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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    Leefbaarheidsinitiatieven op het platteland : analyse van eigenheid en eigenaarschap
    Bock, Bettina ; During, Roel ; Dam, Rosalie van; Donders, Josine ; Kruit, Jeroen ; Pleijte, Marcel ; Witte, David de - \ 2018
    Wageningen : Wageningen University & Research - 89
    In onze dorpen is het heel gewoon: inwoners steken de handen uit de
    mouwen. Met grote en kleine initiatieven zorgen ze ervoor dat hun dorp
    vitaal en leefbaar blijft. Dat is altijd al zo geweest. Dorpen hebben hun
    eigen feesten en evenementen. Buren zorgen voor buren. Zo doen we dat.
    Sinds onze koning het begrip participatiesamenleving introduceerde,
    is er veel aandacht voor het enorme zelforganiserende vermogen in de
    dorpen. En hoe gewoon wij dat vermogen ook vinden, het is tegelijkertijd
    ontzettend bijzonder. Want mensen komen en gaan, initiatieven in
    dorpen blijven. Hoe kan dat?
    Dit jaar viert de P10 haar 10-jarig bestaan. Net als vijf jaar geleden lieten
    we een onderzoek doen. Dit keer stonden bewonersinitiatieven en de
    leefbaarheid in dorpen centraal, de grote gemene deler in de P10. We
    vroegen ons af wat bewoners beweegt en hoe zij naar hun leefbaarheid
    kijken. En we probeerden te achterhalen hoe wij als P10 het zelforganiserend
    vermogen kunnen stimuleren en benutten in ons streven naar een
    vitaal platteland.
    Handen uit de mouwen voor natuurliefhebbers
    Zandt, A. ; Buijs, A.E. ; Dam, R.I. van; Donders, J.L.M. ; Koedoot, M. ; Bakker, S. ; Vis, J. - \ 2012
    Trouw (2012). - 1 p.
    Morphology of the small intestinal mucosal surface of broilers in relation to age, diet formulation, small intestinal microflora and performance
    Leeuwen, P. van; Mouwen, J.M.V.M. ; Klis, J.D. van der; Verstegen, M.W.A. - \ 2004
    British Poultry Science 45 (2004)1. - ISSN 0007-1668 - p. 41 - 48.
    1. Three experiments were performed to relate morphological characteristics of the small intestinal mucosal surface to age, dietary factors, small intenstinal microflora and performance of broilers. Characterisation of the small intestinal mucosal surface using a dissecting microscope was based on the orientation of the villi, villus shape and the presence of convoluted villi. 2. In Trial 1, the morphological changes of the mucosal surface were studied weekly in the period from 7 to 28 d of age. At d 7 mainly tongue- and leaf-shaped villi together with some ridge-shaped ones were observed in the middle section of the small intestine, displaying a regular zigzag pattern on 53% of the mucosal surface. During the period from d 7 to 14, the area with ridge-shaped villi increased from 7 to 63% and did not change significantly over the next 2 weeks. 3. In Trial 2, three protein sources, soy isolate (SI), wheat gluten (WG), hydrolysed wheat gluten (HWG) and SI with added l-glutamine (SI + Gln), were studied with respect to their effect as dietary components on villus morphology in the mid-small intestine and performance. Diets were fed with (0 to 14 d) and without pectin (14 to 21 d). Feed conversion ratio on the HWG diet improved in comparison to the native WG diet. During the period 0 to 14 d of age the mucosal area with zigzag-oriented villi increased when the pectin diet was supplemented with Gln. Moreover, weight gain of birds fed the SI + Gln diet increased in the period 41 to 21 d. 4. In Trial 3, a study was made of the morphological response of the villi to a stimulation of microbial activity in the digesta after addition of highly methylated pectin to the soybean meal (SBM) diet. This was performed with and without inoculation of a non-virulent Salmonella typhimurium on d 7. By d 21 the birds fed the pectin diet showed impaired weight gain and higher feed conversion. The pectin affected the mucosal surface by decreasing the area with the zigzag pattern and increasing the area with convoluted, mainly ridge-shaped villi. The Salmonella typhimurium infection increased the effects of pectin on performance and mucosal morphology.
    Significance of combined nutritional and morphological precaecal parameters for feed evaluations in non-ruminants
    Leeuwen, P. van - \ 2002
    Wageningen University. Promotor(en): M.W.A. Verstegen; J.M.V.M. Mouwen. - S.l. : S.n. - ISBN 9789058086426 - 151
    niet-herkauwers - spijsvertering - spijsverteringsstelsel - voederwaardering - voedingsfysiologie - morfologie - voer - samenstelling - darmslijmvlies - nonruminants - digestion - digestive system - feed evaluation - nutrition physiology - morphology - feeds - composition - intestinal mucosa

    In this thesis the hypothesis is tested that the nutritional evaluation of dietary formulations in non-ruminants requires both functional-nutritional and functional-morphological parameters. The functional-nutritional parameters provide data on the outcome of the digestive process. Additionally, the functional-morphological parameters provide information about the effects of feed components on the small intestinal mucosa.

