Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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

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

Exploring novel food proteins and processing technologies : a case study on quinoa protein and high pressure –high temperature processing
Avila Ruiz, Geraldine - \ 2016
Wageningen University. Promotor(en): Tiny van Boekel, co-promotor(en): Guido Sala; Markus Stieger. - Wageningen : Wageningen University - ISBN 9789462579095 - 152
dietary protein - chenopodium quinoa - whey protein - food process engineering - heat treatment - in vitro digestibility - fractionation - maillard reaction products - ph - viscosity - gelation - aggregation - high pressure technology - sds-page - voedingseiwit - wei-eiwit - levensmiddelenproceskunde - warmtebehandeling - in vitro verteerbaarheid - fractionering - maillard-reactieproducten - viscositeit - gelering - aggregatie - hogedruktechnologie

Foods rich in protein are nowadays high in demand worldwide. To ensure a sustainable supply and a high quality of protein foods, novel food proteins and processing technologies need to be explored to understand whether they can be used for the development of high-quality protein foods. Therefore, the aim of this thesis was to explore the properties of a novel food protein and a novel processing technology for the development of high-quality protein foods. For this, quinoa was chosen as an alternative protein source and high pressure – high temperature (HPHT) processing was chosen as a novel processing technology.

Quinoa protein has been found to have a balanced amino acid profile and to be allergen-free. As this combination is not common among plant proteins, it is worth studying physicochemical and functional protein properties of quinoa further (Chapter 1). Extraction and processing conditions can influence protein properties and thus functionality. Therefore, quinoa protein properties were examined at different extraction and processing conditions (Chapter 2 and 3). For this, the protein was isolated from the seed using alkaline extraction and subsequent acid precipitation. The quinoa protein isolates (QPIs) obtained were examined in terms of protein purity, yield, solubility, denaturation, aggregation and gelation behaviour, and digestibility.

It was found that when extraction pH increased, protein yield and denaturation increased, which was explained by a higher protein charge, leading to increased unfolding and solubilisation (Chapter 2). Protein purity decreased with increasing extraction pH, which was associated with a possible co-extraction of other seed components. QPIs obtained at extraction pH 8 (E8) and 9 (E9) had a higher solubility in the pH range of 3-4.5 (E9 solubility was highest at pH 7) compared to the isolates obtained at extraction pH 10 (E10) and 11 (E11). It was hypothesised that at a higher extraction pH, the larger extent of protein denaturation led to the exposure of hydrophobic groups, thus decreasing surface polarity and solubility. When suspensions of E8 and E9 were heated, protein aggregation increased and semi-solid gels with a dense microstructure were formed. In contrast, suspensions of E10 and E11 aggregated to a lower degree and did not form self-supporting gels upon heating. The gels obtained with E10 and E11 had furthermore a microstructure showing loose particles. Increased protein aggregation and improved gel formation at lower extraction pH were hypothesised to be due to a higher degree of hydration and swelling of protein particles during heating, leading to increased protein-protein interactions. These findings show that QPI obtained at an extraction pH below 9 might be used to prepare semi-solid gelled foods, while QPI obtained at pH values higher than 10 might be more suitable to be applied in liquid foods.

Heat treatments of QPI suspensions lead to an increased protein denaturation and aggregation but to a decreased in vitro gastric protein digestibility, especially at a high temperature (120°C) and extraction pH (11) (Chapter 3). It was hypothesised that QPIs obtained at a higher extraction pH and treated at higher temperature were denatured to a greater extent and contained stronger protein crosslinks. Therefore, enzyme action was impaired to a higher degree compared to lower temperatures and extraction pH values. This means that by controlling extraction pH and treatment temperature the digestibility of quinoa protein can be optimised.

The disadvantage of the conventional fractionation method used in Chapter 2 and 3 is that it requires high amounts of energy and water and the solvents used can denature the protein, possibly leading to a loss in functionality. Therefore, recently, a new method has been developed, hybrid dry and aqueous fractionation, which uses less energy and water and has proved successful for obtaining protein-rich fractions from pea. It was not known whether hybrid dry and aqueous fractionation can be used to obtain protein-rich fractions of quinoa (Chapter 4). Quinoa seeds were carefully milled to disentangle the protein-rich embryo from the starch-rich perisperm. Using subsequent air-classification, the embryo and perisperm were separated based on size into a protein-rich fraction and a starch-rich fraction, respectively (dry fractionation). The protein-rich fraction was further milled to a smaller particle size and suspended in water. This step was to solubilise the protein (aqueous fractionation), whereby a smaller particle size and adding NaCl optimised the solubilisation efficiency. The addition of salt helped to extract more salt-soluble proteins from quinoa, next to the water-soluble proteins. After centrifugation, the protein-enriched top aqueous phase was decanted and ultrafiltered for further protein concentration. The process generated a quinoa protein-rich fraction with a protein purity of 59.4 w/dw% and a protein yield of 62.0%. Having used 98% less water compared to conventional protein extraction, this new method is promising for industry to obtain quinoa protein concentrates in a more economic, sustainable and milder way.

