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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    Do anabolic nutritional supplements stimulate human growth hormone secretion in elderly women with heart failure?
    Smeets, Ellen T.H.C. ; Schutzler, Scott E. ; Wei, Jeanne Y. ; Azhar, Gohar ; Wolfe, Robert R. - \ 2017
    Physiological Reports 5 (2017)15. - ISSN 2051-817X - 7 p.
    Amino acids - arginine - lysine

    Growth hormone treatment has gained attention over the past decade as a treatment for heart failure. Human growth hormone (HGH) must be administered by injections (usually daily), so there is considerable advantage to stimulation of endogenous secretion by amino acid-based nutritional supplementation. However, studies investigating the effect of amino acid (AA) supplementation show conflicting results. Therefore, in this study we aimed to investigate the effect of nutritional supplementation on HGH production in elderly women with heart failure. Eight elderly women with heart failure participated in this randomized cross-over study. Plasma HGH concentration was measured before and for 4 h following ingestion of a mixture of protein, carbohydrate, and fat or an AA beverage. HGH concentration was determined with ELISA kits and AA concentrations were analyzed by Liquid Chromatography–Mass Spectrometry (LCMS). Linear mixed models was performed to analyze the effect of time, treatment, and interaction. Plasma arginine and lysine concentrations were significantly higher after consumption of the AA drink compared to the mixture of protein, carbohydrate, and fat. Nonetheless, only ingestion of the protein, carbohydrate, and fat mixture (meal replacement) increased HGH concentration. HGH concentration was increased in elderly women with heart failure following consumption of a meal replacement containing protein, carbohydrate, and fat. Consumption of a mixture of amino acids failed to increase HGH concentration despite significantly greater elevations in plasma amino acid concentrations, including arginine and lysine. The stimulatory effect of the protein/carbohydrate/fat mixture was presumably mediated by factors other than increases in free amino acid concentrations.

    Ecophysiology of novel intestinal butyrate-producing bacteria
    Bui, Thi Phuong Nam - \ 2016
    Wageningen University. Promotor(en): Willem de Vos, co-promotor(en): Caroline Plugge. - Wageningen : Wageningen University - ISBN 9789462577015 - 202
    butyrates - butyric acid bacteria - intestines - microbial interactions - faecal examination - mice - man - infants - genomics - intestinal physiology - microbial physiology - biochemical pathways - lysine - sugar - butyraten - boterzuurbacteriën - darmen - microbiële interacties - fecesonderzoek - muizen - mens - zuigelingen - genomica - darmfysiologie - microbiële fysiologie - biochemische omzettingen - lysine - suiker

    The human intestinal tract harbours a trillion on microbial cells, predominantly anaerobes. The activity and physiology of these anaerobes is strongly associated with health and disease. This association has been investigated for a long time.However, this has not been fully understood. One of the reasons is the limited availability of cultured representatives. It is estimated that there may be more than 3000 species colonised in the gut of healthy individuals, however, only a bit over 1000 species have been isolated and characterised. Among the intestinal microbes, butyrate-producing bacteria are of special interest as the butyrate produced, is crucial to maintain a healthy gut. In addition, butyrate-producing bacteria have shown a reverse correlation with several intestinal diseases. In Chapter 2 we described a novel species Anaerostipes rhamnosivorans 1y2T isolated from an infant stool. This strain belonged to genus Anaerostipes within Clostridium cluster XIVa. A. rhamnosivorans had a capability of converting rhamnose into butyrate that is unique within intestinal butyrate-producing bacteria. The genomic analysis also revealed the entire rhamnose fermentation pathway as well as the acetyl-CoA pathway for butyrate production. This bacterium is able to produce butyrate from a wide range of sugars as well as lactate plus acetate. In Chapter 3, we described the microbial interactions between A. rhamnosivorans and Bacteriodes thetaiotaomicron in dietary pectins; Blautia hydrogenotrophica in lactate and small amount of acetate; Methanobrevibacter smithii in glucose. We observed that A. rhamnosivorans was able to benefit from its partners in all cocultures for butyrate production. This is likely due to its high metabolic flexibility. While the interaction between A. rhamnosivorans and B. thetaiotaomicron appeared as syntrophy, the interaction between A. rhamnosivorans and hydrogenotrohic microbes were cross-feeding type where hydrogen was transferred between two species. The latter resulted in an increase in butyrate level. In Chapter 4 we described a novel species Intestinimonas butyriciproducens SRB521T representing a novel genus Intestinimonas from a mouse caecum within Clostridium cluster IV. This bacterium produced butyrate and acetate as end products from Wilkins-Chalgren-Anaerobe broth.

