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.

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Nitrogen-to-Protein Conversion Factors for Three Edible Insects : Tenebrio molitor, Alphitobius diaperinus, and Hermetia illucens
Janssen, Renske H. ; Vincken, Jean Paul ; Broek, Lambertus A.M. van den; Fogliano, Vincenzo ; Lakemond, Catriona M.M. - \ 2017
Journal of Agricultural and Food Chemistry 65 (2017)11. - ISSN 0021-8561 - p. 2275 - 2278.
Alphitobius diaperinus - amino acids - black soldier fly - edible insects - Hermetia illucens - lesser mealworm - nitrogen-to-protein conversion factor (Kp) - protein extraction - Tenebrio molitor - yellow mealworm

Insects are considered a nutritionally valuable source of alternative proteins, and their efficient protein extraction is a prerequisite for large-scale use. The protein content is usually calculated from total nitrogen using the nitrogen-to-protein conversion factor (Kp) of 6.25. This factor overestimates the protein content, due to the presence of nonprotein nitrogen in insects. In this paper, a specific Kp of 4.76 ± 0.09 was calculated for larvae from Tenebrio molitor, Alphitobius diaperinus, and Hermetia illucens, using amino acid analysis. After protein extraction and purification, a Kp factor of 5.60 ± 0.39 was found for the larvae of three insect species studied. We propose to adopt these Kp values for determining protein content of insects to avoid overestimation of the protein content.

Trimming proline dehydrogenase : protein and cofactor minimization
Huijbers, Mieke M.E. - \ 2017
Wageningen University. Promotor(en): Willem van Berkel. - Wageningen : Wageningen University - ISBN 9789463430517 - 181
proline - thermus thermophilus - enzymes - amino acids - binding proteins - catalysts - enzymen - aminozuren - bindende eiwitten - katalysatoren

Proline is one of the proteinogenic amino acids and one of the most abundant amino acids in the cell. Next to serving as one of the non-essential amino acids, proline also has a central role in metabolism. In Chapter 1, the different functions of this imino acid are described, as well as the proline metabolic enzymes. The focus is on the enzyme proline dehydrogenase (ProDH), which catalyzes the flavin-dependent conversion of L-proline to Δ1-pyrroline-5-carboxylate (P5C). Malfunctioning of this enzyme has severe implications for human health and has been associated with tumorigenesis and schizophrenia.

This thesis deals with the engineering and biochemical characterization of Thermus thermophilus ProDH (TtProDH) in order to gain more insight into the structure-function relationship of this thermo-resistant flavoenzyme. TtProDH is a membrane-associated protein and recombinant soluble forms of the enzyme have only been obtained in limited amounts. Chapter 2 describes the heterologous production of TtProDH in Escherichia coli. Using maltose-binding protein (MBP) as solubility tag, high yields of active holoenzyme are obtained. The MBP-tag can be efficiently removed from the fusion protein with trypsin, yielding native TtProDH. This enzyme is thermotolerant as well as solvent tolerant; however, both fused and clipped TtProDH are prone to aggregation. In Chapter 3, we show that the hydrophobic N-terminal helix of TtProDH is responsible for this non-native self-association. Phe10 and Leu12, located at the protein surface, were replaced by glutamates, generating the F10E/L12E (EE) variant of MBP-TtProDH. This more polar variant exclusively forms tetramers and exhibits excellent catalytic features. Specific removal of the MBP-tag of the EE variant is less easy than for WT, as trypsinolysis of the fusion enzyme leads to degradation of TtProDH. Since the MBP tag does not influence the spectral and catalytic properties of the enzyme, further experiments were performed with MBP-tagged variants of TtProDH.

