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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    Feeds, water quality, gut morphology and digestion in Nile tilapia (Oreochromis niloticus)
    Trần Ngọc Thiên Kim, Kim - \ 2017
    Wageningen University. Promotor(en): J.A.J. Verreth, co-promotor(en): J.W. Schrama; Arjen J. Roem. - Wageningen : Wageningen University - ISBN 9789463431484 - 127
    tilapia - oreochromis niloticus - feeds - fish feeding - water quality - digestion - digestibility - intestines - morphology - fish culture - aquaculture - tilapia - oreochromis niloticus - voer - visvoeding - waterkwaliteit - spijsvertering - verteerbaarheid - darmen - morfologie - visteelt - aquacultuur

    Diet composition, ingredient and nutrients, are important to consider for maintaining intestinal functions. Studies on both positive (using feed additives) and negative effects (using high inclusion of plant ingredients) of fish feeds are numerous, however, between studies results are often highly variable, both in type of response and in significance. The central hypothesis of this study was that adverse environmental conditions may aggravate negative effects of plant ingredients on the intestinal functions to the extent that mild effects become severe and perceptible. To do so, dietary factors and environmental conditions were evaluated and the interaction between diet composition and environmental conditions were studied in Nile tilapia.

    In Chapter 2, six common raw materials including hydrolysed feather meal (HFM), soybean meal (SBM), rice bran (RB), rapeseed meal (RM), sunflower meal (SFM) and dried distiller grains with solubles (DDGS) were chosen to determine the effect of nutrient digestibility, nitrogen/energy balance and changes in intestinal morphology. The study demonstrated that feed ingredients do have an impact on the alteration in intestinal parameters, but also on the nutrient digestibility and the nitrogen/energy balance. Although being well digested, soybean meal caused the most obvious alteration in the intestinal morphology. These alterations were not related to the nutrient digestibility nor to nitrogen/energy balance parameters. Soybean meal, causing the most alterations in the intestinal morphology, was further used in all subsequent chapters of this thesis.

    Chapter 3 and 4 described the interaction between diet composition and environmental conditions on the intestinal functions. This was studied with two different environmental conditions, dissolved oxygen (Chapter 3) and salinity (Chapter 4). These two chapters evaluated whether suboptimal environmental conditions (low dissolved oxygen or elevated salinity in water) may interact with a soybean meal based diet in nutrient digestion and intestinal morphology of tilapia. The study demonstrated that environmental stressors can aggravate/reveal the negative intestinal morphology changes induced by a soybean meal based diet. However, these effects of adverse environmental conditions on the intestinal functions were not homogenously dispersed over the whole intestinal length. The effect of salinity on the intestinal morphology occurred predominantly in the distal intestine, whereas the effect of low oxygen concentration was more visible at the proximal intestine. Alterations in the intestinal morphology, as found in this study, have wider effects on the performance of the affected fish. In Chapter 3, the protein digestibility decreased under hypoxic conditions at week 8, which parallels with the time related alteration in intestinal morphology. Chapter 4 showed that when fish were raised at 15 ‰ salinity, nutrient digestibility increased; however, this positive effect decreased when the intestinal morphology changed. The study also found that the combined effect of a soybean meal based diet and hypoxia was stronger compared to the combination with elevated salinity. Therefore, the combination with hypoxia was further used in the next study of this thesis.

    In Chapter 5, the combination of hypoxic condition and a soybean meal based diet was chosen to test the hypothesis that only under stressful conditions, the effects of feed additives can be noticed. The impact of two dietary organic acids, formic acid and butyric acid, on nutrient digestibility and intestinal morphology was determined under optimal (normoxia) and suboptimal conditions (hypoxia). The results showed that although organic acids did not significantly improve growth performance and nutrient digestibility under normoxic condition, they did so under hypoxic conditions. Fish fed organic acid supplemented diets all showed improvements in the morphology of intestine under normoxic conditions, and these effects were more enhanced under hypoxic conditions. This indicates that environmental conditions can alter the effect of organic acid on nutrient digestibility and intestinal morphology in tilapia.

    Finally, Chapter 6 provided a synthesis of the main findings, and a reflection on the methodologies used in Chapters 2-5 as well as a discussion on the relevance of this study to aquaculture. It is concluded that although being well digested, soybean meal caused the most obvious alteration in intestinal morphology. The adverse environmental conditions aggravated negative effects of soybean meal based diets on the intestinal functions to the extent that mild effects become severe and visible. The negative effect on intestinal morphology of soybean meal in the diet is enhanced at low oxygen level and at elevated salinity. The effect of salinity on the intestinal morphology occurs predominantly in the distal intestine, whereas the effect of low oxygen concentration is more visible at the proximal intestine. The thesis indicated that the impact of organic acids on intestinal functions is dependent on environmental conditions, being more pronounced under challenging conditions (e.g. hypoxia). Therefore, studies on both positive (using feed additives) and negative effects (using high inclusion of plant ingredients) of dietary factors should be done under suboptimal conditions.