    Butyrate production is assumed to derive from carbohydrate employing acetyl-CoA pathway. No gut bacterium is known to convert proteins or amino acids to butyrate although butyrogenic pathways from amino acid degradation have been detected in the human gut using metagenomic approach. In Chapter 5 we discovered a novel butyrate synthesis pathway from the amino acid lysine and the Amadori product fructoselysine in Intestinimonas butyriciproducens AF211 that was isolated from human stool. This strain appeared to grow much better in lysine as compared to sugars although lysine and acetyl-CoA pathways were both detected in its complete genome. Moreover, the strain AF211 was able to metabolise efficiently fructoselysine into butyrate, and acetate was found to affect the fructoselysine fermentation, representing the impact of the environmental conditions where acetate is abundant in the gut. While the lysine pathway was found in the gut of many individuals, the fructoselysine pathway was present in only half of those samples. The finding that strain I. butyriciproducens AF211 is capable of the butyrogenic conversion of amino acid lysine and fructoselysine, an Amadori product formed in heated foods via the Maillard reaction, indicated a missing link that coupling protein metabolism and butyrate formation. As this Amadori product has been implicated to play a role in aging process, the use of strain AF211 as fructoselysine clearance in the gut needs further investigation. In Chapter 6 we performed genomic and physiological comparison between the I. butyriciproducens strain AF211 (human isolate) and SRB521T (mouse isolate). I. butyriciproducens was the most abundant species within the Intestinimonas genus and highly prevalent in humans based on metadata analysis on 16S amplicons. We confirmed that the butyrogenesis from lysine was a shared characteristic between the two I. butyriciproducens strains. We also observed the host specific features including tolerance to bile, cellular fatty acid composition, more efficient capability of converting sugars into butyrate, especially galactose and arabinose, in the human strain AF211. In addition, genomic rearrangements as well as variations in bacteriophages differed among strains.

    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.

    The effect of steam pelleting of a dry dog food on the Maillard reaction
    Rooijen, C. van; Bosch, G. ; Wierenga, P.A. ; Hendriks, W.H. ; Poel, A.F.B. van der - \ 2014
    Animal Feed Science and Technology 198 (2014). - ISSN 0377-8401 - p. 238 - 247.
    glycation end-products - physical quality - nutritive-value - animal feed - lysine - diet - digestibility - absorption - components - proteins
    During processing of pet foods, the Maillard reaction (MR) can occur, which reduces the bioavailability of essential amino acids like lysine and results in the formation of advanced Maillard reaction products (MRPs). This study examined 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 MR (total lysine, reactive lysine, fructoselysine, ¿-N-carboxymethyllysine, (5-hydroxymethyl)-2-furfural, lysinoalanine), browning development and CIE-Lab color. Steam pelleting variables did not cause a significant loss of lysine or change in color and absorbance values. Analyzing the unprocessed ingredient mix suggests that the choice of the ingredients used in the ingredient mix, rather than the pelleting process applied, is responsible for the RL/TL ratio observed in the dry standard dog food used in this study. MRP content increased during steam pelleting (fructoselysine: 366.2 to 538.8 mg/kg DM; ¿-N-carboxymethyllysine: 12.6 to 14.8 mg/kg DM; lysinoalanine: 5.7 to 7.7 mg/kg DM; P <0.05). Increasing conditioning temperature from 65 to 90 °C increased fructoselysine (475.9 to 601.6 mg/kg DM; P <0.01) and ¿-N-carboxymethyllysine (14.3 to 15.1 mg/kg DM; P = 0.003). An increased die hole length of 80 mm decreased fructoselysine content compared to 45 and 65 mm (461.3 vs. 573.3 and 581.6 mg/kg DM; P <0.01) but increased lysinoalanine content (8.8 vs. 7.4 and 6.8 mg/kg DM; P = 0.002). Analyzing total and reactive lysine and absorbance values are not accurate enough to predict the MR and formation of MRPs during processing.
