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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Onderzoek Energie Producerende Kas Stef Huisman - Bergerden (Huissen)
Noort, F.R. van; Zwart, H.F. de - \ 2007
kassen - energie - energiebehoud - teelt onder bescherming - glastuinbouw - greenhouses - energy - energy conservation - protected cultivation - greenhouse horticulture
Onderzoek van de Energieproducerende kas: nieuwe teeltmogelijkheden en bevindingen
Long-term effects of drying conditions on the essential oil and color of tarragon leaves during storage
ArabHosseini, A. ; Boxtel, A.J.B. van; Huisman, W. ; Muller, J. - \ 2007
Journal of Food Engineering 79 (2007)2. - ISSN 0260-8774 - p. 561 - 566.
quality - l. - temperature - kinetics - fruits - pulp
The effect of storage on the essential oil content and color of French Tarragon (Artemisia dracunculus L.) leaves is studied. Tarragon leaves were dried at temperatures 45, 60 and 90 °C with, respectively, the relative humidity levels 17%, 7% and 2.5%. At 60 °C also a relative humidity level of 18% was applied. The air velocity was constant at 0.6 m/s. Oil content and color were measured for the fresh and dried leaves just after drying as well as after storage during 15, 30, 60 and 120 days. The essential oil compounds of the material were isolated by the hydro-distillation method and analyzed by GC¿FID as well as GC¿MS. A Chroma meter was used to measure the color of the samples. The results showed a reduction of the oil content and changed color parameters during the storage period. The largest changes of the essential oil content (about 50% after 30 days) and color expressed by the hue value was found for the material dried at 90 °C. Drying at 45 °C resulted in the smallest quality changes
Loss of essential oil of tarragon (Artemisia dranunculus L.) due to drying
ArabHosseini, A. ; Padhye, S. ; Beek, T.A. van; Boxtel, A.J.B. van; Huisman, W. ; Posthumus, M.A. ; Müller, J. - \ 2006
Journal of the Science of Food and Agriculture 86 (2006)15. - ISSN 0022-5142 - p. 2543 - 2550.
aroma - constituents - volatiles - parsley
The effect of hot air-drying on the essential oil constituents and yield in French and Russian tarragon (Artemisia dracunculus L.) leaves was studied. The tarragon leaves were dried at air temperatures ranging from 40 to 90 °C. The drying stopped when the moisture content of the samples reached 10% or for some of the treatments reached 7, 20 and 30%. The essential oil of the fresh and dried leaves was isolated by hydrodistillation and analysed by capillary gas chromatography and gas chromatography-mass spectrometry. The decrease of oil during the drying process was highest at 60 °C drying temperature. For French tarragon the decrease in the amount of oil was significantly lower at 90 °C. The effect of the relative humidity of the drying air at each temperature was not significant. The main compounds were estragole in French tarragon (69%) and sabinene in Russian tarragon (40%). The drying process changed the relative percentage of the constituents in the oil; for instance, the relative percentages of estragole decreased and sabinene increased in French tarragon
Design and operation of nitrifying trickling filters in recirculating aquaculture: a review
Eding, E.H. ; Kamstra, A. ; Verreth, J.A.J. ; Huisman, E.A. ; Klapwijk, A. - \ 2006
Aquacultural Engineering 34 (2006)3. - ISSN 0144-8609 - p. 234 - 260.
fixed-film nitrification - fish culture systems - biofilm reactors - water-treatment - temperature - performance - ph - effluents - discharge - impact
This review deals with the main mechanisms and parameters affecting design and performance of trickling filters in aquaculture. Relationships between nitrification rates and easily accessible process parameters, like bulk phase concentration of TAN, O2, organic matter (COD), nitrite, temperature, HCO3¿, pH and the hydraulic loading of the trickling filter, are discussed in relation to the design and operation of such filters. Trickling filter design procedures are presented and one of them, a model describing the nitrification performance of trickling filters by plug-flow characteristics, is discussed in greater detail. Finally, practical aspects in relation to filter design and operation are presented
Optimization of drying tarragon (Artemisia dracunculus L.)
ArabHosseini, A. ; Boxtel, A.J.B. van; Huisman, W. ; Muller, J. - \ 2006
- 6 p.
Sorption isotherms of tarragon (Artemisia dracunculus L.)
ArabHosseini, A. ; Huisman, W. ; Boxtel, A.J.B. van; Muller, J. - \ 2006
Zeitschrift für Arznei- und Gewürzpflanzen 5 (2006)1. - ISSN 1431-9292 - p. 48 - 51.
Nutritional strategy affects gut wall integrity in weaned piglets
Verdonk, J.M.A.J. - \ 2006
Wageningen University. Promotor(en): Martin Verstegen, co-promotor(en): J. Huisman. - [S.l. ] : S.n. - ISBN 9085043468 - 153
biggen - spenen - melk - dunne darm - fysiologische functies - voeropname - maag - spijsvertering - morfologie - permeabiliteit - diervoeding - piglets - weaning - milk - small intestine - physiological functions - feed intake - stomach - digestion - morphology - permeability - animal nutrition
BOS valse meeldauw en bladvlekkenziekte uien : resultaten onderzoek 2003 en 2004
Wander, J.G.N. ; Meier, R. ; Huisman, M. - \ 2005
Lelystad : Praktijkonderzoek Plant & Omgeving B.V. - 53
uien - peronospora farinosa - gewasbescherming - spuiten - pesticiden - schimmelbestrijding - plantenziektebestrijding - bladvlekkenziekte - plantenplagen - beslissingsondersteunende systemen - akkerbouw - onions - peronospora farinosa - plant protection - spraying - pesticides - fungus control - plant disease control - leaf spotting - plant pests - decision support systems - arable farming
Omdat de aantasting door valse meeldauw in kleine uien zoals zilveruien en eerstejaars plantuien niet altijd goed onder controle te houden zijn met behulp van het BeslissingsOndersteunend Systeem, werd vanaf 2003 een project gefinancierd om na te gaan of het BOS voor kleine uien verbeterd kan worden. Omdat het BOS in zaaiuien wel goed voldoet, werd in de eerste jaren van het onderzoek een vergelijking gemaakt tussen kleine uien en zaaiuien. In beide teelten werd het gewasklimaat bepaald.
Simulation of Nile tilapia (Oreochromis niloticus niloticus L.) culture in ponds, through individual-based modelling, using a population dynamic approach
Graaf, G.J. de; Dekker, P.J. ; Huisman, E.A. ; Verreth, J.A.J. - \ 2005
Aquaculture Research 36 (2005)5. - ISSN 1355-557X - p. 455 - 471.
gariepinus burchell 1822 - natural mortality - african-catfish - growth - fish - aquaculture - biology
A simulation model for the production of the Nile tilapia (Oreochromis niloticus niloticus L.) for mixed- or mono-sex culture and for poly-culture with the African catfish (Clarias gariepinus Burchell 1822) or African snakehead (Parachanna obscura Günther 1861) is presented. The model is based on an exponential decay model used in population dynamics and follows an individual-based approach. The model consists of a tilapia sub-model representing population dynamics, growth and recruitment and a predator sub-model representing the predation process and population dynamics and growth of the used predator. The model was calibrated with data on mixed- or mono-sex culture of Nile tilapia and for poly-culture with the African catfish or African snakehead obtained in Congo Brazzaville and validated with similar data from the Philippines, Thailand and the Ivory Coast. The model visualized major underlying processes in tilapia farming and aspects for further improvement of the model; growth is one of the most sensitive input parameters and should be quantitatively related to feeding level and feed quality; length at first maturity and quantification of the recruitment of Nile tilapia has a relatively large influence and recruitment should be related to the length of the females; prey¿predator relations are too coarse and should be more fine-tuned with the relation between prey size and predator size. Incorporation of these features would provide the basis of a model that can serve as a predictive and decision-making support tool
Alternatieve evenwichten. Experiment
Huisman, T. ; Nes, E.H. van; Hemerik, L. - \ 2005
In: Troebele plassen in Nederland Wageningen : Wageningen UR (Dossiers VWO campus 79) - 16 p.
Voedingswaarde van planten - gewichtstoename van rupsen. Experiment
Huisman, T. ; Loon, J. van; Hemerik, L. - \ 2005
Wageningen : VWO-campus - 8
voedingswaarde - planten - insecten - pieris brassicae - gewichtstoename - rupsen - nutritive value - plants - insects - pieris brassicae - weight gain - caterpillars
Het doel van dit experiment is het bepalen van het effect van voedseltype op gewichtstoename. Om zo’n effect vast te stellen op een wetenschappelijke manier, worden de gegevens geanalyseerd met de Wilcoxon tweesteekproeventoets
Degradation of archaeological values in the Dutch subsoil; Definition Study / Degradatie van archeologische waarden in de Nederlandse Ondergrond (RGI-project 028); Definitiestudie
Gessel, S. van; Heeringen, R. van; Huisman, H. ; Koomen, A.J.M. ; Maas, G.J. ; Schoorl, J.M. ; Veldkamp, A. - \ 2005
Amersfoort : ROB (now: RACM) - 37 p.
Modelling of drying tarragon (Artemisia dracunculus L.)
ArabHosseini, A. ; Boxtel, A.J.B. van; Huisman, W. ; Muller, J. - \ 2005
Effect of drying on the essential oil of Tarragon (Artemisia dracunculus L.)
ArabHosseini, A. ; Padhye, S. ; Beek, T.A. van; Boxtel, A.J.B. van; Huisman, W. - \ 2005
SchimmelBOS ondersteunt teler en beleid
Wander, J.G.N. ; Schepers, H.T.A.M. ; Esselink, L.J. ; Evenhuis, A. ; Huisman-de Lange, M. ; Kessel, G.J.T. ; Kalkdijk, J.R. ; Meier, R. ; Spits, H.G. ; Wilms, J.A.M. - \ 2005
Gewasbescherming 36 (2005)Suppl.. - ISSN 0166-6495 - p. 48S - 48S.
Quality, energy requirement and costs of drying tarragon (Artemisia dracunculus L)
ArabHosseini, A. - \ 2005
Wageningen University. Promotor(en): J. Mueller, co-promotor(en): W. Huisman; Ton van Boxtel. - Wageningen : - ISBN 9085042976 - 115
dragon - artemisia dracunculus - energieproductiekosten - drogen - voedselbewaring - droogkwaliteit - luchtdroging - extractie - etherische oliën - keukenkruiden - medicinale planten - iran - nederland - tarragon - artemisia dracunculus - energy cost of production - drying - food preservation - drying quality - air drying - extraction - essential oils - culinary herbs - medicinal plants - iran - netherlands
Modeling of drying tarragon (Artemisia dracunculus L)
ArabHosseini, A. ; Boxtel, A.J.B. van; Huisman, W. ; Mueller, J. - \ 2005
Modeling of the Equilibrium Moisture Content (EMC) of Tarragon (Artemisia Dracunculus L.)
ArabHosseini, A. ; Huisman, W. ; Boxtel, A.J.B. van; Mueller, J. - \ 2005
International Journal of Food Engineering 1 (2005)5. - ISSN 1556-3758 - p. art. 7 - art. 7.
The equilibrium moisture content of tarragon, Artemisia dracunculus L. (stem and leaf separately) was determined by using the saturated salt solutions method at three temperatures (25, 50 and 70°C) within a range of 5 to 90% relative humidity. Both adsorption and desorption methods were used for stem and leaf of two varieties: Russian and French tarragon. Experimental curves of moisture sorption isotherms were fitted by modified Henderson, modified Halsey, modified Oswin, modified Chung-Pfost and GAB equations and evaluated by residual sum squares, standard error of estimate and mean relative deviation. The modified Halsey and GAB equations were found to be the most suitable for describing the relationship among equilibrium moisture content, relative humidity and temperature. There was no significant difference between the equilibrium moisture content of the Russian and French tarragon.
Koolstof in broeikasgas en biomassa. Experiment
Huisman, T. ; Hemerik, L. ; Lever-De Vries, C. - \ 2005
Wageningen : VWO-campus - 31 p.
Windenergie nader berekend: De samenhang tussen windsnelheid en rendement
Hemerik, L. ; Huisman, T. - \ 2005
Wageningen : VWO-Campus Wageningen Universiteit - 14 p.
Inventarisatie, voorspelling en beheersing zwarte vlekken ziekte in peen : projectrapport over het in 2003/2004 uitgevoerde onderzoek
Wander, J.G.N. ; Elderson, J. ; Esselink, L.J. ; Huisman-de Lange, M. ; Kastelein, P. ; Köhl, J. ; Meier, R. ; Velema, R. - \ 2004
PPO Sector AGV/PRI/Hilbrands Laboratorium BV
groenteteelt - veldgewassen - wortelgewassen - daucus carota - gewasbescherming - schimmelziekten - laesies - aantasting - peenvlekkenvirus - vegetable growing - field crops - root crops - daucus carota - plant protection - fungal diseases - lesions - infestation - carrot mottle virus
Tussen en binnen de verschillende monsters vertoonden de penen een verscheidenheid aan aantastingbeelden. Van elk monster is van de daarin aangetroffen aantastingbeelden een representatief aantal laesies onderzocht op aanwezigheid van laesies. Bij 14% is een schimmel uitgegroeid waarvan bekend is dat deze zwarte vlekken kan veroorzaken. Naast schimmels, waren in de meest leasies ook bacterien aanwezig.
Bestrijding van koprot in uien
Plentinger, M.C. ; Broek, R.C.F.M. van den; Huisman-de Lange, M. ; Visser, C.L.M. de - \ 2004 2004 (2004)15 aug.
gewasbescherming - pesticiden - fungiciden - ziektebestrijding - uien - botrytis allii - plant protection - pesticides - fungicides - disease control - onions
Dit onderzoeksproject had de volgende doelstellingen: 1. vaststellen van het (neven-)effect van toegelaten fungiciden in uien op een infectie door Botrytis allii, de veroorzaker van koprot in uien; 2. de vraag beantwoorden of er perspectieven zijn om de sporulatie dan wel de aanwezigheid van de schimmel te detecteren; 3. In 2003 proberen om m.b.v. een adviessysteem het tijdstip van bespuiten nauwkeuriger vast te stellen.
Tropical agricultural residues and their potential uses in fish feeds: the Costa Rican situation
Ulloa Rojas, J.B. ; Weerd, J.H. van; Huisman, E.A. ; Verreth, J.A.J. - \ 2004
Waste Management 24 (2004)1. - ISSN 0956-053X - p. 87 - 97.
coffee pulp - body-composition - cyprinus-carpio - growth-response - practical diets - wastes - tilapia - replacement - meal