ProDH has a distorted (βα)8 TIM-barrel fold which is conserved throughout the PutA/ProDH family. In contrast, the N-terminal sequence of ProDH is poorly conserved. TtProDH contains, next to the distorted TIM-barrel, three N-terminal helices, αA, αB and αC, of which the function is not well understood. In Chapter 4, we describe the characterization of helical arm-truncated variants, lacking respectively one (ΔA), two (ΔAB), or three (ΔABC) N-terminal helices. All three variants show flavin properties that are highly similar to EE, indicating no changes in the microenvironment of the flavin isoalloxazine ring. ΔA and ΔAB are highly active tetramers, whereas removal of the complete N-terminal arm (ΔABC) results in poorly active dimers. Furthermore, EE, ΔA and ΔAB rapidly react with the suicide inhibitor N-propargylglycine, while ΔABC is not capable of forming a flavin adduct with N-propargylglycine. This indicates that helix αC has a crucial role in both the oligomerization and activity of TtProDH. Closer examination revealed an ionic interaction as well as a hydrophobic patch between helices αC and α8, the latter helix being crucial for substrate recognition. To investigate the functional role of helix αC in further detail, additional enzyme variants were created that disrupt the interactions between both helices. While disrupting the ionic interaction had minor effects, disrupting the hydrophobic patch leads to dimer formation, loss of activity and decreased reactivity with N-propargylglycine. This supports that helix αC is crucial for TtProDH catalysis and tetramerization through positioning of helix α8.

The quaternary structure of TtProDH was investigated in more detail in Chapter 5. Two ionic interactions at the dimeric interface were selectively disrupted by changing Asp205 and Glu207 of TtProDH variants EE, ΔA, ΔAB and ΔABC into lysines. These KK-variants form monomers (except for EE KK, which forms dimers) and have improved catalytic properties at moderate temperatures compared to their non-KK counterparts. However, their melting temperatures are decreased by more than 20 °C. This indicates that a trade-off is made between thermostability and catalytic activity.

In Chapter 6, we studied the cofactor binding of TtProDH. Flavoenzymes contain either FAD or FMN as cofactor. FAD often binds to a Rossmann fold, while FMN prefers a TIM-barrel or flavodoxin-like fold. Proline dehydrogenase is denoted as an exception: it possesses a TIM barrel-like fold while binding FAD. To study the cofactor binding of TtProDH, we produced MBP-TtProDH EE in its apoform using a riboflavin auxotrophic E. coli strain. Reconstitution of the enzyme with either FAD or FMN revealed that MBP-TtProDH has no preference for FAD as cofactor. Kinetic parameters of both holo-FAD and holo-FMN are similar, as are the dissociation constants for FAD and FMN release. We show that the holo form of MBP-TtProDH, as produced in E. coli TOP10 cells, contains about three times more FMN than FAD. In addition, we obtained the crystal structure TtProDH ΔABC, which shows no electron density for an AMP moiety of the cofactor. This indicates the presence of mainly FMN in the enzyme. The capability of TtProDH to display equal properties with both cofactors is unique for flavoenzymes, and classification of TtProDH as an FAD-containing enzyme should be reconsidered.

In Chapter 7, we discuss the novel findings described in this thesis and put them in a broader perspective. We have created a minimalist ProDH that is an excellent catalyst, but is deprived of all structural features that are unnecessary for in vitro functioning. Our results expand the knowledge on the structure-function relationship of ProDHs, and give insight into enzyme functionality from an industrial perspective. We also discuss how this knowledge might be used in future studies for a better understanding of the properties of eukaryotic ProDHs, with a special interest in the human enzyme.

Protein quality of pig diets : processing effects on amino acid digestibility and post-absorptive utilization
Hulshof, Tetske - \ 2016
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Paul Bikker; Thomas van der Poel. - Wageningen : Wageningen University - ISBN 9789462579026 - 175
pigs - protein quality - pig feeding - feeds - feed processing - amino acids - protein digestibility - digestive absorption - protein utilization - nutrition physiology - animal nutrition - varkens - eiwitkwaliteit - varkensvoeding - voer - voedermiddelbewerking - aminozuren - eiwitverteerbaarheid - verteringsabsorptie - eiwitgebruik - voedingsfysiologie - diervoeding

The increasing world population and per capita income imposes a risk for protein scarcity. It is, therefore, necessary to use current ingredients more efficiently which includes the accurate assessment of protein quality before inclusion in animal diets. Protein quality is defined in this thesis as the capacity of a dietary protein to meet a pig’s requirement for nitrogen (N) and amino acids (AA) to meet a particular production target. Protein quality is influenced by processing applied to feed ingredients which may lead to the formation of Maillard reaction products (MRP) or cross-link products. The Maillard and cross-link reactions mainly involve lysine (Ly)s and their products may decrease ileal crude protein (CP) digestibility. During the acid hydrolysis step used to analyze AA, part of the early MRP revert back to Lys. This reverted Lys is not bioavailable for animals. Therefore, methods that specifically analyze Lys with a free ε-amino group (that is, not bound to other nutrients) have been developed. The guanidination reaction with O-methylisourea (OMIU) is one such method. The initial aim of this thesis was to evaluate the ileal digestible reactive Lys assay as a more accurate measure for protein quality of processed protein sources than the ileal digestible total Lys assay. Soybean meal (SBM) and rapeseed meal (RSM) were used as sole protein sources throughout this thesis. Processing of SBM and RSM by toasting at 95°C for 30 min in the presence of a sugar-rich lignosulfonate was used as model for over-processed protein sources.