Next to exploring novel food proteins for the development of high-quality protein foods, novel processing technologies are also important to study. This is because traditional thermal processing can deteriorate the quality of protein-rich foods and beverages by causing undesired browning or too high viscosities. Therefore, for sterilisation purposes, HPHT processing was investigated for the treatment of protein foods (Chapter 5). Model systems, whey protein isolate – sugar solutions, were used to study the effect of pressure at high temperature on Maillard reactions, browning, pH, protein aggregation and viscosity at different pH. It was found that pressure retarded early and advanced Maillard reactions and browning at pH 6, 7 and 9, while it inhibited protein aggregation and, thereby, a high viscosity at pH 7. The mechanism behind this might be that pressure induces a pH drop, possibly via dissociation of ionisable compounds, and thus slows down Maillard reactions. Differences in protein conformation, protein-protein interactions and sensitivity of whey proteins, depending on pH, pressure and heat, might be at the base of the reduced protein aggregation and viscosity observed at pH 7. The results show that HPHT processing can potentially improve the quality of protein-sugar containing foods, for which browning and high viscosities are undesired, such as high-protein beverages.

Finally, the properties of quinoa protein and HPHT processing were discussed in a broader context (Chapter 6). It was concluded that QPI obtained at pH 9 is a promising alternative to pea and soy protein isolate from a technical perspective and that QPI protein yields can be optimised. Also, quinoa protein-rich fractions obtained with the hybrid dry and aqueous fractionation method were predicted to have comparable properties to QPI, soy and pea protein isolates. However, from a marketing perspective, the protein-rich fraction was considered more advantageous to be up-scaled compared to QPI. High pressure at ambient or high temperature was found to have an added value compared to heat, which can be used for the development of high-quality protein food. Lastly, quinoa protein and HPHT processing might become more attractive for industry in the light of current trends, if present predictions can be confirmed and remaining issues can be resolved.

Dietary protein, blood pressure and mortality : the value of repeated measurements
Tielemans, S.M.A.J. - \ 2016
Wageningen University. Promotor(en): Marianne Geleijnse; Daan Kromhout, co-promotor(en): Hendriek Boshuizen. - Wageningen : Wageningen University - ISBN 9789462577916 - 169 p.
cardiovascular diseases - blood pressure - dietary protein - mortality - cardiovascular disorders - hypertension - urea - meta-analysis - antihypertensive agents - plant protein - animal protein - hart- en vaatziekten - bloeddruk - voedingseiwit - mortaliteit - hart- en vaatstoornissen - hypertensie - ureum - meta-analyse - antihypertensiva - plantaardig eiwit - dierlijk eiwit

Cardiovascular diseases (CVD) are the main cause of death worldwide. In 2012, about 17.5 million people died from CVD, accounting for 30% of all deaths. High blood pressure (BP) is a major cardiovascular risk factor, which was responsible for 10.4 million deaths in 2013. Diet and lifestyle play an important role in the etiology of hypertension. Maintenance of a desirable body weight, physical activity, and low intake of alcohol and salt are well-known measures to avoid high BP. Whether dietary protein, or more specifically plant and animal protein, could contribute to maintaining a healthy BP is less clear. The association between BP and CVD mortality has been extensively investigated. BP in prospective studies can be analyzed using different approaches, such as single BP (measured at one moment in time), single BP adjusted for regression dilution, average BP, and trajectories of BP. It is not yet clear which of these approaches is to be preferred for CVD risk prediction.

This thesis is centered on BP as a major cardiovascular risk factor. In the first part (Chapter 2, 3 and 4), the relation of dietary protein intake with BP level and change was examined. In the second part (Chapter 5 and 6), various approaches for analyzing repeated BP measurements were compared in relation to CVD and all‑cause mortality risk. The final chapter discusses the main findings and their implications.

Chapter 2 describes the association of 24-h urinary urea excretion, as a biomarker of total protein intake, with 9-year incidence of hypertension. We analyzed data of ~4000 men and women aged 28–75 years, who participated in the Prevention of Renal and Vascular Endstage Disease (PREVEND) study, a prospective cohort study. BP was measured four times during 1997–2009 and participants were followed for hypertension incidence, defined as BP ≥140/90mmHg or use of antihypertensive medication. Urea excretion was assessed in two consecutive 24-h urine collections at baseline and approximately 4 years later, from which total protein intake was estimated. Protein intake based on 24-h urinary urea excretion was not associated with incident hypertension.

