analysis showed that total neutral fucosylated HMO concentrations in Chinese human milk were higher in the two secretor groups as compared to the nonsecretor group. On the basis of the total neutral fucosylated HMO concentrations in Chinese human milk, HMO profiles within the Se+Le+ group can be divided into two subgroups. HMOs that differed in level between Se+Le+ subgroups were 2′FL, DF-L, LNFP I, and F-LNO. HMO profiles in Dutch human milk also showed Se+Le+ subgroup division, with 2′FL, LNT, and F-LNO as the driving force.

No Adverse Programming by Post-Weaning Dietary Fructose of Body Weight, Adiposity, Glucose Tolerance, or Metabolic Flexibility
Bouwman, Lianne M.S. ; Fernández-Calleja, José M.S. ; Swarts, Hans J.M. ; Stelt, Inge van der; Oosting, Annemarie ; Keijer, Jaap ; Schothorst, Evert M. van - \ 2018
Molecular Nutrition & Food Research 62 (2018)2. - ISSN 1613-4125
carbohydrates - indirect calorimetry - metabolic programming - metabolism - monosaccharides
Scope: Metabolic programming can occur not only in the perinatal period, but also post-weaning. This study aims to assess whether fructose, in comparison to glucose, in the post-weaning diet programs body weight, adiposity, glucose tolerance, metabolic flexibility, and health at adult age. Methods and results: Three-week-old male and female C57BL6/JRccHsd mice are given an intervention diet with 32 energy percent (en%) glucose or fructose for only 3 weeks. Next, all animals are switched to the same 40 en% high fat diet for 9 weeks. Neither body weight nor adiposity differs significantly between the animals fed with glucose or fructose diets at any point during the study in both sexes. Glucose tolerance in adulthood is not affected by the post-weaning diet, nor are activity, energy expenditure, and metabolic flexibility, as measured by indirect calorimetry. At the end of the study, only in females fasting serum insulin levels and HOMA-IR index are lower in post-weaning fructose versus glucose diet (p = 0.02), without differences in pancreatic β-cell mass. Conclusions: Our present findings indicate no adverse programming of body weight, adiposity, glucose tolerance, and metabolic flexibility by dietary (solid) fructose in comparison to glucose in the post-weaning diet in mice.
Probing the bacterial cell wall with chemical biology tools
Sminia, Tjerk J. - \ 2017
University. Promotor(en): Han Zuilhof; Willem de Vos, co-promotor(en): Tom Wennekes. - Wageningen : Wageningen University - ISBN 9789463437080 - 196
bioengineering - sugars - labelling - synthesis - biochemical techniques - akkermansia muciniphila - gastrointestinal microbiota - carbohydrates - suikers - etiketteren - synthese - biochemische technieken - microbiota van het spijsverteringskanaal - koolhydraten

After DNA and proteins, carbohydrates are the third language of life. Chapter 1 introduces the reader to this class of biomolecules, also called sugars or glycans, that can be found on the outer surface of almost all cells and plays a critical role as the social messengers of a cell. Although our knowledge about the role of glycans in eukaryotic cells has increased considerably in recent decades, our understanding of the glycan layer on bacterial cells is still very limited. Besides the carbohydrates that are present in both eukaryotes and prokaryotes an additional wide range of unique (e.g. microbial sialic acid), often very complex (e.g. pseudaminic acid), carbohydrates is present in prokaryotes. This chapter briefly introduces two research fields, carbohydrate chemistry and chemical biology, that when combined provide a powerful way to investigate the biological role of these unique bacterial carbohydrates at the molecular level. This chemistry-based approach, termed chemical microbiology, often starts with the development of a chemical synthesis for a target bacterial carbohydrate. Subsequently, the synthetic route towards this target allows for the introduction of unnatural functional groups, like chemical reporters, that result in the molecular tools needed to study their biological function. The studies described in this thesis, focus on developing such molecular tools to study the role of glycans and glycoconjugates in human gut bacteria and human-associated bacteria.

Chapter 2 provides an overview of metabolic oligosaccharide engineering (MOE) a popular chemical biology technique to label glycans in living cells. In MOE, carbohydrates derivatives are synthesised with unnatural chemical reporters and used to study their incorporation in glycans of eukaryote to prokaryote species. The progress in this field over the last 6 years is reviewed in detail with a special emphasis on the synthesis of the unnatural carbohydrates from commercially available sources. The principle behind MOE is that these unnatural carbohydrates with e.g. azide, alkyne, cyclopropene, or isonitrile chemical reporter groups, are still recognised by the endogenous enzymes in the cell that salvage this new carbohydrate. In this way they can enter the associated biochemical pathways and end up in newly biosynthesised cellular glycans. Subsequent labelling techniques, such as strain promoted azide alkyne cycloaddition or tetrazine ligation, enable the visualisation of these incorporated unnatural carbohydrates with for instance fluorescence microscopy.

Metabolic labelling is further explored in chapter 3. Key cell envelope glycoconjugates in the mucin-degrading gut microbiota member, Akkermansia muciniphila, were subjected to chemistry-based functional analysis, with Escherichia coli being used as a control species. Two novel non-toxic peptidoglycan (PG) probes were designed and synthesised to investigate the presence of PG in this species. Their design was based on the natural d-alanine dipeptide motif found in PG. Inspired by the fact that d-alanine dipeptide-derivatives were previously reported to be incorporated in newly synthesised PG, we synthesised a cyclopropene and isonitrile d-alanine dipeptide. Our probes proved to be non-toxic, as shown by growth and viable count analysis, and were therefore superior over existing PG probes. Another beneficial property was that the probes also did not influence the specific growth rate of A. muciniphila or E. coli. The PG probes were successfully incorporated into the peptidoglycan layer of A. muciniphila and visualised using a tetrazine click-ligation with a fluorophore. Our analysis proved for the first time that A. muciniphila has a PG layer. Besides PG labelling, we also investigated metabolic labelling of other glycoconjugates on the outer surface of A. muciniphila. This part of the study showed that azido-monosaccharide derivatives of N-acetylglucosamine, N-acetylgalactosamine, and fucose are successfully processed by A. muciniphila salvage pathways and incorporated into its surface glycoconjugates. Especially 6-azido-fucose was readily processed by the recently discovered l-fucose salvage pathway of A. muciniphila. The two compatible labelling techniques were next combined in a dual labelling experiment. Our isonitrile dipeptide peptidoglycan probe and 6-azido-fucose were successfully incorporated into A. muciniphila. Subsequent fluorescent labelling with bio-orthogonal techniques resulted in dual labelling of peptidoglycan and fucose-containing glycans in live A. muciniphila cells.