Digestibility, post-absorptive utilization, and pig growth performance

In Chapter 2, protein quality in processed protein sources was determined using the content of AA, OMIU-reactive Lys, MRP, and lysinoalanine (LAL; as cross-link product), the standardized ileal digestibility (SID) of AA and OMIU-reactive Lys and pig growth performance. The SBM and RSM diets contained furosine and carboxymethyllysine (CML) as MRP, and LAL indicating that the Maillard and cross-link reactions had taken place in SBM and RSM, presumably during the oil extraction/desolventizing process. The amounts of furosine, CML, and LAL were elevated in the pSBM and pRSM diets due to further processing. Processing resulted in a reduction in total and OMIU-reactive Lys contents, a decreased pig growth performance as determined by the gain to feed ratio (G:F), and the SID of CP, AA, and OMIU-reactive Lys. The SID AA contents of the protein sources from Chapter 2 were used to formulate the diets of the main in vivo experiment (Chapters 3 and 4). In this experiment, six experimental diets were used of which four contained either SBM, pSBM, RSM, or pRSM as sole protein source. The remaining two experimental diets contained pSBM or pRSM and were supplemented with crystalline AA to the same SID AA levels as the SBM or RSM diet. These supplemented diets were used to verify that processing affected AA digestibility rather than post-absorptive AA utilization. The effects of processing on CP digestibility and N solubilization along the small intestine, metabolic load as assessed by organ weight, and nutrient composition of the empty body of growing pigs are described in Chapter 3. The small intestine was divided in three segments of similar length and digesta was collected from the last 100 cm of each segment. The amount of insoluble N as a fraction of N in digesta at each small intestinal segment was not affected by processing. Thus, the reduced SID of CP and AA reported in Chapter 2 was not caused by a reduced N solubility but by a general increase of N in digesta. Processing reduced the SID of CP, CP content in the empty body, and G:F. Supplementing crystalline AA to diets containing pSBM or pRSM increased the CP content and G:F to the level of the SBM and RSM diets. Processing also reduced the weight of several organs and supplementing crystalline AA restored organ weight. The effects of processing on whole body AA composition, nutrient retention, and post-absorptive utilization of AA in growing pigs are described in Chapter 4. Post-absorptive AA utilization was calculated as percentage of SID AA intake used for AA retention. Processing affected the AA composition of protein in the organ fraction (that is, empty organs and blood), carcass, and empty body. The Lys concentration in body protein was mainly reduced by processing. Supplementing crystalline AA restored the AA composition of body protein for SBM and RSM. Processing reduced AA retention and again supplementing crystalline AA restored AA retention for both SBM and RSM. Since crystalline AA were supplemented on an SID AA basis, the results indicated that processing affected AA digestibility but not post-absorptive AA utilization. Thus, correcting AA retention for SID AA intake would result in a similar post-absorptive AA utilization which was found for most AA for the RSM diets. However, the post-absorptive AA utilization was lower for the pSBM diet than for the SBM diet which might be related to an imbalanced AA supply after absorption in the first diet.

The assessment of ileal digestibility and utilization is expensive and laborious. Therefore, two alternative in vitro methods for determining protein digestibility for processed protein sources were evaluated (Chapter 5). The protein digestibility determined using the pH-STAT method and a 2-step enzymatic method was compared with the in vivo SID of CP reported in Chapter 2. Initial pH and the degree of hydrolysis assessed in the pH-STAT method were positively correlated to SID of CP. Protein digestibility determined with the 2-step enzymatic method, simulating digestion in the stomach and small intestine, tended to correlate to SID of CP. Both the 2-step enzymatic method and pH-STAT method were suitable alternatives for the assessment of SID of CP. However, only four ingredients were tested. The suitability of the methods should be further studied using multiple (processed) feed ingredients before they can be used as alternatives for in vivo assays.