    Phytate degradation in broilers
    Krimpen, M.M. van; Emous, R.A. van; Spek, J.W. ; Kwakernaak, C. - \ 2016
    Wageningen : Wageningen Livestock Research (Wageningen Livestock Research report 978) - 50
    broilers - phytic acid - digestibility - poultry feeding - vleeskuikens - fytinezuur - verteerbaarheid - pluimveevoeding
    Maillard reaction products in pet foods
    Rooijen, C. van - \ 2015
    Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Guido Bosch; Peter Wierenga. - Wageningen : Wageningen University - ISBN 9789462575523 - 182
    gezelschapsdieren - huisdierenvoer - maillard-reactie - voedselverwerking - voedingswaarde - diergezondheid - lysine - stoom - omhullen - verteerbaarheid - voedselchemie - voedertechnologie - pets - pet foods - maillard reaction - food processing - nutritive value - animal health - lysine - steam - pelleting - digestibility - food chemistry - feed technology

    Pet dogs and cats around the world are commonly fed processed commercial foods throughout their lives. Often heat treatments are used during the processing of these foods to improve nutrient digestibility, shelf life, and food safety. Processing is known to induce the Maillard reaction, in which a reducing sugar binds to a free reactive amino group of an amino acid. In intact proteins, the ε-amino group of lysine is the most abundant free amino group. The reaction reduces the bioavailability of lysine and results in the formation of advanced Maillard reaction products. The aim of this thesis was to determine the occurrence and progression of the Maillard reaction during the manufacturing of pet foods, the subsequent impact on nutritive value of the food, and the bioavailability of Maillard reaction products in cats.

    In Chapter 2, the scientific literature was reviewed to investigate the current state of knowledge on the Maillard reaction and its potential effect on the nutritive value of pet foods and on pet health. Determination of the difference between total and reactive lysine by chemical methods provides an indication of the Maillard reaction in pet foods. Studies reported that the proportion of reactive lysine is on average 73% (range 39 – 100%) of total lysine, and that foods for growing dogs may be at risk of supplying less lysine than the animals require. The endogenous analogues of Maillard reaction products, advanced glycation end-products, have been associated with age-related diseases in humans, such as diabetes and impaired renal function. In dogs, data indicate higher advanced glycation end-product contents in plasma from dogs suffering from canine diabetes mellitus compared with healthy control animals. In addition, elevated levels of advanced glycation end-products in tissue proteins in dogs were observed for a number of diseases. To date it was unknown to what extent Maillard reaction products were present in pet foods, and whether dietary Maillard reaction products can be associated with the development of diseases such as diabetes and impaired renal function in pet animals. As the Maillard reaction is induced by processing, changing processing conditions should have an influence on the severity of the reaction. However, effects of processing conditions on the difference in total and reactive lysine contents in pet foods were inconsistent and did not always correspond to model systems. Processing temperature was reported to be the most important factor followed by moisture level. In addition, differences between total and reactive lysine were observed in several ingredients commonly used in pet foods. Reviewing the literature indicates that it is unknown to which extent the Maillard reaction occurs and whether Maillard reaction products are present in pet foods. There might be a risk for certain foods not meeting minimal lysine requirements. It is also unknown what the exact effect of processing on the Maillard reaction is in pet foods.

    The experiment described in Chapter 3 was designed to evaluate whether commercial pet foods meet minimal lysine requirements. Sixty-seven extruded, canned and pelleted commercially available dog and cat foods formulated for growth and maintenance were analysed using conventional amino acid analysis and O-methylisourea as reagent for reactive lysine. Sixty out of the 67 foods in this study, regardless of the type of processing technology used, contained a lower reactive lysine than total lysine content. On average, pelleted and extruded foods contain lower reactive to total lysine ratios compared to canned foods (0.85, 0.89, and 0.93, respectively). All cat foods and foods for adult dogs met minimal lysine requirements. However, eight dry foods for growing dogs contained reactive lysine contents between 96 and 138% of the minimal lysine requirement, indicating that reactive lysine has to be between 62 and 104% digestible to meet minimal requirement. Considering the variability in reactive lysine digestibility, these foods could be at risk of not meeting minimal lysine requirements for growing dogs.

    In Chapter 4, the foods from Chapter 3 were used to quantitate the Maillard reaction products fructoselysine (FL), carboxymethyllysine (CML), hydroxymethylfurfural (HMF), and the cross-linked amino acid lysinoalanine (LAL) using UPLC-MS. In all foods, Maillard reaction products and LAL were found but in highly variable amounts. Type of processing seems to be a key factor for the concentration of FL, CML and HMF, with on average higher amounts in canned foods than pelleted and extruded foods (on a dry matter basis). The contents of CML and HMF found in commercial pet foods are, on average, within the range reported in processed human food products. Average daily intake (mg/kg body weight0.75) of HMF was 122 times higher for dogs and 38 times higher for cats than the calculated average intake for adult humans. Average daily intake of CML was comparable to the intake of adult humans.

    As Chapters 3 and 4 indicated that pelleted foods contain more Maillard reaction products than extruded foods, despite the less severe production process, an experiment was designed to gain insight in the effect of steam pelleting on the Maillard reaction in a dog food (Chapter 5). The aim was to examine the effect of conditioning temperature (65 and 90°C) and die hole length (ø 5 × 45, 65, and 80 mm) during pelleting processing of a standard dry dog food on selected indicators of the Maillard reaction (total lysine, reactive lysine, FL, CML, HMF, LAL), browning development and CIE-Lab colour. Steam pelleting did not cause a significant loss of reactive lysine and change of absorbance values. This indicates that the effect of steam pelleting on the nutritive value of the foods is low. However, steam pelleting did increase the content of Maillard reaction products. The formation of the Maillard reaction products was associated with an increase in temperature and die hole length during the steam pelleting process. The unprocessed ingredient mix already contained a larger difference between reactive and total lysine, and contents of Maillard reaction products than was induced during steam pelleting. Therefore, the choice of the ingredients used in this study mainly determines reactive lysine content and Maillard reaction products in the pet food formulation.