Chapter 3 presents findings for long-term total, animal and plant protein intake in relation to 5‑year BP change. Analyses were based on 702 observations of 272 men who participated in the Zutphen Elderly Study. Participants did not use antihypertensive medication and were initially free of CVD. Physical and dietary examinations were performed in 1985, 1990, 1995, and 2000. BP was measured twice at each examination and protein intake was assessed using the cross-check dietary history method. The upper tertiles of plant protein intake were associated with a mean 5‑year change in systolic BP of ‑2.9 mmHg (95% CI: ‑5.6, ‑0.2), compared with the bottom tertile. Total and animal protein intake was not associated with BP.

Chapter 4 describes a meta‑analysis of 12 observational studies and 17 randomized controlled trials (RCTs) of dietary protein, including animal and plant protein, in relation to BP. Protein intake in prospective cohort studies was not associated with incident hypertension. For RCTs that used carbohydrate as a control treatment, the pooled BP effect was ‑2.1 mmHg systolic (95% CI: ‑2.9, ‑1.4) for a weighted mean contrast in protein intake of 41 grams per day. There was no differential effect of animal and plant protein on BP.

Chapter 5 describes repeated BP measures and their association with CVD and all‑cause mortality and life years lost in two prospective and nearly extinct cohorts of middle-aged men, the Minnesota Business and Professional Men Study (n=261) and the Zutphen Study (n=632). BP was measured annually during 1947–1957 in Minnesota and 1960–1970 in Zutphen. After 10 years of BP measurements, men were followed until death on average 20 years later. Each 25-mmHg increase in average SBP was associated with a 49% to 72% greater CVD mortality risk, 34% to 46% greater all-cause mortality risk and 3 to 4 life years lost. Four systolic BP trajectories were identified, in which mean systolic BP increased by 5 to 49 mmHg in Minnesota and 5 to 20 mmHg in Zutphen between age 50 and 60. In Zutphen, a 2-times greater CVD and all-cause mortality risk and 4 life years lost were observed when comparing trajectories. In Minnesota, associations were twice as strong. BP trajectories were the strongest predictors of CVD mortality and life years lost in Minnesota men, whereas in Zutphen men, the average BP was superior to other measures.

Chapter 6 presents findings for average BP and BP trajectories in relation to CVD and all-cause mortality, taking into account antihypertensive medication. A total of 762 participants aged ≥50 years of the Rancho Bernardo Study were examined five times from 1984 to 2002 and monitored for cause‑specific mortality from 2002 to 2013. Each 20‑mmHg increment in average systolic BP was associated with 35% greater CVD mortality and 25% greater all-cause mortality risk. We identified four trajectories for systolic BP for which BP increases ranged from 5 to 12 mmHg between age 60 and 70. In individuals who belonged to the higher trajectories, 2‑3 times greater CVD mortality and 1.5-times greater all-cause mortality risks were observed, compared to those who belonged to the lowest trajectory. Long-term systolic BP trajectories and average systolic BP were both significant predictors of CVD and all-cause mortality. The associations were not modified by antihypertensive medication.

As described in Chapter 7, various approaches were used to study the relation between protein intake and BP. Findings from individual studies and a meta-analysis suggest that dietary protein per se does not affect BP within the range of intake generally consumed in the Netherlands. Replacing carbohydrates by protein, however, has a beneficial effect on BP.

Moreover, this thesis showed that BP trajectories are not superior to average BP in predicting CVD and all-cause mortality. A few repeated BP measurements, e.g. three or four, are likely to be sufficient for obtaining a reliable average BP and had a similar predictive value for mortality compared to BP trajectories. Therefore, average BP can be considered the most practical tool for estimating mortality risk.

Impact of health status on amino acid requirements of growing pigs : towards feeding strategies for farms differing in health status
Kampman-van de Hoek, E. - \ 2015
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Walter Gerrits; Alfons Jansman. - Wageningen : Wageningen University - ISBN 9789462573437 - 184
varkens - afmesten - diergezondheid - aminozuren - voedingsstoffenbehoeften - voedingseiwit - aminozuurmetabolisme - stikstofretentie - immuniteitsreactie - immuunsysteem - varkensvoeding - diervoeding - pigs - finishing - animal health - amino acids - nutrient requirements - dietary protein - amino acid metabolism - nitrogen retention - immune response - immune system - pig feeding - animal nutrition