Reactive Lys analysis

O-methylisourea was reported to bind specifically to the ε-amino group of Lys. The results of Chapter 2, however, cast doubt on the specificity of OMIU to react only with the ε-amino group of Lys. A series of experiments was conducted to study this specificity (Chapter 6). Incubating crystalline L-Lys with OMIU under standard conditions (OMIU pH of 10.6, OMIU to AA ratio of 1000:1, and reaction time of 7 d) resulted in a low homoarginine (that is, Lys with OMIU bound to its ε-amino group) recovery. The reaction of OMIU with the α-amino group of Lys was confirmed by mass spectrometry analysis with double derivatized Lys being identified. Several reaction conditions (OMIU pH, OMIU to Lys ratio, and reaction time) were studied but none of these resulted in 100% recovery of homoarginine. Binding of OMIU to the α-amino group of Lys could result in an underestimation of the reactive Lys content when significant levels of Lys with a free α-amino group (that is, crystalline L-Lys (HCl), free and N-terminal Lys) are present in food/feed ingredients, diets, and ileal digesta. The free Lys content in food/feed ingredients was on average 1.3% of total Lys. The free Lys content can be substantial in certain diets and was reported to be 13% of total Lys in ileal digesta. The latter might result in an overestimation of the OMIU-reactive Lys digestibility. The reaction of OMIU with α-amino groups may necessitate analysis of free Lys to accurately quantify reactive lysine in samples containing a large proportion of Lys with a free α-amino group.

The results presented in this thesis indicate that the effects of processing on SID of CP and AA, body composition, nutrient retention, post-absorptive AA utilization, and growth performance could be substantial. These effects should, therefore, be taken into account when using processed feed ingredients in diets for growing pigs. The extent of protein damage in feed ingredients can be assessed by the analysis of OMIU-reactive and total Lys, MRP, and cross-link products. However, OMIU-reactive Lys only provides accurate results when samples contain small levels of Lys with a free α-amino group (that is, crystalline L-Lys (HCl), free and N-terminal Lys). When samples contain significant levels of Lys with a free α-amino group, it is recommended to use standard guanidination conditions (OMIU pH of 10.6, OMIU to AA ratio of 1000:1, and reaction time of 7 d) to convert protein-bound Lys to homoarginine and to separately analyze such samples for free Lys.

Biorefinery of proteins from rubber plantation residues
Widyarani, R. - \ 2016
Wageningen University. Promotor(en): Johan Sanders, co-promotor(en): Marieke Bruins; E. Ratnaningsih. - Wageningen : Wageningen University - ISBN 9789462576643 - 236 p.
biorefinery - biomass conversion - rubber - rubber plants - protein extraction - latex - hydrolysis - hydrophobicity - amino acids - wheat gluten - residual streams - biobased economy - bioraffinage - biomassaconversie - rubberplanten - eiwitextractie - hydrolyse - hydrofobiciteit - aminozuren - tarwegluten - reststromen

Biorefinery of rubber tree side streams could add economic value and income for farmers, who already grow the trees for latex production. The objective of this research was to design a process for the recovery of proteinaceous fractions from rubber tree. The aimed applications were expected to be suitable for local use, particularly in Indonesia, being one of the world’s largest rubber producers. Rubber seed was selected as a model biomass based on its availability (21-144 kg-protein/ha) and its oil content that enables the combination of protein and biodiesel productions within a biorefinery framework. Experimental works were focused on three parts: separation of protein and oil from rubber seed kernel, enzymatic hydrolysis of rubber seed protein into amino acids, and separation of amino acids from hydrolysate. Using alkaline extraction, up to 80% protein from the total original amount of protein in the kernel could be recovered in the extract, comparable to protein recoveries from other oilseeds and oilseed cakes. Seed type and pre-treatment had the most influence on protein recovery. Following protein extraction, the extracted proteins were recovered via isoelectric precipitation, resulting in rubber seed protein concentrate that can be used as such or can be processed further. Different protease combinations were used to hydrolyse rubber seed protein concentrate. After 24 h hydrolysis of rubber seed protein, up to 53% degree of hydrolysis and 35% protein recovery as free amino acids could be achieved. Combination of Pronase + Peptidase R resulted in the highest recovery and concentration of hydrophobic amino acids (phenylalanine, leucine, isoleucine, tyrosine, tryptophan, valine, methionine, and proline) in the hydrolysate. Some hydrophobic amino acids are essential in human and farm animal diets, therefore they can potentially be applied as a group in food and feed. Ethanol was used as an anti-solvent for selective precipitation of amino acids. Ethanol was able to selectively increase the hydrophobic amino acid fraction in rubber seed protein hydrolysate from 59% (mol/mol) in the starting material to 76% in the supernatant. Leucine and valine contributed most to this increase. The results of this study show that rubber seed proteins can be applied locally as animal feed or in industries for technical applications.