In Costa Rica as many other tropical countries, the disposal problem of agricultural wastes is widely recognized but efforts to find solutions are not equal for different sectors. This study describes the situation of major agricultural residues in Costa Rica, identifying the activities with higher amounts produced and, the potential use of these residues in fish feeds. In Costa Rica, during the 1993¿1994 production season, major agricultural sectors (crop and livestock) generated a total amount of 3.15¿3.25 million MT of residues (classified in by-products: used residues and wastes: not used residues). Some residues are treated to turn them into valuable items or to diminish their polluting effects (e.g., the so-called by-products). About 1.56¿1.63 million MT of by-products were used for different purposes (e.g. fertilization, animal feeding, fuel, substrates in greenhouses). However, the remainder (1.59¿1.62 million MT) was discharged into environment causing pollution. About 1.07¿1.2 million MT wastes came from major crop systems (banana, coffee, sugarcane and oil palm) whereas the remainder came from animal production systems (porcine and poultry production, slaughtering). These data are further compared to residues estimates for the 2001¿2002 production season coming from the biggest crops activities. Unfortunately, most of the studied wastes contain high levels of moisture and low levels of protein, and also contain variable amounts of antinutritional factors (e.g., polyphenols, tannins, caffeine), high fibre levels and some toxic substances and pesticides. All these reasons may limit the use of these agricultural wastes for animal feeding, especially in fish feeds. The potential use of the major vegetable and animal residues in fish feeds is discussed based on their nutritional composition, on their amount available over the year and on their pollution risks. Other constraints to use these wastes in fish feeds are the extra costs of drying and, in most cases, of transportation from several dispersed locations. It was stated that most interesting wastes are rejected green banana and coffee pulp
Drying characteristics of Estragon (Artemisia dracunculus L.)
ArabHosseini, A. ; Huisman, W. ; Muller, J. - \ 2004
Use of salts of superacids as stabiliser in vinyl halide polymers
Es, D.S. van; Huisman, H.W. ; Haveren, J. van; Kolk, J.C. van der; Klaess, P. - \ 2004
Octrooinummer: WO2004072166, verleend: 2004-08-26.
The present invention pertains to the use of at least one Brönsted superacid or metal salt of said Brönsted superacid with a DeltaGacid value of 316 kcal/mol or less, as a heat and/or colour stabiliser for polyvinyl halide resin compositions. The superacid is not a perchlorate or a trifluoromethane sulphonate. The metal in the metal salt of the Brönsted superacid is preferably selected from the group consisting of alkali metals, alkali earth metals, transition metals, lanthanide metals, actinide metals, Al, Ga, In, TI, Ge, Sn, Pb, and Sb.
Drying characteristics of estragon (Artemisia Dracunculus L)
ArabHosseini, A. ; Boxtel, A.J.B. van; Huisman, W. ; Mueller, J. - \ 2004
Plantenhormonen: effect op plantengroei. Experiment
Holtkamp, R. ; Huisman, T. ; Hemerik, L. ; Plas van der, L. - \ 2004
Wageningen : VWO-campus - 11 p.
Optimisation of the pond rearing of Nile tilapia (Oreochromis niloticus L.). The impact of stunting processes and recruitment control
Graaf, G.J. de - \ 2004
Wageningen University. Promotor(en): E.A. Huisman; Johan Verreth. - [S.I.] : S.n. - ISBN 9085041201 - 167
tilapia - oreochromis niloticus - visvijvers - visteelt - voortplanting - geslachtsrijpheid - groei - populatie-aanwas - simulatiemodellen - aquacultuur - tilapia - oreochromis niloticus - fish ponds - fish culture - reproduction - sexual maturity - growth - recruitment - simulation models - aquaculture
Overview on harvesting chains for fibre crops
Venturi, P. ; Huisman, W. - \ 2004
Agroindustria 3 (2004)1. - p. 23 - 28.
Fast determination of the degree of methyl esterification of pectins by head-space GC.
Huisman, M.M.H. ; Oosterveld, A. ; Schols, H.A. - \ 2004
Food Hydrocolloids 18 (2004)4. - ISSN 0268-005X - p. 665 - 668.
ester content - methanol
A new, fast method for the quantitative analysis of methoxyl groups in pectin using head-space gas chromatography (HS-GC) has been developed. With this method, results were obtained which were in reasonable agreement with the conventional HPLC method, and the reproducibility of the measurements is high. The advantages of the HS-GC method are that only a small amount of sample (2 mg) per analysis is needed, the chromatogram shows a nice symmetrically shaped methanol peak which is very easy to integrate, the sample preparation for HS-GC is short and easy, and for soluble pectins the sample in the head space vial can also directly be used for analysis of the galacturonic acid content and the degree of acetylation.
A xylogalacturonan epitope is specifically associated with plant cell detachment.
Willats, W.G.T. ; McCartney, L. ; Steele-King, C.G. ; Marcus, S.E. ; Mort, A.J. ; Huisman, M.M.H. ; Alebeek, G.J.W.M. van; Schols, H.A. ; Voragen, A.G.J. ; Goff, A. le; Bonnin, E. ; Thibault, J.F. ; Knox, J.P. - \ 2004
Planta 218 (2004)4. - ISSN 0032-0935 - p. 673 - 681.
pectic polysaccharides - spatial regulation - hairy regions - pea hulls - walls - homogalacturonan - tomato - cotyledons - separation - pericarp
A monoclonal antibody (LM8) was generated with specificity for xyloglacturonan (XGA) isolated from pea (Pisum sativum L.) testae. Characterization of the LM8 epitope indicates that it is a region of XGA that is highly substituted with xylose. Immunocytochemical analysis indicates that this epitope is restricted to loosely attached inner parenchyma cells at the inner face of the pea testa and does not occur in other cells of the testa. Elsewhere in the pea seedling, the LM8 epitope was found only in association with root cap cell development at the root apex. Furthermore, the LM8 epitope is specifically associated with root cap cells in a range of angiosperm species. In embryogenic carrot suspension cell cultures the epitope is abundant at the surface of cell walls of loosely attached cells in both induced and non-induced cultures. The LM8 epitope is the first cell wall epitope to be identified that is specifically associated with a plant cell separation process that results in complete cell detachment.
Genetic parameters for daily feed intake patterns of growing Dutch Landrace gilts
Huisman, A.E. ; Arendonk, J.A.M. van - \ 2004
Livestock Production Science 87 (2004)2-3. - ISSN 0301-6226 - p. 221 - 228.
food-intake - pigs - growth - behavior - traits - weight - models
Daily feed intake (DFI) was described as a function of days on test using a spline random regression model. Order of fit for the spline random regression model was varied, models were compared using Schwarz's Bayesian Information Criterion. The objective was to investigate whether there are genetic differences in DFI patterns. Data were DFI records of 257 growing gilts, which had ad libitum access to food. Gilts were 94 days old at start of test. All gilts were from a Dutch Landrace line. Number of random regression coefficients was varied from zero to nine for both random effects (animal and permanent environment), the model with four random regression coefficients resulted in the most optimal fit. Six traits were derived to capture differences in DFI patterns, average DFI over test, variance of DFI over test, DFI at day 5 on test, DFI at day 50 on test, DFI at day 95 on test and the difference between DFI at day 95 and day 5. Heritability for DFI decreased from 0.53 at 5 days on test to 0.24 at 95 days on test. Genetic correlations between DFI at 5 days on test and 95 days on test, and between DFI at 50 days on test and 95 days on test were low (around 0.3). The results suggested that DFI at different days on test could not be regarded as repeated measurements of a single trait with constant variance and heritability. Based on the results presented, it can be concluded that changes in feed intake patterns through selection are possible. (C) 2003 Elsevier B.V. All rights reserved.
Ontwikkeling en evaluatie van een PCR-toets voor Fusarium-droogrot
Kalkdijk, J.R. ; Lamers, J.G. ; Esselink, L.J. ; Huisman-de Lange, M. ; Berg, W. van den - \ 2003 2003 (2003)15 sept.
pootaardappelen - aardappelen - grondanalyse - fusarium - fungiciden - plantenziekteverwekkende schimmels - aardappelopslagplaatsen - koudeopslag - seed potatoes - potatoes - soil analysis - fungicides - plant pathogenic fungi - potato stores - cold storage
Door het toetsen van de grond op de aanwezigheid van Fusarium kan worden ingeschat of een fungicidenbehandeling tijdens inschuren dan wel tijdens het sorteren kan worden uitgespaard
Bestrijding van ritnaalden in aardappelen
Huiting, H.F. ; Ester, A. ; Arkema, M.W. ; Gruppen, R. ; Huisman, M. - \ 2003 2003 (2003)15 maart.
elateridae - coleoptera - larven - bodeminsecten - plagenbestrijding - insecticiden - bestrijdingsmethoden - gewasbescherming - aardappelen - oogstschade - elateridae - coleoptera - larvae - soil insects - pest control - insecticides - control methods - plant protection - potatoes - crop damage
De ritnaald of koperworm, larve van de kniptor, is een polyfaag insect. Ze kan in diverse gewassen schade veroorzaken. De schade in de aardappelteelt komt vaak voor op gescheurd grasland, maar ook in bouwplannen die rijk zijn aan bijvoorbeeld meerjarig graszaad of graszaad onder dekvrucht kan schade optreden. De aantasting door ritnaalden is in de meeste gevallen kwalitatief. De ritnaalden vreten gaatjes in de aardappelknollen. Een partij aardappelen met vraatschade kan sterk in waarde teruglopen en worden afgekeurd. Doordat de gaatjes van ritnaalden vaak klein zijn, is een aangetaste partij meestal moeilijk uit te lezen. De schade door ritnaalden lijkt de laatste jaren toe te nemen, mogelijk als gevolg van een reductie in het gebruik van (breedwerkende) insecticiden. Tevens is de problematiek van ritnaalden meer in de belangstelling gekomen, als gevolg van het wegvallen van de actieve stof chloorpyrifos en de discussie rond de stof ethoprofos. De praktijktoepassing van 20 kg/ha Mocap volvelds laat in dit onderzoek geen afdoende bestrijding zien. Enkele (nog) niet toegelaten middelen hebben een goede bestrijding laten zien. Aan het toelatingsdossier voor deze middelen wordt (soms) verder gewerkt door de firma's zelf
Biological treatments affect the chemical composition of coffee pulp
Ulloa Rojas, J.B. ; Verreth, J.A.J. ; Amato, S. ; Huisman, E.A. - \ 2003
Bioresource Technology 89 (2003)3. - ISSN 0960-8524 - p. 267 - 274.
Biological treatments were applied to fresh coffee pulp (CoP) to improve its nutritive value for monogastric animals by reducing its content of cellulose and antinutritional factors (ANFs) such as total phenols, tannins and caffeine. Treatments were: (1) ensiling with 0, 50 and 100 g kg¿1 molasses for 2 and 3 months, (2) aerobic decomposition for 0, 7, 14, 21, 28, 35 and 42 days, (3) aerobic bacterial inoculation (Bacillus sp.) for 0, 7, 14, 21 and 28 days. Ensiled CoP (E-CoP) showed higher fat and ash contents than oven-dried-CoP (OD-CoP; P
Silicon surface passivation by organic monolayers: Minority charge carrier lifetime measurements and Kelvin probe investigations
Sieval, A.B. ; Huisman, C.L. ; Schonecker, A. ; Schuurmans, F.M. ; Heide, A.S.H. van der; Goossens, A. ; Sinke, W.C. ; Zuilhof, H. ; Sudhölter, E.J.R. - \ 2003
The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical 107 (2003)28. - ISSN 1520-6106 - p. 6846 - 6852.
hydrogen-terminated silicon - ultrathin sio2 overlayers - alkyl monolayers - recombination velocity - photoconductance decay - si(111) surfaces - germanium surfaces - si-sio2 interface - si(100) surface - air
The silicon surface passivation of monolayers of organic compounds that are bound to Si surfaces by a covalent Si-C bond has been investigated. The effective lifetime eff of minority charge carriers in the surface-modified semiconductor has been determined by modulated free carrier absorption (MFCA) measurements. The results show that on 1-2 ·cm p-type Si(100) surfaces modified with a monolayer obtained from CH2=CH-(CH2)8-C(=O)-O-CH3 maximum effective lifetimes eff 130 s can be obtained. This value corresponds to a maximum surface recombination velocity Seff of 120 cm/s, a value that is similar to those obtained using other passivation techniques, which demonstrates that these monolayers provide an interesting alternative for silicon surface passivation. During these MFCA measurements an unusual time dependence of the effective lifetime is observed: eff rises continuously during illumination of the substrate. Kelvin probe measurements show that there is a slow shift of the Fermi level of the semiconductor under illumination, which seems to be the result of a slow, reversible filling of surface traps
Use of halogenated sulfonates as a stabilizer booster in PVC
Es, D.S. van; Haveren, J. van; Frissen, A.E. ; Kolk, J.C. van der; Schmets, G.H.F. ; Huisman, H.W. ; Harvey, H.B. - \ 2003
Octrooinummer: WO03016390, verleend: 2003-02-27.
The invention relates to a process to make stabilized PVC wherein use is made of at least one compound of formula (I), wherein M is selected from the group consisting of alkali metals, alkali earth metals, Al, and transition elements, and R is selected from the group consisting of substituted, linear or branched, alkyl, cycloalkal, aryl alkaryl, and aralkyl moieties, the substituents comprising at least one or more electron-withdrawing groups, as a color stability booster.
Optimising harvesting and storage systems for energy crops in the Netherlands
Huisman, W. - \ 2003
Conservation, storage and pre-treatment of fibre crops
Huisman, W. ; Venturi, P. - \ 2003
Agroindustria 2 (2003)2/3. - p. 113 - 116.
Dietary carnitine supplements increased lipid metabolism and decreased protein oxidation in African catfish (Clarias gariepinus) juveniles fed high fat levels
Ozório, O.A. ; Verreth, J.A.J. ; Aragao, C.R. ; Vermeulen, C.J. ; Schrama, J.W. ; Verstegen, M.W.A. ; Huisman, E.A. - \ 2003
Journal of aquaculture in the tropics 18 (2003)3. - ISSN 0970-0846 - p. 225 - 238.
Soil water content interpolation using spatio-temporal kriging with external drift
Snepvangers, J.J.J.C. ; Heuvelink, G.B.M. ; Huisman, J.A. - \ 2003
Geoderma 112 (2003). - ISSN 0016-7061 - p. 253 - 271.
bodemwatergehalte - infiltratie - nederland - geostatistiek - soil water content - infiltration - netherlands - geostatistics - time - space - variability - design - model
In this study, two techniques for spatio-temporal (ST) kriging of soil water content are compared. The first technique, spatio-temporal ordinary kriging, is the simplest of the two, and uses only information about soil water content. The second technique, spatio-temporal kriging with external drift, uses also the relationship between soil water content and net-precipitation to aid the interpolation. It is shown that the behaviour of the soil water content predictions is physically more realistic when using spatio-temporal kriging with external drift. Also, the prediction uncertainties are slightly smaller. The data used in this study consist of Time Domain Reflectometry (TDR) measurements from a 30-day irrigation experiment on a 60 x 60-m grassland in the Netherlands. (C) 2002 Elsevier Science B.V. All rights reserved.
Monitoring temporal development of spatial soil water content variation: comparison of ground penetrating radar and time domain reflectometry
Huisman, J.A. ; Snepvangers, J.J.J.C. ; Bouten, W. ; Heuvelink, G.B.M. - \ 2003
Vadose Zone Journal 2 (2003)4. - ISSN 1539-1663 - p. 519 - 529.