    Part I (chapters 2 - 4) considers the apparent digestibility as a functional-nutritional parameter for feed evaluation in pigs and roosters, whereas Part II (chapters 5 - 8) presents studies with functional-morphological parameters of the small intestinal mucosa of chickens, calves and piglets in relation to feed composition and additives.


    The amount of protein and amino acids, which disappears in the large intestine of pigs, is not available for animal body maintenance and production (Zebrowska, et al ., 1978). Degradation of protein in the large intestines is mainly fermentative resulting in non-amino acid N end products, which are not available to the animal. This finding implies that precaecal digestion rather than whole tract digestion provides a more accurate parameter for the estimation of protein availability (Dierick et al., 1987). The in vivo determination of precaecal protein digestion relies on quantifying the ratio between the amount of the ingested protein to that which disappears proximal to the caecum. In digestibility experiments the diets and digesta, collected immediately after the ileum, are analysed on their protein contents. But digesta also contain undigested dietary protein of endogenous origin. Therefore, this ratio is determined as the apparent digestibility. Apparent digestibility is a quantitative parameter providing information on the digestive progress measured by nutrient disappearance at a defined site.

    Quantitative studies concerning the digestive processes in the small intestine require reproducible collection of digesta from the small intestine. Present procedures can be divided into techniques by which digesta are collected after sacrifying the animals and techniques based on a surgical intervention. Collection of digesta from animals after euthanasia is often used in experiments with broilers (Ravindran et al., 1999). This method, however, requires a large number of animals and for this reason is not commonly used in pigs. There are different surgical techniques described in literature for precaecal digesta collection. It is generally concluded that flexible (silicone) rubber is preferable to rigid materials. Regarding surgical techniques for intestinal studies in pigs, there is a consensus that simple T-shaped cannulae in the ileum and ileo-rectal anastomose (IRA) may not provide representative samples of digesta and/or may interfere with the animal's physiology (Köhler, 1992), whereas collection of digesta from re-entrant cannulae is considered to be hampered by technical difficulties (van Leeuwen et al ., 1987).

    In part I of the thesis surgical techniques and procedures for digesta collection in pigs and roosters are described and results of digestibility determinations are given.

    Chapter 1 describes a surgical procedure, which is called the Post Valve T-Caecum (PVTC) cannulation and is considered to be an alternative to the existing digesta collection methods. The prerequisites of this technique are that there is minimal hinder of the animal's physiology. Moreover, digesta samples should be representative, and the surgical technique acceptable in terms of animal welfare. The PVTC technique relies on partial caecectomy followed by placement of a wide flexible silicone T-cannula in the caecum. A considerable advantage of this technique is that the region of the intestine to be studied is not surgically treated. Gargallo and Zimmerman (1981) studied the possible effects of caecectomy on digestion in pigs. They observed small effects on overall digestibility of cellulose and nitrogen. Their final conclusion was that the absence of the caecum in pigs did not significantly alter digestive function. Darragh and Hodgkinson (2000) commented that the PVTC cannulation procedure appears to be the preferred method for the collection of ileal digesta.