Het effect van aminozuuraanbod en -samenstelling van het voer op zoötechnische prestaties van beren gehuisvest onder verschillende sanitaire condities
Meer, Y. van der; Gerrits, W.J.J. ; Jansman, A.J.M. - \ 2016
Wageningen UR Livestock Research (Livestock Research rapport 938) - 32 p.
beren (varkens) - aminozuren - eiwit - voedselsamenstelling - varkensvoeding - mestresultaten - hygiëne - varkenshouderij - zoötechniek - dierlijke productie - boars - amino acids - protein - food composition - pig feeding - fattening performance - hygiene - pig farming - zootechny - animal production
Dit experiment was opgezet om het effect van eiwitniveau (normaal versus verlaagd) en aminozuursamenstelling in het rantsoen te evalueren op de technische prestaties van beren gehuisvest onder een tweetal sanitaire condities.
Essential amino acids in the gluten-free diet and serum in relation to depression in patients with celiac disease
Hees, Nathalie J.M. van; Giltay, E.J. ; Tielemans, S.M.A.J. ; Geleijnse, J.M. ; Puvill, Thomas ; Janssen, Nadine ; Does, Willem van der - \ 2015
Coeliac disease - gluten intolerance - psychopathology - depression - diet adherence - gluten-free diet - amino acids - tryptophan - tyrosine - Trp/LNAA ratio
Introduction: Celiac disease (CD) is associated with an increased risk of major depressive disorder, possibly due to deficiencies in micronutrients in the gluten-free diet. We aimed to investigate whether essential amino acids (i.e., the precursors of serotonin, dopamine and other neurotransmitters) are depleted in the diet and serum of CD patients with major depressive disorder. Methods: In a cross-sectional study we assessed dietary intake of amino acids and serum levels of amino acids, including in 77 CD patients on a gluten-free diet and in 33 healthy controls. , major depressive disorder was assessed with structured interviews (using the Mini International Neuropsychiatric Interview Plus). Dietary intake of amino acids was assessed (using a 203-item food frequency questionnaire), and serum levels of amino acids were assessed. Results: Participants had a mean age of 55 years and 74% were women. The intake of vegetable protein was significantly lower in CD patients than in healthy controls (mean difference of 7.8 g/d; 95% CI: 4.7 - 10.8), as were serum concentrations of tyrosine, phenylalanine and tryptophan (all p < 0.005). However, within the CD patient groups, the presence of major depressive disorder (n = 42) was not associated with intake or serum levels of essential amino acids. Conclusions: We found that patients with CD on a long-term successful gluten-free diet, with good adherence, consume significantly less vegetable protein than controls, and their serum levels of several essential amino acids were also lower in CD versus controls. Despite its potential adverse effect, intake and serum levels of essential amino acids were not related to major depression.
DNA : the recipe book for all the processes in the plant : all cells have the same generic information
Heuvelink, E. ; Kierkels, T. - \ 2015
In Greenhouses : the international magazine for greenhouse growers 4 (2015)4. - ISSN 2215-0633 - p. 12 - 13.
dna - plantenveredeling - genetische modificatie - transfer rna - messenger rna - ribosomen - eiwitten - aminozuren - enzymen - mutaties - plant breeding - genetic engineering - ribosomes - proteins - amino acids - enzymes - mutations
It’s sometimes called a blueprint: DNA, the carrier of genetic information. But the term recipe book covers it better. It explains how the plant can respond to changing conditions. Plant breeders take advantage of natural variations in DNA. Genetic modification can make their job easier.
Fulfilling 100% organic poultry diets: concentrates : ICOPP Technical Note 1
Crawley, K. ; Krimpen, M.M. van - \ 2015
ICOPP Consortium
pluimveehouderij - pluimveevoeding - biologische landbouw - eiwitbronnen - aminozuren - voedergewassen - poultry farming - poultry feeding - organic farming - protein sources - amino acids - fodder crops
This guide analyses the potential of locally produced and novel protein sources as viable, alternative feed sources for the organic poultry industry.
Impact of health status on amino acid requirements of growing pigs : towards feeding strategies for farms differing in health status
Kampman-van de Hoek, E. - \ 2015
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Walter Gerrits; Alfons Jansman. - Wageningen : Wageningen University - ISBN 9789462573437 - 184
varkens - afmesten - diergezondheid - aminozuren - voedingsstoffenbehoeften - voedingseiwit - aminozuurmetabolisme - stikstofretentie - immuniteitsreactie - immuunsysteem - varkensvoeding - diervoeding - pigs - finishing - animal health - amino acids - nutrient requirements - dietary protein - amino acid metabolism - nitrogen retention - immune response - immune system - pig feeding - animal nutrition


