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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    Effects and moderators of coping skills training on symptoms of depression and anxiety in patients with cancer : Aggregate data and individual patient data meta-analyses
    Buffart, L.M. ; Schreurs, M.A.C. ; Abrahams, H.J.G. ; Kalter, J. ; Aaronson, N.K. ; Jacobsen, P.B. ; Newton, R.U. ; Courneya, K.S. ; Armes, J. ; Arving, C. ; Braamse, A.M. ; Brandberg, Y. ; Dekker, J. ; Ferguson, R.J. ; Gielissen, M.F. ; Glimelius, B. ; Goedendorp, M.M. ; Graves, K.D. ; Heiney, S.P. ; Horne, R. ; Hunter, M.S. ; Johansson, B. ; Northouse, L.L. ; Oldenburg, H.S. ; Prins, J.B. ; Savard, J. ; Beurden, M. van; Berg, S.W. van den; Brug, J. ; Knoop, H. ; Verdonck-de Leeuw, I.M. - \ 2020
    Clinical Psychology Review 80 (2020). - ISSN 0272-7358
    (individual patient data) meta-analysis - Anxiety - Coping skills training - Depression - Neoplasm - Psychosocial care

    Purpose: This study evaluated the effects of coping skills training (CST) on symptoms of depression and anxiety in cancer patients, and investigated moderators of the effects. Methods: Overall effects and intervention-related moderators were studied in meta-analyses of pooled aggregate data from 38 randomized controlled trials (RCTs). Patient-related moderators were examined using linear mixed-effect models with interaction tests on pooled individual patient data (n = 1953) from 15 of the RCTs. Results: CST had a statistically significant but small effect on depression (g = −0.31,95% confidence interval (CI) = −0.40;-0.22) and anxiety (g = −0.32,95%CI = -0.41;-0.24) symptoms. Effects on depression symptoms were significantly larger for interventions delivered face-to-face (p =.003), led by a psychologist (p =.02) and targeted to patients with psychological distress (p =.002). Significantly larger reductions in anxiety symptoms were found in younger patients (pinteraction < 0.025), with the largest reductions in patients <50 years (β = −0.31,95%CI = -0.44;-0.18) and no significant effects in patients ≥70 years. Effects of CST on depression (β = −0.16,95%CI = -0.25;-0.07) and anxiety (β = −0.24,95%CI = -0.33;-0.14) symptoms were significant in patients who received chemotherapy but not in patients who did not (pinteraction < 0.05). Conclusions: CST significantly reduced symptoms of depression and anxiety in cancer patients, and particularly when delivered face-to-face, provided by a psychologist, targeted to patients with psychological distress, and given to patients who were younger and received chemotherapy.

    IgE cross-reactivity measurement of cashew nut, hazelnut and peanut using a novel IMMULITE inhibition method
    Bastiaan-Net, Shanna ; Batstra, Manou R. ; Aazamy, Nasrin ; Savelkoul, Huub F.J. ; Valk, Johanna P.M. Van Der; Gerth Van Wijk, Roy ; Schreurs, Marco W.J. ; Wichers, Harry J. ; Jong, Nicolette W. De - \ 2020
    Clinical Chemistry and Laboratory Medicine (2020). - ISSN 1434-6621
    allergy diagnostics - cashew nut - hazelnut - IgE cross-reactivity - IMMULITE technology - peanut

    Tree nut-allergic individuals are often sensitised towards multiple nuts and seeds. The underlying cause behind a multi-sensitisation for cashew nut, hazelnut, peanut and birch pollen is not always clear. We investigated whether immunoglobulin E antibody (IgE) cross-reactivity between cashew nut, hazelnut and peanut proteins exists in children who are multi-allergic to these foods using a novel IMMULITE®-based inhibition methodology, and investigated which allergens might be responsible. In addition, we explored if an allergy to birch pollen might play a role in this co-sensitisation for cashew nut, hazelnut and peanut. Serum of five children with a confirmed cashew nut allergy and suffering from allergic symptoms after eating peanut and hazelnut were subjected to inhibition immunoassays using the IMMULITE® 2000 XPi. Serum-specific IgE (sIgE) to seed storage allergens and pathogenesis-related protein 10 (PR10) allergens were determined and used for molecular multicomponent allergen correlation analyses with observed clinical symptoms and obtained inhibition data. IgE cross-reactivity was observed in all patients. Hazelnut extract was a strong inhibitor of cashew nut sIgE (46.8%), while cashew nut extract was less able to inhibit hazelnut extract (22.8%). Peanut extract showed the least inhibition potency. Moreover, there are strong indications that a birch pollen sensitisation to Bet v 1 might play a role in the observed symptoms provoked upon ingestion of cashew nut and hazelnut. By applying an adjusted working protocol, the IMMULITE® technology can be used to perform inhibition assays to determine the risk of sIgE cross-reactivity between very different food components.

    Raw meat structure and feeding behaviour of domestic cats: how important is testure in determining long-term intake?
    Thomas, David ; Schreurs, Nicola ; Hendriks, W.H. ; Bosch, G. - \ 2019
    - p. 27 - 30.
    The objective of this work was to study the effect of food texture on feeding behavior and associated food intake in cats. Raw meat from beef carcasses was fed as strips or in puréed form to eight cats, and the number of bites, bite size, oral processing time, and number of meals were recorded. The physical structure of the food had a significant effect on the feeding behavior in cats, but less effect on the amount of food ingested. The study is now continuing to look at beef offal with different textural and palatability properties.
    Transformative governance for public health: A scoping review
    Schreurs, F. ; Bekker, M.P.M. ; Helderman, J.K. ; Jansen, M. ; Ruwaard, D. - \ 2019
    European Journal of Public Health 29 (2019)Supplement_4. - ISSN 1101-1262 - p. 645 - 646.

    Raw meat structure and feeding behaviour of domestic cats
    Thomas, David ; Schreurs, Nicola ; Hendriks, W.H. ; Bosch, G. - \ 2018
    Archeologisch onderzoek in de omgeving van het prehistorische vuursteenmijnveld te Rijckholt - St.Geertruid : De resultaten van 2011, 2012 en 2013
    Brinkkemper, O. ; Bruinink, A.C. ; Deeben, J. ; Guralnik, B. ; Hoebe, P. ; Huisman, H. ; Kort, J.W. de; Laarman, F. ; Meirvenne, M. van; Orbons, J. ; Os, B. van; Parys, V. van; Schreurs, J. ; Theunissen, L. ; Verhegge, J. ; Versendaal, Alice ; Wallinga, J. - \ 2018
    Amersfoort : Rijksdienst voor het Cultureel Erfgoed - ISBN 9789057993022 - 371 p.
    A novel scoring system for the classification of the health status of growing-finishing pig farms
    Jansman, A.J.M. ; Kampman-van der Hoek, E. ; Sakkas, P. ; Beers-Schreurs, H.M.G. van; Peet-Schwering, C.M.C. van der; Borne, J.J.G.C. van den; Gerrits, W.J.J. - \ 2016
    - p. 132 - 132.
    Health status of pig farms can vary considerably and relates to the variation in zootechnical performance among farms. Classification of farm health can be helpful in monitoring farm health status in time and for the application of intervention strategies to improve farm health status. The aim of the current study was to develop a concept for classification of the health
    status of growing-finishing pig farms. Six traits were incorporated into a health status web, related to the zootechnical performance and measurements at slaughter. Performance data from 1,074 and 783 Dutch pig farms, and abattoir data of 50,208 and 47,426 farm deliveries to slaughterhouses, acquired over 2011 and 2012 respectively, were used as a representative sample for the Dutch growing-finishing pig population to calculate the 25th and 75th percentiles of each trait per year. Per farm, a score was calculated per trait by inter- and extrapolation using the 25th and 75th percentiles from the Dutch pig population. The farm score was defined as the mean score over the six traits. A farm was classified as having a suboptimal health with a farm score between 50 and 62.5, as having a conventional health status with a farm score between 62.5 and 87.5 and as having a high health status with a farm score between 87.5 and 100. Further, two datasets were compiled: dataset 1 with farm data of 179 farms over the year 2011, and dataset 2 with farm data of 70 farms over both 2011 and 2012. In dataset 1, 13 farms were characterized as high health, 159 farms as conventional and seven farms as having a low health status. Analysis of dataset 2 revealed that farm scores are consistent across years,
    indicating that the farm score is farm specific and the health status web is a valuable concept to characterize growing-finishing pig farms on their health status.
    The association between portion size, nutrient intake and gestational weight gain : A secondary analysis in the WATCH study 2006/7
    Blumfield, M.L. ; Schreurs, M. ; Rollo, M.E. ; Macdonald-Wicks, L.K. ; Kokavec, A. ; Collins, C.E. - \ 2016
    Journal of Human Nutrition and Dietetics 29 (2016)3. - ISSN 0952-3871 - p. 271 - 280.
    Gestational weight gain - Nutrient intake - Portion size - Pregnancy