    As it is unknown to which extent extrusion processing influences the Maillard reaction in pet foods, the effect of extrusion processing on selected indicators of the Maillard reaction was determined (Chapter 6). The extrusion parameters temperature (140 and 165°C), moisture content (200 and 300 g/kg) and screw speed (100 and 200 rpm) were applied to two dry dog foods formulated using either intact or hydrolysed proteins. Extrusion processing in general results in a decrease in total and reactive lysine and an increase in FL, CML, HMF and LAL content. However, this effect appeared more pronounced in the diet containing hydrolysed protein. Decreasing temperature and moisture content led to higher total and reactive lysine contents, and less Maillard reaction products in the dog foods. Increasing screw speed had a positive influence on total and reactive lysine, but a negative influence on Maillard reaction products. As was found in Chapter 5, the unprocessed ingredient mixtures in this experiment contained already more Maillard reaction products than was induced during extrusion processing.

    Whether the Maillard reaction products reported in pet foods are physiologically relevant in pet animals depends on the bioavailability of these components. Therefore, urinary excretion was studied in adult cats fed commercial moist and dry foods containing varying amounts of FL, CML and the amino acid LAL (Chapter 7). A pilot study was first conducted to determine the adaptation time required for stable urinary excretion of the Maillard reaction products when changing diets with contrasting contents of Maillard reaction products. An adaptation time of 1 d was deemed sufficient in adult cats. The short adaptation time indicates an effective urinary excretion of Maillard reaction products. In the main study, six commercially processed dry and six moist diets were fed to 12 adult female cats in two parallel randomized, 36-day, balanced Latin square designs. Urine was collected quantitatively and FL, CML and LAL were analysed in foods and collected urine using HPLC-MS. Daily urinary excretion of FL and CML showed a positive relationship with daily intake in the dry and moist foods. For LAL, no significant relationship was observed. The observed increase in urinary excretion with increasing dietary intake indicates that dietary Maillard reaction products are absorbed from the gastro-intestinal tract of cats and excreted in the urine. Minimum apparent absorption based on urinary excretion (assuming 100% of the excreted component originates from the diet) of FL, CML and LAL was found to range between 8 to 23%, 25 to 73% and 6 to 19%, respectively. Urinary recovery (% ingested) showed a negative relationship with daily intake for FL, CML and LAL in the dry foods and for CML and LAL in the moist foods. The observed decrease in urinary recovery with increasing intake suggests a limiting factor in digestion, absorption, metabolism or urinary excretion.

    The studies reported in this thesis are one of the first to determine Maillard reaction products in pet foods and the bioavailability of FL, CML and LAL in cats. In addition, the results highlight the importance of reactive lysine measurement in foods for growing dogs used as weaning diets. Contribution of the absorption of dietary Maillard reaction products to the pathogenesis of various health conditions requires further study, as well as the potential role of restriction of dietary Maillard reaction products in prevention and treatment of long-term health implications. Extrusion and pelleting processing do increase the Maillard reaction, however, choice of ingredients appears to have a larger effect on the content of Maillard reaction products and can, therefore, be a useful strategy for pet food manufacturers that want to decrease the content of Maillard reaction products in their pet foods.

    Estimating requirements for apparent faecal and standardised ileal digestible amino acids in laying hens by a metaanalysis approach
    Krimpen, M.M. van; Veldkamp, T. ; Riel, J.W. van; Khaksar, V. ; Hashemipour, H. ; Blok, M.C. ; Spek, W. - \ 2015
    Wageningen : Wageningen UR Livestock Research (Livestock research report 848) - 71
    hennen - aminozuren - voer - meta-analyse - verteerbaarheid - eiwitverteerbaarheid - dunne darm - voedingsstoffengehalte - voedingsstoffenbehoeften - voedingsbehoeften - pluimvee - pluimveevoeding - hens - amino acids - feeds - meta-analysis - digestibility - protein digestibility - small intestine - nutrient content - nutrient requirements - feed requirements - poultry - poultry feeding
    The aim of the present study is to update the requirements for the essential amino acids of laying hens, both on a AFD and SID basis, by performing a meta-analysis on dose-response studies used to derive requirement values for essential amino acids (lysine, methionine+cysteine, threonine and tryptophan) in laying hens as presented in the literature. In this meta-analysis, the data are fitted by use of the Wood equation (see paragraph 2.4). The amino acid intake levels for realizing maximal rate of lay, egg mass and feed efficiency are provided. The amino acid requirements for use in practice are based on the amino acid intake levels at which 95% of these maximum responses were reached.
    De in vitro verteerbaarheid van gewelde maïs en maïsbijproduct en de in vivo verteerbaarheid van maïsbijproduct gemeten bij vleesvarkens
    Bikker, P. ; Krimpen, M.M. van; Dekker, R.A. ; Wikselaar, P.G. van; Diepen, J.T.M. van - \ 2014
    Wageningen : Wageningen UR Livestock Research (Report / Wageningen UR Livestock Research 788) - 28
    varkens - varkenshouderij - diervoeding - maïs - maïsbijproducten - verteerbaarheid - in vitro verteerbaarheid - in vivo experimenten - spijsvertering - voederconversie - voer - voederwaardering - varkensvoeding - pigs - pig farming - animal nutrition - maize - maize byproducts - digestibility - in vitro digestibility - in vivo experimentation - digestion - feed conversion - feeds - feed evaluation - pig feeding
    In opdracht van PPO (PPS Kleinschalige Bioraffinage) is de in vitro verteerbaarheid van gewelde maïs en van het maïsbijproduct na fermentatie bepaald. Als referentiegrondstoffen zijn in deze studie sojaschroot en kuilgras meegenomen. Tevens is in deze studie de in vivo verteerbaarheid van het maïsbijproduct bij varkens onderzocht. Dit rapport beschrijft zowel de resultaten van het in vitro als van het in vivo onderzoek.
    Effects of available phosphorus (aP), calcium/aP ratio, and growth rate on P deposition, P digestibility, performance and leg quality in broilers
    Krimpen, M.M. van; Diepen, J.T.M. van; Wikselaar, P.G. van; Bikker, P. ; Jongbloed, A.W. - \ 2013
    Lelystad : Wageningen UR Livestock Research (Report / Wageningen UR Livestock Research 670) - 29
    vleeskuikens - scheenbeen - verteerbaarheid - fosfor - groeitempo - vleeskuikenresultaten - broilers - tibia - digestibility - phosphorus - growth rate - broiler performance
    The standard Ca/aP ratio (2.2) can be recommended for application in practical diets. Based on the results of this experiment, no proof was found for our hypothesis that the development of the skeleton in fast growing broilers could not keep pace with the gain of the soft tissues. This experiment showed that the P requirement was not fulfilled with the low aP level in the diet. For determination of the optimal dietary aP level, however, a dose – response experiment should be performed.
    Rumen fermentation profile and intestinal digestibility of maize and grass silages
    Ali, M. - \ 2013
    Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): John Cone; Gert van Duinkerken. - S.l. : s.n. - ISBN 9789461736581 - 157
    melkkoeien - maïskuilvoer - graskuilvoer - pensfermentatie - verteerbaarheid - darmfysiologie - chemische samenstelling - diervoeding - voedingsfysiologie - dairy cows - maize silage - grass silage - rumen fermentation - digestibility - intestinal physiology - chemical composition - animal nutrition - nutrition physiology