There is large variation in the production performance of commercial growing-finishing pig farms. This variation even exists when pigs have a similar genetic background and fed similar diets. The health status is one of the major factors contributing to this large variation in pig performance, as activation of the immune system can decrease feed intake, body weight gain and increase nutrient utilisation for immune system functioning. As a consequence, amino acids (AA) are repartitioned from skeletal muscle deposition towards utilisation for immune system functioning. Current requirement estimates for growing-finishing pigs are formulated to maximize protein deposition for growth and do not take into account the increased utilization of AA for immune functioning as induced by health challenging conditions. This lack of knowledge hampers the ability of feed manufacturers to optimize diets and improve pig performance. The main objective of the present thesis was to quantify the effect of health status on AA requirements for body protein deposition and for immune system functioning of growing pigs.

A health status web was developed as a tool to categorize growing-finishing pig farms on the basis of their health status. The health status web can be of use for feed manufacturers to develop targeted strategies to accommodate the nutritional requirements of pigs belonging to particular groups of farms sharing a common health status. A dose-response technique was developed, which is a simple, accu­rate technique to quantitatively estimate changes in AA requirements of individual meal-fed pigs. Nevertheless, a minimum time period of 21 days is required for each individual, which makes the technique inappropriate for studying the effect of immune system activation on AA requirements. The combined measurements of whole body N retention, plasma irreversible loss rate (ILR, i.e. the amount of free AA that disappears per unit of time from the plasma pool for protein synthesis or oxidation), urea entry and appearance of 13C into plasma proteins, provided insight into the consequences of immune system activation on AA metabolism.

Pigs selected from a farm with a suboptimal health status had greater serum haptoglobin, lower serum albumin concentrations, and greater leukocyte counts in blood at the start of the experiment than pigs selected from a farm with a high health status, indicating a higher level of immune system activation. The occurrence of compensatory gain in pigs from a farm characterized as having a suboptimal health status proves, however, that it is difficult to maintain a contrast in health status, and that pigs can adapt quickly to a change in housing conditions. In the absence of effects on feed intake, health challenging conditions may affect performance due to alterations in post-absorptive AA metabolism, as also indicated by increased urinary N losses, and a tendency for a reduced N retention and a lower utilization of digestible N for N retention in pigs with a systemic inflammation, or by a reduction in faecal nutrient digestibility as indicated for dry matter and N in pigs from a farm with a suboptimal health status. The observed changes in protein and AA metabolism after immune stimulation imply that especially tryptophan may become limiting during immune system activation, whereas lysine becomes excessive. Furthermore, the utilization of methionine, tyrosine, and valine for immune system functioning seems to increase in pigs with a systemic lung inflammation. In addition, the dietary AA or protein supply was able to modulate the acute phase response pre- and post-challenge, stressing the importance of an adequate dietary AA supply for appropriate functioning of the immune system of growing-finishing pigs.

Before implementing targeted feeding strategies for farms sharing a common health status, future research should be conducted to study the possible beneficial effects of increasing the dietary supply of particularly tryptophan, methionine, tyrosine, and valine relative to lysine for immune system function and for body protein deposition in pigs from farms with a different health status.