    Chapter 2 describes digesta collection procedures and implications when using PVTC cannulated pigs. Collection of digesta after PVTC cannulation necessitates the use of an inert marker in the diets, to quantify the amounts of nutrients present in ileal digesta for determination of diet digestibility. Two experiments were conducted to evaluate chromic oxide (Cr 2 O 3 ) and HCl-insoluble ash as digestive markers by determining the apparent digestibility of dry matter (DM) and crude protein (CP). In addition, studies were performed of the effects of age (i.e. three different body weight (BW) classes) on apparent ileal DM and CP digestibilities. In experiment 1, barrows were fitted with PVTC cannulae to determine apparent ileal DM and CP digestibility of a wheat gluten/wheat bran ration and a soybean meal ration. Immediately after the morning feeding ileal digesta were collected on an hourly basis for a period of 12 hours. Subsequently, nitrogen (N) and marker contents were determined in these samples. The postprandial Cr/N ratio was more constant than the HCl-insoluble ash/N ratio. Therefore, chromic oxide is considered more suitable as a marker than HCl-insoluble ash when apparent digestibility of protein is the parameter to be studied. In experiment 2, apparent ileal DM and CP digestibilities were determined in 18 rations using twelve barrows fitted with PVTC cannulas (BW from 40 - 100 kg). The protein sources for these rations were derived from feedstuffs of different origin. Apparent precaecal digestibility differed significantly (P < 0.05) on the marker in four rations for DM and in three rations for CP. Digestibility coefficients were not systematically higher or lower for either marker. Besides these methodological aspects, a slight increase in apparent ileal CP digestibility was observed with an increase in body weight.

    Chapter 3 examines precaecal digestion of protein and amino acids (AA) in roosters. Similar to pigs, undigested AA which reach the caeca are deaminated by the microflora and the end- products have no nutritional value (McNab, 1989). Moreover, Parsons (1986) observed a closer relationship between amino acid availability measured in chick growth assays, and digestibility determined in caecectomised rather than in intact birds. This means that, in poultry, digestion in the distal region of the intestines, more specifically the caeca, is mainly fermentative and that the AA synthesized in, or disappearing from the caeca, are not available for protein synthesis by the animal. Therefore, a procedure for ileostomy in adult roosters has been described with the use of flexible silicon cannulae. Apparent ileal digestibility coefficients for dry matter (aDC DM), crude protein (aDC CP) and amino acids (aDC AA) were determined in diets formulated with maize/wheat gluten meal, wheat gluten meal, faba beans, lupins, soybean meal and casein as the main protein sources. These determinations were performed in ileostomised roosters fitted with silicon cannulae. In addition, aDC data determined using roosters (present study) were correlated with previously published aDC data of the same diets determined with pigs (van Leeuwen et al., 1996a, 1996b).

    The ileal aDC CP in roosters significantly (P < 0.05) differed in aDC CP and aDC AA between diets. Over diets significant linear relationships were found for the digestibility data determined with roosters and pigs and inturn explained 85 % of the variation in ileal aDC CP between the six diets evaluated in roosters and pigs. Variation between roosters and pigs in ileal aDC AA could be explained for 62-90%, for the individual amino acids, with the exception of aDC of arginine. The standard errors of prediction of the models for aDC AA in roosters using aDC AA in pigs were < 0.04 percentage units. Although, more work is needed to validate these correlations, it is likely that this approach can be used for the prediction of aDC values for roosters from values determined in pigs. The results showed a similarity in the level of digestibility coefficients for protein and amino acids in both species. This means that, despite the differences in anatomy between pigs and poultry (Moran Jr., 1982) the differences in apparent precaecal digestibility of CP and AA were limited. The two animal species with their differences in intestinal structures, differences in amounts and activity of the endogenous components were both capable of digesting protein to a similar extent suggesting a similar precaecal digestive capacity.

    Regarding methodological aspects the study showed comparable aDC CP and AA for soybean meal determined in the present experiment with the cannulated roosters and data from literature using adult caecectomised roosters. Secondly, the roosters provided with cannulae introduced after ileostomy can be used for periods up to a year after surgery.


    The qualitative functional-morphological parameters of the small intestinal mucosa are examined in the chapters 5 - 8.

    Chapter 5 considers the morphology of the mucosal surface of the small intestine of broilers and the relationship with age, diet formulation, small intestinal microflora and growth performance. The villi of the small intestine were examined with a dissecting microscope and the surface was described using a morphological scoring scale. As illustrated by pictures, zigzag oriented ridges were observed in the broilers, which seem to be characteristic for poultry.

    The results showed that in clinically healthy broilers the shape and orientation of the small intestine villi were related to the age of the animal and the intestinal location. Effects of dietary composition and microflora are also demonstrated. Fermentable pectin as dietary component decreased the zigzag villus orientation and reduced performance. Addition of glutamin to a soybean diet limited the decrease of the zigzag villus-orientation caused by pectin and had a beneficial effect on performance. An oral challenge with a non-virulent Salmonella typhimurium increased the effects of dietary pectin on the small intestine morphology and performance.