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

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

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

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

Body composition and reproduction in broiler breeders: impact of feeding strategies
Emous, R.A. van - \ 2015
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Rene Kwakkel; Marinus van Krimpen. - Wageningen : Wageningen University - ISBN 9789462572386 - 173
vleeskuikenouderdieren - vleeskuikens - lichaamssamenstelling - gevogeltevoeding - voer - voedingseiwit - voeropname - diergedrag - corticosteron - voortplanting - vrouwelijke vruchtbaarheid - prestatieniveau - diervoeding - broiler breeders - broilers - body composition - fowl feeding - feeds - dietary protein - feed intake - animal behaviour - corticosterone - reproduction - female fertility - performance - animal nutrition


Key words: broiler breeder, feeding strategies, body composition, reproduction, behavior

Nowadays, welfare issues in broiler breeders associated with nutrition and reproductive characteristics, are becoming increasingly challenging. Due to genetic selection on broilers, body composition of breeders has changed dramatically during the last 50 years to less fat and more breast muscle. It is postulated that a certain amount of body fat in broiler breeders at the onset of lay is necessary for maximum performance and offspring quality. Body composition of breeders can be influenced by different feed allowances during rearing and lay, as well as by changes in nutrient composition of the diet. However, little is known about the effects of body composition on reproduction of broiler breeders. In this thesis, we investigated the effects of different feeding strategies during the rearing period on body composition at the end of rearing. Moreover, the effects of differences in body composition at the end of rearing, and feeding strategies during lay were evaluated on breeder performance, incubation traits, offspring performance, behavior and feather cover. From this study, it can be concluded that feeding a low protein diet during rearing decreased breast muscle and increased abdominal fat pad, whereas providing an increased feeding schedule, which resulted in a high growth pattern, only increased abdominal fat pad, at the end of rearing. The higher abdominal fat pad content resulted in an increased hatchability during the first phase of lay and a larger number of eggs during the second phase of lay. For maintaining growth pattern, broiler breeders had to provide a higher amount of feed with an increased energy to protein ratio compared to broiler breeders that were fed a diet with a standard energy to protein ratio. This resulted in an increased eating time and less stereotypic object pecking, which may indicate a reduced hunger and frustration. On the other hand, a low daily protein intake during the rearing and first phase of lay can lead to a poor feather cover. Feeding a high-energy diet during the second phase of lay resulted in increased hatchability, decreased embryonic mortality and more first grade chicks.

Dietary protein and blood pressure : epidemiological studies
Altorf-van der Kuil, W. - \ 2012
Wageningen University. Promotor(en): Pieter van 't Veer, co-promotor(en): Marianne Geleijnse; Marielle Engberink. - S.l. : s.n. - ISBN 9789461733078 - 203
voedingseiwit - bloeddruk - epidemiologische onderzoeken - eiwitinname - dieet - dietary protein - blood pressure - epidemiological surveys - protein intake - diet

Elevated blood pressure is a major risk factor for cardiovascular diseases. Diet and lifestyle have a substantial impact on blood pressure, but the role of protein intake is not yet clear. This thesis focuses on total dietary protein, types of protein (i.e. plant and animal), protein from specific sources (i.e. dairy, meat, and grain), and specific amino acids in relation to blood pressure levels and incident hypertension.

The associations of dietary protein, protein types, and protein from specific sources with population blood pressure levels were cross sectionally examined in 20,820 Dutch adults aged 25 to 65 y (MORGEN Study). The relation with risk of hypertension was examined in 3,588 of these adults with 15 years of follow-up (Doetinchem Study) and in 2,241 older Dutch adults (≥55y) with 6 years of follow-up (Rotterdam Study). In the latter cohort we also examined the relation of specific amino acids (i.e. glutamic acid, arginine, lysine, cysteine, tyrosine, and essential amino acids) with blood pressure levels and risk of hypertension. As an ancillary Study, a fully controlled randomized cross over trial with different protein-rich diets was conducted to obtain objective biomarkers for dietary protein types that may be used in future epidemiological studies. Finally, we performed several meta-analyses to summarize our findings for dietary protein and protein types in relation to blood pressure and incident hypertension, combined with data from the literature.