With the positive results of MOE in A. muciniphila in hand, chapter 4 describes the further investigation of MOE. After successful validation of our Ac4FucAz probe for MOE in Bacteroides fragilis we continued their application in other human gut microbiota members, including the butyrate-producing Anaerostipes rhamnosivorans, Intestimonas butyriciproducens, and Eubacterium hallii. Labelling of these human gut microbes proved to be rather challenging with a-specific cellular labelling with the fluorophore being the major problem. Initial results, however, did show that a 6-azido-l-rhamnose probe resulted in fluorescent labelling of A. rhamnosivorans, which provides initial evidence for the existence of an as of yet undocumented salvage pathway. In this species the 6-azido-fucose probe was not salvaged. Via confocal microscopy and flow cytometry analysis we observed that the 6-azido-rhamnose probe was selective for A. rhamnosivorans in the presence of A. muciniphila. Such a co-culture experiment is a first step in mimicking the complex human gut microbiome. For E. hallii Ac4GalNAz gave clear metabolic labelling and the majority of the cell population could be labelled with the fluorescent dye after a strain-promoted azide alkyne cycloaddition. Other glycan probes (Ac4GlcNAz, Ac4FucAz, and Neu5Az) also resulted in labelling, but not as prominent as Ac4GalNAz. Surprisingly, MOE has never been reported for the common lab strain Escherichia coli MG1655. Curious to investigate this in more detail we started MOE in E. coli. However, no labelling was obtained when Ac4GlcNAz probe was added to E. coli, most likely due to the fast growth, metabolism and turnover. Only, when fresh Ac4GlcNAz probe was added every 30 minutes, metabolic labelling in E. coli was observed. To further investigate the influence of GlcNAc metabolism in E. coli on MOE, single-gene knock-outs of E. coli GlcNAc metabolism from the Keio collection were investigated. Labelling was observed for NagA (N-acetyl glucosamine 6 P deacetylase) and NagK (N-acetyl-d-glucosamine kinase) E. coli mutants. Both enzymes are involved in the last step of the biosynthesis towards UDP-N-acetylglucosamine. When the overall E. coli metabolism was inhibited, after addition of the respiration inhibitor sodium azide, no metabolic labelling was observed. These results indicate that MOE in E. coli is possible, but challenging and can only be performed under specific circumstances.

An investigation into the total synthesis of pseudaminic acid, a sialic acid produced by specific human-associated prokaryotes, is described in chapter 5. Sialic acids are typically found at the terminal positions of surface glycoconjugates in both eukaryotes and prokaryotes. Other related microbial sialic acids are legionaminic and acinetaminic acid. The total synthesis of these microbial sialic acids is notoriously difficult, as exemplified by the fact that only a few chemical synthesis routes towards them are currently known. Our total synthesis of pseudaminic acid started from the readily available amino acid l-threonine that was transformed into a key versatile Garner aldehyde derivative intermediate. With this aldehyde in hand, the Henry nitro-aldol condensation reaction was investigated. After studying numerous conditions, such as asymmetric catalysis or elongated reaction times, and extensive optimisation efforts we were never able to obtain the Henry reaction product to continue with this route. As an alternative, a tethered aminohydroxylation was investigated for its ability to introduce the key functional group and stereochemistry onto an intermediate obtained from the Garner aldehyde derivative. This reaction indeed gave the desired amino-alcohol motif in the correct stereochemistry, but another diastereomer proved very difficult to separate from the desired product. After some additional transformations and protection steps we obtained a derivative in which the primary alcohol could be oxidised to provide a hexose intermediate that resembles the hexose intermediate present in pseudaminic acid biosynthesis. This key hexose intermediate will likely enable a subsequent Barbier reaction, a chain elongation step, in future studies. With most of the key transformations accomplished, the completion of a pseudaminic total synthesis based on l-threonine should soon be possible. Besides finishing the total synthesis, future work should also focus on adapting this synthesis route to allow installation of chemical reporter groups on pseudaminic acid for its application in MOE.

Chapter 6 is the general discussion about all the work mentioned in the other chapters. It also contains additional information and suggestions for further research in the field of chemical microbiology.

The evaluation of energy in fish feed
Haidar, Mahmoud - \ 2017
University. Promotor(en): Johan Verreth, co-promotor(en): Johan Schrama. - Wageningen : Wageningen University - ISBN 9789463438049 - 155
oreochromis niloticus - fish feeding - feed formulation - digestible energy - dietary protein - dietary fat - carbohydrates - growth - feed evaluation - fish culture - aquaculture - visvoeding - voersamenstelling - verteerbare energie - voedingseiwit - voedingsvet - koolhydraten - groei - voederwaardering - visteelt - aquacultuur

New and alternative plant ingredients are increasingly incorporated in fish feed due to the scarcity of captured fish and increased fishmeal and fish oil prices. As a result, current fish feeds are characterized by a highly variable ingredients composition, leading to a similar variability in the dietary macronutrients composition, especially the carbohydrates fraction. Appropriate formulation of the energy component in fish feeds requires information on nutrient digestibility, energy requirements for maintenance, and the efficiency of utilization of digestible energy for growth (kgDE). In fish feed formulation, the energy evaluation is based on digestible energy (DE) basis. The main assumptions of this DE system are that maintenance requirements and kgDE are independent of dietary factors. The main objective of this thesis was to evaluate and improve the DE system for Nile tilapia. Data showed that, opposite to what is assumed in literature and irrespective of the feeding level applied, an optimal digestible protein to digestible energy ratio (DP/DE) for young Nile tilapia could not be detected. In addition, it was expected that Nile tilapia would show a maximal protein deposition in relation to a wide range of DP/DE ratios, however, this was either observed. Further investigations showed that different body compartments/organs responded differently in terms of protein and fat composition as a result of changes in the dietary DP/DE ratio. In tilapia, viscera and the “rest” fraction (head, skin, fins and bones) were the main site for fat retention. In addition, protein content of fillets seems to be constant (about 17%) and not affected by dietary factors in Nile tilapia. In addition, the effect of using new plant ingredients in Nile tilapia diets was also investigated. The results showed that the ingredients composition had an effect on the maintenance requirements of Nile tilapia. Further, changes in the ratio of starch vs non starch carbohydrates revealed that energy retention was lower when more dietary fibers were included. In addition, the net energy retention differed also when the levels of digestible protein, fat and carbohydrates changed in the diets. The latter results proved that kgDE was not constant and was dependent on diet composition. All aforementioned results led us to calculate the energetic efficiencies of digestible protein, fat and carbohydrates for net energy retention. These estimated efficiencies were used to propose a net energy evaluation system being feasible for Nile tilapia.