    Maize and grass silages are commonly used as major feed materials for dairy cows in Europe and are becoming common parts of dairy cow rations in other parts of the world. Thenutritive value of maize and grass silages varies greatly due to variation in chemical composition. A combination of different factors such as the use of various cultivars, fertilization practices, growing conditions, harvesting technology, maturity at harvest and ensiling conditions cause this variation in chemical composition. The first aim of this thesis was to investigate relationships between the chemical composition and the in situ rumen degradation characteristics and in situ mobile nylon bag digestibility of dietary nutrients of maize and grass silages. Maize and grass silages with a broad range in chemical composition and quality parameters were selected from different Dutch commercial farms. The broad range in the chemical composition of the maize and grass silages resulted in a large variation in rumen degradable fractions of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fibre (NDF) and starch. The intestinal digestibility of CP, NDF and/or starch was affected by the concentration of these components in the maize and grass silages, by the rumen incubation time and the rumen escape content. Regression equations were developed describing relationships between the chemical composition and the in situ ruminal and postruminal degradation characteristics of dietary nutrients of maize and grass silages. A number of the developed regression equations presented in this thesis can be used for accurate and rapid estimation of the ruminal and postruminal degradation characteristics of dietary nutrients of maize and grass silages, without conducting time consuming and expensive in situ experiments. The second aim of this thesis was to determine whether three cows are sufficient to cover the variation between individual cows in in situ rumen degradation characteristics of dietary nutrients of maize and grass silages. Significant differences (P<0.05) were found between individual cows for a number of parameters of DM, OM and CP of maize silages, indicating that four or more cows should be used for nylon bag incubations of maize silages. For grass silages, no significant differences (P>0.05) between individual cows were found for all the parameters of DM, OM, CP and NDF. The results suggest that using three cows are sufficient for nylon bag incubations of grass silages and pooling of rumen incubated residues is allowed to obtain a representative sample. The third aim of this thesis was to compare two fractionation methods; the washing machine method and a modified method, for nitrogen (N) and starch fractions of maize silages and N fractions of grass silages. The N and/or starch fractions of maize and grass silages determined, using the washing machine method (washing with water for 40 min) and the modified method (shaking with buffer solution for 60 min) were compared. The different methodological approaches of both methods resulted in different values for the washout (W), the soluble (S) and the non-washout (D+U) fractions of N of maize and grass silages and for the W, the insoluble washout (W-S) and the D+U fractions of starch of maize silages. The loss of insoluble small particles of starch was less during shaking of nylon bags in buffer solution, compared to washing nylon bags in the washing machine. Therefore, large differences were found between the D+U fractions of starch determined by both methods compared to the D+U fractions of N of maize silages. The developed regression equations for W, S and D+U fractions of N in grass silages and for D+U fractions of starch in maize silages determined by both methods can be used for rapid estimation of these fractions from chemical characteristics of maize and grass silages. The information on nutrient bioavailability of maize and grass silages presented in this thesis can be used to more accurately formulate dairy ration in terms of maintenance, health and production of dairy cows.