    Background: Excessive gestational weight gain (GWG) is associated with adverse maternal-child health outcomes. Managing energy intake and GWG versus optimising nutrient intake can be challenging. The present study aimed to examine the relationships between dietary portion size, GWG and nutrient intakes during pregnancy. It is hypothesised that, after adjustment for potential confounders, portion size would be positively associated with both GWG and nutrient intakes during pregnancy. Methods: Prospective data were obtained for 179 Australian women from the Women and Their Children's Health Study. A validated food frequency questionnaire was used at 18-24 and 36-40 weeks of gestation to quantify diet and portion size during the previous 3 months of pregnancy. Nutrient intakes were compared with Australian Nutrient Reference Values (NRVs). GWG was measured up to 36 weeks and compared with the Institute of Medicine weight gain recommendations (WtAdh). Results: In multivariate regression models, portion size factor (PSF) was positively associated with GWG in women with high socio-economic status (SES; β = 0.20, P = 0.04) and those with an overweight/obese pre-pregnancy body mass index (BMI) (β = 0.28, P = 0.04). PSF uniquely accounted for 8.2% and 3.7% of the variability in GWG for women with high SES and overweight/obese pre-pregnancy BMIs, respectively. Nutrient intakes and PSF were similar regardless of WtAdh. Women achieved NRVs for calcium and zinc in all PSF categories. Most of the women with large PSF still failed to achieve the NRVs for folate (95.7%), iron (89.6%) and fibre (85.5%). Conclusions: All women require advice on quality food choices during pregnancy to optimise health outcomes. Targeting portion size alone is insufficient to manage GWG but may prove to be a valuable tool in pregnant women of high SES and/or those who are overweight/obese pre-pregnancy.

    Dietary Amino Acid Deficiency Reduces the Utilization of Amino Acids for Growth in Growing Pigs after a Period of Poor Health
    Hoek, E. van de; Jansman, A.J.M. ; Borne, J.J.G.C. van den; Peet-Schwering, C.M.C. van der; Beers-Schreurs, H.M.G. van; Gerrits, W.J.J. - \ 2016
    The Journal of Nutrition 146 (2016)1. - ISSN 0022-3166 - p. 51 - 58.
    amino acid deficiency
    Background: During immune system activation, partitioning of amino acids (AAs) changes between protein gain and use by the immune system. Objective: We determined the effects of health status and dietary AA deficiency on nitrogen retention and AA utilization in pigs. Methods: Barrows (55 d of age) were obtained from good health (GH, n = 14) or poor health (PH, n = 14) status farms and allocated to a diet either adequate in essential amino acids (Adq) or 25% deficient in Met + Cys, Thr, and Trp (Def). Nitrogen balance was measured and AA irreversible loss rates (ILRs) were measured after an intravenous bolus of U-13C–labeled L-AAs. Results: On arrival at the experimental facilities, the PH pigs had 14% lower serum albumin and 50% greater serum haptoglobin and blood leukocyte counts than the GH pigs (P < 0.01), but the PH pigs showed signs of recovery during the trial. Total tract nitrogen digestibility was 3 percentage points lower in the PH pigs (P < 0.01). The PH-Adq pigs had compensatory body weight gain after arrival, coinciding with 7% greater nitrogen retention (P < 0.01) in the PH pigs than in the GH pigs. The PH pigs had a 24% greater ILR for Lys. Health status × diet interactions for Lys (P = 0.07), Val (P = 0.03), and Leu (P = 0.10) pool sizes and a greater urea pool size in the PH pigs (P = 0.01) support the observation that the increase in the ILR of Lys in the PH pigs was related to oxidation when feeding the Def diet, but to synthesis when feeding the Adq diet. Feeding Def diets increased monocyte counts by 30% (P < 0.01). Conclusions: This study illustrates how the competition for AAs between protein synthesis associated with immune system activation and body protein deposition is greater when the dietary supply of Met + Cys, Thr, and Trp is limited in pigs during and after a period of poor health.
    Postprandial oxidative losses of dietary leucine depend on the time interval between consecutive meals : A model study with rats
    Myszkowska-Ryciak, J. ; Keller, J.S. ; Bujko, J. ; Stankiewicz-Ciupa, J. ; Koopmanschap, R.E. ; Schreurs, V.V.A.M. - \ 2015
    Journal of Animal and Feed Sciences 24 (2015)1. - ISSN 1230-1388 - p. 71 - 79.
    Breath test - Consecutive meals - Rat - Time intervals - [1-<sup>13</sup>C]-leucine oxidation

    Postprandial oxidative losses of egg white-bound [1-13C]-leucine were studied as 13C recovery in the breath of rats in relation to different time intervals between two meals. Male Wistar rats (n = 48; 68.3 ±5.9 g) divided into 4 groups (n = 12) were fed two meals a day (9:00 and 16:30; interval 7 h) of a 13.2% egg white-based diet for 30 min. After 14 days, 3 out of the 4 groups received the 2nd meal at shorter time intervals of 3, 1, and 0 h. Two [13CO2] breath tests (BT) were performed on days 19 and 40. The breath samples were analyzed for 13C Atom % (At %) enrichment by IRMS, and the results were expressed as the rate of 13C At % excess and cumulative recovery (% of dose). The 7 h interval group showed higher 13C cumulative recovery after the 2nd meal during both the BT and after the 1st meal on the day 40 BT compared with the 3, 1, and 0 h intervals. In groups with the 3, 1, and 0 h intervals, the cumulative recovery of 13C after the 2nd meal was lower compared with the 1st meal due to interaction between meals, which probably caused dilution of the tracer in the larger volume of feed in the rat's stomach. On day 40, all cumulative recovery values were higher than on day 19. An important finding of this study is that despite the differences in postprandial Leu oxidation among interval groups, the weight gain of all rats was similar.