Samenstelling van blad, stengel en rhizomen in relatie tot optimaal oogst-tijdstip van Miscanthus x giganteus
Kasper, G.J. ; Kolk, J.C. van der; Putten, J.C. van der - \ 2017
Wageningen : Wageningen Livestock Research (Wageningen Livestock Research rapport 1022) - 27
brandstofgewassen - biobased economy - miscanthus - grassen - oogsttijdstip - gewasopbrengst - akkerbouw - plantensamenstelling - suikergehalte - lignine - pectinen - droge stof - koolhydraten - stengels - wortelstokken - fuel crops - grasses - harvesting date - crop yield - arable farming - plant composition - sugar content - lignin - pectins - dry matter - carbohydrates - stems - rhizomes
A plurality of components (such as sugars, lignin, pectin) of Miscanthus x giganteus has been studied in stem, leaf, and rhizomes for the harvest times July and January in view of the optimal harvest time. Additional literature search shows that the end of October is the optimum time for harvesting on the basis of the maximum above-ground dry matter yield and sugar yield, and dry matter yield in the next year. It will have to be investigated whether the optimal harvest time also applies to long-term research.
Mild disintegration of green microalgae and macroalgae
Postma, Richard - \ 2016
University. Promotor(en): Michel Eppink; Rene Wijffels, co-promotor(en): Giuseppe Olivieri. - Wageningen : Wageningen University - ISBN 9789462579477 - 181
algae - chlorella vulgaris - bioprocess engineering - biorefinery - proteins - milling - carbohydrates - biobased economy - disintegrators - technology - extraction - algen - bioproceskunde - bioraffinage - eiwitten - maling - koolhydraten - desintegrators - technologie - extractie

An increased worldwide protein demand for food and feed and the necessity to release the water soluble proteins in the first stage of the cascade biorefinery require the development of mild protein extraction technologies. Cell disintegration is the first hurdle and is considered as one of the most energy consuming steps. Therefore, this thesis focused on the development of a mild, scalable and energy efficient disintegration technology for green microalgae and macroalgae (seaweed) aimed on extraction of water soluble components (like proteins and carbohydrates).

For microalgae disintegration, two main technologies were investigated. First of all the conventional technology bead milling and second a novel approach using Pulsed Electric Field (PEF). In Chapter 2 a benchmark was set by means of bead milling for the release of water soluble protein from the green microalgae Chlorella vulgaris. Overall, protein yields between 32 and 42% were achieved, while the energy consumption was reduced with 85% by selective protein extraction to values as low as 0.81 kWh kgDW-1. Remarkably, the benchmark was much better than expected.

In Chapter 3 the bead mill was further optimized by decreasing the applied bead size, furthermore the applicability of bead milling on two additional microalgae species (Neochloris oleoabundans, Tetraselmis suecica) was shown. In addition, to be able to better understand the disintegration mechanism, the so-called stress model was applied. This model describes the comminution process in a bead mill as function of the amount of bead contacts and the force of each impact. The release kinetics could be improved and thereby the specific energy consumption could be reduced to 0.45‒0.47 kWh kgDW-1 by using 0.3 mm beads for all algae.

Chapter 4 describes a screening on the applicability of PEF, over a broad range of operating conditions, for the extraction of water soluble proteins from the microalgae C. vulgaris and N. oleoabundans. No substantial protein yields were observed under the investigated conditions. This led to the conclusion that PEF is not suitable to release water soluble proteins, not even at specific energy consumptions much higher than those for the benchmark, bead milling.

In Chapter 5 it was attempted to improve the performance of PEF by investigating the synergistic effect with the processing temperature. The PEF experiments were performed using a pilot scale continuous flow electroporation unit in which the processing temperature was controlled between 25 – 65 °C. The results showed that under the tested conditions, the combined PEF-Temperature treatment did not cause substantial disintegration of the algal cells to effectively release water soluble proteins.

In addition to the microalgae, macroalgae were subject of investigation in the search for new protein sources in Chapter 6. Four batch technologies were used to disintegrate the green macroalgae Ulva lactuca, being; osmotic shock, enzyme incubation, PEF and High Shear Homogenization (HSH). In descending order the highest protein yields per treatment; HSH (~40%) > enzyme degradation (~25%) > osmotic shock (~20%) > PEF (~15%).

In the final chapter the main results and remaining bottlenecks are discussed and a future outlook on microalgae disintegration is presented. To date, bead milling is the only technology able to disintegrate fresh microalgae at specific energy consumptions below 10% of the total energy available from the algae and release substantial amounts of water soluble protein. The future outlook was based on a techno-economic evaluation, which showed that the cultivation costs are limiting the economic feasibility of microalgae biorefinery. Future focus should be on the cultivation.