    Quantitation of Maillard reaction products in commercially available pet foods
    Rooijen, C. van; Bosch, G. ; Poel, A.F.B. van der; Wierenga, P.A. ; Alexander, L. ; Hendriks, W.H. - \ 2014
    Journal of Agricultural and Food Chemistry 62 (2014)35. - ISSN 0021-8561 - p. 8883 - 8891.
    performance liquid-chromatography - advanced glycation endproducts - infant milk formulas - nutritive-value - furfural compounds - canine diets - breast-milk - lysine - proteins - furosine
    During processing of pet food, the Maillard reaction occurs, which reduces the bioavailability of essential amino acids such as lysine and results in the formation of advanced Maillard reaction products (MRPs). The aim of this study was to quantitate MRPs (fructoselysine (FL), carboxymethyllysine (CML), hydroxymethylfurfural (HMF)) and the cross-link lysinoalanine (LAL) in commercial pet foods. Sixty-seven extruded, canned, and pelleted dog and cat foods for growth and maintenance were analyzed using UPLC-MS. Canned pet foods contained on average the most FL, CML, and HMF (4534, 37, and 1417 mg/kg dry matter, respectively) followed by pelleted and extruded foods. Average daily intake (mg/kg body weight0.75) of HMF is 122 times higher for dogs and 38 times higher for cats than average intake for adult humans. As commercial pet foods are most often the only source of food for dogs and cats, future research focus should be on the bioavailability and long-term health implications of MRP consumption by dogs and cats.
    Production of platform chemicals in plants: lysine and itaconic acid
    Meer, I.M. van der; Arkel, J. van; Hakkert, J.C. ; Gaussand, G. ; Graaff, J. de; Koops, A.J. - \ 2010
    chemicaliën uit biologische grondstoffen - genetische modificatie - transgene planten - lysine - barnsteenzuur - biobased economy - biobased chemicals - genetic engineering - transgenic plants - lysine - succinic acid - biobased economy
    Poster met onderzoeksinformatie.
    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 - lysine - feed supplements - performance - animal nutrition - vietnam

    The studies reported in this thesis were carried out in Central Vietnam where pig production plays an important role and pig farmers face a general dietary protein shortage for their animals. The objectives of the work presented were (1) to investigate the crude protein (CP) supply to local Mong Cai (MC) pigs as well as lean type pigs (including crossbreds); (2) to derive CP requirements under high temperature conditions in the tropics; (3) to determine optimal lysine content in the diet of lactating Mong Cai (MC) sows and their piglets; (4) to evaluate the effects of floor types and dietary CP content on performance of sows and piglets. An interview based study of smallholders farmers showed that poor nutritive value of the diets for fattening pigs and sows is observed in three agro–ecological zones (Upland, Lowland and Coastal) in Central Vietnam. Pig on smallholder farms can produce more lean meat if they feed their pigs a higher dietary CP level. The optimum dietary CP level for the different breeds of pigs investigated (MC; F1, Large White Mong Cai and F2, (Landrace Mong Cai) Large White) were found to be 13 % for MC, 15 % for F1 and 16 % for F2 pigs. High dietary CP levels (>19 % CP) for MC, F1 and F2 negatively affected growth performance. The optimum dietary CP content for lean type pigs kept under the hot humid tropical climate of Central Vietnam to ascertain the maximum growth performance and carcass characters in Large White (LW) and Landrace (LD) pigs must be more than 16 % CP. The other study indicated that increasing dietary lysine level from 0.7 to 1.2 % reduced the sows weight loss during lactation. No effect was found on the number of piglets born nor piglet survival at 7 days. The number of piglets weaned was improved by lysine levels of over 1.02 %. Using raised wooden floors resulted in a higher number of piglets and litter weight at weaning compared to piglets on ground clay and concrete floor. In conclusion, the current work indicates that improving protein quantity and quality in traditional diets for Vietnamese pigs kept by smallholder farmers can significantly improve productivity of MC, F1 and F2 pigs, and as such improve the income of farmers.