We compare the capability of ground penetrating radar (GPR) and time domain reflectometry (TDR) to assess the temporal development of spatial variation of surface volumetric water content. In the case of GPR, we measured surface water content with the ground wave, which is a direct wave between the sender and receiver through the upper centimeters of the soil. Spatial water content variation was measured on 18 d with GPR and TDR during a 30-d monitoring period. To ensure large fluctuations in the spatial water content variation, we created a heterogeneous pattern of water content by irrigation on 2 d. The temporal development of the spatial variation was studied by means of the variogram and interpolated water content maps. To compare GPR and TDR variograms, we estimated confidence intervals of the experimental variograms and the variogram model parameters with a jackknife approach and a first-order approximation of model parameter uncertainty. The results showed that the 95% confidence intervals of the GPR experimental variogram were one to two orders of magnitude smaller than the 95% confidence intervals of the TDR experimental variogram because of the larger number of GPR measurements. Consequently, the uncertainty in the variogram model parameters was also much lower for GPR, which meant that the temporal development of the fitted GPR variogram model parameters was easier to interpret. Furthermore, the larger GPR measurement volume resulted in a low spatial nugget variance of 1 × 10-6 to 1 × 10-9 (m3 m-3)2 because short distance variation was averaged. This meant that GPR accurately measured spatial correlation lengths, even in the case of low water content variation. Interpolated maps showing the increase of water content due to irrigation and the subsequent gradual drying of the soil were more accurate and reproducible for GPR. It was concluded that the noninvasive GPR measurements provide the means to accurately and consistently monitor the development of spatial water content variation in time.
Differences in the methylester distribution of pectins
Schols, H.A. ; Huisman, M.M.H. ; Bakx, E.J. ; Voragen, A.G.J. - \ 2003
In: Advances in Pectin and Pectinase Research / Voragen, A.G.J., Schols, H.A., Visser, R.G.F., Dordrecht : - ISBN 140201144X - p. 75 - 90.
Pectic substances from soybean cell walls distinguish themselves from other plant cell wall pectins
Huisman, M.M.H. ; Schols, H.A. ; Voragen, A.G.J. - \ 2003
In: Advances in pectin and pectinases / Voragen, A.G.J., Schols, H.A., Visser, R.G.F., Dordrecht : Kluwer - ISBN 140201144X - p. 159 - 168.
pectinen - celwanden - galactanen - sojabonen - glucanen - xyloglucanen - enzymen - pectins - cell walls - galactans - soyabeans - glucans - xyloglucans - enzymes
The uncommon structural features of soybean cell wall pectic substances explain their resistance to degradation by enzymes generally used to degrade this kind of polymers, and indicates that a search for new enzymes is required to enable enzymatic modification of these polysaccharides
Uncertainty in daily catch rate in the light fisheries around Ambon and the Lease Islands: characterisation, causes and consequences
Oostenbrugge, J.A.E. van - \ 2003
Wageningen University. Promotor(en): E.A. Huisman, co-promotor(en): Leo Nagelkerke. - Wageningen : Wageningen University - ISBN 9058089789
visserij - sportzeevisserij - variatie - onzekerheid - karakterisering - technieken - visserijbeheer - inkomen - indonesië - molukken - visvangsten - vismethoden - fisheries - sea fishing - variation - uncertainty - characterization - techniques - fishery management - income - indonesia - maluku - fish catches - fishing methods
New organic stabilizers for vinyl resins II
Es, S. van; Frissen, A.E. ; Haveren, J. van; Kolk, J.C. van der; Harvey, H.B. ; Mellor, M. ; Huisman, H. - \ 2003
Research disclosure (2003)465. - ISSN 0374-4353 - p. P30 - P32.
Why plankton communities have no equilibrium: solutions to the paradox
Scheffer, M. ; Rinaldi, S. ; Huisman, J. ; Weissing, F.J. - \ 2003
Hydrobiologia 491 (2003)1. - ISSN 0018-8158 - p. 9 - 19.
time-series analysis - resource competition - intermediate disturbance - laboratory experiments - strange attractors - food-chain - prey model - chaos - dynamics - phytoplankton
In a classical paper, Hutchinson (1961) argued that the large number of species in most plankton communities is remarkable in view of the competitive exclusion principle, which suggests that in homogeneous, well-mixed environments species that compete for the same resources cannot coexist. Few ideas in aquatic ecology have evoked more research than this `paradox of the plankton'. This review is an effort to put the main solutions to the paradox that have been proposed over the years into perspective. Hutchinson himself already suggested that the explanation could be that plankton communities are not in equilibrium at all due to weather-driven fluctuations. Subsequent research confirmed that such externally imposed variability can allow many species to coexist. Another important point is that in practice the homogeneous well-mixed conditions assumed in the competitive exclusion principle hardly exist. Even the open ocean, for instance, has a spatial complexity resulting from meso-scale vortices and fronts that can facilitate coexistence of species. Perhaps most excitingly, theoretical work on species interactions has given a counter-intuitive new dimension to the understanding of diversity. Various competition and predation models suggest that even in homogeneous and constant environments plankton will never settle to equilibrium. Instead, interactions between multiple species may give rise to oscillations and chaos, with a continuous wax and wane of species within the community. Long-term laboratory experiments support this view. This chaotic behavior implies among other things that plankton dynamics are intrinsically unpredictable in the long run when viewed in detail. Nonetheless, on a higher aggregation level, indicators such as total algal biomass may show quite regular patterns.
Genetic parameters for various random regression models to describe the weight data of pigs
Huisman, A.E. ; Veerkamp, R.F. ; Arendonk, J.A.M. van - \ 2002
Journal of Animal Science 80 (2002)3. - ISSN 0021-8812 - p. 575 - 582.
trajectories - selection
Various random regression models have been advocated for the fitting of covariance structures. It was suggested that a spline model would fit better to weight data than a random regression model that utilizes orthogonal polynomials. The objective of this study was to investigate which kind of random regression model fits best to weight data of pigs. Two random regression models that described weight of individual pigs, one using orthogonal polynomials, and the other using splines, were compared. A comparison with a multivariate model, Akaike's information criterion, and the Bayesian-Schwarz information criterion were used to select the best model. Genetic, permanent environmental, and total variances increased with age. Heritabilities for the multivariate model ranged from 0.14 to 0.19, and for both random regression models the heritabilities were fluctuating around 0.17. Both genetic and phenotypic correlations decreased when the interval between measurements increased. The spline model needed fewer parameters than the multivariate and polynomial models. Akaike's information criterion was least for the spline model and greatest for the multivariate model. The Bayesian-Schwarz information criterion was least for the polynomial model and greatest for the multivariate model. Residuals of all models were normally distributed. Based on these results, it is concluded that random regression models provide the best fit to pig weight data.
Effect of different chemical treatments on nutritional and antinutritional properties of coffee pulp
Ulloa Rojas, J.B. ; Verreth, J.A.J. ; Weerd, J.H. van; Huisman, E.A. - \ 2002
Animal Feed Science and Technology 99 (2002)39539. - ISSN 0377-8401 - p. 195 - 204.
proteins - tannins - sorghum - beans - diets - grain
Different chemical treatments were tested to improve the nutritional value of coffee pulp (CoP): (1) alkali, NaOH solutions of 5 and 10% for 24 and 48 h; (2) a combination of acid and alkali, with first a treatment with HCl (1.5 and 3 M for 24 and 48 h), followed by a NaOH solution of 5% for 48 h; (3) A combination of alkali and ensilage, with first a treatment with a NaOH solution of 5% for 48 h, followed by ensilage with molasses (50 and 100 g molasses/kg of CoP) for 2 and 3 months. The CoP treated with NaOH alone or with the combination HCl¿NaOH showed higher contents of ash, fat and cellulose but lower contents of antinutritional factors (ANFs) (polyphenols, tannins and caffeine) than oven-dried-CoP (OD-CoP) (P
Recensie van: J.Huisman, e.a. - Honderd jaar wonen in Nederland, 1900-2000
Schuurman, A.J. - \ 2002
Bijdragen en Mededelingen betreffende de geschiedenis der Nederlanden = BMGN : Low Countries Historical Review 117 (2002). - ISSN 0165-0505 - p. 51 - 53.
Preliminary study on haemocyte response to white spot syndrome virus infection in black tiger shrimp, Penaeus monodon
Braak, C.B.T. van de; Botterblom, M.H.A. ; Huisman, E.A. ; Rombout, J.H.W.M. ; Knaap, W.P.W. van de - \ 2002
Diseases of Aquatic Organisms 51 (2002). - ISSN 0177-5103 - p. 149 - 155.
The role of haemocytes and the lymphoid organ in the clearance of injected Vibrio bacteria in Penaeus monodon shrimp
Braak, C.B.T. van de; Botterblom, M.H.A. ; Huisman, E.A. ; Rombout, J.H.W.M. ; Knaap, W.P.W. van der - \ 2002
Fish and Shellfish Immunology 13 (2002). - ISSN 1050-4648 - p. 293 - 309.
In order to study the reaction of Penaeus monodon haemocytes, live Vibrio anguillarum bacteria were injected and the shrimp were periodically sampled. Immuno-double staining analysis with specific antisera against the haemocyte granules and bacteria showed that large numbers of haemocytes encapsulated the bacteria at the site of injection. A rapid decrease of live circulating bacteria was detected in the haemolymph. Bacterial clearance in the haemolymph was induced by humoral factors, as observed by agglutinated bacteria, and followed by uptake in different places in the body. Bacteria mainly accumulated in the lymphoid organ (LO), where they, or their degradation products, could be detected for at least 7 days after injection. The LO consists of folded tubules with a central haemal lumen and a wall, layered with cells. The haemolymph, including the antigens, seemed to migrate from the central tubular lumen through the wall, where the bacteria are arrested and their degradation is started. Electron microscopy of the LO revealed the presence of many phagocytic cells that morphologically resemble small-granular haemocytes. It is proposed that haemocytes settle in the tubule walls before they phagocytose. Immunostaining suggests that many of the haemocytes degranulate in the LO, producing a layer of fibrous material in the outer tubule wall. These findings might contribute to the reduced haemocyte concentration in the haemolymph of diseased animals or following injection of foreign material. It is proposed that the LO is a filter for virtually all foreign material encountered in the haemolymph. Observations from the present study are similar to clearance mechanisms in the hepatic haemolymph vessel in most decapod crustaceans that do not possess a LO. The experimental shrimp appeared to contain many LO spheroids, where bacterial antigens were finally observed as well. It is proposed that the spheroids have a degradation function for both bacterial and viral material, and that their presence is primarily related to the history of the infectious burden of the shrimp.
Use of random regression models to analyse longitudinal records on weight and gain of growing pigs
Huisman, A.E. ; Hermesch, S. ; Bennett, C. - \ 2002
In: Abstracts of the European Association of Animal Production, Egypt, 2-5 September - p. 40 - 40.
Genetic parameters for different random regression models to describe weight data of pigs
Huisman, A.E. ; Veerkamp, R.F. ; Arendonk, J.A.M. van - \ 2002
In: Abstracts of the 52nd Meeting of the European Association for Animal Production, Budapest, 26-29 August - p. 5 - 5.
Genetic course of live weight and feed intake over an 8-week test period
Huisman, A.E. ; Hermesch, S. ; Bennett, C. - \ 2002
In: Proceedings 7th World Congress on Genetics Applied to Livestock Production, Montpellier, 19-23 August. Vol. 31 - p. 245 - 248.
Altered cell wall disassembly during ripening of Cnr tomato fruit : implications for cell wall adhesion and fruit softening
Orfila, C. ; Huisman, M.M.H. ; Willats, W.G.T. ; Alebeek, G.J.W.M. van; Schols, H.A. ; Seymour, G.B. ; Knox, J.P. - \ 2002
Planta 215 (2002). - ISSN 0032-0935 - p. 440 - 447.
The Cnr (Colourless non-ripening) tomato (Lycopersicon esculentum Mill.) mutant has an aberrant fruit-ripening phenotype in which fruit do not soften and have reduced cell adhesion between pericarp cells. Cell walls from Cnr fruit were analysed in order to assess the possible contribution of pectic polysaccharides to the non-softening and altered cell adhesion phenotype. Cell wall material (CWM) and solubilised fractions of mature green and red ripe fruit were analysed by chemical, enzymatic and immunochemical techniques. No major differences in CWM sugar composition were detected although differences were found in the solubility and composition of the pectic polysaccharides extracted from the CWM at both stages of development. In comparison with the wild type, the ripening-associated solubilisation of homogalacturonan-rich pectic polysaccharides was reduced in Cnr. The proportion of carbohydrate that was chelator-soluble was 50␕ess in Cnr cell walls at both the mature green and red ripe stages. Chelator-soluble material from ripe-stage Cnr was more susceptible to endo-polygalacturonase degradation than the corresponding material from wild-type fruit. In addition, cell walls from Cnr fruit contained larger amounts of galactosyl- and arabinosyl-containing polysaccharides that were tightly bound in the cell wall and could only be extracted with 4 M KOH, or remained in the insoluble residue. The complexity of the cell wall alterations that occur during fruit ripening and the significance of different extractable polymer pools from cell walls are discussed in relation to the Cnr phenotype.
Cost evaluation of bale storage systems for rice straw
Huisman, W. ; Jenkins, B.M. ; Summers, M.D. - \ 2002
In: Proceedings Bioenergy 2002 : Bioenergy 2002, Boise Idaho USA, 22-26 september 2002 Wisconsin : Omnipress Madison
Opslagsystemen voor biomassa
Huisman, W. - \ 2002
In: Nederlandse duurzame energie conferentie : De versnelling, Rotterdam, 27 en 28 februari 2002 / Van Namen & Westerlaken Nijmegen : - p. 43 - 44.
Genetic analysis of growth and feed intake patterns in pigs
Huisman, A.E. - \ 2002
Wageningen University. Promotor(en): J.A.M. van Arendonk. - S.l. : S.n. - ISBN 9789058087669 - 148
varkens - fokwaarde - groei - prestatieniveau - voeropname - genetische analyse - selectie - regressieanalyse - dierveredeling - pigs - breeding value - growth - performance - feed intake - genetic analysis - selection - regression analysis - animal breeding