    Chapter 6, contains a study of the functional-morphological effects of virginiamycin (VM), used as feed additive in piglets. The objective of this study was to determine the effects of VM on morphological parameters of the small intestinal mucosa, animal growth and feed conversion ratio (feed intake/weight gain) in piglets. The study comprised three trials: two experiments to study the morphological effects of VM on the small intestinal mucosa, whereas the third experiment was a performance study. Each experiment comprised a control group fed a diet without VM, and a VM group fed a diet containing 40 mg/kg VM. In the first experiment, the piglets were individually kept and an oral dose of K88 positive enterotoxigenic Escherichia (E.) coli (ETEC) was given as a sub-clinical challenge. The housing conditions in experiments 2 and 3 were according to practical standards. The results showed that the VM decreased feed conversion ratio and increased villus heights in conventionally kept piglets. Crypt depths were decreased in the individually kept piglets seven days after the ETEC challenge. Corpet (1999) and Anderson et al. (2000) reviewed the mode of action of antibiotics as feed additives and suggested that the antibiotics suppress bacterial activity and decomposition of bile salts resulting in a more slender villus structure. Increased villus heights indicated an increased mucosal surface and absorption capacity, which is in agreement with the improved precaecal nutrient digestibility of diets with VM, as observed by Decuypere et al . (1991). The difference in morphological response to the VM illustrated variation in the morphological characteristics between clinically healthy piglets.

    In chapter 7 the effect of the use of the combination of two bioactive proteins, lactoperoxidase- system (LP-s) and lactoferrin (LF), on a milk replacer diet were investigated. This study examined the severity of diarrhoea, morphology of the small intestinal mucosa and the microbiology of digesta and faeces in young weaned calves.

    Following weaning, the incidence of diarrhoea and mortality of calves is usually higher than that for unweaned calves (Reynolds et al ., 1981). In conventional calf production, antibiotics are added to the milk replacer to reduce gastrointestinal disorders caused by pathogenic bacteria in the gut. Recent legislation restricts the addition of antibiotics in diets for calves (EC, 1998) because of possible repercussions on human health (Van den Boogaard and Stobberingh, 1996).

    LP and LF are both specific protein constituents of colostrum. These naturally occurring proteins are probably at least partly inactivated during the processing of milk because of their thermo-instability, and the remaining levels are not constant. Moreover, in dairy milk replacers a significant part of the protein is of vegetable origin and therefore lacks LP and LF.

    The experiment with calves comprised the first two weeks post weaning. One group received a control diet and a second group a diet with LP-s/LF. Results showed that faecal consistency of the LP-s/LF group, as assessed by faecal consistency scores, was significantly improved compared to the control group. The numbers of E. coli in faeces were significantly lower and the villi in the distal jejunum more finger shaped and longer in those of the LP-s/LF group compared to the control group. These findings showed that the effects of LP-s/LF are mainly located in the distal region of the gastrointestinal tract. Reiter and Perraudin (1991) also showed positive effects of LP-s on live weight change in field trials. Still et al . (1989) studied the effects of a combination of LP-s and LF on the severity of diarrhoea in calves for a period 0 to 6 days after an experimental E. coli infection. They concluded that LP-s/LF had preventive and curing effects after the E. coli challenged infection. The results of the present experiment were in agreement with their observations.

    Chapter 8 considers the functional-morphological implications of condensed tannins in faba beans (Vicia faba L.). The nutritional value of faba beans is limited by the presence of these tannins (Marquardt et al., 1977). Jansman et al. (1993) studied the effects of tannins on the apparent faecal digestibility of a control diet, a diet containing hulls of white flowering, low-tannin faba beans, and a diet with hulls of coloured flowering, high-tannin faba beans. They concluded that whole tract crude protein digestibility of the high-tannin diet was significantly (P < 0.05) lower than the control and low-tannin diets. This effect was partly explained by an increase of the endogenous fraction in the faeces and by an increase of the undigested tannin-feed complexes. In addition, the present study investigated samples of the proximal-, mid- and distal jejunum were investigated histologically and biochemically. The histological differences between the diets were not significant. However, differences in aminopeptidase activity were observed in the proximal small intestine. The amino-peptidase activity of the high tannin group was significantly (P < 0.05) depressed compared to the control and low-tannin groups. Furthermore, a correlation was calculated within the three groups between amino peptidase activity, as a functional parameter of the brush border, and the apparent faecal digestibility of CP, as a quantitative nutritional characteristic. No significant correlations were found between apparent CP digestibility and the aminopeptidase activity in the animals fed the control or low-tannin diet. But when the high tannin diet was fed, the correlation was significantly positive (P < 0.002; R = 0.91). This correlation indicated that a decreased aminopeptidase activity of the small intestine mucosa explained, at least in part, the effects of tannins on CP digestibility.

