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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    Comparison of Protein Hydrolysis Catalyzed by Bovine, Porcine, and Human Trypsins
    Deng, Yuxi ; Gruppen, Harry ; Wierenga, Peter A. - \ 2018
    Journal of Agricultural and Food Chemistry 66 (2018)16. - ISSN 0021-8561 - p. 4219 - 4232.
    LC-MS - peptide release kinetics - protein digestibility - secondary specificity - tryptic hydrolysis
    Based on trypsin specificity (for lysines and arginines), trypsins from different sources are expected to hydrolyze a given protein to the same theoretical maximum degree of hydrolysis (DHmax,theo). This is in contrast with experiments. Using α-lactalbumin and β-casein, this study aims to reveal if the differences among experimental DHmax (DHmax,exp) by bovine, porcine, and human trypsins are due to their secondary specificity. Peptide analysis showed that ∼78% of all the cleavage sites were efficiently hydrolyzed by porcine trypsin, and ∼47 and ∼53% were efficiently hydrolyzed by bovine and human trypsins, respectively. These differences were explained by the enzyme secondary specificity, that is, their sensitivities to the amino acids around the cleavage sites. The DHmax predictions based on the secondary specificity were 4 times closer to the DHmax,exp than the predictions based on trypsin specificity alone (DHmax,theo). Proposed preliminary relations between binding sites and trypsin secondary specificity allow DHmax,exp estimations of tryptic hydrolysis of other proteins.
    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.

    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.
    Improving performance of broilers fed lower digestible protein diets
    Qaisrani, S.N. - \ 2014
    Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Rene Kwakkel; Marinus van Krimpen. - Wageningen : Wageningen University - ISBN 9789462570313 - 182
    vleeskuikens - eiwitverteerbaarheid - vleeskuikenresultaten - fermentatie - einddarm - boterzuur - voer - voedingsfysiologie - pluimveevoeding - diervoeding - broilers - protein digestibility - broiler performance - fermentation - hindgut - butyric acid - feeds - nutrition physiology - poultry feeding - animal nutrition

    Background and Problem Statement

    There is a great interest in recent years to replace soybean meal by cost effective protein sources such as rapeseed meal and maize gluten in animal feed. In poultry, this replacement, however, may result in a poorer performance due to among others its low ileal digestibility, which may lead to hindgut protein fermentation. This hindgut protein fermentation can result in the production of harmful compounds such as ammonia, branched chain fatty acids, biogenic amines and different sulfur containing compounds such as skatole, indole and phenolic compounds. This can negatively affect the cost of broiler meat production. When digestibility is low gut health may be compromised. Also feed to gain ratios will be high and overall performance will be low. Apart from the economic losses, good digestible protein sources may be preferably used for human consumption. Thus, the challenge is to provide the basis for the development of a new feeding strategy that meets the nutrient requirements of modern-day broilers, especially when they are fed a low ileal digestible protein source, i.e. rapeseed meal and maize gluten, thereby minimizing the interruption of their production performance.

    Objectives of the Study

    The aim of the study was to find ways to improve protein digestibility of poor ileal digestible resources, to reduce potential hindgut protein fermentation by developing appropriate dietary strategies such as an adequate diet structure, the supplementation of organic acids and/or fermentable energy that improve nutrient availability at ileal level and gut health in broilers.

    The specific objectives of the present study were to:

    Review various factors that influence hindgut protein fermentation in broilers and nutritional strategies that may reduce hindgut protein fermentation (Chapter 2). Determine the effects of protein source, differing in fermentation characteristics, and of digestible dietary protein content on performance, gut morphology and cecal fermentation characteristics in broiler (Chapter 3). Investigate the effects of diet structure combined with different levels of indigestible dietary protein source on performance and gut morphology in broilers (Chapter 4). Study the main and interactive effects of protein source, diet structure, butyric acid and fermentable energy supplementations on performance, gut morphology and cecal fermentation characteristics (Chapter 5). Analyze the effects of protein source, diet structure, butyric acid and fermentable energy supplementation on cecal microbiota population and composition (Chapter 6).

    Major Findings of the Thesis

    This thesis provides a literature review and describes the results of three experiments in which different nutritional strategies were tested. All experiments were carried out with Ross-308 broilers.