    Tumor Necrosis Factor Receptor 1 Gain-of-Function Mutation Aggravates Nonalcoholic Fatty Liver Disease but Does Not Cause Insulin Resistance in a Murine Model
    Aparicio-Vergara, M. ; Hommelberg, P.P.H. ; Schreurs, M. ; Gruben, N. ; Stienstra, R. ; Shiri-Sverdlov, R. ; Kloosterhuis, N.J. ; Bruin, A. de; Sluis, B. van der; Koonen, D.P.Y. ; Hofker, M.H. - \ 2013
    Hepatology 57 (2013)2. - ISSN 0270-9139 - p. 566 - 576.
    alpha-converting-enzyme - tnf-alpha - dietary-cholesterol - hepatic steatosis - gene-expression - mice - steatohepatitis - obesity - inflammation - activation
    Ectodomain shedding of tumor necrosis factor receptor 1 (TNFR1) provides negative feedback to the inflammatory loop induced by TNF alpha. As the significance of this mechanism in obesity-associated pathologies is unclear, we aimed to unravel how much TNFR1 ectodomain shedding controls the development of nonalcoholic fatty liver disease (NAFLD), as well as its role in the development of insulin resistance. We used knockin mice expressing a mutated TNFR1 ectodomain (p55Dns), incapable of shedding and dampen the inflammatory response. Our data show that persistent TNF alpha signaling through this inability of TNFR1 ectodomain shedding contributes to chronic low-grade inflammation, which is confined to the liver. In spite of this, hepatic lipid levels were not affected by the nonshedding mutation in mice fed a chow diet, nor were they worse off following 12 weeks of high-fat diet (HFD) than controls (p55(+/+)) fed an HFD. We detected inflammatory infiltrates, hepatocellular necrosis, and apoptosis in livers of p55(Delta ns/Delta ns) mice fed an HFD, suggesting advanced progression of NAFLD toward nonalcoholic steatohepatitis (NASH). Indeed, fibrosis was present in p55(Delta ns/Delta ns) mice, but absent in wildtype mice, confirming that the p55(Delta ns/Delta ns) mice had a more severe NASH phenotype. Despite low-grade hepatic inflammation, insulin resistance was not observed in p55(Delta ns/Delta ns) mice fed a chow diet, and HFD-induced insulin resistance was no worse in p55(Delta ns/Delta ns) mice than p55(+/+) mice. Conclusion: TNFR1 ectodomain shedding is not an essential feedback mechanism in preventing the development of hepatic steatosis or insulin resistance. It is, however, pivotal in attenuating the progression from "simple steatosis" towards a more serious phenotype with many NASH features. Targeting TNFR1 could therefore be beneficial in attenuating NASH. (HEPATOLOGY 2013;57:566-576)
    Stressors and resources mediate the association of socioeconomic position with health behaviours
    Mulder, B.C. ; Bruin, M. de; Schreurs, H. ; Ameijden, E.J.C. van; Woerkum, C.M.J. van - \ 2011
    BMC Public Health 11 (2011). - ISSN 1471-2458 - 10 p.
    psychosocial factors - perceived control - risk-factors - european countries - physical-activity - chronic diseases - life events - mortality - inequalities - disparities
    Background Variability in health behaviours is an important cause of socioeconomic health disparities. Socioeconomic differences in health behaviours are poorly understood. Previous studies have examined whether (single) stressors or psychosocial resources mediate the relationship between socioeconomic position and health or mortality. This study examined: 1) whether the presence of stressors and the absence of resources can be represented by a single underlying factor, and co-occur among those with lower education, 2) whether stressors and resources mediated the relation between education and health behaviours, and 3) addressed the question whether an aggregate measure of stressors and resources has an added effect over the use of individual measures. Methods Questionnaire data on sociodemographic variables, stressors, resources, and health behaviours were collected cross-sectionally among inhabitants (n = 3050) of a medium-sized Dutch city (Utrecht). Descriptive statistics and bootstrap analyses for multiple-mediator effects were used to examine the role of stressors and resources in mediating educational associations with health behaviours. Results Higher levels of stressors and lower levels of resources could be represented by a single underlying factor, and co-occurred among those with lower educational levels. Stressors and resources partially mediated the relationship between education and four health- behaviours (exercise, breakfast frequency, vegetable consumption and smoking). Financial stress and poor perceived health status were mediating stressors, and social support a strong mediating resource. An aggregate measure of the stressors and resources showed similar associations with health behaviours compared to the summed individual measures. Conclusions Lower educated groups are simultaneously affected by the presence of various stressors and absence of multiple resources, which partially explain socioeconomic differences in health behaviours. Compared to the direct associations of stressors and resources with health behaviours, the association with socioeconomic status was modest. Therefore, besides addressing structural inequalities, interventions promoting financial management, coping with chronic disease, and social skills training have the potential to benefit large parts of the population, most notably the lower educated. Further research is needed to clarify how stressors and resources impact health behaviours, why this differs between behaviours and how these disparities could be alleviated.
    Lactic acid and lactates
    Schreurs, V.V.A.M. - \ 2010
    NUTRAfoods 9 (2010)1. - ISSN 1827-8590 - p. 7 - 16.
    This review aims to integrate the present state of knowledge on lactate metabolism in human and mammalian physiology as far as it could be subject to nutritional interventions. An integrated view on the nutritional, metabolic and physiological aspects of lactic acid and lactates might open a perspective for innovative nutritional applications of lactates in health and wellness. Lactic acid was classically considered to be a dead end waste product of anaerobic glycolysis during severe exercise. Mammals, however, do not excrete lactate indicating that lactate cannot be considered as a dead metabolic end product. Despite a rapid and massive production of lactate, lactate is finally oxidized to the normal metabolic end products CO2 and H2O. Besides direct metabolic effects, nutritional applications of lactic acid and lactates are also considered in relation to dietary mineral supply. To the background that lactic acid is in fact a semi manufactured metabolic product, various nutritional applications are proposed in relation to metabolic training of athletes, modulation of metabolic rate, appetite control and excretion of faecal fat for weight management, lowering the glycemic index of bread and improved mineral supplementation in nutritional formulas for infants and people using proton inhibitors.
    Intermittent suckling affects feeder visiting behaviour in litters with low feed intake
    Kuller, W.I. ; Soede, N.M. ; Bolhuis, J.E. ; Beers-Schreurs, H.M.G. van; Kemp, B. ; Verheijden, J.H.M. ; Taverne, M.A.M. - \ 2010
    Livestock Science 127 (2010)2-3. - ISSN 1871-1413 - p. 137 - 143.
    social facilitation - weight-gain - solid food - pigs - piglets - performance - consumption - growth - birth
    Intermittent suckling (IS) has proven to stimulate creep feed intake in suckling piglets. This paper describes the development of feeding behaviour in three litters with high (H) and three litters with low (L) feed intake during lactation in both control (C) and IS treatment. In order to synchronize the start of intermittent suckling within a farrowing room, treatment day 0 (T0) was designated as the start of data collection. IS litters were separated from the sow for a period of 12 h/day (0930 to 2130) from T14 to weaning (T25). Feeder visits of individual piglets and nursing behaviour were analysed from continuous video recordings at 5 treatment days: T13, T16, T24, T25 and T26. A high number of CL piglets never visited the feeder during lactation; at T24, 56% of the CL piglets did not visit the feeder. On the other hand, 91% of the ISL and CH piglets and all ISH piglets visited the feeder at least once at T24. In contrast to the other groups, no increase was seen in visiting frequency during lactation in CL piglets. At T24, visiting frequency was higher in ISL than in CL piglets. So, IS stimulated piglets from low feed intake litters to visit the feeder. Between T16 and T24, total feeder time increased in piglets from all groups (P <0.05), except in CL piglets in which no change was found (P > 0.10). Latency to first visit to the feeder after weaning did not differ between groups. It is concluded that IS stimulates piglets from litters with a low level of creep feed intake to visit the feeder during lactation, which familiarizes them with the feeder and the feed during lactation. The IS treatment does not affect feeder visiting behaviour of piglets with an anyhow high level of feed intake during lactation
    Platform Technology for Developing Purification Processes
    Eppink, M.H.M. ; Schreurs, R. ; Gijsen, A. ; Verhoeven, K. - \ 2009
    BioPharm International 22 (2009)3. - ISSN 1542-166X - p. 32 - 42.
    To shorten time to market for new therapeutic proteins, new and fast methods, such as high throughput screening, are needed to speed up downstream processing. The platform technology discussed in this article includes a structural approach that can be used as a general procedure to purify therapeutic proteins. The approach starts with ligand screening and selection-on-a-chip, with the Surface Enhanced Laser Desorption Ionization–Time of Flight (SELDI–TOF) mass spectrometer system. Next, resin screening and supplier selection are performed using robotics, followed by scouting studies under dynamic conditions to select the best resin. Finally, optimization studies of critical parameters are carried out with statistical design approaches (design of experiments). Examples are presented to explain the platform approach for purification development in more detail.
    Postprandial oxidative losses of free and protein-bound amino acids in the diet: interactions and adaptation
    Nolles, J.A. ; Verreijen, A.M. ; Koopmanschap, R.E. ; Verstegen, M.W.A. ; Schreurs, V.V.A.M. - \ 2009
    Journal of Animal Physiology and Animal Nutrition 93 (2009)4. - ISSN 0931-2439 - p. 431 - 438.
    growing-pigs - nitrogen-utilization - free lysine - breath test - humans - metabolism - assimilation - catabolism - retention - casein
    Postprandial oxidation of dietary free amino acids or egg white protein was studied using the [13CO2] breath test in rats, as well as in humans. Thirty-eight male rats were assigned to four dietary test groups. Two diets only differed in their protein fraction. Diet I contained 21% egg white protein. For the breath test egg white protein, intrinsically labelled with [1-13C]-leucine, was used as a substrate. Diet II contained the same amino acids as diet I, though not as egg white protein but in free form. Free [1-13C]-leucine was used to label this diet. In addition, two 1:1 mixtures of both diets were used. During the breath test either the free amino acid or the protein fraction was labelled as in diets I or II. The animals were breath-tested following short-term (day 5) and long-term adaptation (day 20) to their experimental diet. For all diets, including the mixed diets, postprandial oxidative losses on day 5 were significantly higher for the free leucine compared with the protein-derived leucine. Differences between free and protein-derived leucine oxidation had, however, largely disappeared on day 20. The human subjects were breath-tested without any adaptation period to the diets. The oxidative losses of free leucine were also higher than those of protein-derived leucine. None of the studies showed any indication for an interaction between the oxidation of protein-derived amino acids and free amino acids. It is concluded that free and protein-derived amino acids in the diet are mainly metabolized independently