    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.

    Productie van platformchemicaliën door planten
    Meer, I.M. van der; Koops, A.J. - \ 2010
    chemische industrie - lysine - polymeren - transgene planten - aardappelen - biobased economy - monomeren - chemicaliën uit biologische grondstoffen - chemical industry - lysine - polymers - transgenic plants - potatoes - biobased economy - monomers - biobased chemicals
    Info sheet over de productie van platformchemicaliën door planten. Chemicaliën die stikstofatomen bevatten en als uitgangsmateriaal dienen voor de petrochemische industrie zijn chemisch moeilijk te maken. Productie van dergelijke chemicaliën is vaak kostbaar en vervuilend. Sommige van deze stikstofbevattende chemicaliën komen echter ook in planten voor. Ook andere bouwsteenmoleculen uit aardolie worden door planten gemaakt, zoals organische zuren. Deze infosheet geeft een voorbeeld van de ontwikkeling van platformchemicaliën in planten.
    Verslag van een studiereis naar de bijdrage van krachtvoergrondstoffen en grasproducten aan de eiwitvoorziening van biologische biggen
    Jongbloed, A.W. ; Peet-Schwering, C.M.C. van der - \ 2009
    Lelystad : Animal Sciences Group, Wageningen UR (Rapport / Animal Sciences Group 233) - 15
    biologische landbouw - varkenshouderij - varkensvoeding - biggen - biggenvoeding - biologische productie - methionine - lysine - zonnebloemzaden - raapzaad - organic farming - pig farming - pig feeding - piglets - piglet feeding - biological production - methionine - lysine - sunflower seeds - rapeseed
    Competitive and suitable protein-rich organically-grown raw materials for piglets are scarce. Therefore, an inventory on this aspect was undertaken during a study trip to several countries. Processing of rape seed and sunflower seed seems to be most promising because of their high ratio of digestible methionine to digestible lysine
    Effects of extrusion processing on nutrients in dry pet food
    Tran, Q.D. ; Hendriks, W.H. ; Poel, A.F.B. van der - \ 2008
    Journal of the Science of Food and Agriculture 88 (2008)9. - ISSN 0022-5142 - p. 1487 - 1493.
    resistant starch - cannulated dogs - protein-sources - digestibility - quality - lysine - diets - cooking - lipids - cats
    Extrusion cooking is commonly used to produce dry pet foods. As a process involving heat treatment, extrusion cooking can have both beneficial and detrimental effects on the nutritional quality of the product. Desirable effects of extrusion comprise increase in palatability, destruction of undesirable nutritionally active factors and improvement in digestibility and utilisation of proteins and starch. Undesirable effects of extrusion include reduction of protein quality due to e.g. the Maillard reaction, decrease in palatability and loss of heat-labile vitamins. Effects of extrusion processing on the nutritional values of feeds for livestock have been well documented. Literature results concerning effects of extrusion on dry pet foods, however, are scarce. The present review discusses the results of studies investigating the impact of extrusion cooking on the nutritional quality of dry pet foods.
    Low Molecular Weight Melanoidins in Coffee Brew
    Bekedam, E.K. ; Roos, E. ; Schols, H.A. ; Boekel, M.A.J.S. van; Smit, G. - \ 2008
    Journal of Agricultural and Food Chemistry 56 (2008)11. - ISSN 0021-8561 - p. 4060 - 4067.