    Chapter 2 reviews the literature on hindgut fermentation in broilers with special attention to protein fermentation, its detrimental effects on performance, gut health and on gut microbiota population. A wide range of harmful products such as ammonia, branched chain fatty acids, biogenic amines and different sulfur containing compounds such as skatole, indole and phenols are produced as a result of protein fermentation. Greater concentrations of biogenic amines, branched chain fatty acids, hydrogen sulfide, ammonia, indole, phenols, cresol and skatole in the cecal indicate more proteolytic fermentation. Low concentrations of some of the protein fermentation products including biogenic amines are necessary for a normal gut development. This may result in distinct differences in protein digestibility when measured at the ileum and the total digestive tract. It was concluded that nutritional strategies, such as a reduction in dietary CP, supplementation of pre- and probiotics and organic acids, or feeding diets with coarse particles may increase ileal CP digestibility, thereby reducing the amount of substrate available for fermentation. These nutritional interventions can potentially enhance protein digestion in the upper gastrointestinal tract and, therefore, reduce the chances of protein fermentation in the hindgut.

    In Chapter 3, effects of three major protein sources, soybean meal, rapeseed meal and maize gluten at two different digestible CP levels (15.8 and 17.2%) were studied to test the hypothesis that broilers fed a diet with high levels of indigestible protein, will result in a reduced growth performance, lower villus heights, deeper crypts, and more protein fermentation products in cecal digesta. In total, 288 one-day-old male broilers were used for this study. Broilers fed soybean meal diet showed a better performance compared with those fed rapeseed meal and maize gluten diets due its greater ileal digestibility compared with the other two protein sources. High digestible CP (17.2%) diet fed broilers showed better performance compared with those on low digestible CP (15.8%) diet. No significant effects of protein source as well as digestible CP level were found on gastrointestinal tract development, cecal ammonia and volatile fatty acid concentrations. Broilers fed soybean meal had improved duodenal morphology compared with those fed the rapeseed meal and maize gluten diets. A lower cecal pH and greater branched chain fatty acids concentrations in the cecal digesta were observed in broilers fed the rapeseed meal diet compared with those fed the soybean meal and maize gluten diets, indicating more proteolytic fermentation. In conclusion, protein source as well as digestible CP level affected growth performance, gut morphology and protein fermentation characteristics in broilers.

    In Chapter 4, a hypothesis that a coarse diet improves performance of broilers fed a poorly digestible protein source was tested by using 210 one-day-old broilers. A highly digestible protein diet based on soybean meal was gradually replaced by a low digestible protein diet based on rapeseed meal (RSM) in five steps (RSM-0%, RSM-25%, RSM-50%, RSM-75% and RSM-100%) with two diet structures (fine vs. coarse). An increase in indigestible dietary protein decreased the performance of broilers. Total cecal volatile fatty acid concentrations decreased from 209 to 126 mmol/kg DM digesta in broilers with increasing rapeseed meal in diets. Increase in the indigestible protein level, from RSM-0% to RSM-100%, decreased villus heights (1782 vs. 1574 µm), whereas crypt depths increased (237 vs. 274 µm). A coarse diet improved the performance with a 15% heavier empty gizzard weight and changed gut morphology. Coarseness of the diet reduced the empty weights of the crop, proventriculus and jejunum, and reduced gizzard pH by 16%. Protein fermentation indices such as branched chain fatty acids and biogenic amines were reduced by 24 and 12%, respectively, in the cecal digesta of broilers fed coarse diets compared with those fed fine diets. In conclusion, feeding coarse particles improved the performance of broilers even with a poorly digestible protein source. Hindgut protein fermentation was reduced in broilers fed diets with a low CP digestibility by coarse grinding of the diet.

    In Chapter 5, the effects of protein source, diet structure and supplementation of butyric acid and fermentable energy on growth performance and cecal digesta characteristics were investigated to test the hypothesis that a coarse diet supplemented with butyric acid and fermentable energy improves growth performance of broilers fed a poorly digestible protein source. The interaction effects of diet structure (fine vs. coarse), fermentable energy (with vs. without) and butyric acid supplementation (with vs. without) in a poorly digestible diet based on rapeseed meal were evaluated. Coarseness of the diet positively affected performance and improved relative empty gizzard weights by on average 14%. The relative empty weights of the crop, duodenum, jejunum and ileum, were reduced in coarse diets fed broilers compared with those fed fine diets. Broilers fed coarse diet showed a 6% greater ileal protein digestibility, 20% lower gizzard pH, improved gut morphology, and 23% reduced cecal branched chain fatty acids compared with those fed the fine diets. Broilers fed butyric acid supplemented diets had improved performance and gut morphology compared with those fed the diets without butyric acid. Fermentable energy supplementation did not influence growth performance nor gut development and contents of total branched chain fatty acids and total biogenic amines in the cecal digesta. Supplementation with fermentable energy, however, decreased the concentration of spermine by approximately 31%. In conclusion, feeding a coarse diet supplemented with butyric acid improves growth performance of broilers even if they are fed a diet containing a poorly digestible protein source. The negative effects of a low digestible protein source can thus be partly counterbalanced by coarse grinding and butyric acid supplementation in the diet.