    Nutrition of grazing cattle in the Mid Rift Valley of Ethiopia: use of an improved n-alkane method to estimate nutrient intake
    Derseh, M.B. - \ 2013
    Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Wilbert Pellikaan; A. Tolera. - S.l. : s.n. - ISBN 9789461734686 - 160
    rundvee - begrazing - weiden - merkers - voedingsstoffenopname (mens en dier) - voedselsamenstelling - voedingswaarde - verteerbaarheid - ruwvoer (roughage) - diervoeding - ethiopië - cattle - grazing - pastures - markers - nutrient intake - food composition - nutritive value - digestibility - roughage - animal nutrition - ethiopia

    Nutrient intake is an important factor that determines the performance of production animals. In free ranging animals, direct measurement of nutrient intake is difficult to conduct, and it is frequently estimated indirectly by the aid of markers. The aim of this thesis was to investigate the potential of using cuticular n-alkanes and their carbon isotope enrichments (δ13C) as markers to study the nutritional ecology of grazing animals under tropical conditions. In addition, this improved method was used to determine the seasonal patterns of nutrient intake and diet composition of grazing cattle in the Mid Rift Valley grasslands of Ethiopia. The first focus of the thesis was to quantify the interspecies variability in the n-alkane profile and δ13C values of alkanes among commonly available pasture species in the Mid Rift Valley of Ethiopia. The analysis showed that the variability is sufficiently large to allow n-alkane and their δ13C values to be used as diet composition markers, with a combined use of the two increasing the discriminatory power. Faecal recovery of dosed and natural alkanes in cattle consuming low-quality tropical roughages was investigated in an indoor balance study. The recovery of synthetic alkanes dosed in the form of molasses boluses was considerably higher than adjacent natural odd-chain alkanes, and correction appears necessary when intake is estimated with the double n-alkane method. The next focus of the thesis was to generate information on the nutritive value of pasture species and nutritional status of grazing cattle in the region. Large variability was observed in the nutritive value and methane production potential of pasture species as evaluated in vitro, with scope for selection of genotypes with high nutritive value and low methane production potential for a sustainable pastureland management. The nutritional status of grazing cattle measured using a combination of n-alkanes, their δ13C values and visual observations showed that diet composition and nutrient intake of the animals is highly dependent on rainfall patterns, with a cyclic positive (wet period) and negative (dry period) energy and nutrient balance observed over the grazing seasons. Energy intake was more limiting than crude protein for body weight gain in most of the grazing seasons. While mature and non-producing animals appeared to tolerate nutritional restriction in the dry period and regain lost body condition in the following wet periods, young animals before the age of puberty may need supplementary feeding. Furthermore, concentrate supplementation of finishing animals needs to coincide with the onset of the wet season to take advantage of compensatory growth. In conclusion, the n-alkanes method coupled with isotope enrichment in n-alkanes and visual observations as used in the present study can provide realistic nutritional data for free-ranging cattle which correlates well with changes in body conditions.

    Keeping local foods on the menu: a study on the small-scale processing of cowpea
    Madodé, Y.E.E. - \ 2012
    Wageningen University. Promotor(en): Tiny van Boekel; D.J. Hounhouigan, co-promotor(en): Anita Linnemann; Rob Nout. - S.l. : s.n. - ISBN 9789461734358 - 176
    vignabonen - voedselverwerking - landrassen - antinutritionele factoren - verteerbaarheid - west-afrika - benin - cowpeas - food processing - landraces - antinutritional factors - digestibility - west africa - benin

    Agriculture plays a significant role in the economy of most African countries. Yet malnutrition and micronutrient deficiencies occur regularly. Concomitantly, many carbohydrate rich staple foods and meat products are dumped on the African market and compet strongly with local products. The present thesis studied the potential of indigenous resources and locally developed practices to supply culturally acceptable and nutritious foods to African resource-poor people, using cowpea as model crop. This research is implemented using an interdisciplinary approach, which comprised plant breeding, food science and technology, human nutrition and social sciences. This thesis reports the findings of the research on food science and technology.

    This study aimed to (i) characterise cowpea landraces in use in Benin with regard to nutritional, anti-nutritional and functional properties; (ii) determine present cowpea processing methods and eating habits with special reference to the content of cowpea dishes in available iron, zinc and calcium; (iii) assess the effect of the use of alkaline cooking aids on amino acids of cooked cowpea, and (iv) assess the impact of processing techniques on the flatulence generated by the intake of cowpea foods.

    The genetic, nutritional and technological characterisation of cowpea landraces in use in Benin showed that a high level of similarity among unpigmented landraces as opposed to pigmented landraces. The cluster of unpigmented landraces significantely differed from the pigmented landraces for their fibre (24 vs. 56 g/kg, d.w.) and phenolics (3 vs. 8 g/kg, d.w.) contents as well as their seed size (200 vs. 139 g/1000 seeds, d.w.) and water absorption capacity (1049 vs. 1184 g/kg, d.w.).

    An inventory of 18 cowpea dishes was obtained, which are produced by the combination of the following main unit operations: cooking, dehulling, deep-fat frying, steaming, roasting and soaking. Fermentation and germination are unusual technological practices in West-Africa. Consumers mainly consume Ata, Atassi and Abobo. These dishes contain little available iron because their [phytate] : [iron] molar ratio is above the required thresholds for a good iron uptake by the human body. The incorporation of cowpea leaves in certain dishes resulted in appropriate available iron and calcium potentials.

    The constraints to cowpea processing were identified as: their long cooking time, the tediousness of the dehulling process and the perishability of beans and dishes. The local answer to the long cooking time is the use of alkaline cooking aids. These alkaline salts and the applied cooking conditions did not induce any significant change in the amino acid composition of pigmented landraces. Moreover, the toxicity potentially associated with this practice was not confirmed as no lysinoalanine could be quantified while using up to 0.5 % (w/v) of alkaline cooking aids.

    Flatulence was indicated as the main constraint to cowpea consumption. Cowpea hulls are usually pointed as the main responsible for flatulence. In this research, galactose-oligosaccharides that are indigestible for humans and cause flatulence formation were not found in cowpea hulls. Fermentation wih Rhizopus or Bacillus bacteria reduced significantly the fermentability of cowpea in vitro and in vivo as compared with traditional processes.