    Effect of a lactoperoxydase system and lactoferrin, added to a milk replacer diet, on severity of diarrhoea, intestinal morphology and microbiology of digesta and faeces in young calves
    Leeuwen, P. van; Oosting, S.J. ; Mouwen, J.M.V.M. ; Verstegen, M.W.A. - \ 2000
    Journal of Animal Physiology and Animal Nutrition 83 (2000). - ISSN 0931-2439 - p. 15 - 23.
    The objective of the present study was to determine the effects of the combination of a lactoperoxidase system (LP-s) and lactoferrin (LF) added to a milk replacer diet on severity of diarrhoea, the morphology of the small intestinal mucosa, and the microbiology of digesta and faeces in young calves, in comparison with a control diet. The experiment was conducted with 30 young calves, 15 per treatment, during the period of 7-21 days of age. During this period, calves are sensitive to gastrointestinal disturbances that can cause diarrhoea. The results showed a significantly (p < 0.05) reduced severity of diarrhoea in the LP-s/LF group compared to the control group as assessed by faecal consistency scores. Numbers of CFU (colony forming units) of Escherichia coli in jejunal and colonic digesta and in faeces were lower in the LP-s/LF group compared with the control group. The differences were significant in both colonic digesta (p < 0.1) and in faeces (p < 0.05). Examination of the small intestinal mucosa, using a dissecting microscope, indicated more finger shaped villi in the distal jejunum of LP-s/LF-treated calves compared with the control group (p < 0.05). Histometrical measurements showed that these villi were significantly (p < 0.05) longer.
    Klimaatregeling met koude-opslag in vleesvarkensstallen
    Verdoes, N. ; Telle, M.G. ; Mouwen, I.A.A.C. ; Tuinte, J.H.G. ; Vrielink, M.G.M. ; Brakel, C.E.P. van - \ 1996
    Rosmalen : Praktijkonderzoek varkenshouderij (Proefverslag / Praktijkonderzoek Varkenshouderij P1.161) - 40
    energie - opslag - geothermische energie - watervoerende lagen - varkensstallen - afmesten - varkens - nederland - energy - storage - geothermal energy - aquifers - pig housing - finishing - pigs - netherlands
    Automatisch geregelde natuurlijke ventilatie bij vleesvarkens
    Mouwen, I.A.A.C. ; Geurts, P.J.W.M. ; Binnendijk, G.P. ; Brakel, C.E.P. van - \ 1996
    Rosmalen : Praktijkonderzoek varkenshouderij (Proefverslag / Praktijkonderzoek Varkenshouderij P1.153) - 40
    klimaatregeling - automatische regeling - gebouwen - koelen - engineering - varkensstallen - stallen - ventilatie - air conditioning - automatic control - buildings - cooling - engineering - pig housing - stalls - ventilation
    Studie naar klimatisering van de dekstal in relatie tot emissie en energie
    Mouwen, I.A.A.C. ; Plagge, J.G. - \ 1995
    Rosmalen : Praktijkonderzoek varkenshouderij (Proefverslag / Praktijkonderzoek Varkenshouderij P1.125) - 40
    luchtverontreiniging - ammoniak - gebouwen - economie - emissie - energie - energiebeleid - verwarming - isolatie (insulation) - varkensstallen - probleemanalyse - bescherming - temperatuur - ventilatie - vervluchtiging - binnenklimaat - air pollution - ammonia - buildings - economics - emission - energy - energy policy - heating - insulation - pig housing - problem analysis - protection - temperature - ventilation - volatilization - indoor climate
    Mouwen, I. ; Brakel, C. van - \ 1995
    Praktijkonderzoek varkenshouderij 9 (1995)4. - ISSN 1382-0346 - p. 16 - 17.
    gebouwen - klimaat - kosten-batenanalyse - energiebehoud - milieubeheersing - varkensstallen - varkens - regulatie - buildings - climate - cost benefit analysis - energy conservation - environmental control - pig housing - pigs - regulation
    Op het Varkensproefbedrijf 'Zuid en West-Nederland' te Sterksel heeft vergelijkend onderzoek plaatsgevonden naar grondbuisventilatie bij verschillende diercategorieën. Aan de hand van de gevonden energiebesparingen is een kosten-batenanalyse gemaakt voor de verschillende diercategorieën. Uit de onderzoeksresultaten blijkt dat grondbuizen alleen economisch rendabel zijn bij guste en dragende zeugen.
    Recirculatie van stallucht; de mogelijkheden
    Mouwen, I. ; Plagge, G. - \ 1995
    Praktijkonderzoek varkenshouderij 9 (1995)1. - ISSN 1382-0346 - p. 18 - 19.