    In Chapter 6, the effects of protein source, diet structure, butyric acid and fermentable energy supplementations on cecal microbiota population and composition in broilers were evaluated. Cecal digesta samples collected in experiments 1, 2 and 3 were therefore, analysed for some microbiota. The results indicated that cecal microbial diversity was suppressed by dietary coarseness. Similarly, butyric acid and fermentable energy supplementation also resulted in a lower microbial diversity. Soybean meal promoted the average relative contribution of health beneficial L. paracasei and C. lactifermentans spp. compared with those fed rapeseed meal. Dietary coarseness reduced the average relative contribution of E. coli. Butyric acid supplementation promoted the average relative contribution of C. lactifermentans and R. bromii, and suppressed the pathogenic C. perfringens in the cecal digesta. Fermentable energy, in contrast, promoted C. perfringens. In conclusion, feeding a poorly digestible protein source, with coarse grinding and supplemented with butyric acid may be an effective strategy to promote health beneficial and suppress pathogenic microbiota in the cecal digesta.


    The main conclusion of the study is that rapeseed meal diets reduce performance and gut health, but these negative effects can be partially counterbalanced by coarse grinding and butyric acid supplementation. Some specific conclusions based on the results of the studies described in this thesis are:

    Rapeseed meal is a poorly digestible protein source for broilers and results in reduced growth performance and gut morphology (Chapter 3). Coarse diet feeding enhances the development of the foregut, specially the gizzard, and it increases villus heights and reduces crypts depths in the duodenum (Chapters 4 and 5). The negative effects of moderate inclusion of indigestible protein can be counterbalanced to some extent by feeding a coarse diet (Chapters 4 and 5). The improved foregut development and villus height in the duodenum is associated with an enhanced ileal digestibility of protein, thereby allowing less protein available for fermentation in the hindgut (Chapter 5). Butyric acid supplementation improves growth performance and gut morphology (Chapter 5). Both soybean meal and dietary coarseness suppress cecal microbial diversity and promotes health beneficial microbiota (Chapter 6). Dietary coarseness suppresses pathogenic bacteria and promotes health beneficial microbiota in the ceca (Chapter 6). Coarsely ground diet with a moderate inclusion of poorly digestible protein source, supplements with butyric acid, is a good strategy to improve the ileal digestibility of protein and thus growth performance of broilers (Chapters 4 and 5).

    Practical Implementations

    This study might have some practical conclusions. Rapeseed meal can be used as a protein source in a broiler ration. Coarsely ground rapeseed meal, supplemented with butyric acid (approximately €2.1/100 broilers), can potentially replace soybean meal. It will not only provide a cheaper protein source but will also reduce the cost of feed production by reducing the steps in grinding the feed ingredients or using a roller mill instead of a hammer mill. These coarse particles will improve gut morphology and growth performance of broilers as well as increase the profitability of broiler feed producers and also broiler farmers (approximately €6/100 broilers). The most perspective feeding strategy to enhance the growth performance of broilers fed a poorly digestible protein source is the use of coarsely ground supplemented with butyric acid.