    The present study demonstrates the opportunities to improve the quality of cowpea dishes by the incorporation of the leaves and the possibilities to sustain the consumption of cowpea by focusing on soaking and/or fermentation processes.

    Effect of increased maturity of silage maize at harvest on conservation, dairy cow performance and methane emission
    Zom, R.L.G. ; Bannink, A. ; Goselink, R.M.A. - \ 2012
    Lelystad : Wageningen UR Livestock Research (Report / Wageningen UR Livestock Research 578) - 16
    melkveehouderij - rundveevoeding - krachtvoeding - maïskuilvoer - rijpingsfase - droge stof - melkopbrengst - voeropname - verteerbaarheid - voersamenstelling - dairy farming - cattle feeding - force feeding - maize silage - ripening stage - dry matter - milk yield - feed intake - digestibility - feed formulation
    Increasing maturity at harvest is evaluated as a cost-free method to increase starch concentration and rumen by-pass starch of maize silage, reducing methane emission. Results showed no effect on cow performance or silage stability, but the calculated effect on methane emission was low with the maize cultivar used.
    Fosforbehoefte van melkvee, vleesvee, varkens en pluimvee: een literatuurstudie = Phosphorus requirements of dairy cattle, beef cattle, pigs and poultry: a review
    Krimpen, M.M. van; Goessink, R.M.A. ; Heeres, J.J. ; Jongbloed, A.W. - \ 2012
    Wageningen : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 574) - 34
    melkveehouderij - vleesvee - vleesproductie - varkenshouderij - pluimveehouderij - rundveevoeding - varkensvoeding - pluimveevoeding - fosfor - mineralenvoeding - verteerbaarheid - dairy farming - beef cattle - meat production - pig farming - poultry farming - cattle feeding - pig feeding - poultry feeding - phosphorus - mineral nutrition - digestibility
    Literature was reviewed to update phosphorus requirements of dairy cattle, beef cattle, pigs and poultry. It has been shown that the dietary P-content in most species can be safely reduced, compared to the P-levels applied in 2010, without negatively affecting animal performance and health status of the animals. Because of lack on recent information, no estimation of possible percentage of P reduction in poultry is provided.
    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.

    Verteerbaarheid van biologisch geteelde veevoedergrondstoffen bij leghennen = Digestibility of organic processed feed ingredients in laying hens
    Krimpen, M.M. van; Diepen, J.T.M. van; Reuvekamp, B.F.J. ; Harn, J. van - \ 2011
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 422) - 27
    biologische landbouw - pluimveevoeding - hennen - voersamenstelling - verteerbaarheid - voedingswaarde - organic farming - poultry feeding - hens - feed formulation - digestibility - nutritive value
    In two experiments, digestibility and nutritive value for laying hens of organically-grown feed raw materials was assessed. Digestibility and metabolisable energy content of the products differed considerably compared to those listed in the CVB Feedstuff Table.
    Stikstofverteerbaarheid in voeders voor landbouwhuisdieren : berekeningen voor de TAN-excretie
    Bikker, P. ; Krimpen, M.M. van; Remmelink, G.J. - \ 2011
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-werkdocument 224) - 62
    diervoedering - veevoeder - voer - verteerbaarheid - eiwitmetabolisme - stikstof - excretie - ammoniakemissie - dierhouderij - inventarisaties - animal feeding - fodder - feeds - digestibility - protein metabolism - nitrogen - excretion - ammonia emission - animal husbandry - inventories
    De ammoniakemissie vanuit de veehouderij wordt momenteel berekend op basis van de excretie van ruw eiwit (stikstof) in de mest, zonder onderscheid te maken tussen stikstof in feces en urine. Met behulp van de TAN-excretie (totaal ammoniakaal stikstof) kan een betere inschatting gemaakt worden van de emissie omdat hierbij rekening gehouden wordt met de verdeling van uitgescheiden stikstof (N) over de urine en feces. De TAN-excretie wordt berekend uit de opname aan verteerbaar ruw eiwit (VRE) en de retentie van eiwit in dierlijk product. De VRE wordt bepaald uit het ruw eiwit (RE)-gehalte van het voer en de fecale verteerbaarheid van het RE (VC-RE). Op dit moment zijn geen gegevens over de fecale eiwitverteerbaarheid van in de praktijk gebruikte voeders beschikbaar. Daarom is in deze studie met behulp van lineaire programmering en gepubliceerde en in de praktijk gebruikte randvoorwaarden van diervoeders en prijzen van grondstoffen, de gemiddelde fecale vertering van eiwit berekend voor de gehanteerde diercategorieën van het Centraal Bureau voor de Statistiek (CBS).
    Eiwitwaardering weer bij de tijd - Moderne kuilen nieuwe basis voor ruwvoerwaardering
    Klop, A. ; Kruisdijk, J. ; Nicolasen, S. - \ 2011
    Veeteelt 28 (2011)1/2. - ISSN 0168-7565 - p. 46 - 47.
    voederwaardering - kuilvoer - ruwvoer (roughage) - rundveevoeding - verteerbaarheid - eiwitwaarde - berekening - feed evaluation - silage - roughage - cattle feeding - digestibility - protein value - calculation
    Voor de berekening van voederwaarden van ruwvoer waren rekenregels in gebruik die gebaseerd zijn op kuilen uit de vorige eeuw. Productschap Diervoeder, BLGG AgroXpertus en Wageningen UR hebben nieuwe kuilen onderzocht om de rekenregels voor 2011 te actualiseren
    Efficacy and safety of dietary N,N-dimethylglycine in broiler production
    Kalmar, I.D. - \ 2011
    Wageningen University. Promotor(en): Wouter Hendriks; Martin Verstegen, co-promotor(en): G.P.J. Janssens. - S.l. : s.n. - ISBN 9789085858751
    vleeskuikens - aminozuurderivaten - metabolieten - pluimveevoeding - voedertoevoegingen - voedersupplementen - vleeskuikenresultaten - verteerbaarheid - karkasopbrengst - oxidatieve stress - ascites - voederveiligheid - voedselveiligheid - voedingsfysiologie - diervoeding - broilers - amino acid derivatives - metabolites - poultry feeding - feed additives - feed supplements - broiler performance - digestibility - carcass yield - oxidative stress - ascites - feed safety - food safety - nutrition physiology - animal nutrition