The epidemiological studies presented in this thesis and a meta analysis of observational studies showed no associations of total protein and animal protein with blood pressure or incident hypertension. A meta analysis of 14 randomized controlled trials, however, showed a pooled blood pressure effect of protein supplementation (weighed mean contrast in intake of 41 g/d) of 2.1 mmHg systolic (95%-CI: 2.9 to 1.4) when compared to carbohydrate intake. In the epidemiological studies in this thesis plant protein was significantly inversely associated to blood pressure levels ( 1.8/ 1.0 mmHg with 14 grams higher energy adjusted intake), but not with incident hypertension (all HR per SD ~1.00). Meta-analyses of cross sectional studies showed a small differential association of plant and animal protein with blood pressure (-0.52 mmHg per SD of dietary plant protein versus +0.03 mmHg per SD of animal protein), but this association was not present in meta-analyses of prospective studies and trials. The epidemiological analyses on meat protein and dairy protein in this thesis revealed no consistent associations with blood pressure or incident hypertension. Grain protein was inversely associated with diastolic (but not systolic) blood pressure, and with borderline significant lower risk of hypertension in a general Dutch population (HR: 0.75, 95% CI: 0.73 to 1.00), but this association was absent in older adults. No associations with blood pressure or incident hypertension were found for amino acid intakes. Finally, we identified a combination of 3 urinary amino acids as a potential biomarker for meat protein intake and a combination of 7 plasma amino acids as a potential biomarker for grain protein intake

Results from this thesis suggest a small beneficial effect of protein on blood pressure if consumed instead of carbohydrates. Plant protein, e.g. from grain, may be more beneficial to blood pressure than animal protein but data are too limited to draw firm conclusions. After validation, future epidemiological studies could make use of biomarkers as more robust estimates for protein from specific sources and amino acid intakes. Randomized controlled trials are warranted to examine the blood pressure effect of specific types of protein, reflecting habitual intakes in western societies, compared to different types of carbohydrate. At present, a prudent diet for the prevention of hypertension with adequate amounts of dietary protein, preferable from plant sources, is recommended.

Beweging wordt efficiënter met juiste voeding
Tieland, Michael - \ 2012
elderly - nutrition and health - exercise - physical activity - proteins - dietary protein - elderly nutrition
Protein and energy nutrition of marine gadoids, Atlantic cod (Gadus morhua L.) and haddock (Melanogrammus aeglefinus L.)
Tibbetts, S. - \ 2012
Wageningen University. Promotor(en): S.P. Lall; Johan Verreth, co-promotor(en): Johan Schrama. - [S.l.] : s.n. - ISBN 9789461731357 - 221
kabeljauw - schelvis - zeevissen - voedingseiwit - energie - visvoeding - diervoeding - verteerbaarheid - ingrediënten - mengvoer - voedingsstoffenbehoeften - visteelt - aquacultuur - cod - haddock - marine fishes - dietary protein - energy - fish feeding - animal nutrition - digestibility - ingredients - compound feeds - nutrient requirements - fish culture - aquaculture

Primary goals of this thesis were to: 1) examine the in vivo digestion of macronutrients from conventional or alternative feed ingredients used in practical diets of juvenile gadoids (Atlantic cod and haddock), 2) document growth potential of fish at the juvenile grower phase given varying levels of dietary protein and energy and 3) assess the potential of in vitro pH-Stat methods for rapid screening protein quality of feed ingredients, specifically for gadoids. All primary research questions were linked to and built upon one another with the goal of gaining a better understanding of protein and energy utilization of juvenile grower phase gadoids. Studies showed that cod and haddock have a high capacity to utilize a wide range of dietary feed ingredients, such as fish meals, zooplankton meal, soybean products (meal, concentrate and isolate) and wheat gluten meal. New dietary formulations for gadoids may also utilize pulse meals, corn gluten meal, canola protein concentrate and crab meal. Digestibility data in this thesis is currently the only research that examined both in vivo and in vitro macronutrient digestibility of a large number and wide range of individual ingredients, specifically for gadoids. This is essential to gain new knowledge on protein and energy utilization as well as for least-cost ration formulations and effective substitution of ingredients into new formulations. Data has demonstrated a dietary digestible protein/digestible energy (DP/DE)ratio of 30 g DP/MJ DE is required for gadoids during the juvenile phase (<100 g) to ensure maximum somatic tissue growth, high digestibility, maximum nitrogen and energy retention efficiency and minimal excessive liver growth. Preliminary nutrient requirement studies together with an applied nutritional approach has identified that feeds for juveniles farmed in the Western North Atlantic should contain 50-55% crude protein, <12% fat and <17% carbohydrate. Data in this thesis is currently the first aimed at development and application of an in vitro closed-system pH-Stat assay for rapid screening protein quality of test ingredients that is ‘species-specific’ to gadoids. It is demonstrated that in vitro results generally reflected results obtained through conventional in vivo protein digestibility methods. Studies resulted in the first generation of a ‘gadoid-specific’ proteolytic enzyme extraction method and in vitro closed-system pH-Stat assay which may be useful to investigate protein digestion, absorption and metabolism of gadoids and further development of their feeds.