Objective of this thesis was to quantify genetic differences in performance patterns of pigs by means of random regression models. Emphasis was on growth and feed intake patterns in pigs. Genetic parameters for weight, daily gain and daily feed intake were estimated using random regression models, where traits were modelled on a continuous scale, i.e. age, days on test or weight. Interactions between weight, daily gain, and daily feed intake during a trajectory were studied. The possibilities to change (part of) performance pattern of pigs through selection were investigated using simulation. Random regression models provide a method to analyse longitudinal records in animal breeding that reveal specific patterns of change over a trajectory. Advantages of the application of random regression models were a higher accuracy of selection, the use of information of the course of traits, and the possibility to change the course of a trait through selection. Measurements of live weight, daily gain, and daily feed intake taken at different points along this trajectory cannot be regarded as repeated measurements of the same trait. It is possible to change patterns of weight, daily feed intake, and daily gain over an age trajectory through genetic selection; the extent of change depends on the genetic correlation structure. A set of multivariate random regression models can be set up, yielding estimated breeding values for traits of interest along a trajectory, e.g. a weight - or age trajectory. These estimated breeding values for different points along a trajectory can be considered as estimated breeding values of separate traits. A breeding goal that incorporates all these traits can be set up, putting more emphasis on that part of the trajectory that we want to change. Random regression models are a helpful tool in identifying and selecting animals that show desired patterns for a combination of traits