Influence of pectin supplementation on feed fermentation characteristics in rats and pigs
Tian, L. - \ 2016
University. Promotor(en): Harry Gruppen; Henk Schols. - Wageningen : Wageningen University - ISBN 9789462577282 - 142 p.
pigs - rats - pectins - feed supplements - dietary fibres - digestion - digestive tract - carbohydrates - microbial flora - nutrition physiology - animal nutrition - food chemistry - varkens - ratten - pectinen - voedersupplementen - voedingsvezels - spijsvertering - spijsverteringskanaal - koolhydraten - microbiële flora - voedingsfysiologie - diervoeding - voedselchemie

The physiological effects of dietary fiber (DFs) depend on several factors including structural features of the DFs, composition and activity of colonic microbiota, and products formed during fermentation. In this thesis, the influence of pectin supplementation to feed fermentation characteristics in rats and pigs was studied. The non-starch polysaccharides (NSP) present in the selected feed ingredient oats were characterized. Distinct populations of arabinoxylans (AXs) were observed in oats, compared to those reported for other cereals like wheat and barley. The fate of cereal AXs and soybean pectin during fermentation and the consequent effects on appetite regulation and fat accumulation were studied in rats as a model. Oat AXs were fermented less rapidly than wheat AXs in the caecum of rats. Soy pectin was fermented more early and efficiently than cereal AXs. A significant inverse correlation between rat retroperitoneal fat-pad weight and concentration and relative SCFA proportion of butyrate was observed. In a following in vivo rat experiment, commercial soy pectin together with three other soluble pectins originating from citrus and sugar beet and differing in their methyl esterification were individually supplemented to the diets. Their effects on the utilization of the different DFs present in the feed and the consequent effect on the microbial community in the colon of rats was studied. All pectins were fermented rapidly and consequently shifted fermentation of other consumed DFs (e.g. cereal AXs) to more distal part of colon, although low-methyl esterified pectin was more efficiently fermented by the microbiota than high-methyl esterified pectin. Results suggested that pectins can confer beneficial health effects through modulation of the gut microbiota. In a last in vivo experiment, citrus pectins together with a hydrothermal treated soybean meal were supplemented to pig diets to study their effect on the digestion and fermentation of carbohydrates in both the small and large intestine. Pectins, and more particularly low-methyl esterified pectin, decreased the ileal digestibility of digestible starch resulting in more starch to be fermentated in the proximal colon of pigs. Consequently, also the fermentation patterns of DFs and the microbiota composition was affected. All pectins tested shaped the colonic microbiota from a Lactobacillus-dominated microbiota to a Prevotella-dominated community, with potential health-promoting effects.

How mushrooms feed on compost: conversion of carbohydrates and linin in industrial wheat straw based compost enabling the growth of Agaricus bisporus
Jurak, E. - \ 2015
University. Promotor(en): Harry Gruppen, co-promotor(en): Mirjam Kabel. - Wageningen : Wageningen University - ISBN 9789462573116 - 156
paddestoelen - champignonmest - koolhydraten - degradatie - substraten - compostering - agaricus bisporus - mushrooms - mushroom compost - carbohydrates - degradation - substrates - composting


In this thesis, the fate of carbohydrates and lignin was studied in industrial wheat straw based compost during composting and growth of Agaricus bisporus. The aim was to understand the availability and degradability of carbohydrates in order to help improve their utilization in the compost. The wheat straw based compost was characterized as being composed mainly of cellulose and lowly substituted xylan. During the first phase of composting, ester-bound substituents were removed from the xylan backbone and during the second phase of composting 50% of carbohydrates present in the original material where metabolized in a uniform manner. Lignin structure, however, remained unaltered during these composting stages. Over the period of A. bisporus mycelium growth, 20% of the original xylan became water soluble while xylan structures remained rather similar and the remaining water insoluble xylan was partially degraded. In addition, 40% of lignin was metabolized during mycelium growth with an increase in the ratio of syringyl to guaiacyl lignin units from 0.5 to 0.7 in mycelium grown compost compared to the basic compost mixture. During the fruiting body formation minor changes in lignin structure occurred, while accumulation of xylan substituents was observed for arabinosyl residues and glucuronic acid substituents. Finally, putative genes encoding carbohydrate degrading enzymes were identified in A. bisporus’ genome. Genes involved in the pentose and hexose catabolic pathway were found to be upregulated in A. bisporus mycelium. A. bisporus was found to produce both xylan and cellulose degrading enzymes and maximum activity was observed during the formation of the 1st flush of mushrooms. But, as observed from the remaining xylan structures analyzed, A. bisporus lacks the enzymatic activity to degrade xylan substituted with two arabinosyl- residues and glucuronic acid substituted xylan.

Edita Jurak

How Mushrooms feed on compost: Conversion of carbohydrates and linin in industrial wheat straw based compost enabling the growth of Agaricus bisporus

Gestational diabetes mellitus in Tanzania : public health perspectives
Mwanri, A.W. - \ 2015
University. Promotor(en): Edith Feskens, co-promotor(en): J.L. Kinabo; K. Ramaiya. - Wageningen : Wageningen University - ISBN 9789462572645 - 202
diabetes mellitus - voedselintolerantie - zwangerschap - zwangerschapscomplicaties - obesitas - koolhydraten - food intolerance - pregnancy - pregnancy complications - obesity - carbohydrates

Gestational diabetes mellitus in Tanzania – public health perspectives


Background: Gestational diabetes mellitus (GDM) is defined as carbohydrate intolerance resulting in hyperglycaemia of variable severity with onset or first recognition during pregnancy. Women with GDM are at increased risk for preeclampsia during pregnancy and for delivery complications. In most cases GDM ends after pregnancy, but it increases the risk for future type 2 diabetes, and cardiovascular diseases, to both the mother and the child. With the current increase in prevalence of overweight/obesity and type 2 diabetes in Tanzania and other Sub Saharan African countries, it is possible that GDM may exist and may be on the rise.

Methods: A cross-sectional survey was done in 2011 through 2013 where 910 women in Tanzania (609 from urban, 301 from rural areas) were studied during their usual antenatal clinic visits. Weight, height, mid upper arm circumference (MUAC), blood pressure and haemoglobin levels were measured by a trained technician. Blood glucose was measured at fasting and at two hours after 75 g oral glucose tolerance test. Women were classified as having GDM using WHO 1999 criteria. Sociodemographic information was collected through face-to-face interviews using structured questionnaire or retrieved from the antenatal clinic card. Dietary intake data was collected using 24-hour recall interview and foods were categorised into groups based on dietary diversity. The international physical activity questionnaire (IPAQ) was used to assess activities in the past one week. Information on birth outcome was obtained from 466 urban mothers (response rate 77%) through telephone interviews. To estimate the burden of GDM in the region, we additionally conducted a systematic search of published literature on the prevalence and risk factors of GDM in Sub Saharan Africa. Out of the 22 reviewed studies, 15 studies graded as having low or moderate risk of bias were included in a meta-regression analysis. Finally, a review of literature regarding the health system and antenatal care was done and supported by a survey to assess antenatal care services in 24 health facilities that provide maternal and childcare services in Dar es Salaam region.