    N,N-dimethylglycine (DMG), the dimethyl derivative of the amino acid glycine, is a naturally occurring intermediary metabolite in the choline to glycine metabolism. The molecule was first reported in 1943 and is currently used for a variety of applications, including the enhancement of athletic performances in both man and racing animals. With respect to its biological activities, DMG is for instance suggested to enhance oxygen utilisation and to posses non-enzymatic anti-oxidant properties. The studies described in this thesis aimed to evaluate DMG as a feed additive in chickens for fattening.

    In a pilot study, broilers were challenged with both cold stress and a high energy feed in order to incite broiler ascites syndrome. This metabolic disease results from an imbalance between oxygen requirement and supply, and is an important cause of financial losses and a major welfare issue in the modern broiler industry. A low dosage of dietary DMG effectively attenuated progression towards ascites. We hypothesize that this effect results from reduction in endothelial damage and dysfunction caused by plasma free fatty acids, which were substantially lowered by DMG supplementation. Furthermore, DMG improved nutrient digestibility and reduced nitrogen emission, which can be attributed to an emulsifying effect of DMG at the gut level. A subsequent trial revealed dose-dependent effects of dietary DMG on technical performance, carcass yield, oxidative stress parameters and broiler ascites syndrome. However, the nature and magnitude of the effects depended on fatty acid profile of the basal ration. Herein, effects were most pronounced when fed a diet rich in
    poly-unsaturated fatty acids. Generally, effects showed a linear relationship with dose, except for progression towards broiler ascites syndrome, which showed a quadratic relationship with dietary DMG content. Next, a series of efficacy trials were performed on farms at different European locations, using broiler strains and rearing conditions common to each region. Basal flock efficiency showed a wide range between trials; still, DMG systematically improved broiler performance. Finally, a safety and tolerance trial demonstrated a wide safety range of DMG in the target species. Moreover, DMG did not accumulate in consumer parts of broilers when included in diets at the recommended dosage, and bioaccumulation in meat at tenfold dosage did not exceed DMG content in for instance spinach.

    In conclusion, current investigations clearly demonstrate a wide applicability of DMG as a new feed additive in broiler production, in which both economic efficiency and environmental load as well as animal welfare is enhanced without compromising consumer safety.

    Mestinnovatie "Bioraffinage van veevoergrondstoffen; een verkenning van opties om de verteerbaarheid van veevoergrondstoffen te vergroten en fosfaat te verwijderen"
    Meesters, K.P.H. ; Broek, L.A.M. van den; Sanders, J.P.M. - \ 2010
    Wageningen : Agrotechnology & Food Sciences Group (VPP 2009/004) - 36
    veevoeding - voersamenstelling - voedermiddelbewerking - fosfaat - dierlijke meststoffen - verteerbaarheid - voedingswaarde - livestock feeding - feed formulation - feed processing - phosphate - animal manures - digestibility - nutritive value
    Door het fractioneren van mengvoedercomponenten kan fosfor uit het veevoer verwijderd worden voordat het de koe of het varken ingaat. Hierdoor zal de mest minder fosfaat bevatten en dus gemakkelijker afzet kunnen vinden op het land van de omliggende boeren. De gewonnen fosfaat kan gebruikt worden als kunstmestvervanger. Dezelfde voorbehandeling kan ook leiden tot een betere verteerbaarheid van het voer. Omdat niet alle eiwitten in het voer door de dieren opgenomen kunnen worden, eten de dieren op dit moment meer eiwit dan strikt noodzakelijk. In deze studie is aangetoond dat de bovengenoemde strategie een bijdrage kan leveren aan de oplossing van de mestproblematiek. Verschillende lignocellulosehoudende mengvoeder grondstoffen zijn beter beschikbaar gemaakt m.b.v. organische zuren bij hoge temperatuur. Het voordeel van deze methode is dat de suikers uit de lignocellulosefractie bij gaan dragen aan de energiewaarde van het voer.
    Bioavailability of lysine in heat-treated foods and feedstuffs
    McArtney Rutherfurd, S. - \ 2010
    Wageningen University. Promotor(en): Wouter Hendriks; Martin Verstegen, co-promotor(en): P.J. Moughan. - [S.l. : S.n. - ISBN 9789085856825 - 139
    lysine - biologische beschikbaarheid - voer - voedingsmiddelen - melkproducten - huisdierenvoer - ontbijtgranen - warmtebehandeling - maillard-reactie - maillard-reactieproducten - verteerbaarheid - lysine - bioavailability - feeds - foods - milk products - pet foods - breakfast cereals - heat treatment - maillard reaction - maillard reaction products - digestibility
    During the processing of foodstuffs, lysine can react with other compounds present to form nutritionally unavailable derivatives, the most common example of which are Maillard products. Maillard products can cause serious problems when determining the available lysine content of processed foods or feedstuffs as they can revert to lysine during amino acid analysis. Several methods have been developed to determine the dietary lysine available for the metabolic processes of animals including animal growth-based assays, reactive lysine chemical methods and digestibility assays. However, growth-based assays are laborious, highly variable and tend to determine utilization rather than availability. Chemically reactive lysine assays do accurately determine the unmodified lysine in a food or feedstuff, but do not determine available lysine as they incorrectly assume that reactive lysine digestion and absorption is 100%. Ileal digestibility assays measure digestible total lysine rather than digestible reactive lysine (available lysine) and so are inaccurate, especially when applied to processed protein sources. This thesis describes the development of a true ileal digestible reactive lysine assay for determining dietary (bio)available lysine. This assay couples the guanidination reaction, for determining reactive lysine, with a true ileal digestibility assay. The resulting apparent digestibility estimate is corrected to a true digestibility value by accounting for the endogenous ileal lysine flow.