Stress and stress disorders in a teleost fish, the common carp Cyprinus carpio L.
Ruane, N.M. - \ 2002
Wageningen University. Promotor(en): E.A. Huisman; J. Komen. - S.l. : S.n. - ISBN 9789058087485 - 160
karper - zoetwatervissen - stressreactie - stress - hydrocortison - fysiologie - dierenwelzijn - visteelt - afwijkingen - psychologische fysiologie - carp - freshwater fishes - stress response - stress - hydrocortisone - physiology - animal welfare - fish culture - abnormalities - psychological physiology

Unlike research using mammalian animal models such as rats or mice, experimental fish often come from wild or commercial sources, leading to a lack of well defined experimental animal models. Isogenic carp offer us a well defined fish model for physiological research. The aim of this thesis was to, therefore, investigate the physiological stress response of isogenic strains of carp. Increased levels of stress in intensively reared animals results in large economical losses (due to disease mortalities, poor growth) and an increased understanding of the stress response is therefore relevant to the fish farming industry. Using a standard stressor, we aimed to examine the influence of environmental disturbances (e.g. high densities, restricted feeding levels) on the physiological response of the carp to this stressor. Fish showed a mild response to the period of crowding, although they appeared to recover physiologically, fish reared at a high density were more sensitive to an additional disturbance as seen by the higher levels of stress-hormones in the circulation. In addition, alternate periods of optimal or maintenance feeding levels were also found to affect the response to stress. An alternative method for measuring chronic stress in fish was also established through hormonal measurements in the water. A stress disorder was noted in one strain, these fish appear to suffer from a disorder similar to the 'chronic adrenal hyperplasia' which occurs in mammals. As this has never been described in a lower vertebrate, these fish may prove to be an important model for future studies on fish endocrinology.