    Nutritional characteristics of mung bean foods
    Dahiya, P.K. ; Nout, M.J.R. ; Boekel, M.A.J.S. van; Khetarpaul, N. ; Grewal, R.B. ; Linnemann, A.R. - \ 2014
    British Food Journal 116 (2014)6. - ISSN 0007-070X - p. 1031 - 1046.
    protein digestibility - ascorbic-acid - nutrient composition - iron-absorption - phytic acid - bioavailability - phytate - antinutrients - germination - zinc
    Purpose – The purpose of this paper is to address malnourishment in developing countries by a food-based approach in which locally produced and consumed foods are improved by applying food processing techniques that benefit the amount and availability of desirable nutrients. Design/methodology/approach – To facilitate this approach, this paper reports on the composition and in vitro micronutrient accessibility of 14 traditional mung bean foods from India in relation to their preparation methods. Findings – Proximate composition, in vitro mineral accessibility, phytic acid and polyphenol contents varied among the range of products. Products requiring either fermentation or germination, had higher in vitro iron, zinc and calcium accessibility. Average in vitro iron, zinc and calcium accessibility of the mung bean products were 16, 9 and 418¿mg¿kg-1 dry weight. Phytic acid and polyphenols averaged 2.1 and 1.8¿g¿kg-1 dry weight, respectively, and were negatively correlated with in vitro mineral accessibility. Practical implications – Different mung bean products (100¿g) cover 12.0-59.5, 5.2-45.6, 4.2-28.6 and 1.1-7.1 per cent of the recommended dietary allowance for protein, iron, zinc and calcium, respectively, for seven- to nine-year-old Indian children. Originality/value – This study demonstrated the wide range of traditional mung bean foods in India and presents options to tackle malnourishment by a food-based approach.
    Nutrient composition of selected newly bred and established mung bean varieties
    Dahiya, P.K. ; Linnemann, A.R. ; Nout, M.J.R. ; Boekel, M.A.J.S. van; Grewal, R.B. - \ 2013
    Food Science and Technology = Lebensmittel-Wissenschaft und Technologie 54 (2013)1. - ISSN 0023-6438 - p. 249 - 256.
    greengram vigna-radiata - arietinum-l cultivars - phytic acid content - protein digestibility - antinutritional factors - starch digestibility - zinc bioavailability - human-nutrition - legume seeds - phytate
    Seven newly bred and three established varieties of mung bean were analysed for proximate composition, minerals, anti-nutrients and in vitro mineral accessibility. They contained 18–23 g protein, 4.0–5.6 g crude fibre and 2.5–4.1 g ash per 100 g dry sample. Iron, zinc, calcium, sodium and potassium ranged from 3.4 to 4.6, 1.2 to 2.3, 79 to 115, 8.1 to 13.5 and 362 to 415 mg/100 g dry weight, respectively. Phytic acid and polyphenols averaged 769 and 325 mg/100 g dry weight, respectively. Varieties differed significantly in terms of nutrient and anti-nutrient contents. Phytic acid and polyphenols were negatively correlated with in vitro mineral accessibility and nutrient digestibility. Protein and starch digestibility ranged from 53 to 67 g/100 g dry weight and 20 to 29 mg maltose released/g dry weight, respectively. Average molar ratios of phytic acid to iron and zinc were 16.8 and 52.7, respectively. Differences in in vitro iron and zinc accessibility could not be explained by phytic acid to calcium nor magnesium molar ratios. However, the phytic acid amount in mung beans suffices to bind all minerals into indigestible complexes. The newly bred varieties have better agronomic yields but no better nutritional potential than the established varieties tested.
    In vitro digestibility of b-casein and b-lactoglobulin under simulated human gastric and duodenal conditions
    Mandalari, G. ; Adel-Patient, K. ; Barkholt, V. ; Baro, C. ; Bennett, L. ; Bublin, M. ; Gaier, S. ; Graser, G. ; Ladics, G.S. ; Mierzejewska, D. ; Vassilopoulou, E. ; Vissers, Y.M. ; Zuidmeer, L. ; Rigby, N.M. ; Salt, L.J. ; Defernez, M. ; Mulholland, F. ; Mackie, A.R. ; Wickham, M.S.J. ; Mills, E.N.C. - \ 2009
    Regulatory Toxicology and Pharmacology 55 (2009)3. - ISSN 0273-2300 - p. 372 - 381.
    human pancreatic-juice - food allergens - gastrointestinal proteolysis - protein digestibility - pepsin digestion - stability - fluid - hydrolysis - resistance - ph