Proteins in biomass streams
Mulder, W.J. - \ 2010
Wageningen : Food & Biobased Research (Rapport 1134) - 60
eiwitten - agro-industriële sector - landbouwindustrie - biomassa - voedingseiwit - diervoedering - financiën - biobased economy - bioraffinage - productieprocessen - chemicaliën uit biologische grondstoffen - economische aspecten - proteins - agroindustrial sector - agribusiness - biomass - dietary protein - animal feeding - finance - biorefinery - production processes - biobased chemicals - economic aspects
The focus of this study is to give an overview of traditional and new biomasses and biomass streams that contain proteins. When information was available, the differences in molecular structure and physical and chemical properties for the different proteins is given. For optimal biomass use, isolation of valuable compounds like proteins can be an important aspect. To make decisions possible if biorefinery strategies by which the isolation of proteins is feasible, the economical value and production volumes of the different biomass streams will be discussed (when available). Also the industrial relevance and possible applications, such as technical applications and chemicals derived from proteins, will be reported. In addition, the outlet of protein-rich biomass resources in the feed sector will be pointed out.
Evaluation of the optimum protein requirements for Vietnamese pigs
Pham, K.T. - \ 2010
Wageningen University. Promotor(en): Martin Verstegen; Wouter Hendriks, co-promotor(en): N. Le Duc. - [S.l. : S.n. - ISBN 9789085856115 - 188
varkens - eiwitbehoefte - varkensvoeding - voer - voedingseiwit - lysine - voedersupplementen - prestatieniveau - diervoeding - vietnam - pigs - protein requirement - pig feeding - feeds - dietary protein - feed supplements - performance - animal nutrition
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 9085043352 - 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
Modelling responses of broiler chickens to dietary balanced protein
Eits, R.M. - \ 2004
Wageningen University. Promotor(en): Martin Verstegen; Leonard den Hartog, co-promotor(en): Rene Kwakkel. - [S.I.] : S.n. - ISBN 9085040701 - 163
vleeskuikens - pluimvee - voedingseiwit - voedingsstoffen - eiwitbalans - groeitempo - voederconversie - karkasopbrengst - vleesopbrengst - vleeskuikenresultaten - groeimodellen - diervoeding - pluimveevoeding - voedingsfysiologie - broilers - poultry - dietary protein - nutrients - protein balance - growth rate - feed conversion - carcass yield - meat yield - broiler performance - growth models - animal nutrition - poultry feeding - nutrition physiology
Post prandial oxidative losses for free amino acids in the diet: studies on interactions with dietary protein and on long term adaptation
Nolles, J.A. ; Verreijen, A.M. ; Koopmanschap, R.E. ; Schreurs, V.V.A.M. - \ 2003
In: Progress in research on energy and protein metabolism. Proceedings of the International Symposium on Energy & Protein Metabolism and Nutrition, Rostock-Warnemünde, Germany, 13th-18th September 2003. - Rostock-Warnemünde, Germany : Wageningen Academic Publishers - ISBN 9076998248 - p. 713 - 716.
voedingseiwit - aminozuren - aminozuurmetabolisme - ratten - isotopenlabelling - dietary protein - amino acids - amino acid metabolism - rats - isotope labeling
In this study we have tried to elucidate differences in postprandial oxidation between free and protein bound amino acids both after short and long term exposure. By labeling the different dietary forms their fate of the different dietary forms could be traced independently. By this approach we were also able to study potential interactions between the oxidation of free and protein-bound amino acids when both are mixed in one meal
Extra zetmeel overbodig bij onbeperkt voeren van drachtige zeugen
Peet-Schwering, C. van der; Binnendijk, G. - \ 2002
Praktijkkompas. Varkens 16 (2002)4. - ISSN 1570-8578 - p. 18 - 19.
varkenshouderij - varkens - varkensvoeding - zeugenvoeding - onbeperkte voedering - bijvoeding - aanvullend voer - zetmeel - worpgewicht - gewicht - biggen - voersamenstelling - voedingsbehoeften - eiwit - voedingseiwit - voedingsrantsoenen - zeugen - zwangerschap - pig farming - pigs - pig feeding - sow feeding - unrestricted feeding - supplementary feeding - supplementary feeds - starch - litter weight - weight - piglets - feed formulation - feed requirements - protein - dietary protein - feed rations - sows - pregnancy
Onbeperkt gevoerde drachtige zeugen krijgen een zetmeelarm, ruwecelstofrijk voer verstrekt om vervetting van de zeugen te voorkomen.
Influence of dietary protein sources on putative in vitro and in vivo colon cancer biomarkers
Vis, E.H. - \ 2002
Wageningen University. Promotor(en): J.H. Koeman; Tiny van Boekel. - S.l. : S.n. - ISBN 9789058086525 - 160
voedingseiwit - caseïnaten - sojaeiwit - colorectaal kanker - rattenvoeding - muizen - biologische indicatoren - dietary protein - caseinates - soya protein - colorectal cancer - rat feeding - mice - biological indicators