Results: The prevalence of GDM was much higher among women residing in the urban (8.4%) compared to those in the rural areas (1.0%), which was much higher compared to 0% reported in the 1990s. Prevalence of GDM was higher for women who had a previous stillbirth, family history of type 2 diabetes and MUAC ≥28 cm, and lower for women with normal haemoglobin concentrations compared to those with anaemia. Likewise, the prevalence of hypertension disorders of pregnancy (HDP) was higher in urban (8.9%) compared to rural areas (5.3%). Risk factors for HDP in urban women were advanced maternal age, high MUAC, gestional age and being HIV positive, and in rural women age and gestational age.

We reviewed 22 studies conducted in six out of the 47 Sub saharan African countries. Heterogeneity between the studies was high and it could not be significantly explained by study setting, population, diagnostic criteria, or the year the study was done. Nevertheless, a relatively higher prevalence was observed in studies done after the year 2000, when women at risk were selected and when more current diagnostic criteria were used. The prevalence was up to about 14.0% when women with at least one risk factor were studied. In Dar es Salaam women, despite a high prevalence of anemia and HIV, the prevalence of macrosomia was higher (5.9%) compared to the prevalence of low birth weight (3.6%). Presence of GDM (OR 3.46, 95% CI 1.01-11.85) and birth weight of the previous child (OR 2.42, 95% CI 1.17-4.99) were the main predictors of macrosomia and HDP (OR 3.75, 95% CI 1.11-12.68) was the main predictor of low birth weight. Although glucose testing in urine appeared to be universally done in the urban setting, the sensitivity of this test for detection of GDM is low. Therefore selective blood glucose testing should be implemented and HIV testing and counselling may be used as an entry point.

Conclusions: The prevalence of GDM and HDP was higher in the urban compared to the rural areas in Tanzania, indicating an increasing in women who are at risk for delivery complications, poor pregnancy outcomes, type 2 diabetes and cardiovascular diseases in later life. The risk factors observed can be used to identify risk groups for screening and as target for prevention interventions. To inform policy makers and for better health care planning, further studies on the costs for blood glucose testing during the usual antenatal clinic visits and on the management of women with GDM are warranted.

Koolhydraten bieden scala aan mogelijkheden voor gezonde levensmiddelen
Schols, H.A. - \ 2014
Wageningen : Wageningen UR
voedingsvezels - koolhydraten - voeding en gezondheid - voedingsstoffen - analytische methoden - voedselonderzoek - dietary fibres - carbohydrates - nutrition and health - nutrients - analytical methods - food research
Koolhydraten in onze voeding leveren energie en zorgen voor een gemakkelijke stoelgang. Van de vele verschillende koolhydraatmoleculen, waaronder tal van soorten kleine suikers, zetmeel en voedingsvezels, weten we echter betrekkelijk weinig. Dat geldt ook voor hun rol tijdens het bewaren en verwerken van levensmiddelen of voor de invloed van koolhydraten op de gezondheid.
GM1-derived carbohydrates for pathogen and antibody detection : synthesis and biological evaluation
Garcia Hartjes, J. - \ 2014
University. Promotor(en): Han Zuilhof, co-promotor(en): Tom Wennekes. - Wageningen : Wageningen University - ISBN 9789462571273 - 240
koolhydraten - moleculaire detectie - antilichamen - pathogenen - remmers - biotesten - carbohydrates - molecular detection - antibodies - pathogens - inhibitors - bioassays
Dietary carbohydrates and denitrification in recirculating aquaculture systems
Meriac, A. - \ 2014
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.

Fructan biosynthesis in crop plants : the molecular regulation of fructan biosynthesis in chicory (Cichorium intybus L.)
Arkel, J. van - \ 2013
University. Promotor(en): Harro Bouwmeester, co-promotor(en): Ingrid van der Meer. - S.l. : s.n. - ISBN 9789461736635 - 158
cichorium intybus - gewassen - zea mays - solanum tuberosum - transgene planten - koolhydraten - fructanen - biosynthese - inuline - polymerisatie - crops - transgenic plants - carbohydrates - fructans - biosynthesis - inulin - polymerization

Fructan is a polymer of fructose produced by plants and microorganisms. Within the plant kingdom about 45.000 species accumulate fructan as storage carbohydrate in addition to, or instead of, starch. Fructan accumulating species are mainly found in temperate and sub-tropical regions with seasonal or sporadic rainfall. During the last decades, the use of fructan in the (food) industry has rapidly evolved, because of its health promoting characteristics and interesting functional properties.Chicory (Cichorium intybus L.) is a biennial taproot-bearing crop plant that is grown for the production of inulin on an industrial scale. Inulin, a ß(2,1) linked linear fructan with a terminal glucose residue, is stored in the chicory taproots. The degree of polymerisation (DP) determines the application of the inulin and hence the value of the crop. This leads us to the central question of this thesis:

What regulates the fructan yield and the degree of polymerisation, and how can we modify this?