    Initially the resistance to digestion of two cow's milk allergens, beta-casein, and beta-lactoglobulin (beta-Lg), was compared using a "high-protease assay" and a "low-protease assay" in a single laboratory. The low-protease assay represents an alternative standardised protocol mimicking conditions found in the gastrointestinal tract. For the high-protease assay, both proteins were incubated with either pepsin or pancreatin and digestion monitored by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and reverse phase-high performance liquid chromatography. The low-protease assay involved gastroduodenal digestion in the presence or absence of phosphatidylcholine (PC). Both beta-casein and beta-Lg were susceptible to hydrolysis by pepsin and pancreatin in the high-protease assay. In contrast, the kinetics of beta-casein digestion in the low-protease assay were slower, beta-Lg being pepsin resistant. During duodenal digestion, beta-Lg was gradually degraded and addition of PC slowed digestion. Subsequently, the reproducibility of the low-protease assay was assessed in 12 independent laboratories by visual assessment of the gels and densitometric analysis: the inter- and intra-laboratory variability was affected by sampling and electrophoresis method employed. The low-protease assay was shown to be reproducible. Future studies will extend these findings using a broader panel of proteins
    Eiwitwaarde vers gras = Protein evaluation fresh gras
    Klop, A. ; Jonge, L.H. de; Brandsma, G.G. - \ 2008
    Wageningen : Animal Sciences Group (Rapport / Animal Sciences Group 124) - 11
    begrazing - graskuilvoer - graslanden, conditie - gewaskwaliteit - eiwitgehalte - chemische samenstelling - voedingswaarde - eiwitverteerbaarheid - grazing - grass silage - grassland condition - crop quality - protein content - chemical composition - nutritive value - protein digestibility
    Het CVB van het Productschap Diervoeder heeft het eiwitwaarderingsysteem uit 1991 in 2007 herzien. Daarvoor zijn van diverse voedermiddelen aanvullende analyses gedaan om tot betrouwbare rekenregels te komen. Voor vers gras is aanvullend onderzoek gedaan naar de oplosbare en uitwasbare fractie van ruw eiwit. In het DVE/OEB- 2007 systeem worden die gegevens gebruikt om te komen tot een betrouwbare schatting van de hoeveelheid darmverteerbaar bestendig eiwit en microbieel eiwit. Het CVB heeft de onderzoeksgegevens toegepast in de nieuwe rekenregels van het DVE/OEB-2007 systeem. Voor zowel de uitwasbare als de oplosbare eiwitfractie wordt een vaste waarde gehanteerd van 5,7%. Met het verbeterde systeem wordt de DVE waarde van vers gras gemiddeld 7% lager gewaardeerd dan voorheen. De OEB waarde stijgt met gemiddeld 7%. De verandering is niet alleen het gevolg van de uit dit onderzoek verkregen resultaten maar vooral ook met gewijzigde rekenregels voor Fermenteerbare Organische Stof en daarmee voor de hoeveelheid darmverteerbaar microbieel eiwit (DVME)
    Eiwitwaardering voor herkauwers; het DVE-OEB 2007 systeem
    Tamminga, S. ; Brandsma, G.G. ; Duinkerken, G. van; Vuuren, A.M. van; Blok, M.C. - \ 2007
    Wageningen : Wageningen University (CVB-documentatierapport nr. 52) - 62
    herkauwers - eiwitten - voederwaardering - eiwitverteerbaarheid - eiwitwaarde - eiwitbalans - pensvertering - herkauwersvoeding - diervoeding - ruminants - proteins - feed evaluation - protein digestibility - protein value - protein balance - rumen digestion - ruminant feeding - animal nutrition
    Protein evaluation for ruminants : the DVE/OEB 2007-system
    Tamminga, S. ; Brandsma, G.G. ; Duinkerken, G. van; Vuuren, A.M. van; Blok, M.C. - \ 2007
    Wageningen : Wageningen University (CVB-documentation report no. 53) - 58
    herkauwers - eiwitten - voederwaardering - eiwitverteerbaarheid - eiwitbalans - eiwitwaarde - pensvertering - herkauwersvoeding - diervoeding - ruminants - proteins - feed evaluation - protein digestibility - protein balance - protein value - rumen digestion - ruminant feeding - animal nutrition
    Limiting factors for the enzymatic accessibility of soybean protein
    Fischer, M. - \ 2006
    Wageningen University. Promotor(en): Harry Gruppen; Fons Voragen. - [S.l.] : S.n. - ISBN 9789085044963 - 139
    sojaeiwit - hydrolyse - aggregatie - koolhydraten - eiwitextractie - eiwitvertering - eiwitverteerbaarheid - peptiden - soya protein - hydrolysis - aggregation - carbohydrates - protein extraction - protein digestion - protein digestibility - peptides