    luchtverontreiniging - ammoniak - huisvesting, dieren - dierenwelzijn - gebouwen - klimaat - efficiëntie - emissie - energie - energiegebruik - milieubeheersing - brandstofverbruik - varkensstallen - regulatie - zeugen - vervluchtiging - air pollution - ammonia - animal housing - animal welfare - buildings - climate - efficiency - emission - energy - energy consumption - environmental control - fuel consumption - pig housing - regulation - sows - volatilization
    Op het Varkensproefbedrijf in Raalte is onderzocht of het klimaat in een dekstal beter beheerst kan worden door middel van recirculatie en koeling van de stallucht in combinatie met extra isolatie. Gebleken is dat er een constante temperatuur gerealiseerd kan worden evenals een zeer lage ammoniakuitstoot, namelijk 5% van de huidige norm.
    Natural ventilation: State of the art
    Klooster, C.E. van 't; Mouwen, I.A.A.C. - \ 1995
    Pigs : an international magazine on pig keeping 11 (1995)3. - ISSN 0168-9533 - p. 8 - 9.
    automatisering - gebouwen - klimaat - milieubeheersing - mechanisatie - varkensstallen - regulatie - ventilatie - automation - buildings - climate - environmental control - mechanization - pig housing - regulation - ventilation
    De stand van zaken en kosten van geautomatiseerd bestuurde natuurlijke ventilatie-systemen
    Tannin induced changes in the cellular metabolism of differentiated CaCO2 cells: differences between white and coloured-flowering genotypes of faba beans (Vicia faba L.).
    Koninkx, J.F.J.G. ; Kok, W. ; Jansman, A.J.M. ; Bos, K.D. ; Mouwen, J.M.V.M. - \ 1993
    In: Recent advances of research in antinutritional factors in legume seeds, A.F.B. van der Poel et al. (eds.). EAAP publ. 70, Wageningen Press - p. 331 - 334.
    Onderzoek naar de schadelijkheid van tanninen in het CaCO2 model.
    Koninkx, J.F.J.G. ; Bos, K.D. ; Kok, W. ; Jansman, A.J.M. ; Mouwen, J.M.V.M. - \ 1993
    In: Antinutritionele factoren in vlinderbloemigen en nutritionele effecten bij éénmagige landbouwhuisdieren. Themadag Produktschap Veevoeder, Kwaliteitsreeks nr. 23 - p. 73 - 82.
    Effects of condensed tannins in faba beans (Vicia faba L.) on some morphological and functional parameters of the small intestinal mucosa of piglets.
    Leeuwen, P. van; Koninkx, J.F.J.L. ; Jansman, A.J.M. ; Mouwen, J.M.V.M. - \ 1993
    In: Recent advances of research in antinutritional factors in legume seeds, A.F.B. van der Poel et al. (eds.). EAAP Publ. 70, Wageningen Press - p. 335 - 339.
    Effecten van ANF's op de excretie van endogeen eiwit.
    Leeuwen, P. van; Huisman, J. ; Verstegen, M.W.A. ; Schulze, H. ; Jansman, A.J.M. ; Koninkx, J.F.J.G. ; Mouwen, J.M.V.M. - \ 1993
    In: Antinutritionele factoren in vlinderbloemigen en nutritionele effecten bij éénmagige landbouwhuisdieren. Themadag Produktschap Veevoeder, Kwaliteitsreeks nr. 23 - p. 109 - 119.
    Pathological changes of the small intestinal mucosa of pigs after feeding Phaseolus vulgaris beans.
    Kik, M.J.L. ; Huisman, J. ; Poel, A.F.B. van der; Mouwen, J.M.V.M. - \ 1990
    Veterinary Pathology 27 (1990). - ISSN 0300-9858 - p. 329 - 334.
    Performance and organ weights of piglets, rats and chickens fed diets containing Pisum sativum.
    Huisman, J. ; Poel, A.F.B. van der; Kik, M.J.L. ; Mouwen, J.M.V.M. - \ 1990
    Journal of Animal Physiology and Animal Nutrition 63 (1990). - ISSN 0931-2439 - p. 273 - 279.
    Effect of variable protein contents in diets containing Phaseolus vulgaris beans on performance, organ weights and blood variables in piglets, rats and chickens
    Huisman, J. ; Poel, A.F.B. van der; Mouwen, J.M.V.M. ; Weerden, E.J. van; Kik, M.J.L. - \ 1990
    The British journal of nutrition 64 (1990)3. - ISSN 0007-1145 - p. 755 - 764.
    Antinutritional effects of legume seeds in piglets, rats and chickens
    Huisman, J. - \ 1990
    Agricultural University. Promotor(en): M.W.A. Verstegen; J.M.V.M. Mouwen. - S.l. : Huisman - 149
    Fabaceae - voederplanten - voederpeulvruchten - diergeneeskunde - voer - eiwitten - samenstelling - spijsverteringsziekten - Fabaceae - fodder plants - fodder legumes - veterinary science - feeds - proteins - composition - digestive system diseases