    maillard reaction-products - chemical-characterization - antioxidant activity - colored compounds - roasted coffee - arabica beans - model systems - polysaccharides - xylose - lysine
    Analysis of low molecular weight (LMw) coffee brew melanoidins is challenging due to the presence of many non-melanoidin components that complicate analysis. This study focused on the isolation of LMw coffee brew melanoidins by separation of melanoidins from non-melanoidin components that are present in LMw coffee brew material. LMw coffee fractions differing in polarity were obtained by reversed-phase solid phase extraction and their melanoidin, sugar, nitrogen, caffeine, trigonelline, 5-caffeoylquinic acid, quinic acid, caffeic acid, and phenolic groups contents were determined. The sugar composition, the charge properties, and the absorbance at various wavelengths were investigated as well. The majority of the LMw melanoidins were found to have an apolar character, whereas most non-melanoidins have a polar character. The three isolated melanoidin-rich fractions represented 56% of the LMw coffee melanoidins and were free from non-melanoidin components. Spectroscopic analysis revealed that the melanoidins isolated showed similar features as high molecular weight coffee melanoidins. All three melanoidin fractions contained ~3% nitrogen, indicating the presence of incorporated amino acids or proteins. Surprisingly, glucose was the main sugar present in these melanoidins, and it was reasoned that sucrose is the most likely source for this glucose within the melanoidin structure. It was also found that LMw melanoidins exposed a negative charge, and this negative charge was inversely proportional to the apolar character of the melanoidins. Phenolic group levels as high as 47% were found, which could be explained by the incorporation of chlorogenic acids in these melanoidins
    Extrusion processing : effects on dry canine diets
    Tran, Q.D. - \ 2008
    Wageningen University. Promotor(en): Martin Verstegen; Wouter Hendriks, co-promotor(en): Thomas van der Poel. - [S.l.] : S.n. - ISBN 9789085049036 - 108
    honden - hondenvoeding - droogvoer - diëten - uitpersing - drogen - eiwit - lysine - zetmeelkorrels - smakelijkheid - voedermiddelbewerking - dogs - dog feeding - dry feeds - diets - extrusion - drying - protein - lysine - starch granules - palatability - feed processing
    Keywords: Extrusion, Canine diet, Protein, Lysine, Starch gelatinization, Palatability, Drying.

    Extrusion cooking is a useful and economical tool for processing animal feed. This high temperature, short time processing technology causes chemical and physical changes that alter the nutritional and physical quality of the product. Effects of extrusion on the feed quality for other animals than pets have been well recognized. Our studies investigated to what extent extrusion and/or drying of a complete canine diet affects lysine reactivity, amino acids, fatty acids, starch gelatinization and physical parameters.
    In order to create a general view of dog food quality in practice, the physical and nutritional quality of commercial canine diets available in the Netherlands were examined. This study showed unveiled variation in lysine reactivity and starch gelatinization of commercial dry canine diets. A study was then carried out on the effects of extrusion on the physical and nutritional values of canine diets in a FIDO model. The extrusion conditions (temperatures in the range of 110 to 150ºC, 300 g/kg moisture) increased lysine reactivity, starch gelatinization and in-vitro starch digestibility. Protein digestibility and dispersibility were not affected by the extrusion conditions used. The increase in the extrusion temperature used (110 to 150ºC) decreased kibble durability but did not affect hardness. This study also concluded that optimisation of extrusion conditions during production of commercial canine diets should include the measurement of the reactive to total lysine ratio. Single ingredients of a complete canine diet did not respond in a similar way during extrusion: extrusion had no effects on animal ingredients (higher lysine contents) while extrusion could decrease (in barley) or increase (in rice) the reactive lysine content in vegetable ingredients (lower lysine content). Both reactive lysine content and ratios of reactive to total lysine of the mixture of all vegetable ingredients were hugely increased during extrusion. Finally, an additional study was carried out on the effects of drying on extruded canine diets. The results of this study showed that drying temperature (in the range of 120-160ºC) and drying time did not affect the quality of extruded canine diets in terms of amino acids and fatty acids levels while these drying temperatures reduced drying time from hours to minutes. Drying temperature only affected the reactive lysine content and, therefore, the ratio of reactive to total lysine of kibbles dried at a temperature of 200ºC. Drying temperature also affected a minority of fatty acids with fatty acid C18:3 n-3 being the most affected at a drying temperature of 200ºC.
    In conclusion, extrusion at temperatures in the range of 130-150ºC and at a moisture of 300 g/kg is a mild heat treatment with respect to protein quality for pet food production. Measurement of the ratio of reactive to total lysine should be included in optimisation of extrusion conditions during pet food production. Drying temperature in the range of 120-160ºC and drying time do not affect the amino acids and fatty acids level of extruded canine diets.