    Levende boerderij, lerende kinderen : beschrijving en effecten van verschillende vormen van educatie op de boerderij
    Hassink, J. ; Haubenhofer, D.K. ; Meer, I.M. van der; Kamp, N. van der; Schreurs, E. ; Schuler, Y.D. - \ 2009
    Wageningen : Plant Research International (Rapport / Plant Research International 257)
    onderwijs - informeel onderwijs - praktijkonderwijs - voorlichting - boerderijen - nederland - milieueducatie - multifunctionele landbouw - boerderijeducatie - natuur- en milieueducatie - education - non-formal education - practical education - extension - farm dwellings - netherlands - environmental education - multifunctional agriculture - farm education - nature and environmental education
    Verschillende vormen van boerderij-educatie werden onderzocht. Te weten: excursie, boerderijweek, boerderij-atelier en boerderijschool. Van elk van deze vormen is onderzocht welk effect ze hadden op de kinderen. Voor de verschillende vormen zijn aanbevelingen opgesteld die moeten leiden tot een betere benutting ervan
    Dietary amino acids fed in free form or as protein do differently affect amino acid absorption in a rat everted sac model
    Nolles, J.A. ; Peeters, I.G.S. ; Bremer, B.I. ; Moorman, R. ; Koopmanschap, R.E. ; Verstegen, M.W.A. ; Schreurs, V.V.A.M. - \ 2008
    Journal of Animal Physiology and Animal Nutrition 92 (2008)5. - ISSN 0931-2439 - p. 529 - 537.
    brush-border membrane - whole-body nitrogen - growth-performance - mouse intestine - digestion rate - milk protein - transport - metabolism - retention - ingestion
    In the present study, the effect of free amino acid (FAA) diets on the intestinal absorption rate of methionine and leucine was studied 'ex vivo' with rats adapted for different periods of time to the diets, using the everted sac method. The adaptation period to the 21% FAA diet with an amino acid content based on casein was either, 0 (no adaptation, N-ADA), 5 (short-term adaptation, ST-ADA), or 26-33 days (long-term adaptation, LT-ADA). Within the ST-ADA and the LT-ADA groups, three different levels of methionine were included: 50%, 100% and 200% of the level normally present in casein. All diets were iso-nitrogenous and iso-caloric. After the adaptation period (0, 5, or 26-33 days), intestinal everted sacs were prepared. Methionine or leucine was added to the medium as transport substrate. The methionine absorption rate of the rats of the LT-ADA groups was higher than that of the N-ADA groups. Furthermore, adaptation to 200% dietary methionine levels caused a significantly slower leucine absorption compared to the 100%, and 50% group. Methionine absorption was similar in the 100% and 200% groups, but the absorption of methionine in the 50% group was enhanced in the distal part of the intestines. We concluded that in response diets with 21% FAAs as only amino acid source, amino acid absorption is decreased to avoid toxic effects of high levels of methionine in the circulation.
    Op zoek naar een leuke activiteit? Educatie op de boerderij
    Haubenhofer, D.K. ; Hassink, J. ; Schreurs, E. ; Schuler, Y.D. ; Kamp, N. van der - \ 2008
    Ga voor gezond: nieuwsbrief 2008 (2008)Feb..
    Consequences of intermittent suckling for performance in the pig
    Kuller, W.I. - \ 2008
    Utrecht University. Promotor(en): J.H.M. Verheijden; M.A.M. Taverne; Bas Kemp, co-promotor(en): Nicoline Nieuwenhuizen-Soede; H.M.G. van Beers-Schreurs. - - 139 p.
    Tool for evaluation initiatives aiming at reducing overweight in order to generate best practices
    Schreurs, M.H.G.M. ; Raaij, J.M.A. van; Bemelmans, W. ; Schuit, J. - \ 2007
    Measuring intestinal blood flow in group-housed weaner pigs using Physiogear TM I: A pilot study
    Berkeveld, M. ; Hendriksen, S.W.M. ; Beers-Schreurs, H.M.G. van; Koets, A.P. ; Langendijk, P. ; Essen, G.J. van; Taverne, M.A.M. ; Verheijden, J.H.M. - \ 2007
    Livestock Science 108 (2007)1-3. - ISSN 1871-1413 - p. 159 - 162.
    The objective of this study was to determine whether intestinal blood flow can be measured adequately in group-housed animals using the recently developed Physiogear (TM) I wireless flowmeter. We used the weaner pig as one of many possible animal models. Four 7-kg piglets were instrumented with a 3-mm flowprobe around the superior mesenteric artery (SMA) and SMA flow was measured pre- and post-weaning. During measurements, behavior was recorded. The piglets did not show any abnormal behavior and were not restrained by the flowmeter. Severe reductions (> 75%) in SMA flow coincided with nursing (pre-weaning) and aggressive behavior (post-weaning) and were only short-lived. Our results demonstrate that the Physiogear (TM) I flowmeter can be used to measure flow in group-housed animals without any human contact, providing the opportunity to relate flow measurements to undisturbed animal behavior. (c) 2007 Elsevier B.V. All rights reserved.
    Mathematical analysis of human [13CO2]-breath test results: post prandial fate of amino acids is related to their ditary form.
    Schreurs, V.V.A.M. ; Nolles, J.A. ; Krawielitzki, K. ; Bujko, J. - \ 2007
    In: 2nd International Symposium on Energy and Protein Metabolism and Nutrition, EAAP publication 124, Vichy, France, 9 - 13 Septenber, 2007. - Wageningen, The Netherlands : Wageningen Academic Publishers - ISBN 9789086860418 - p. 237 - 238.
    Energetic and metabolic consequences of aerobic and an-aerobic ATP-production.
    Schreurs, V.V.A.M. ; Aarts, M.J. ; IJssennagger, N. ; Hermans, J. ; Hendriks, W.H. - \ 2007
    Agro Food Industry Hi-Tech 18 (2007)5. - ISSN 1722-6996 - p. 25 - 28.
    high-altitude - exercise - protein
    ATP, the currency of cellular energy metabolism, can be produced during aerobic and an-aerobic oxidation of metabolic substrates. The aerobic oxidation yields CO2 + H2O as metabolic end products while ATP is produced by oxidative phosphorylation in the mitochondria. Carbohydrate, protein and fat provide a similar amount of 12-13 ATP/MJ ME when the ME is based on their value as body constituent. The energetic efficiency is 42-43 percent. In the anaerobic mode, for glucose only, ATP is produced by substrate level phosphorylation during cytoplasmic glycolysis, the normal first step in the aerobic oxidation of glucose. However, under an-aerobic conditions cytoplasmic glycolysis produces lactate which requires one of two ways of aerobic clearance to avoid lactic acidosis. The 'ketogenic clearance' re-channels the lactate in aerobic oxidation of glucose, but elsewhere in the body. This ketogenic clearance can contribute to the normal ATP-requirement of the whole body, but causes a move to carbohydrate as energy substrate. If necessary these carbohydrates can be produced from body protein, with a decrease in the energetic efficiency to 29 percent. The "glucogenic clearance" re-cycles the lactate to glucose. This glucogenic pathway (Cori cycle) further lowers the energetic efficiency of ATP-production for peripheral use to 14.1 percent. The Cori cycle requires extra ATP and causes a move to fat as energy substrate. This desk study shows that the energetic efficiency of ATP-production for peripheral use will range between 14-43 percent depending on the need and availability of glucose. It is suggested that these results could be used to develop specific nutritional, physiological and environmental strategies to benefit physical fitness and weight management in daily practice.
    Postweaning growth check in pigs is markedly reduced by intermittent suckling and extended lactation
    Berkeveld, M. ; Langendijk, P. ; Beers-Schreurs, H.M.G. van; Koets, A.P. ; Taverne, M.A.M. ; Verheijden, J.H.M. - \ 2007
    Journal of Animal Science 85 (2007)12. - ISSN 0021-8812 - p. 258 - 266.
    feed-intake characteristics - digestive enzyme-activity - housed weanling pigs - early-weaned pig - small-intestine - boar exposure - crypt depth - performance - sows - consumption
    The objective of this study was to determine whether intermittent suckling (IS) combined with an extended lactation can reduce postweaning growth check in pigs. Three weaning regimens [ conventional weaning (CW), IS with 6-h separation intervals (IS6), and IS with 12-h separation intervals (IS12)] were compared. In CW (n = 17 litters), litters had continuous access to the sow until weaning (d 21, d 0 = farrowing). In IS6 and IS12, litters were separated from the sow for 12 h/d, beginning at d 14 and lasting until weaning (d 41 to 45). Litters were with the sow from 1400 to 2000 and from 0200 to 0800 (IS6, n = 14) or between 2000 and 0800 (IS12, n = 14). Litter size was standardized within 2 d after farrowing by crossfostering, resulting in an average litter size of 10.9 +/- 1.8 piglets. Piglets had ad libitum access to creep feed from d 7 onward. One week after the onset of IS (d 20), creep feed intake was increased in litters from both IS groups compared with CW litters (P <0.05). Both IS groups consumed considerable amounts of creep feed before weaning (d 41 to 45). Total feed intake before weaning was greater (P = 0.004) in IS12 (3,808 +/- 469 g/ piglet) than in IS6 (2,717 +/- 404 g/ piglet). In comparison, CW litters consumed 18 +/- 9 g/ piglet before weaning (d 21). Irrespective of weaning regimen, total feed intake of litters before weaning was highly correlated with postweaning feed intake (P <0.001). Furthermore, in all treatment groups, total preweaning feed intake was correlated with postweaning growth (P <0.10). Irrespective of treatment, piglets suckling anterior teats grew faster than piglets suckling middle or posterior teats during the first 2 wk of lactation. Body weights at the end of the experiment (d 55) were similar among weaning regimens. Onset of IS induced a growth check in both IS groups (34% for IS12 and 22% for IS6). Only a mild growth check was observed after weaning of IS litters (14% for both IS groups). However, a serious growth check (98%) was observed after weaning of CW litters. Results of the current study indicate that IS stimulated feed intake during lactation, providing a more gradual transition to weaning. Because the IS6 regimen did not prevent the growth check after the onset of IS and is rather laborious, we suggest that IS12 might be preferable for a practical implementation of IS.
    Does a time interval for methionine supplementation favour weight gain and body composition? A model study with growing rats.
    Gas, M. ; Bujko, J. ; Chudobinska, E. ; Verstegen, M.W.A. ; Koopmanschap, R.E. ; Schreurs, V.V.A.M. - \ 2007
    In: Energy and protein metabolism and nutrition, EAAP publication No. 124, Vichy, France, 9 - 13 September, 2007. - Wageningen, The Netherlands : Wageningen Academic Publishers - ISBN 9789086860418 - p. 95 - 96.
    Addition of chromic oxide to creep feed as a fecal marker for selection of creep feed-eating suckling pigs
    Kuller, W.I. ; Beers-Schreurs, H.M.G. van; Soede, N.M. ; Taverne, M.A.M. ; Kemp, B. ; Verheijden, J.H.M. - \ 2007
    American Journal of Veterinary Research 68 (2007)7. - ISSN 0002-9645 - p. 748 - 752.
    weanling pigs - performance - consumption