    There is a growing interest in Europe to be self-supporting with regard to the protein supply for animal diets. Peas and beans growing well under European climatic conditions could provide alternatives to soya. However, these legume seeds contain the same classes of antinutritional factors (ANFs) as those found in raw soybeans. The use of such seeds in the raw state, therefore, is seriously hampered due to the presence of these ANFs. The role of ANFs in animal nutrition may become more important in the future. This is related to the expectation among zootechnicians that in the future farm animals will grow faster and deposit more body protein because of advances in animal breeding, health care and housing. It has been shown that the feed intake capacity has not increased in these fast growing animals, so they will therefore require relatively more highly digestible protein in the future. As a result, feedstuffs with a high protein content will become more important. However, most plant protein-rich seeds contain ANFs. The ANFs in peas, beans and soybeans have negative effects on digestibility and performance. In this respect it is necessary to find economically feasible inactivation processes which eliminate ANF activity. To achieve this, it is essential to know more about the way ANFs affect the digestion and absorption processes in animals. In this thesis, firstly a literature review (Chapter 1) was prepared on the occurrence and role of ANFs in peas ( Pisumsativum ), common beans ( Phaseolusvulgaris ) and soybeans ( Glycinemax). The main aspects to be considered were the state of the art concerning the action of ANFs in monogastric animals, the effect of ANFs on nutritional value, and the analytical methods for determining these ANFs. Also, recommendations for future research are given. The literature review (Chapter 1) shows that there are many unclear points related to the mode of action of ANFs in the animal. Major points being:
    - Most research into nutritional effects of ANFs in animals is carried out using small laboratory animals such rats, mice and chickens. An important question is whether results obtained in these animals are applicable to pigs.
    - Peas and beans always contain more than one ANF. In most studies whole ANF-containing seeds were fed to the animal. Information obtained in these studies gave no insight into the specific effects of separate ANFs. Only a limited amount of research has been done using isolated ANFs, and even then it was only carried out on small laboratory animals. To understand the relevance and the way ANFs act in the target animal, it is necessary to use isolated and purified ANFs in the investigations.
    - When a low apparent protein digestibility is measured it is not clear whether this is related exclusively to ANFs or whether the native protein itself may also be resistent to the hydrolysis by digestive enzymes.
    - Many analytical methods are not adequate. This has hampered the real identification of ANFs.
    - In the literature, lectin research is mainly focussed on the lectins present in Phaseolus vulgaris. Information about the mode of action of lectins in other seeds is limited.
    - There is insufficient information about the possibilities of eliminating ANF-activity.
    - There is insufficient information about the threshold levels, being the dietary levels of ANFs which can be tolerated without causing negative effects.
    In this thesis, aspects of the first three points were studied. The other points are being studied in related programmes.