Diseases of aquatic organisms
Braak, C.B.T. van de; Botterblom, M.H.A. ; Huisman, E.A. ; Rombout, J.H.W.M. ; Knaap, W.M.W. van der - \ 2002
In: Diseases of aquatic organisms / Braak Bangkok : Inter Research - p. 149 - 155.
The influence of feeding history on the acute stress response of common carp (Cyprinus carpio)
Huisman Ruane, N.M. ; Huisman, E.A. ; Komen, J. - \ 2002
Aquaculture 210 (2002). - ISSN 0044-8486 - p. 245 - 257.
Use of coffee pulp as feed ingredient for tilapia culture
Ulloa Rojas, J.B. - \ 2002
Wageningen University. Promotor(en): E.A. Huisman; J.A.J. Verreth. - S.l. : S.n. - ISBN 9789058086471 - 133
tilapia - oreochromis aureus - koffiepulp - diervoeding - visvoeding - visteelt - voedingswaarde - tilapia - oreochromis aureus - coffee pulp - animal nutrition - fish feeding - fish culture - nutritive value

This research focused on the feasibility of using coffee pulp (CoP) in diets for tilapia ( Oreochromis aureus ). First, a literature survey analyzed the limitations of CoP as an animal foodstuff (several antinutritional factors: ANF's, and high fibre contents), different ways to upgrade the CoP nutritional value and the maximal inclusion level of CoP in diets for ruminants, monogastric animals and fish ( Chapter 1 ).