    Soy is a commonly used ingredient is food and animal feed. With particular focus on the in-soluble fractions, this thesis deals with the effects of proteases and carbohydrate degrading enzymes on different soybean meals subjected to different extent of heating. The primary aim is to improve the understanding of enzymatic hydrolysis of SBM with emphasis on proteins and to identify barriers limiting the efficiency of the process. The results show that aggregation behavior of peptides during enzymatic processing of soy proteins is potentially a limiting factor for efficacy of protein extraction. Surprisingly, it is also demonstrated that aggregation is not limited to in vitro incubations, but is also occurring in vivo in the digestive system of pigs.
    Sorghum grain as human food in Africa: relevance of content of starch and amylase activities
    Dicko, M.H. ; Gruppen, H. ; Traore, A.S. ; Voragen, A.G.J. ; Berkel, W.J.H. van - \ 2006
    African journal of biotechnology 5 (2006)5. - ISSN 1684-5315 - p. 384 - 395.
    bicolor l moench - beta-amylase - alpha-amylase - kernel characteristics - protein digestibility - functional ingredient - chemical-composition - partial-purification - cultivated sorghum - fermented sorghum
    Sorghum is a staple food grain in many semi-arid and tropic areas of the world, notably in Sub-Saharan Africa because of its good adaptation to hard environments and its good yield of production. Among important biochemical components for sorghum processing are levels of starch (amylose and amylopectin) and starch depolymerizing enzymes. Current research focus on identifying varieties meeting specific agricultural and food requirements from the great biodiversity of sorghums to insure food security. Results show that some sorghums are rich sources of micronutrients (minerals and vitamins) and macronutrients (carbohydrates, proteins and fat). Sorghum has a resistant starch, which makes it interesting for obese and diabetic people. In addition, sorghum may be an alternative food for people who are allergic to gluten. Malts of some sorghum varieties display a-amylase and ß-amylase activities comparable to those of barley, making them useful for various agro-industrial foods. The feature of sorghum as a food in developing as well as in developed countries is discussed. A particular emphasis is made on the impact of starch and starch degrading enzymes in the use of sorghum for some African foods, e.g. ¿tô¿, thin porridges for infants, granulated foods ¿couscous¿, local beer ¿dolo¿, as well agro-industrial foods such as lager beer and bread.
    Digestibility, faeces recovery, and related carbon, nitrogen and phosphorus balances of five feed ingredients evaluated as fishmeal alternatives in Nile tilapia, Oreochromis niloticus L.
    Schneider, O. ; Amirkolaie, A.K. ; Vera-Cartas, J. ; Eding, E.H. ; Schrama, J.W. ; Verreth, J.A.J. - \ 2004
    Aquaculture Research 35 (2004)14. - ISSN 1355-557X - p. 1370 - 1379.
    trout oncorhynchus-mykiss - rainbow-trout - soybean-meal - apparent digestibility - protein digestibility - dietary-protein - atlantic salmon - practical diets - african catfish - growth
    This study shows that alternatives for fishmeal in a fish diet affect not only fish growth but also faeces stability and nitrogen (N) and phosphorus (P) waste production. Wheat gluten diet (WGD), soybean meal extract diet (SBE), soybean meal diet (SBM), duckweed diet (DWD) and single-cell protein diet (SCP) were evaluated as a fishmeal replacement on a 15% weight weight(-1) basis in tilapia diets. Fishmeal replacement affected dry matter (dm), protein, ash and P digestibility significantly. Faeces recovery (6.8-11.2%) was not significantly affected, although the amount of non-recovered faeces and total faeces showed significant differences. Duckweed diet and SCP resulted in the largest amounts of non-recovered and total faeces (199-210, 224-225 g dm kg(-1) feed dm). Compared with fishmeal diet (FMD), the WGD and SBE resulted in similar growth, but higher non-faecal N losses (471-495 vs. 416 g N kg(-1) N). Soybean meal diet, DWD and SCP resulted in lower growth but less non-faecal loss (409-450 g N kg(-1) N). The DWD and FMD had the highest N retention (480 g N kg(-1) N) compared with the other diets (431-451 g N kg(-1) N). Carbon retention, faecal and non-faecal losses and P retention were similar for all diets (302-358, 142-176 and 489-523g C kg(-1) C, 606-704 g P kg(-1) P). Phosphorus faecal loss was lower for all diets (329-381 g P kg(-1) P) than for the FMD (401 g P kg(-1) P).
    ISO ringtest pepsine verteerbaarheid 1981
    Gast, C.H. ; Nijenhuis, A. - \ 1981
    Lelystad : IVVO (Documentatierapport / IVVO no. 86) - 7
    pepsine - eiwitverteerbaarheid - in vitro verteerbaarheid - kwaliteitscontroles - pepsin - protein digestibility - in vitro digestibility - quality controls
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