    Animal species differences between piglets, rats and chickens were studied in three experiments. The results are described in Chapter 2. With common beans in the diet, performance was much more depressed in piglets than in rats or chickens. The piglets even lost weight. Weight loss in the piglets was also evident when extra protein was included in the diet. This indicates that a toxic factor must be associated with the reduced performance and not an insufficient amino acid supply. Protein digestibility was also markedly more depressed in piglets than in rats. The pancreas weight increased in the rats and chickens but not in the piglets. Increase in pancreas weight in rats and chickens may be related to the trypsin inhibitors present in the beans. Weights of the spleen and thymus were reduced in piglets but not in rats or chickens. With peas a reduction in weight gain was observed in piglets, but not in rats or chickens. Pancreas weight increased in the rats and chickens but not in the piglets. In all the animal species the weights of spleen and thymus were hardly affected by peas. Kidney and liver weights were not affected by either peas or beans. The results show that piglets are much more sensitive than rats or chickens to factors present in peas and beans. Some effects in piglets were the complete opposite of those found in rats and chickens. It is concluded, therefore, that ANF-research should be carried out using the target animals.

    In order to study which factor in peas caused the negative effects on protein digestibility, different fractions from peas were prepared: a pea protein isolate from which ANFs and carbohydrates were removed, a protein fraction with very high concentrations of ANFs and a fraction consisting of a mix of soluble and insoluble carbohydrates and free of protein and ANFs. Two pea varieties were involved, a summer variety with low trypsin inhibitor levels and a winter variety with relatively high levels of trypsin inhibitors. The fractions prepared from both varieties were applied in apparent ileal and faecal digestibility experiments with piglets. The results of these studies are described in Chapter 3. The apparent ileal protein digestibility of raw peas was with both varieties 14 units lower than in the pea protein isolate. Strikingly, the apparent ileal digestibility of some essential amino acids (S-containing amino acids, tryptophan and threonine) was very low at ileal level. The addition of pea carbohydrates to diets did not alter the apparent ileal protein digestibility. Small intestinal chyme flow increased due to pea carbohydrates. This effect could be related to a release of osmotic active components from the pea carbohydrates into the ileal chyme during the digestion process. The addition of pea-ANFs to a diet with pea protein isolate (low in ANFs) as the sole protein source, reduced the apparent ileal protein digestibility by about seven units. Weight gain of the piglets fed the diet enriched with ANFs was about 17% less compared with the control piglets. This demonstrates that ANFs are an important factor in explaining the reduced weight gain when more than 15-20% peas are included in the diets of piglets. The difference in apparent ileal protein digestibility between raw peas and pea protein isolate was 14 units. The other seven units which could not be attributed to ANFs could possibly be related to other factors such as antigenicity of the pea protein. True ileal and faecal protein digestibility of peas and common beans were measured using the 15N dilution technique. The results of this study are presented in Chapter 4. The apparent ileal protein digestibility of the raw summer and winter pea varieties were 79% and 74% respectively, the true protein digestibilities were between 93% and 95%. The apparent faecal protein digestibility was 85% for both varieties, the true faecal protein digestibility of both pea varieties was between 96% and 98%, respectively. These results indicate that native raw pea protein is highly digestible, and that digestion is nearly completed in the small intestine. The low apparent protein digestibility must be almost completely related to the secretion of endogenous protein. Common beans were studied in toasted form because the piglets refused the diets when raw Phaseolus beans were included. These beans were tested only for ileal and not for faecal digestibilities Apparent ileal protein digestibility of the toasted beans was about zero. The true protein digestibility was about 66%. The very low apparent ileal protein digestibility must therefore, be related to a very high secretion of endogenous protein. It was concluded that measurements of true protein digestibility are important for (bio)technologists. In order to improve protein digestibility it is necessary to know whether the treatments need to be focussed on the inactivation of ANFs and elimination of e.g antigenicity or to changes in protein structure. Our results show that with peas it is relevant to pay attention to factors causing an increased secretion of endogenous protein and not to the protein structure. With common beans, treatments should be directed to both: to factors causing an increased secretion of endogenous protein and to the protein itself. It was demonstrated (see GENERAL DISCUSSION), that when raw pea and soya protein are fed to piglets, guinea pigs and veal calves, trypsin activity in the small intestinal chyme and pancreatic activity was reduced and also protein digestibility was decreased. The lower pancreatic activity indicates that the low levels of trypsin inhibitors did not activate the negative feedback mechanism which in turn caused a hypersecretion of pancreatic enzymes. This negative feedback mechanism seems to be not present in pigs, veal calves or guinea pigs. This is in contrast to what is stated for rats. To elucidate which factor primarily is responsible for this observation, ANFs or possibly protein quality further research is required.

    Pathological changes of the small intestinal mucosa of piglets after feeding Phaseolus vulgaris beans.
    Kik, M.J.L. ; Huisman, J. ; Poel, A.F.B. van der; Mouwen, J.M.V.M. - \ 1989
    In: Proc. 1st Int. Workshop Recent advances of research in antinutritional factors in legume seeds, J. Huisman, A.F.B. van der Poel, I.E. Liener (eds.). Pudoc, Wageningen - p. 49 - 53.
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