<p>Colon cancer (cancer of the large intestine) is a worldwide problem in especially Western countries. The diet might be responsible for up to 90% of these colon cancer cases. This means that decreasing colon cancer risk should be possible by changing the diet. The research presented in this thesis concerns the question what the influence is of dietary protein sources on colon cancer risk. As described in <strong>Chapter</strong><strong>1</strong> , casein was compared to other dietary protein sources (mainly soy protein) for its influence on:</p><OL><p><LI>the carcinogen scavenging capacity of proteins,</LI></p><p><LI>early stages of colon cancer,</LI></p><p><LI>fecal colon cancer biomarkers.</LI></p></OL><strong><p>Chapter</strong><strong>2</strong> provides information on various fields of study in the research on dietary proteins and colon cancer, including background information on the methods used. It is explained how dietary proteins can act as carcinogen scavengers by binding to carcinogens in the gastro-intestinal lumen. The carcinogen can be transported along the intestinal tract and be taken up by the body. If a carcinogen is not taken up, it will be excreted with the feces. Furthermore, the influence of the <em>amount</em> of protein intake in the diet on colon cancer risk is discussed. It is concluded that either no or a positive correlation between the amount of protein intake and colon cancer risk, exists. Another important research area is protein digestibility because a low protein digestibility results in a high amount of protein in the colon. Furthermore, the amino acid composition of a protein is important for two reasons. When an essential amino acid is present in a limiting amount, growth of both the individual and the tumor is inhibited. Secondly, some amino acids are needed for specific biological functions. For example, sulfur containing amino acids can stimulate the biotransformational system. The last important factor discussed in the research area of proteins on colon cancer risk is the presence of various non-protein components. As an example, saponins and isoflavones present in many soy proteins and known to be biologically active, are discussed.</p><p>In Chapter 3 and 4 it is described how dietary proteins can scavenge carcinogens <em>in vitro</em> . In <strong>Chapter</strong><strong>3</strong> it is shown that carcinogen scavenging is influenced by many factors, such as heat treatment of the protein, degree of protein digestion and presence of bile acids or lipase. Protein type did not have a major influence so no effect of feeding different dietary protein sources on colon cancer risk is expected.</p><p>In <strong>Chapter</strong><strong>4</strong> it is shown that the carcinogen scavenging capacity of proteins is also very much dependent on the type of carcinogen. Benzo[a]pyrene, a large non-reactive pro-carcinogen, interacted only with intact dietary proteins, whereas MNNG, as described in Chapter 3, strongly interacted with both intact as well as hydrolyzed proteins. Again no difference between dietary protein sources was shown, suggesting no difference in colon cancer risk.</p><p>In <strong>Chapter 5</strong> the first animal experiments are described. In Study 1, the influence of the addition of 1% methionine to the diet on colonic cell proliferation was tested. Methionine is an important methyl donor in many metabolic routes and is present in different amounts in casein and soy protein preparations. Colonic cell proliferation was used as an indication of colon cancer risk, because cell proliferation is an important phase in the process of colon cancer. The study showed no influence of methionine on colonic cell proliferation. In Study 2 rats were fed different amounts of soy non-nutrients to test the influence of these non-nutrients on several parameters in the feces. Most important fecal parameter was the fecal fat percentage, because earlier studies reported a correlation between high fecal fat and colon tumors. Study 2 showed that fecal fat excretion in rats is dependent on the amount of soy non-nutrients in the diet. However, the difference in fecal fat excretion between casein and soy protein was smaller (factor 2) than reported in literature. Therefore no major effect on colon cancer risk is expected. The influence of soy non-nutrients on processes in the colon was shown in Study 3. In this <em>in vitro</em> study, soy non-nutrients strongly reduced bile acid induced cell damage, suggesting a small protective effect of dietary soy protein.</p><p>In <strong>Chapter 6</strong> two animal studies on the influence of casein and soy protein on colonic cell proliferation are described. The studies showed no difference in colonic cell proliferation between these two protein sources. However different results for the casein and soy protein diets were obtained for several parameters that were measured in the feces of the animals. These fecal parameters were measured because they show how important steps in the process of colon cancer development are affected. A high fecal fat percentage correlates with a high number of tumors in the colon. Fecal alkaline phosphatase (ALP) activity represents damage to cells of the colonic epithelium because epithelial cells exhibited a high ALP activity. Bile acids and free fatty acids can damage the colonic epithelium because of their lytic potential. The cytolytic activity measures this damaging capacity, because it measures the lytic potential of the colonic contents towards cells in an <em>in vitro</em> test. The pH of the fecal contents was measured because a low pH represents a healthy colonic environment. Fecal<FONT FACE="Symbol">b</font>-glucuronidase and<FONT FACE="Symbol">b</font>-glucosidase activities were measured because they represent the capacity of the colonic contents to liberate toxicants in the colonic lumen that were earlier detoxified by the liver.