    Objective-To determine whether the addition of chromic oxide (Cr2O3) to creep feed could be used as a visual marker in feces for selection of creep feed-eating suckling pigs. Animals-20 suckling pigs. Procedures-Via syringe, 5 pigs (2 to 3 days old on day 0; 1 pig/treatment) from each of 4 litters received oral administrations of 10, 20, 30, or 40 g of creep feed containing 10 g of Cr2O3 center dot kg(-1) on each of 2 consecutive days (days 20 and 21) or 30 g of creep feed containing 10 g of Cr2O3 center dot kg(-1) on day 20 and 30 g of Cr2O3 free creep feed on day 21. On days 21 through 24, 6 fecal samples were collected from each pig at regular intervals between 8:00 Am and 6:00 Pm. Green-colored feces were considered indicative of creep feed consumption (eaters). Data analyses were based on single and multiple fecal samples. Results-On day 22, evaluation of 1 fecal sample/pig and multiple fecal samples per pig resulted in identification of as many as 40% and only 15% of the feed-treated pigs wrongly as noneaters, respectively. Repeated sampling over multiple days would identify 99% of eaters accurately. Pigs erroneously identified as noneaters were those administered either low amounts of Cr2O3 supplemented creep feed for 2 days or Cr2O3 supplemented creep feed on only 1 day. Conclusions and Clinical Relevance-Data suggest that addition of Cr2O3 to creep feed enables selection of individual creep feed-eating suckling pigs via examination of feces, provided that repeated fecal samples are evaluated.
    Creep feed intake during lactation enhances net absorption in the small intestine after weaning
    Kuller, W.I. ; Beers-Schreurs, H.M.G. van; Soede, N.M. ; Langendijk, P. ; Taverne, M.A.M. ; Kemp, B. ; Verheijden, J.H.M. - \ 2007
    Livestock Science 108 (2007)1-3. - ISSN 1871-1413 - p. 99 - 101.
    performance - pigs
    The aim of the study was to measure the effect of creep feeding during lactation on net absorption in the small intestine at 4 days after weaning. Intermittent suckling was used to increase creep feed intake during lactation. Creep feed containing chromic oxide was provided. Based on the colour of the faeces, piglets were classified as `eaters¿ or `non-eaters¿, respectively. At day 4 after weaning, an in vivo small intestine segment perfusion test was performed at 5 sites along the small intestine in 24 piglets (12 eaters and 12 non-eaters). At both sides of each intestinal segment a tube was fitted to perfuse and drain fluid in order to assess net absorption. Net absorption was higher in eaters than in non-eaters (P <0.001). Net absorption varied greatly between and within piglets and was highest in the caudal segments of the small intestine (P <0.001). These data suggest that creep feeding could be a useful tool in the prevention of post-weaning diarrhoea.
    Effects of intermittent suckling and creep feed intake on pig performance from birth to slaughter
    Kuller, W.I. ; Soede, N.M. ; Beers-Schreurs, H.M.G. van; Langendijk, P. ; Taverne, M.A.M. ; Kemp, B. ; Verheijden, J.H.M. - \ 2007
    Journal of Animal Science 85 (2007). - ISSN 0021-8812 - p. 1295 - 1301.
    reproductive-performance - lactating sows - weanling pigs - consumption - estrus - fertility - piglets
    An experiment was conducted to determine if the improved creep feed intake observed during intermittent suckling (IS) is important for postweaning performance. Therefore, creep feed intake of litters was assessed, and within litters, eaters and noneaters were distinguished using chromic oxide as an indigestible marker. Batches of sows were suckled intermittently (IS, 7 batches; n = 31) or continuously (control, 7 batches; n = 31). In the IS group, litters were separated from the sow for a period of 12 h/d (0930 to 2130), beginning 11 d before weaning. Litters were weaned at 4 wk of age. Litters had free access to creep feed from 1 wk of age onward. Five days after weaning, the piglets were moved as a litter to weanling pens. At 8 wk of age, 2 barrows and 2 gilts were randomly chosen from each litter and moved to a finishing facility. Feed intake was improved by IS during the last 11 d of lactation (IS, 284 ± 27 vs. control, 83 ± 28 g/piglet; P <0.001) and after weaning during the first (IS, 201 ± 24 vs. control, 157 ± 25 g·piglet¿1·d¿1; P <0.05) and second (IS, 667 ± 33 vs. control, 570 ± 35 g·piglet¿1·d¿1; P <0.05) wk. Thereafter, no differences were found to slaughter. Weaning BW was lower in IS litters (IS, 7.1 ± 0.01 vs. control, 8.1 ± 0.01 kg/piglet; P <0.05), but 7 d after weaning BW was similar (IS, 8.5 ± 0.2 vs. control, 8.7 ± 0.2 kg/piglet; P = 0.18), and no differences were found to slaughter. The percentage of eaters within a litter was not increased by IS during lactation (IS, 23 ± 4.5% vs. control, 19 ± 4.1%; P = 0.15). Weaning BW did not differ between eaters and noneaters (eater, 7.7 ± 0.1 vs. noneater, 7.5 ± 0.08 kg/piglet; P = 0.63). From 1 until 4 wk after weaning, piglets that were eaters during lactation had heavier BW than noneaters (eater, 20.3 ± 0.3 kg vs. noneater, 18.2 ± 0.2 kg; P <0.05). The influence of eating creep feed during lactation on BW and ADG and the influence of suckling treatment never showed an interaction. We conclude that IS increases ADFI during lactation on a litter level and improves ADG in the first week and ADFI in the first and second weeks after weaning. No long-term effects on ADFI or ADG were observed throughout the finishing period. In the current experiment, in which creep feed intake was low, the percentage of eaters within a litter was not increased, suggesting that creep feed intake of piglets that were already eating was stimulated by IS. Further, piglets that were eaters during lactation had heavier BW up to 4 wk after weaning.
    Application of a [13CO2] breath test to study short-term amino acid catabolism during the postprandial phase of a meal
    Bujko, J. ; Schreurs, V.V.A.M. ; Nolles, J.A. ; Verreijen, A.M. ; Koopmanschap, R.E. ; Verstegen, M.W.A. - \ 2007
    The British journal of nutrition 97 (2007)5. - ISSN 0007-1145 - p. 891 - 897.
    humans - proteins
    A [13CO2] breath test was applied as a non-invasive method to study the catabolism of ingested amino acids shortly after a meal. This test requires the ingestion of a [1-13C]-labelled amino acid and the analysis of expired air for [13C] enrichment and CO2. The recovery of label as [13CO2] reflects the catabolism of the [1-13C]-labelled substrate. Such a non-steady state approach provides information that is complementary to the information obtained by steady-state methods using a primed continuous infusion of tracer amino acids during the fed state. In a model study with twenty adult male rats, two groups of animals were fed twice a day with one of two semi-synthetic iso-energetic diets. One diet contained egg white protein (EW) as the sole amino acid source. The second diet contained a mixture of free amino acids with a pattern similar to that of the EW diet. On day 5 of the dietary treatment, l-[1-13C]leucine, either bound in EW protein or in free form, was ingested as part of the morning meal. The expired air was sampled at 30 min intervals for 5 h. The rate of recovery ranged from 0 % to 6 % of the dose/h. Up to 120 min after the onset of the meal, the recovery values for the free amino acid diet were higher than those for the EW diet. Differences in recovery reflect differences in postprandial utilisation. The differences in label recovery were mainly determined by the [13C] enrichment of the expired air. As a consequence, CO2 measurements are not mandatory when CO2 production is comparable.
    Ingrediënten voor een energieneutrale belichte glastuinbouw in 2020: Position Paper Licht
    Ruijter, J.A.F. de; Marcelis, L.F.M. ; Schreurs, M. - \ 2007
    Arnhem/Wageningen : KEMA/Wageningen UR Glastuinbouw - 110
    kassen - energiegebruik - duurzaamheid (sustainability) - energiebehoud - milieubeheersing - belichting - gebruiksefficiëntie - glastuinbouw - biobrandstoffen - warmtekrachtkoppeling - biobased economy - greenhouses - energy consumption - sustainability - energy conservation - environmental control - illumination - use efficiency - greenhouse horticulture - biofuels - cogeneration - biobased economy
    De glastuinbouw heeft de ambitie geformuleerd in 2020 energieneutraal te telen in nieuw te bouwen kassen. Die ambitie geldt ook voor de belichte glastuinbouw. Een kas (of glastuinbouwbedrijf) is energie-neutraal als er op jaarbasis nette geen fossiele primaire energie wordt verbruikt. Dat wil zeggen dat de kas (minimaal) evenveel benutbare energie exporteert als deze aan primaire (fossiel) energie importeert.
    Effect of weaning on intestinal blood flow : a pilot study
    Berkeveld, M. ; Langendijk, P. ; Beers-Schreurs, H.M.G. van; Hendriksen, S.W.M. ; Essen, G.J. van; Koets, A.P. ; Taverne, M.A.M. ; Verheijden, J.H.M. - \ 2006
    In: Proceedings of the 19th International Pig Veterinary Congress, Copenhagen, Denmark, 16-19 July 2006. - - p. 538 - 538.
    Effect of weaning on intestinal blood flow: a pilot study
    Berkeveld, M. ; Beers-Schreurs, H.M.G. van; Langendijk, P. ; Hendriksen, S.W.M. ; Essen, G.J. van; Koets, A.P. ; Taverne, M.A.M. ; Verheijden, J.H.M. - \ 2006
    Effect of creep feed intake before weaning on the small intestine of intermittently or continuously suckled pig
    Kuller, W.I. ; Beers-Schreurs, H.M.G. van; Soede, N.M. ; Taverne, M.A.M. ; Kemp, B. ; Verheijden, J.H.M. - \ 2006
    Intermittent suckling prevents weaning induced growth check
    Berkeveld, M. ; Langendijk, P. ; Beers-Schreurs, H.M.G. van; Koets, A.P. ; Taverne, M.A.M. ; Verheijden, J.H.M. - \ 2006
    Intermittent suckling prevents weaning induced growth check
    Berkeveld, M. ; Langendijk, P. ; Beers-Schreurs, H.M.G. van; Koets, A.P. ; Taverne, M.A.M. ; Verheijden, J.H.M. - \ 2006
    Comparison of different methods of body fat measurement in non-obese young adults
    Bujko, J. ; Kasprzak, J. ; Hulshof, P.J.M. ; Schreurs, V.V.A.M. - \ 2006
    Polish Journal of Food and Nutrition Sciences 15/56 (2006)S12. - ISSN 1230-0322 - p. 139 - 144.
    Dietary amino acids fed in free form and as protein components do not differently affects postprandial plasma insulin, glucagon, growth hormone and corticosterone responses in rats
    Nolles, J.A. ; Straten, E.M.E. van; Bremer, B.I. ; Koopmanschap, R.E. ; Verstegen, M.W.A. ; Schreurs, V.V.A.M. - \ 2006
    Journal of Animal Physiology and Animal Nutrition 90 (2006)7-8. - ISSN 0931-2439 - p. 289 - 299.
    skeletal-muscle - neonatal pigs - humans - ingestion - leucine - carbohydrate - metabolism - retention - mixtures - nitrogen
    This study examined, whether the postprandial fate of dietary amino acids from different amino acid sources is regulated by the responses of insulin, glucagon, corticosterone and growth hormone (GH). Male Wistar rats were cannulated in the vena jugularis and assigned to dietary groups. The diets contained 21% casein or the same amino acids in free form. In the free amino acid diets, methionine level was varied between the groups. The feed was supplied in two distinct meals. In previous experiments it was established that oxidative amino acid losses of the free amino acid diets and protein diets were different. After 3 weeks on those diets, it appeared that the differences in postprandial oxidative losses had been diminished. GH was measured every 12 min, from 144 min before the start of the experimental meal over the following 144 min. Insulin and corticosterone were measured six times from the start of the meal until 270 min after the meal. No differences have been observed between the hormonal responses to both meals at day 5 and at day 26. In conclusion, it has been found that the differences in the oxidative losses between protein and free amino acid meals are not mediated by the combined action of the insulin, glucagon, corticosterone and GH. Postprandial catabolism of amino acids is most probably regulated by substrate induction.
    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 9789085043423 - 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