    Effect of nutrient dilution on feed intake, eating time and performance of hens in early lay
    Krimpen, M.M. van; Kwakkel, R.P. ; André, G. ; Peet-Schwering, C.M.C. van der; Hartog, L.A. den; Verstegen, M.W.A. - \ 2007
    British Poultry Science 48 (2007)4. - ISSN 0007-1668 - p. 389 - 398.
    protein - diets - strains - lysine
    1. An experiment with 480 ISA Brown layers was conducted to measure the effect of dietary energy ( 11.8, 11.2 and 10.6 MJ/kg) and non-starch polysaccharides ( NSP) ( 128, 146 and 207 g/kg) concentration, soluble NSP content ( 64 and 85 g/kg), particle size distribution of the NSP fraction ( fine and coarse) and feed form ( mash and crumble) on feed intake, eating time and egg performance of laying hens in early lay ( from 18 to 26 weeks of age). Twelve experimental diets were tested, each replicated 4 times. 2. Laying hens in early lay that were fed low- or high-NSP diets were able to compensate for 10% dietary dilution by 9.5 and 4.9% higher feed intakes, respectively. Feeding crumble or coarsely ground mash did not affect feed intake. 3. Eating time of the hens fed the undiluted diets increased over the experimental period from 16.4 to 24.6% of the observation period, but was not affected by sand or grit addition, particle size distribution or feed form. Feeding high-NSP diets increased eating time by 22%. 4. Egg performance and body weight gain of the hens that were fed low- NSP or high-NSP diets were similar or better compared to the undiluted diets, whereas coarse grinding of the diets showed 7 to 10% lower egg performance and weight gain. Egg performance and weight gain were not affected by feed form. 5. It is concluded that hens in early lay, fed energy-diluted diets, by adding sand or grit ( low-NSP) or NSP-rich raw materials ( high-NSP) to the control diet, were able to increase their feed intake, resulting in energy intake and egg performance comparable to the control group. Supplementing diets with insoluble NSP also decreased eating rate. Prolonged eating time using insoluble NSP could be useful in reducing feather pecking behaviour.
    Pelleting of diet ingredients: Diet selection and performance in choice-fed growing pigs
    Brand, H. van den; Verstegen, M.W.A. ; Poel, A.F.B. van der - \ 2007
    Animal Feed Science and Technology 138 (2007)2. - ISSN 0377-8401 - p. 169 - 177.
    physical quality - animal feed - lysine - foods - preferences - tryptophan - threonine - behavior - piglet - sex
    An experiment was completed with individually housed growing pigs to examine whether pigs can compose their optimal diet when allowed a choice of three different pellets. Forty cross-bred pigs (20 castrates and 20 gilts) with an initial live weight of 22.0 ± 2.1 kg were allocated to either a complete control diet (C) or to a choice feed diet (CF) during a 4-week period. The C pigs received a complete feed as one pellet, whereas CF pigs could select their diet out of three pellets being: an energy-rich, protein-rich or premix-rest pellet. The CF pigs were offered their pellets in one feeding trough, which was divided in three compartments. All diets were administered ad libitum. Gilts fed the CF diet selected a higher crude protein (CP) diet than barrows (222 and 193 g/kg DM, respectively), whereas the C pigs, both gilts and castrates, were fed a diet with the same CP content (i.e., 204 g/kg DM; treatment by sex interaction; P
    Dietary balanced protein in broiler chickens. 1. A flexible and practical tool to predict dose-response curves
    Eits, R.M. ; Kwakkel, R.P. ; Verstegen, M.W.A. ; Hartog, L.A. den - \ 2005
    British Poultry Science 46 (2005)3. - ISSN 0007-1668 - p. 300 - 309.