    Selected reaction conditions for the guanidination of lysine in a heated lactose/casein mixture and digesta of rats fed unheated casein and heated lactose/casein was examined. Overall, suitable reaction conditions were 0.6 M O-methylisourea for 7 d in a shaking waterbath at 21 ± 2 °C with an O-methylisourea to lysine ratio of 1000 and a reaction mixture pH of 10.6 for casein and heated lactose/casein and 11.0 for digesta. The accuracy of the guanidination method for determining reactive lysine in a range of “ready-to-eat ” cereal-based breakfast foods and selected feedstuffs was tested by comparison with the reactive lysine content of the same protein sources when determined using the fluorodinitrobenzene method. Overall, there was excellent agreement between the two methods. The accuracy of the newly developed bioassay for determining digestible reactive (available) lysine for predicting lysine deposition was also tested using a heated skim milk powder. The true ileal total and reactive lysine digestibilities were determined for the heated skim milk powder which was then fed to pigs, along with two control diets which were formulated based on either total lysine digestibility or reactive lysine digestibility. All diets were limiting in lysine. The pigs fed the heated skim milk powder deposited the same (P > 0.05) amount of lysine (9.1 g d-1) as the pigs fed the control diet that was formulated based on reactive lysine digestibility (9.1 g d-1) but deposited significantly (P < 0.05) more than the pigs fed the control diet that was formulated based on total lysine digestibility (5.4 g d-1). Consequently for the heated skim milk powder at least, the true ileal digestible reactive lysine assay accurately determined the available lysine content.



    The new assay demonstrated that for a range of milk protein-based foods, there was little difference between digestible total lysine and digestible reactive lysine for most of the milk products tested. In contrast, for a range of “ready-to-eat” cereal-based breakfast foods, available lysine was 5 – 50% lower than that determined using the traditional assay, which is of concern given that breakfast cereals are perceived to be “healthy” foods. Similarly, the available lysine content of a range of moist and dry commercial cat foods was significantly (P < 0.05) lower (15-55% lower) than previously estimated using the traditional true ileal digestible total lysine assay. The assay was also used to examine the effect of storage for extended periods at elevated temperatures on a hydrolysed-lactose skim milk powder and overall, there was a significant decrease in the available lysine content over time, as much as 60% over 6 mth when the powder was stored at 40 °C. In addition, the decrease in available lysine content of the hydrolysed-lactose skim milk powder was 2 – 5.5 times greater than observed for a normal skim milk powder depending on the storage time and temperature. Overall, foods and feedstuffs that have undergone processing often contain lower amounts of available lysine than thought previously. This new assay not only highlights the inaccuracy of the traditional true ileal digestible total lysine assay as a method for determining available lysine in processed protein sources, but permits the accurate assessment of the available lysine content of processed foods and feedstuffs.


    Steeds meer inzicht in de celwand. Oogsttijdstip, groeiomstandigheden en ras bepalen celwandverteerbaarheid maïs
    Cone, J.W. - \ 2009
    Veeteelt 26 (2009)3. - ISSN 0168-7565 - p. 12 - 14.
    melkveehouderij - zea mays - plantenveredeling - voedering - celwanden - verteerbaarheid - dairy farming - zea mays - plant breeding - feeding - cell walls - digestibility
    Na jaren van veredeling op het kolfaandeel in de maisplant krijgt nu ook de celwandverteerbaarheid van de restplant meer aandacht. Waarom is de ene celwand wel verteerbaar en de andere niet? Onderzoek door ASG en Wageningen UR moet nieuwe inzichten geven voor verdere veredeling
    Benutting van biologisch rantsoen slechter?
    Klop, A. ; Bannink, A. - \ 2009
    V-focus 6 (2009)5. - ISSN 1574-1575 - p. 22 - 23.
    melkveehouderij - ruwvoer (forage) - verteerbaarheid - biologische landbouw - pensvertering - zuurgraad - melkveevoeding - voederkwaliteit - dairy farming - forage - digestibility - organic farming - rumen digestion - acidity - dairy cattle nutrition - forage quality
    Een goede vertering van het ruwvoer hangt af van de eigenschappen van het ruwvoer én van het micromilieu in de pens. Een combinatie van beide factoren geeft inzicht in voerbenutting. Vergelijk het met een composteringsproces. Zowel de soort organisch materiaal als het broeiproces in de hoop spelen een grote rol
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