    During the postprandial phase dietary proteins are digested to peptides and amino acids and absorbed. Once absorbed the peptides are further hydrolyzed to amino acids and transported to the tissues. These amino acids are largely incorporated into body proteins. Not all amino acids are, however, incorporated into body proteins part of these amino acids are oxidized, and can, thus, no longer be utilized to support protein metabolism in the body. The objective of this thesis was to increase the understanding of those processes that determine the utilization efficiency of dietary proteins. The studies described in this thesis, focused on the appearance rate of dietary amino acids in the free amino acid pool of the body. The rate of appearance of dietary amino acids in this pool has been shown to modulate the postprandial oxidation of amino acids and thereby also their utilization efficiency for physiological purposes. As a consequence postprandial oxidative losses influence the nutritional protein status of the body. This thesis aimed to elucidate whether the body is able to cope with diets in which the amino acid appearance rate is high and what mechanisms are involved in this process.

    First an effort was made to establish the metabolic consequences of amino acid sources with a high appearance rate in a rat and a human model. Postprandial oxidation of free or protein derived [1-13C]- leucine was determined in a [13CO2]-breath test, using both a diet consisting of only free amino acids including [1-13C]-leucine and a diet consisting of proteins in which [1-13C]-leucine was incorporated, and 1:1 mixtures of both diets. In those mixed diets either the protein part or the free amino acid part was labeled. The postprandial oxidative losses of dietary leucine after 5 days being fed these diets (short-term adaptation) appeared to be significantly higher for the free amino acid diet compared to the protein diet. These differences between dietary free amino acids and dietary protein persisted in the mixed diets, as measured by the [13CO2] breath-test. It was concluded that amino acids derived either from a free amino acid or a protein diet, were handled independently even when ingested simultaneously during the same meal. Results obtained in rats were comparable to the results obtained in humans.