Next, an inventory of agricultural activities in the country (Costa Rica) was realized for one production year (1993-94). The most important agricultural activities were identified and classified in two categories: crop and animal husbandry sectors. Residues (wastes and by-products) of both sectors were characterized by their seasonality, their amounts produced, methods of treating wastes, their use (if any) and their potential pollution risk. In addition, most relevant wastes were more precisely studied and, their chemical composition and the presence of potential ANF's indicated. The CoP was selected for further study because of its annual production and its potential pollution risk. Changes of the chemical composition of CoP during the harvesting season and using different drying methods were examined in more detail ( Chapter 2 ). Limitations to use CoP as a foodstuff for fish were studied and the possible causes of differences on growth responses to CoP diets found in tilapia reared either in extensive and intensive systems (pens in ponds and recirculation-aquaria system) are mentioned ( Chapter 3 ).

As several ANF's were identified in CoP, the critical value of some of them was determined for Oreochromis aureus fingerlings. Based on the growth and feed efficiency (digestibility), the following dietary critical levels of fibre and tannins were determined: 4.4 g kg -1of tannins and 106.5 g kg -1of fibre. Dietary caffeine levels increasing from 2.4 to 4.6 g kg -1tended to reduce fish growth, feed intake and also nutrient digestibility of O. aureus ( Chapter 4 ).

Chemical treatments have been applied to straws and coffee hulls with positive results. Uses of some of these treatments were tested in fresh CoP. The NaOH, the combined HCl-NaOH and NaOH-ensilage treatments were applied to CoP to reduce the content of caffeine, total phenols (polyphenols), tannins and cellulose. Biological treatments were also used to diminish ANF's in CoP but they also may increase CoP protein and fat contents. The ensilage of CoP with molasses was also tested at higher concentration (100 g kg -1) than normally done; however, it did not result in any additive effect. Microbial decomposition was done in a closed lab controlling parameters such as environmental moisture and temperature, photoperiod and temperature of CoP samples. Specific cellulolytic bacteria were used to degrade fibrous components and ANF's of CoP. The inoculation of CoP was done with a cocktail of five species of Bacillus for 28 days under aerobic conditions. The best result in relation with the upgrading of the nutritional quality of CoP was found with the bacterial treatment ( Chapter 5 ).

Subsequently, CoP treated with Bacillusssp. was included in diets for tilapia. The final product was included at different concentrations (0, 60, 120, 180 and 240 g kg -1) in the fish diets and fed to O. aureus fingerlings for 4 weeks. At the end of the experimental period, the fish response was evaluated in terms of growth, feed intake, protein utilization and nutrient digestibility ( Chapter 6 ). Best results were found with diets containing 0 and 60 g kg -1CoP. Problems related to the upscaling of the bacterial treatment are mentioned and discussed.

The overall results are integrated in one general discussion and several conclusions and recommendations are drawn to upgrade coffee residues for animal feeding purposes ( Chapter 7 ). The potential of using CoP in diets for tilapia cultured in extensive or semi-intensive systems is discussed. Technological and engineering aspects impaired the upscaling of the bacterial treatment for CoP and produced a final product with a lower quality than the one obtained at laboratory scale.

Haemocytic defence in black tiger shrimp (Penaeus monodon)
Braak, K. van de - \ 2002
Wageningen University. Promotor(en): E.A. Huisman; W.B. van Muiswinkel; W.P.W. van der Knaap; J.H.W.M. Rombout. - S.l. : S.n. - ISBN 9789058086518 - 159
penaeus monodon - crustacea - garnalen - immuunsysteem - immuniteitsreactie - immuniteit - verdedigingsmechanismen - via de cel overgebrachte immuniteit - rode bloedcellen - hemolymfe - monoclonale antilichamen - experimentele infectie - infectieziekten - garnalenteelt - penaeus monodon - crustacea - shrimps - immune system - immune response - immunity - defence mechanisms - cell mediated immunity - haemocytes - haemolymph - monoclonal antibodies - experimental infection - infectious diseases - shrimp culture

Tropical shrimp culture is one of the fastest growing aquaculture sectors in the world. Since this production sector is highly affected by infectious pathogens, disease control is nowadays a priority. Effective prevention methods can be developed more efficiently when quantitative assays for the evaluation and monitoring of the health status of shrimp are available. The defence mechanisms of crustaceans are poorly understood, but knowledge about these is a prerequisite for the development of such health parameters. Therefore, the aim of this thesis was to obtain a better understanding of the defence system of the major cultured shrimp species in the world, Penaeus monodon . The present study emphasised the cellular components of the circulatory system, which play a central role in the haemolymph defence, i.e. the haemocytes.

To study the usefulness of haemolymph for shrimp health assessment, several cellular and humoral characteristics of P. monodon were determined after haemolymph sampling from the ventral part of the haemocoel (chapter 2). Among other things, five different haemocyte types were distinguished by light microscopy, while electron microscopy revealed granular cells, semigranular cells and hyaline cells. It was concluded that haemolymph characterisation might be a useful tool for health estimation of P. monodon , but that standardisation of the techniques is a prerequisite.

The use of monoclonal antibodies (mAbs) was proposed as a potential approach for the characterisation of haemocytes. Therefore, a set of mAbs specific for P. monodon haemocytes was produced by immunising mice with haemocyte membrane lysates (chapter 3). Four mAbs (WSH 6, WSH 7, WSH 8 and WSH 16) were selected and extensively characterised. For all mAbs, differences in amount and intensity of the labelling were found between immediately fixed haemocytes and non-fixed cells that were kept in Alsever's solution (AS, an anticoagulant which reduces haemocyte activation) and kept in L15 cell culture medium. WSH 6 reacted with the cell membranes of all fixed haemocytes, while WSH 7 and WSH 16 reacted with the cell membranes of the majority of fixed haemocytes. The membrane labelling appeared to decrease when cells were kept in L15 medium. WSH 8 did not react with the haemocyte membranes. All mAbs reacted with some granules, mainly present in the hyaline cells, when the haemocytes were immediately fixed. When non-fixed cells were kept in AS or in L15 medium, positive granules were also observed in semigranular and granular haemocytes as well as in the largest granules of a fourth cell type, that contains many granules of different sizes and electron densities. Immuno-reactive extracellular fibrous material could be observed when cells were kept in L15 medium. The change in staining pattern was extreme for WSH 8, somewhat less for WSH 6 and WSH 7 and lowest for WSH 16. Double labelling revealed that all mAbs showed a different staining pattern on membranes as well as on granules. WSH 16 also showed labelling in cytoplasmic vesicles, as well as in haemolymph plasma on histological sections. The hypothesis was put forward that immuno-reactive molecules recognised by these mAbs, were related to haemocyte activation factors and that the mAbs could be used in studying haemocyte differentiation, behaviour and function in P. monodon shrimp. Later on, WSH 8 indeed proved suitable for this in immuno-histochemical studies.

A better characterisation of the immuno-reactive molecules would support the interpretation of the results. In order to investigate whether the mAbs reacted with well-conserved molecules and with haemocytes in animals with molecules that were better characterised than those of P. monodon , a comparative study was carried out (chapter 4). The mAbs also reacted on haemocyte monolayers of the freshwater shrimp Macrobrachium rosenbergii and the two freshwater crayfish Procambarus clarkii and Pacifastacus leniusculus . Immuno-labelling on haemolymph monolayers of the terrestrial isopod crustacean Porcellio scaber (woodlouse) and on coelomic fluid of the annelid Lumbricus terrestris (earthworm) showed partial reactivity. Immuno-reactivity was not observed on haemolymph monolayers of the insect Spodoptera exigua (Florida moth) and the mollusc Lymnaea stagnalis (pond snail), or on blood cell monolayers of the freshwater fish Cyprinus carpio (carp) and of human. On histological sections of M. rosenbergii and P. clarkii , mAb labelling was observed on the haemolymph plasma and on a proportion of the haemocytes. This comparative study showed reactivity of the mAbs in a wide range of crustaceans and related animals and suggests that well conserved molecules were recognised, which may indicate functional importance. Later on, molecules of P. leniusculus that reacted with WSH 6 were better characterised and it was indicated that this molecule could be clotting protein or filamin, which both could be involved in coagulation processes. Unfortunately, the immuno-reactive molecules of P. monodon with WSH 8 could not be characterised further.