The DP is highly dependent on the field conditions and harvest time, and therefore the first step in answering this question was tostudy the regulation of fructan (inulin) metabolism throughout the growing season. This is described in Chapter 2. Metabolic aspects of inulin production and degradation in chicory were monitored in the field and under controlled conditions. We determined the concentrations of soluble carbohydrates, the inulin mean degree of polymerisation (mDP), inulin yield, gene expression and activity of enzymes involved in inulin metabolism in the taproots. Inulin biosynthesis - catalysed by sucrose: sucrose 1-fructosyltransferase (EC (1-SST) and fructan: fructan 1-fructosyltransferase (EC (1-FFT) - started at the onset of taproot development. Inulin yield increased with time following a sigmoid curve reaching a maximum in November. The maximum inulin mDP of 15 was reached in September and then gradually decreased. Based on the changes observed in the pattern of inulin accumulation, we defined three phases in the growing season and analysed product formation, enzyme activity and gene expression in these defined periods. The results were validated by performing experiments under controlled conditions in climate rooms. Our results show that the decrease in 1-SST is not regulated by day length and temperature. From mid-September onwards the mDP decreased gradually although inulin yield still increased. This is most probably the result from back-transfer activity of 1-FFT and fructan exohydrolase activity (EC (1-FEH). In plants 1-FEH catalyses the breakdown of fructan in order to release the stored carbohydrates necessary in periods of stress, like cold or drought periodsor flowering. This information was used to design two strategies to obtain the desired, increased inulin DP and yield. Overexpression of 1-SSTwas performed to increase the mDP and to keep the sucrose concentration low, to prevent 1-FFT from depolymerizing inulin. The result was a higher mDP during the growing season. Unfortunately, no effect on the mDP was seen at the end of the growing season, most probably due to activity of FEH. Secondly, anFEH I antisense fragment was introduced into chicory in order to block depolymerisation at the end of the growing season. This resulted in a reduction in FEH Iexpression upon cold induction, but had only minor effects on the mDP. The degradation of inulin was most probably caused by the remaining 1-FEH activity. Overall this study showed that inulin metabolism in chicory is tightly regulated, but also revealed options to further steer inulin metabolism in chicory.

The next step in answering the central question was to study the regulation of the genes involved in fructan biosynthesis. In Chapter 3this was studied at three different levels. Firstly, fructan gene expression and carbohydrate concentrations were studied in axial sections of mature chicory root, revealing the highest expression levels and carbohydrate levels in the phloem. Correlations were found between the gene expression patterns of 1-SST, 1-FFT and the carbohydrate levels, suggesting a possible involvement of sugars in the regulation of 1-SSTand 1-FFTgene expression. Secondly, the induction of 1-SSTand 1-FFTexpression was studied in excised chicory leaves. Expression of both 1-SSTand 1-FFTwas induced upon sucrose and glucose feeding, suggesting that both genes are at least partly regulated in the same way. Upon fructose feeding, the induction of fructan biosynthesis was less pronounced than with sucrose. The expression of 1-SSTwas induced by fructose but this resulted in only low amounts of 1-kestose. The expression of 1-FFTwas not induced upon fructose feeding.Thirdly, to further unravel the mechanism of induction, the promoters of 1-SSTand 1-FFTfrom chicory were isolated and characterized through in silicoand in planta(only 1-FFT) analysis. Computational analysis of fructosyltransferase (FT) promoters revealed elements that are common in fructan biosynthesis-promoters among different species and also occur in Arabidopsis promoter sequences. One of these elements is predominantly present in genes involved in sugar metabolism and transport. This element did also contain a core sequence involved in MYB transcription factor binding important for fructan biosynthesis activation in wheat, as was published recently. An 1100bp 1-FFTpromoter fragment was shown to be functional in transgenic chicory and in the non-fructan accumulating plants species, Arabidopsis and potato. Application of carbohydrates resulted in the expression of the reporter gene GUS comparable to 1-FFTexpression upon carbohydrate feeding in chicory. This study provides information on the regulation of inulin biosynthesis, suggestions for studies on transcription factors, and provides a promoter for steering the expression of fructan biosynthetic genes in transgenic plants. An alternative way for the production of inulin with the desired DP and yield, circumventing the problems in chicory rather than trying to solve them, is the introduction of the fructan biosynthetic pathway in non-fructan metabolizing and catabolizing plant species.

Towards this end we have expressed the inulin synthesizing enzymes, 1-SST and 1-FFT from Jerusalem artichoke, in maize and potato, as described inChapter 4. Transgenic maize plants produced inulin type fructan (at 3.2 milligram per gram kernel) and kernel development was not affected. Potato tubers expressing 1-SSTaccumulated 1.8 milligram inulin per gram tuber while tubers with a combined expression of 1-SSTand 1-FFTaccumulated 2.6 milligram inulin per gram tuber. Inulin accumulation in maize kernels was modulated by kernel development, first peaking in young seeds and then decreasing again through degradation during late kernel development. In potato, inulin mDP was relatively stable throughout tuber development and little evidence of degradation was observed. The accumulation of 1-kestose in transgenic maize correlated positively with kernel sucrose concentration and introduction of the fructan biosynthetic pathway in a high-sucrose maize background increased inulin accumulation to 41 milligram per gram kernel kernel. This study shows the importance of sugar availability and the absence of degradation mechanisms in platform crops for tailor-made fructan production.

Further evaluation of the production of tailor-made inulin and putative platform crops is discussed in Chapter5.Here we come to the conclusion that the mDP, the distribution and yield depend on the origin of the fructan biosynthesis genes and the availability of sucrose in the host. The combination of genes from different origins could result in new types and different lengths of fructan molecules resulting in (new) specific properties of fructan. Limitations for the production of tailor-made fructan in chicory are not seen in putative new platform crops, such as sugar beet, sugarcane and rice.

The work described in this thesis on fructan biosynthesis in chicory and in new platform crops has resulted in new insights that will lead new applied and fundamental research in this field.

Physiological ecology of the frankincense tree
Mengistu Woldie, T. - \ 2011
University. Promotor(en): Frans Bongers; G. Fetene, co-promotor(en): Frank Sterck. - S.l. : s.n. - ISBN 9789085859277 - 127
boswellia - koolstof - ecologie - plantenfysiologie - tappen (rubber) - bosgebieden - koolhydraten - bladoppervlakte - bomen - harsen - harswinning - ethiopië - carbon - ecology - plant physiology - tapping - woodlands - carbohydrates - leaf area - trees - resins - resin extraction - ethiopia

Keywords: Boswellia papyrifera, carbon balance, drylands, Ethiopia, frankincense, tapping