    The differences in oxidation between a free amino acid and a protein diet had largely disappeared after long-term adaptation (after 26 to 30 days on the diet). An adaptive decrease in the oxidation of free amino acids was observed. In the second study it was examined to which extent increasing levels of methionine supplements in a diet (50, 100 or 200% methionine supplement relative to casein) were retained in body protein. This was thus far not clear since a higher appearance rate in the free pool has been reported to have a negative influence on the efficiency of utilization of amino acids from the diet. Moreover, only specific patterns of amino acids are supposed to be deposited in body protein. Higher dietary methionine levels resulted in higher postprandial oxidative losses of methionine. The groups, which were fed the diets with the highest methionine levels, showed the lowest methionine retention as part of intake but the highest retention in absolute terms. After long term adaptation, however, to the free amino acid diets, methionine retention was increased in all groups. It was concluded that postprandial retention of dietary amino acids is, at least in part, driven by the amino acid composition of the diet.

    In third study it was examined whether the postprandial fate of different dietary amino acid was regulated by hormonal responses to the diet. It has been observed that the differences in oxidative losses between diets consisting of free amino acids or protein were not mediated by the combined action of insulin, glucagon, corticosterone and GH. Hence, postprandial catabolism of amino acids is probably regulated by other mechanisms. As stated above, the amino acid appearance rate plays a crucial role in determining the postprandial utilization of amino acids. In the fourth study it was, therefore, investigated, whether the amino acid absorption rate can adapt to dietary free amino acids. Rats were kept on a free amino acid diet for 0 (nonadapted), 5, or 26 to 30 days (long-term adaptation). The methionine absorption of long-term adapted rats was lower than that of the non-adapted rats. It was concluded that the absorption of amino acid by the intestine plays a crucial role in minimizing the postprandial oxidative losses.

    Consequences of different strategies of free amino acid supplementation to dietary proteins for physiological utillization
    Gas, M. - \ 2006
    Wageningen University. Promotor(en): Martin Verstegen, co-promotor(en): Victor Schreurs; J. Bujko. - s.n. : S.n. - ISBN 9789085043355 - 150
    ratten - diermodellen - diëten - voer - vrije aminozuren - voedersupplementen - voedingseiwit - katabolisme - oxidatie - voedingsfysiologie - rats - animal models - diets - feeds - free amino acids - feed supplements - dietary protein - catabolism - oxidation - nutrition physiology
    The efficiency of using free amino acids (AAs) as dietary constituent is sometimes lower than that of AAs derived from intact protein. The aim of the project was to evaluate dietary management conditions, which can determine the efficiency of utilization of crystalline AAs in animal diets or in clinical nutrition. The studies in this thesis were focused mainly on differences in short-term catabolism between protein bound and free AAs during the post prandial phase of a meal. The stable isotope technique was used in model studies with laboratory Wistar (WU) rats. In different experiments, so-called [ 13 CO 2 ]-breath test studies were used to compare the metabolic fate of free and protein-bound [1- 13 C]-labeled AAs in a meal in various nutritional situations. The influence of free AA supplementation strategies on weight gain development was also studied. Moreover, protein and fat content in the liver and carcass were analysed.

    The results of the present study confirm literature that showed a higher post prandial catabolic losses of the tracer when dietary protein is replaced with crystalline AAs. In some, but not all situations a lower weight gain was observed for growing animals. Our results showed that short-term catabolic losses of endogenous leucine were modulated by exogenous AA supply. It increased or decreased depending on the adequacy of the dietary supply.