    amino-acid levels - age - performance - nutrition - lysine
    1. An empirical model of exponential form was developed, different versions of which can be used to predict growth rate, feed conversion and carcase and breast meat yield of broiler chickens as a function of dietary balanced protein ( DBP) content. The model was developed to support decision- making by nutritionists. The model helps in determining DBP contents that maximise profit. 2. The model avoids the practical disadvantages of existing methods. In contrast with mechanistic models, only data that are generally known by broiler nutritionists are required as input. Compared with predictions derived from one or a few feeding trials, the model predictions are more accurate ( because the model was derived from many data- sets) and more flexible ( because a description of the type of broiler was included as input for the model). 3. Broiler response studies from the literature and the Nutreco Poultry and Rabbit Research Centre ( 27 data- sets in total) were used in the model development to select significant variables, to quantify the parameters and to evaluate the accuracy of the predictions. 4. Input variables were DBP content, maximum performance level, age, year ( indicating genetic potential) and sex. The model, including the assumption that the shape of the dose - response curves to DBP content is independent of broiler and feed characteristics, gave an accurate simulation of growth rate, feed conversion and breast meat for nearly all data- sets. Effects of DBP content on carcase yield were relatively small, except for carcases without skin and skin fat.
    Maillard reactions and increased enzyme inactivation during oligosaccharide synthesis by a hyperthermophilic glycosidase
    Bruins, M.E. ; Hellemond, E.W. van; Janssen, A.E.M. ; Boom, R.M. - \ 2003
    Biotechnology and Bioengineering 81 (2003)5. - ISSN 0006-3592 - p. 546 - 552.
    thermostable beta-glycosidases - high-temperature process - pyrococcus-furiosus - kinetic-model - glucosidase - hydrolysis - glycine - lactose - lysine - foods
    The thermostable Pyrococcus furiosus beta-glycosidase was used for oligosaccharide production from lactose in a kinetically controlled reaction. Our experiments showed that higher temperatures are beneficial for the absolute as well as relative oligosaccharide yield. However, at reaction temperatures of 80degreesC and higher, the inactivation rate of the enzyme in the presence of sugars was increased by a factor of 2 compared to the inactivation rate in the absence of sugars. This increased enzyme inactivation was caused by the occurrence of Maillard reactions between the sugar and the enzyme. The browning of our reaction mixture due to Maillard reactions was modeled by a cascade of a zeroth- and first-order reaction and related to enzyme inactivation. From these results we conclude that modification of only a small number of amino groups already gives complete inactivation of the enzyme. (C) 2003 Wiley Periodicals.
    De respons van kalkoenhanen op lysine bij een lage en hoge staltemperatuur
    Veldkamp, T. ; Kwakkel, R.P. - \ 2000
    Praktijkonderzoek voor de Pluimveehouderij 11 (2000)1. - ISSN 0924-9087 - p. 50 - 52.
    kalkoenen - huisvesting, dieren - dierenwelzijn - luchttemperatuur - verwarming - regulatie - diervoedering - voer - samenstelling - lysine - aminozuren - eiwitten - turkeys - animal housing - animal welfare - air temperature - heating - regulation - animal feeding - feeds - composition - lysine - amino acids - proteins
    Het doel van het onderzoek dat in dit artikel wordt beschreven, is de respons vast te stellen van jonge kalkoenen op verschillende lysineniveaus bij lage en hoge staltemperaturen.
    Drie-fasenvoedering bij eenden getest
    Buisonjé, F.E. de; Enting, H. ; Wemmers, A. - \ 1999
    Praktijkonderzoek voor de Pluimveehouderij 10 (1999)1. - ISSN 0924-9087 - p. 34 - 37.
    eenden - eendenvoeding - diervoedering - voer - samenstelling - eiwitten - lysine - verteerbaarheid - karkassamenstelling - productiviteit - rentabiliteit - ducks - duck feeding - animal feeding - feeds - composition - proteins - lysine - digestibility - carcass composition - productivity - profitability
    In dit onderzoek naar de eiwit- en lysinebehoefte van vleeseenden in verschillende fasen van de mestperiode gaf drie-fasenvoedering dezelfde technische resultaten en een iets betere slachtkwaliteit dan het gebruikelijke twee-fasen programma, maar de stikstofaanvoer via het voer nam bij toepassing van drie-fasenvoedering enigszins toe.
    Inventarisatie van het furosinegehalte in verse gepasteuriseerde melk
    Kobessen, J.J.H. ; Labrijn, J.F. - \ 1998
    Wageningen : RIKILT-DLO (Rapport / RIKILT-DLO 98.015) - 14
    gepasteuriseerde melk - maillard-reactie - lysine - pasteurized milk - maillard reaction - lysine
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