Estimating requirements for apparent faecal and standardised ileal digestible amino acids in laying hens by a metaanalysis approach
Krimpen, M.M. van; Veldkamp, T. ; Riel, J.W. van; Khaksar, V. ; Hashemipour, H. ; Blok, M.C. ; Spek, W. - \ 2015
Wageningen : Wageningen UR Livestock Research (Livestock research report 848) - 71
hennen - aminozuren - voer - meta-analyse - verteerbaarheid - eiwitverteerbaarheid - dunne darm - voedingsstoffengehalte - voedingsstoffenbehoeften - voedingsbehoeften - pluimvee - pluimveevoeding - hens - amino acids - feeds - meta-analysis - digestibility - protein digestibility - small intestine - nutrient content - nutrient requirements - feed requirements - poultry - poultry feeding
The aim of the present study is to update the requirements for the essential amino acids of laying hens, both on a AFD and SID basis, by performing a meta-analysis on dose-response studies used to derive requirement values for essential amino acids (lysine, methionine+cysteine, threonine and tryptophan) in laying hens as presented in the literature. In this meta-analysis, the data are fitted by use of the Wood equation (see paragraph 2.4). The amino acid intake levels for realizing maximal rate of lay, egg mass and feed efficiency are provided. The amino acid requirements for use in practice are based on the amino acid intake levels at which 95% of these maximum responses were reached.
Specific conversion of amino acids as a means for their separation
Teng, Y. - \ 2014
Wageningen University. Promotor(en): Johan Sanders, co-promotor(en): Elinor Scott. - Wageningen : Wageningen University - ISBN 9789462570658 - 205
aminozuren - scheiding - elektrodialyse - conversie - chemicaliën uit biologische grondstoffen - onderzoek - biobased economy - amino acids - separation - electrodialysis - conversion - biobased chemicals - research
Aminozuren (AZ) zijn interessante uitgangspunten voor stikstofhoudende (amine) chemicaliën. Zij kunnen gewonnen worden als mengsel uit de hydrolyse van potentieel goedkope eiwitten verkregen van de bijproducten van de biobrandstofproductie of agrarische en voedselafvalstromen. Echter, AZ verkregen van zulke bronnen bevinden zich in een mengsel. Hierdoor is een scheiding nodig om de individuele AZ te verkrijgen voor vervolgomzettingen en toepassingen. Electrodialyse (ED) is een veelbelovende scheidingsmethode die toegepast kan worden in continue modus en op grote schaal.
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
Effect of vegetable diets versus diets with processed animal proteins on performance and health status of laying hens = Effecten van plantaardig voer versus voer met dierlijke eiwitten op productieprestaties en gezondheidsstatus van leghennen
Veldkamp, T. ; Krimpen, M.M. van; Jansman, A.J.M. - \ 2008
Wageningen : Animal Sciences Group (Rapport / Wageningen UR, Animal Sciences Group 165) - 18
pluimveehouderij - pluimvee - vleesbeendermeel - vleesmeel - eiwit - aminozuren - mineralen - poultry farming - poultry - meat and bone meal - meat meal - protein - amino acids - minerals
Meat and bone meal and meat meal in diets and their effects on performance and health status of laying hens has been reviewed. Properties of dietary animal proteins are compared with dietary vegetable proteins and possible causative factors for differences in performance and health are described in this report
Nutrient synchrony in preruminant calves
Borne, J.J.G.C. van den - \ 2006
Wageningen University. Promotor(en): Martin Verstegen, co-promotor(en): Walter Gerrits. - [S.l.] : S.n. - ISBN 908504524X - 197
vleeskalveren - diermodellen - kalvervoeding - voedingsstoffenbeschikbaarheid - tijd - eiwitmetabolisme - energiemetabolisme - aminozuren - glucose - synchronisatie - groei - mestresultaten - veal calves - animal models - calf feeding - nutrient availability - time - protein metabolism - energy metabolism - amino acids - synchronization - growth - fattening performance
Postprandial fate of amino acids: adaptation to molecular forms
Nolles, J.A. - \ 2006
Wageningen University. Promotor(en): Martin Verstegen, co-promotor(en): Victor Schreurs. - S.l. : S.n. - ISBN 9085043425 - 120