The degradation of frankincense tree dominated woodlands has been attributed to climatic
conditions and human activities. We lack however information on how such factors influence the
resource balance and productivity of trees. The aim of this study was to evaluate the impact of
resin tapping on the whole tree carbon gain, storage and allocation pattern of frankincense trees
(Boswellia papyrifera (Del.) Hochst) in the dry woodlands of northern Ethiopia. I hypothesized
that the intensive resin tapping of frankincense trees reduces tree vitality, particularly under
relatively dry conditions. I established experimental plots in the highland woodlands of
Abergelle and the lowland woodlands of Metema, and applied tapping treatments to similar sized
adult trees (DBH 20 +/- 3cm). For these trees I also collected data on leaf gas exchange, crown
traits, carbon storage, carbon allocation, growth and frankincense production during a period of
two years (2008-2009).
Trees follow similar leaf gas exchange patterns in contrasting environments, but differ in
annual crown carbon gain between highland and lowland sites. Highland trees of Boswellia had a
higher photosynthetic capacity, were exposed to higher light conditions, but had a shorter leaf
lifespan than lowland trees. Integrating these effects, I showed that the annual crown carbon gain
is higher in the highland trees than in lowland trees. Lowland trees are mainly constrained by
clouded conditions and resultant low light levels during the wet season, limiting their carbon
gain. Moreover, carbon gain was also restricted by atmospheric drought, and much less by soil
water deficit during the growing season. The production of frankincense was not affected by the
annual tree carbon gain implying that trees with smaller total leaf area may suffer sooner from
carbon starvation by tapping.
Tapping reduced storage carbohydrate concentrations in wood, bark and root tissues
indicating that continuous tapping depletes the carbon reserves. A large part of the carbohydrate
concentration in the plant tissues was starch. Boswellia trees have more total nonstructural
carbohydrates (TNC) concentrations and pool sizes in wood than in root and bark tissues.
Because tapped trees face depleting carbon storage pools during the dry tapping season and
cannot fully replenish these pools during the wet season, tapped trees may face higher risks of
carbon starvation compared to untapped trees in the long term.
Estimated total annual carbon sinks to the different plant components were 38-68% of the
annual carbon gain in both study sites. However, Boswellia trees also establish mycorrhizal
associations which may consume an additional 20% of gross primary production. On a wholetree
basis, the percentage of autotrophic respiration may exceed all other costs. The foliage
construction costs and incense production are the second and third largest carbon sinks,
respectively. Contrary to our expectation, the sum of all dry season carbon costs was higher than
the total amount of consumed TNC during the dry season. The high carbon costs during the dry
season imply that trees do not fully depend on TNC to pay for the carbon costs during the dry
season. With the exception of carbon allocation to foliage production and maintenance, a higher
gross primary production does not enhance an overall increase in carbohydrate investments in
the other sinks. Therefore, the carbon allocation pattern is constrained not exclusively by the
absolute amount of carbon gained but also by other factors.
The results clearly indicate that continuous tapping depletes the amount of stored carbon,
the leaf area production and the reproductive effort. These negative effects were however site
specific and could possibly be apparent sooner for smaller trees than for larger ones. Thus,
guidelines for resin tapping of Boswellia trees should consider tapping intensity, tapping
frequency, environmental conditions and tree size and should focus on maintaining vital trees
and populations for the future.