</p><p>Results on cytolytic activity confirmed the lack of difference between casein and soy on colonic cell proliferation because there was no difference between diets. Fecal fat excretion was doubled after feeding soy protein compared to casein. After feeding soy protein, fecal water bile acid concentrations and ALP activity were decreased. However,<FONT FACE="Symbol">b</font>-glucuronidase and<FONT FACE="Symbol">b</font>-glucosidase were increased 10-100 fold. Overall, no consistent conclusion on fecal parameters was possible.</p><p>In <strong>Chapter 7</strong> the influence of casein, soy protein isolate and soy flour on colonic aberrant crypt foci (ACF) is tested. ACFs are considered to be early stages of colonic tumors. Overall no consistent difference of casein and soy protein on aberrant crypt foci was detected. Again<FONT FACE="Symbol">b</font>-glucuronidase,<FONT FACE="Symbol">b</font>-glucosidase and ALP activities were measured in feces.<FONT FACE="Symbol">b</font>-Glucuronidase and<FONT FACE="Symbol">b</font>-glucosidase activities were significantly increased after feeding soy protein suggesting an increased risk after soy feeding.</p><p>In <strong>Chapter 8</strong> the influence of casein, soy protein isolate, soy protein flour and red meat is tested on the occurrence of intestinal polyps in the <em>Apc <sup>Min</em></SUP>model. In this model, mice with a defect <em>Apc</em> gene spontaneously develop polyps in both small and large intestine. The four diets showed no difference in the occurrence of polyps. Again several differences were observed in the fecal parameters.<FONT FACE="Symbol">b</font>-Glucuronidase and<FONT FACE="Symbol">b</font>-glucosidase were strongly increased after soy protein compared to the other diets. The pH of the colonic contents was decreased after soy flour feeding indicating fermentation of fibers present in soy flour preparations has a major influence. Furthermore it was shown that heme in the form of meat protein is not nearly as lytic as heme added to the diet in the pure form. No differences between the diets were found for free fatty acids. The concentrations of bile acids in fecal water were decreased for especially the soy protein diets. Overall, fecal parameters showed marked differences, but again no consistent protective or risk inducing effects.</p><p>In <strong>Chapter 9</strong> all studies performed are compared and discussed with an emphasis on the animal studies. Overall, fecal fat excretion was consistently doubled after feeding soy protein.<FONT FACE="Symbol">b</font>-Glucuronidase and<FONT FACE="Symbol">b</font>-glucosidase, able to release toxicants, were consistently increased after feeding soy protein. Bile acids in fecal water, able to damage colonic epithelium, were consistently decreased after soy protein feeding. Other fecal parameters either showed no difference between diets (pH, cytolytic activity) or variable results (ALP, free fatty acids). It was shown that fecal magnesium excretion has no predictive value for colonic cell proliferation. Fecal<FONT FACE="Symbol">b</font>-glucuronidase,<FONT FACE="Symbol">b</font>-glucosidase, ALP, bile acids and free fatty acids showed large differences in absolute values between animal experiments. Possibly the effect caused by some protein sources on fecal parameters, is also partly dependent on interaction with other dietary constituents such as fat and fiber or non-protein components. Because no differences on cell proliferation, aberrant crypt foci and intestinal polyps were found, a difference in colon cancer risk after consumption of casein or soy protein is unlikely. Correlation studies revealed that none of the fecal parameters tested consistently predicted the outcome of the colonic parameters tested, stressing the need for further research in this area. Because of the variable composition and results obtained with soy, it was concluded that one should be very cautious concerning the interpretation of studies in which soy protein preparations are used.</p><p>The main conclusion from the studies performed is that many significant differences occurred between casein and other dietary protein sources such as soy. Differences specifially occurred on parameters related to the carcinogen scavenging capacity of proteins and on fecal parameters such as fecal bile acid, ALP and<FONT FACE="Symbol">b</font>-glucuronidase excretion. However, no consistent <em>in vivo</em> protective effect of casein occurred on colon cancer, based on markers as colonic cell proliferation, aberrant crypt foci formation and polyp formation. Therefore results do not support an advice on consuming either more or less casein or soy protein containing products.
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