    The common practice for free AA supplementation is to mix it with the deficient protein. In our study we showed that during the post prandial period the best utilization of methionine deficient protein did not occur when methionine supplement was given simultaneously with methionine deficient meal. The best utilisation occurred when there was a delay between the supply of deficient meal and free methionine. Therefore, introducing time interval of free amino acid supplementation to poor quality protein should be considered as a factor with potential to improve physiological utilization of dietary amino acids.A 1h time interval for free methionine supplementation influenced the weight gain, but differently depending on the protein level. Animals fed very deficient protein diet (5%) showed higher weight gain when supplementation of the deficient free methionine was provided with a 1h delay (1h interval). With protein deficient diets and less than 7.5 % protein we found fatty livers in our experiment. We concluded that post prandial AA oxidation influences the post absorptive AA catabolism. This does not always mean effect on growth. For growth in rats lysine deficiency is most limiting but it seems that even a 34% methionine deficiency below the NRC recommendation did not limit growth. We found that methionine deficiency influenced fat metabolism and from the literature we concluded that the mechanism probably works via choline and carnitin
    Intermittent suckling: a system that benefits piglets?
    Kuller, W.I. ; Soede, N.M. ; Beers-Schreurs, H.M.G. van; Langendijk, P. ; Taverne, M.A.M. ; Verheijden, J.H.M. ; Kemp, B. - \ 2005
    Impact of Lys and/or met Deficient Protein on body Weight Gain and Cascass Composition of Growing Rats
    Gas, M. ; Buijko, J. ; Krupa, K. ; Koopmanschap, R.E. ; Schreurs, V.V.A.M. - \ 2004
    In: Physiological Determinants of Progress in Diet Therapy, Warszawa 5-6 XI 2004. - - p. 132 - 137.
    The Influence of a shift in Form of Meal Protein on Postprandial Oxidative Losses of Leucine and Methionine. A Model Study with rats
    Myszkowska-Ryciak, J. ; Buijko, J. ; Schreurs, V.V.A.M. ; Koopmanschap, R.E. - \ 2004
    In: Physiological Determinants of Progress in Diet Therapy, Warszawa 5-6 XI 2004. - - p. 158 - 163.
    Indirect Calorimetry and [13C] - Breath tests: complementary Methods for Study Energy Expenditure and Substrate Oxidation
    Buijko, J. ; Schreurs, V.V.A.M. - \ 2004
    In: Physiological Determinants of Progress in Diet Therapy: International Scientific Conference, Warsaw, 4-5 November 2004 - p. 50 - 57.
    Effect of Intermittent Suckling of Follicular Development during Lactation
    Soede, N.M. ; Kuller, W.I. ; Langendijk, P. ; Beers-Schreurs, H.M.G. van; Taverne, M.A.M. ; Kemp, B. ; Verheijden, J.H.M. - \ 2004
    In: Reproduction in Domestic Animals, 8th Conference of the European Society for Domestic Animal Reproduction, Warsaw, Poland, 23-25 September 2004. - Berlin, Germany : Blackwell Verlag GmbH - p. 285 - 285.
    Intermittent suckling: Effect of feed intake before weaning on net absorption in the small intestine
    Kuller, W.I. ; Beers-Schreurs, H.M.G. van; Soede, N.M. ; Langendijk, P. ; Taverne, M.A.M. ; Kemp, B. ; Verheijden, J.H.M. - \ 2004
    In: Proceedings of the 18th IPVS congress, Hoya, Germany, 27 June - 1 Juky 2004. - Hoya, Germany : IPVS Veranstaltungs GmbH - p. 726 - 726.
    Effect of intermittent suckling on follicular development during lactation
    Kuller, W.I. ; Soede, N.M. ; Langendijk, P. ; Beers-Schreurs, H.M.G. van; Taverne, M.A.M. ; Kemp, B. ; Verheijden, J.H.M. - \ 2004
    In: Proceedings of the 18th IPVS congress, Hoya, Germany, 27 June - 1 July 2004. - Hoya, Germany : IPVS Veranstaltungs GmbH - p. 472 - 472.
    Verschil in metabole benutbaarheid van vrije en eiwitgebonden aminozuren
    Schreurs, V.V.A.M. ; Kwakkel, R.P. ; Verstegen, M.W.A. - \ 2004
    Wageningen : Animal Nutrition (ANU) - 67 p.
    The influence of feeding frequency and protein source in protein status and immune response
    Buijko, J. ; Myszkowska-Ryciak, J. ; Koopmanschap, R.E. ; Kuijf, B. ; Zierikzee, A.M. ; Schreurs, V.V.A.M. - \ 2004
    In: Polish Journal of Food and Nutrition Sciences - p. 15 - 18.
    Intermittent suckling: Effects on piglet and sow performance before and after weaning
    Kuller, W.I. ; Soede, N.M. ; Beers-Schreurs, H.M.G. van; Langendijk, P. ; Taverne, M.A.M. ; Verheijden, J.H.M. ; Kemp, B. - \ 2004
    Journal of Animal Science 82 (2004)2. - ISSN 0021-8812 - p. 405 - 413.
    creep feed consumption - individual variation - litter separation - small-intestine - lactating sows - boar exposure - weanling pigs - estrus - fertility - growth
    An experiment was conducted to study effects of intermittent suckling on creep feed intake and weight gain of litters. Loss of weight and backfat during lactation, as well as reproductive performance, were also measured. Batches of multiparous sows (Parity I to 12, 4.1 on average) were either suckled intermittently (IS, eight batches; n = 50) or continuously (control, eight batches; n = 62). Litters were weaned at 27 +/- 2 d of age, on average. Litter size (11.1 +/- 0.2 piglets, on average) was standardized within a batch within 3 d of birth. All litters had free access to creep feed and water from 1 wk of age onward. In the IS group, litters were separated from the sow for a period of 12 h/d (0930 to 2130), starting 11 d before weaning. Rectal ultrasonography was applied at d 3 after weaning to check the ovaries for follicle development or presence of corpora lutea. Creep feed intake by the litters during lactation was higher in IS litters than in control litters (686 57 vs. 314 +/- 42 g/piglet, P <0.01). The distribution of creep feed intake shifted from a skewed one, with a majority of litters consuming less than 250 g/piglet in control litters, to a normal distribution, with an average creep feed intake of 500 to 750 g/piglet in IS litters. During the 7 d after weaning, creep feed intake in IS litters was also higher (281 +/- 15 vs. 204 +/- 9 g(.)piglet(-1.)d(-1), P <0.01). The ADG of piglets during lactation was negatively affected by IS, resulting in lower weight at weaning (7,229 +/- 140 vs. 7,893 +/- 145 g/piglet, P <0.05). During the 7 d after weaning, however, ADG was higher in IS litters (255 +/- 10 vs. 177 +/- 8 g(.)piglet(-1.)d(-1), P <0.01), and 7 d after weaning, the weights of the litters were similar (9,011 +/- 167 vs. 9,132 +/- 164 g/piglet, P = 0.81). The IS litters that consumed little or no feed during lactation had an ADG after lactation that was higher than in control litters, with comparable creep feed intake during lactation: 204 vs. 136 g/d. Body weight loss by the sows during lactation was lower in IS sows (-10 +/- 2 vs. -16 +/- 1 kg, P <0.05). A higher percentage of IS sows ovulated during lactation (22 vs. 3%, P <0.01), and weaning-to-ovulation interval (excluding sows with lactational ovulation) was shorter in IS sows (4.7 +/- 0.2 vs. 5.3 +/- 0.2 d, P <0.05). We conclude that IS increased creep feed intake during lactation, and that IS increased ADG after weaning, despite lower weaning weights. Ovulation during lactation was induced in 22% of the IS sows.
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