Background information and biorefinery status, potential and Sustainability: Task 2.1.2 Market and Consumers; Carbohydrates
Bos, H.L. ; Harmsen, P.F.H. ; Annevelink, E. - \ 2010
Wageningen : Wageningen UR - Food & Biobased Research (Star-Colibri Deliverable 2.1.2) - 28
koolhydraten - markten - biobased economy - chemie op basis van biologische grondstoffen - biopolymeren - bioraffinage - reststromen - coproductie - carbohydrates - markets - biobased chemistry - biopolymers - biorefinery - residual streams - coproduction
This report was produced to give an overview of present and future market for biorefinery products based on carbohydrates. Various studies show that there is a wealth of possible molecules and products that can be produced from carbohydrates. Carbohydrates already find significant application in starch products and cellulose plastics and fibres. However, for a biorefinery to operate in an economically sustainable way, applications for (preferably all) biomass ingredients need to be found. Presumably the optimal mix of applications will be a combination of larger volume/smaller value and smaller volume/higher value applications. For this study we therefore have taken a molecular approach. Looking at the size of possible end markets for the molecules that can be based on carbohydrates a number of main products come into view: dialcohols, dioic acids, 2,5 furan dicarboxylic acid and ethanol. These molecules with a wide application range can serve as basis targets for the carbohydrate stream of a biorefinery, provided the production processes are optimised to make them competitive to the petrochemical counterparts. Speciality applications for the resulting side streams will then need to be found on a case by case basis.
Plant - Microbiele Brandstofcel (MFC): exudate productie : het optimaliseren van wortelexudatie met een split-root systeem
Khodabaks, M. ; Blok, C. ; Berg, C.C. van den; Snel, J.F.H. - \ 2009
Bleiswijk : Wageningen UR Greenhouse Horticulture - 13
akkerbouw- en tuinbouwbedrijven - kassen - exudaten - wortelexudaten - secreties - aminozuren - organische zuren - micro-organismen - organische stof - suikers - koolhydraten - teelt onder bescherming - microbiële brandstofcellen - glastuinbouw - biobased economy - crop enterprises - greenhouses - exudates - root exudates - secretions - amino acids - organic acids - microorganisms - organic matter - sugars - carbohydrates - protected cultivation - microbial fuel cells - greenhouse horticulture
De plant microbiële brandstofcel of Plant Microbial Fuel Cell (Plant$MFC) is een technologie die het op basis van een nieuw principe mogelijk maakt direct elektriciteit of biofuels aan een plant te onttrekken, zonder dat deze geoogst hoeft te worden (Strik en Helderman, 2004). Levende planten zetten door fotosynthese zonne-energie om in energiehoudende biomassa zoals eiwitten, suikers, zetmeel, cellulose en ligine. Van de netto vastgelegde koolstof wordt doorgaans een fractie van 40 tot 60 % naar de wortels getransporteerd. Van de hoeveelheid koolstof getransporteerd naar het wortelstelsel wordt door planten een fractie van 50 tot 70 % uitgescheiden naar de bodem in oplosbare vorm (exudaten en secreties). Deze exudaten en secreties bestaan onder andere uit suikers, aminozuren, organische zuren en koolhydraten welke gemakkelijk door micro-organismen kunnen worden omgezet. De uitgescheiden organische stof kan deels door natuurlijk voorkomende micro-organismen worden omzet in electriciteit. Als deze electriciteit in de een of ander vorm wordt opgevangen en benut is sprake van een MFC. In een MFC is het zaak het aandeel en de activiteit van de electriciteit producerende micro-organismen hoog te maken en te houden
Schimmels veroorzaken merendeel van de plantenziekten : voortdurende wapenwedloop tussen plant en schimmel
Kierkels, T. ; Heuvelink, E. - \ 2008
Onder Glas 5 (2008)3. - p. 4 - 5.
schimmel - plantenziekteverwekkende schimmels - koolhydraten - assimilatie - ziekteresistentie - antagonisten - ondersteunende maatregelen - gewasbescherming - glastuinbouw - moulds - plant pathogenic fungi - carbohydrates - assimilation - disease resistance - antagonists - support measures - plant protection - greenhouse horticulture
Schimmels kunnen niet zelf assimileren en maken daarom gebruik van dat vermogen van planten. Cruciaal is dat ze planten moeten binnendringen om bij de koolhydraten te kunnen komen. Daartoe hebben ze tal van manieren ontwikkeld, mechanisch en chemisch. De plant op zijn beurt zet blokkades en chemie in om de schimmels te weren. Een goed groeiende, gezonde plant is in het algemeen weerbaar genoeg. Inzicht in de 'wapenwedloop' tussen schimmel en plant wijst een teler de weg naar ondersteunende maatregelen
Onderzoek moet uniformer stek bij siergewassen opleveren (o.a. interview met Hendrik-Jan van Telgen)
Staalduinen, J. van; Telgen, H.J. van - \ 2007
Onder Glas 4 (2007)8. - p. 54 - 55.
siergewassen - rozen - potplanten - vermeerderingsmateriaal - stekken - fotosynthese - meting - technieken - koolhydraten - beworteling - onderzoek - glastuinbouw - snijbloemen - ornamental crops - roses - pot plants - propagation materials - cuttings - photosynthesis - measurement - techniques - carbohydrates - rooting - research - greenhouse horticulture - cut flowers
Het slagingspercentage en de uniformiteit van stekken worden mede bepaald door inwendige factoren, zoals fotosynthesecapaciteit en de koolhydraatstatus in het blad. Met behulp van diverse meettechnieken onderzoekt een projectteam of op basis van de gemeten waarden voorspellingen mogelijk zijn over de mate van beworteling en uitgroei. Als dat zo is, kunnen deze technieken bijdragen aan optimalisatie van de bedrijfsprocessen op vermeerderingsbedrijven
Het effect van voersamenstelling op bacteriële darmaandoeningen bij varkens = The effect of feed composition on bacterial intestinal diseases in pigs
Meulen, J. van der; Peet-Schwering, C.M.C. van der - \ 2007
Lelystad : Animal Sciences Group (Rapport / Animal Sciences Group, Divisie Veehouderij 83) - 14
varkens - dierhouderij - diervoeding - voersamenstelling - koolhydraten - darmziekten - diergezondheid - bacterieziekten - dysenterie - varkensdysenterie - colitis - enteritis - salmonellose - pigs - animal husbandry - animal nutrition - feed formulation - carbohydrates - intestinal diseases - animal health - bacterial diseases - dysentery - swine dysentery - salmonellosis
Feed composition, and especially carbohydrate composition, may affect the development of enteric bacterial diseases. Also the kind of feed ingredients (soybean or not) and feed treatment (milling size, pelletizing, fermentation) may be important. A more coarse grinding, no pelletizing and fermentation may be preferable in the reduction of the development of enteric bacterial diseases.
Chemical composition of lamina and sheath of Lolium perenne as affected by herbage management
Hoekstra, N.J. ; Struik, P.C. ; Lantinga, E.A. ; Schulte, R.P.O. - \ 2007
NJAS Wageningen Journal of Life Sciences 55 (2007)1. - ISSN 1573-5214 - p. 55 - 73.
afsnijhoogte - grasbestand - voedergewassen - lolium perenne - hergroei - rotaties - chemische samenstelling - graslandbeheer - voedingswaarde - lignine - totale hoeveelheid droge stof - koolhydraten - stikstof - vezelgehalte - bloeiwijzen - cutting height - herbage - fodder crops - regrowth - rotations - chemical composition - grassland management - nutritive value - lignin - total solids - carbohydrates - nitrogen - fibre content - inflorescences - water-soluble carbohydrate - neutral detergent fiber - dairy-cows - nitrogen application - nutritive-value - ryegrass varieties - animal nutrition - milk-production - rumen function - l. cultivars
The quality of grass in terms of form and relative amounts of energy and protein affects both animal production per unit of intake and nitrogen (N) utilization. Quality can be manipulated by herbage management and choice of cultivar. The effects of N application rate (0, 90 or 390 kg N ha¿1 year¿1), duration of regrowth period (2¿3, 4¿5, or 6¿7 weeks), and cutting height (8 or 12 cm) on the mass fractions of nitrogen (N), water-soluble carbohydrates (WSC), neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin and ash in lamina and sheath material of a high-sugar (Aberdart) and a low-sugar (Respect) perennial ryegrass (Lolium perenne) cultivar, were studied in a factorial field experiment during four seasons in 2002 and 2003. Expressing NDF and ADF mass fractions in g per kg WSC-free dry matter (DM) increased the consistency of treatment effects. The high-sugar cultivar had generally higher WSC mass fractions than the low-sugar cultivar, especially during the late season. Moreover, the relative difference in WSC mass fraction between the two cultivars tended to be higher for the lamina material than for the sheath material, which suggests that the high-sugar trait may be more important under grazing conditions, when lamina forms the bulk of the intake, than under mowing regimes. Longer regrowth periods and lower N application rates increased WSC mass fractions and decreased N mass fractions; interactions between regrowth period and N application rate were highly significant. The mass fractions of NDF and ADF were much less influenced. The NDF mass fraction in terms of g per kg WSC-free DM tended to be higher at lower N application rates and at longer regrowth periods. The effect of cutting height on herbage chemical composition was unclear. In conclusion, high-sugar cultivars, N application rate and length of the regrowth period are important tools for manipulating herbage quality.
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