ratten - diermodellen - aminozuren - diëten - diervoeding - oxidatie - metabolisme - adaptatie - darmabsorptie - voedingsfysiologie - rats - animal models - amino acids - diets - animal nutrition - oxidation - metabolism - adaptation - intestinal absorption - nutrition physiology
Allermatch / [compiled by] RIKILT, Institute of Food Safety and Plant Research International
RIKILT, Institute of Food Safety, ; Plant Research International, - \ 2004
Wageningen : Wageningen UR
allergies - allergens - amino acids - amino acid sequences - proteins - allergieën - allergenen - aminozuren - aminozuursequenties - eiwitten
Allermatch is a database where you can compare the amino acid sequence of a protein of interest with sequences of allergenic proteins. This database carries out automatically the procedures for predicting the potential allergenicity of proteins by bioinformatics approaches as recommended by the Codex alimentarius and FAO/WHO Expert consultation on allergenicity of foods derived through modern biotechnology. The features of the Allermatch database allow the user in a user-friendly and time-saving manner to enter the input sequence and retrieve, with a few mouse-clicks, the outcomes of interest in an accurate, concise, and comprehensible format.
Zomereenden met wintergroei
Krimpen, M.M. van; Buisonjé, F.E. de; Hoekman, J.J. - \ 2004
De Pluimveehouderij 34 (2004)8. - ISSN 0166-8250 - p. 10 - 11.
eendenvoeding - eenden - voersamenstelling - voederconversie - aminozuren - groei - omgevingstemperatuur - energieopname - slachtdieren - karkaskwaliteit - duck feeding - ducks - feed formulation - feed conversion - amino acids - growth - environmental temperature - energy intake - meat animals - carcass quality
In de zomerperiode, bij hoge omgevingstemperaturen, blijft de energieopname en de groei van vleeseenden achter. Is dat met meer energie en meer aminozuren in het voer te verbeteren, zonder dat de slachtkwaliteit verslechtert? Het Praktijkonderzoek van de Animal Sciences Group van Wageningen UR in Lelystad heeft dit onderzocht
Formation of Amino Acid Derived Cheese Flavour Compounds
Smit, B.A. - \ 2004
Wageningen University. Promotor(en): J.T.M. Wouters; Gerrit Smit, co-promotor(en): W.J.M. Engels. - Wageningen : S.n. - ISBN 9058089967 - 127
geurstoffen en smaakstoffen - aldehyden - kazen - melkzuurbacteriën - aminozuren - aroma - fermentatieproducten - flavour compounds - aldehydes - cheeses - lactic acid bacteria - amino acids - fermentation products
Dormancy, activation and viability of Rhizopus oligosporus sporangiospores
Thanh, N.V. - \ 2004
Wageningen University. Promotor(en): Frans Rombouts; Tran Phuoc Duong, co-promotor(en): Rob Nout. - Wageningen : s.n. - ISBN 9085040981 - 114
rhizopus microsporus - schimmelsporen - sporangia - slaaptoestand - levensvatbaarheid - entstof - zuursels - aminozuren - tempé - fungal spores - dormancy - viability - inoculum - starters - amino acids - tempeh
Mathematical analysis of [13CO2]-expiration curves from human breath tests using [1-13C]-amino acids as oral substrate
Schreurs, V.V.A.M. ; Krawielitzki, K. - \ 2003
In: Progress in research on energy and protein metabolism / Souffrant, W.B., Metges, C.C., Rostock-Warnemünde, Germany : Wageningen Academic Publishers (EAAP publication 109) - ISBN 9076998248 - p. 239 - 242.
eiwitmetabolisme - aminozuren - isotopenlabelling - koolstof - adem - analyse - protein metabolism - amino acids - isotope labeling - carbon - breath - analysis
A [13CO2]-breath test examines the expiration of [13CO2] as function of time after oral intake of a [13C]-labelled test substrate (single dose). In clinical settings, breath test studies are often used as a simple and non-invasive tool to diagnose the activity of metabolic functions. From a nutritional point of view, breath test studies can also be used to trace the catabolic fate of dietary nutrients. The fcMius of this paper was a mathematical analysis of [13CO2]-expiration curves. Human breath test results for [13C]-labelled amino acids (leucine, methionine, lysine) under different dietary conditions were used to illustrate this approach. The mathematical parameters were meant to characterise changes in the catabolic fate of dietary amino acids as influenced by the ingestion of a meal
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