The circulating haemocytes of crustaceans are generally divided into hyaline, semigranular or granular cells, however, this classification is still ambiguous. Not much is known about haemocyte production in penaeid shrimp, but for a better haemocyte classification it is useful to establish how these cells are produced and mature. In order to clarify this, the localisation and (ultra)structure of the haematopoietic tissue and its relation with the circulating haemocytes were studied in chapter 5. The haematopoietic tissue is located in many lobules dispersed in different areas in the cephalothorax, mainly at the dorsal side of the stomach and at the base of the maxillipeds. In order to study the haemocyte production and maturation, shrimp were either injected with LPS, while mitosis was inhibited by vinblastine, or were repeatedly sampled for haemolymph. The presumed precursor cells in the haematopoietic tissue were located towards the exterior of the lobules and maturing young haemocytes towards the inner part, where they can be released into the haemal lacunae. It was proposed that the presumed young haemocytes were generally known as the hyaline cells. Moreover, a new model was proposed where the hyaline cells gave rise to two haemocytic developmental series, i.e., the large- and small-granular cell line. In addition, indications were found that the granular cells of at least the large-granular cell line mature and accumulate in the connective tissue and are easily released into the haemolymph. Light and electron microscopical observations supported the regulation of the haemocyte populations in the circulation by (stored) haemocytes from the connective tissue.

In order to investigate the clearance reaction of P. monodon haemocytes live Vibrio anguillarum bacteria were injected and the shrimp were periodically sampled (chapter 6). Immuno-double staining analysis with specific antisera against the haemocyte granules and bacteria showed that many haemocytes encapsulated the bacteria at the site of injection. Furthermore, a rapid decrease of live circulating bacteria was detected in the haemolymph. Bacterial clearance in the haemolymph was induced by humoral factors, as observed by agglutinated bacteria, and followed by uptake in different places in the body. Bacteria mainly accumulated in the lymphoid organ, where they, or their degradation products, could be detected for at least seven days after injection. The lymphoid organ consists of folded tubules with a central haemal lumen and a wall, layered with cells. The haemolymph, including the antigens, seemed to migrate from the central tubular lumen through the wall, where the bacteria are arrested and their degradation is started. The lymphoid organ of penaeids is also poorly studied. Electron microscopy of the lymphoid organ revealed the presence of many phagocytic cells that morphologically resemble small-granular haemocytes. It was proposed that haemocytes settle in the tubule walls before they phagocytose. Observations from the present study are similar to clearance mechanisms in the hepatic haemolymph vessels in most decapod crustaceans that do not possess a lymphoid organ.

Immuno-staining suggested that many of the haemocytes degranulate in the lymphoid organ, producing a layer of fibrous material in the outer tubule wall. These findings might contribute to the reduced haemocyte concentration in the haemolymph of diseased animals or following injection of foreign material. It is proposed that the lymphoid organ is a filter for virtually all foreign material encountered in the haemolymph. Haemocyte degranulation in the lymphoid organ tubule walls could contribute to the filtering capacity of this organ.

The experimental shrimp appeared to contain many lymphoid organ spheroids, where bacterial antigens were finally also observed. It is proposed that the spheroids have a degradation function for both bacterial and viral material, and that their presence is primarily related to the history of the infectious burden of the shrimp.

White spot syndrome virus (WSSV) is the pathogen that is a major cause of mortality in shrimp culture in the past decade. In contrast to the extensive study of the morphology and genome structure of the viral pathogen, the defence reaction of the host during WSSV infection is hardly studied. Therefore, the haemocyte response upon experimental WSSV infection was examined in P. monodon shrimp (chapter 7). A strong decline in free circulating haemocytes was detected during severe WSSV infection. The combination of in situ hybridisation with a specific DNA probe to WSSV and immuno-histochemistry with a specific antibody against haemocyte granules was carried out on tissue sections. Haemocytic reactions have never been reported in chronic or acute viral infections in shrimp, but the present results showed that many haemocytes leave the circulation and migrate to tissues where many virus-infected cells are present. However, a subsequent response to the virus-infected cells was not detected. During virus infection, the number of cells in the haematopoietic tissue was also reduced. Moreover, it was suggested that many haemocytes degranulated in the lymphoid organ, producing a similar but more obvious layer of fibrous material in the outer tubule wall than after bacterial injection.

The obtained results are summarised and discussed in chapter 8. Furthermore, the results described in chapters 6 and 7 were used to refine the proposed model of chapter 5. The haemocytes of the small-granular cell line are suggested to mature and carry out their function in the lymphoid organ. The results of the present research emphasise the rapid activation of the haemocytes after stimulation of the animal and illustrate several relevant functions of those cells. The present knowledge provides reliable grounds for further discussions about production, maturation and activation of the haemocytes in penaeid shrimp and possibly also in related animals like other shrimp species, crayfish, lobsters and crabs. Knowledge of the functioning of the defence system is of extreme importance since stimulation of this system is considered as a potential intervention strategy in shrimp culture to overcome the infectious diseases.

Changes in amino acid composition in the tissues of African catfish (Clarias gariepinus) as a consequence of dietary L-carnitine supplements
Ozorio, R.O.A. ; Booms, G.H.R. ; Huisman, E.A. ; Verreth, J.A.J. - \ 2002
Journal of Applied Ichthyology 18 (2002). - ISSN 0175-8659 - p. 140 - 147.
Semen collection and preservation in African catfish, Clarias gariepinus
Viveiros, A. - \ 2002
Wageningen University. Promotor(en): E.A. Huisman; J. Komen; H. Woelders. - S.l. : S.n. - ISBN 9789058085610 - 144
clarias gariepinus - vissen - visteelt - sperma - strippen - spermaconservering - cryopreservering - hormonen - geneesmiddelenbehandeling - voortplantingsstoornissen - genetische bronnen van diersoorten - clarias gariepinus - fishes - fish culture - semen - stripping - semen preservation - cryopreservation - hormones - drug therapy - reproductive disorders - animal genetic resources

Stock improvement using quantitative and molecular genetics is an essential part of nowadays production of farm animals and fish. To achieve this in aquaculture, germplasm of both parental sexes should be obtained in a life-saving manner. In captivity, male African catfish, Clariasgariepinus , do not release semen under abdominal massage and have to be sacrificed to obtain sperm from the macerated testes. Of course, this is regarded as a major constrains by the catfish farming sector. Against this background, the research of the present thesis had a two-pronged approach and aimed (a) to induce semen release and facilitate stripping of semen under abdominal massage, and (b) to optimize protocols for cryopreserving semen of the African catfish. To facilitate hand-stripping of semen, several maturational hormones that increase plasma gonadotropin levels and drugs that stimulate contractions of the reproductive tract, such as oxytocin, were tested. The response to some of these treatments was compared between normal males and males that possessed undeveloped seminal vesicles - a possible block of the sperm flow during abdominal massage. Based on the results, it is unlikely that catfish males kept in captivity are not strippable because of a lack of gonadotropin surge. Fertile semen was hand-stripped from males that possessed undeveloped seminal vesicles but not from normal males, suggesting that seminal vesicles actually block the sperm flow during hand-stripping. However, stripping was possible only after treatment with pituitary extract. Oxytocin may play a role in sperm transport in catfish, but more research is needed to optimize dose and latency time. To optimize protocols for semen cryopreservation, different cryoprotectors, cooling rates and temperatures at which plunging into liquid nitrogen occurred, were evaluated. Catfish semen showed good tolerance to freezing and thawing. Hatching rates similar to the fresh semen were obtained with semen frozen in 10% methanol, at a cooling rate of -2, -5 or -10ºC/min to -40ºC and plunged into liquid nitrogen as soon as semen temperature reached -38ºC. Samples plunged into liquid nitrogen from a semen temperature above -30ºC or below -50ºC produced decreasing hatching rates. Post-thaw semen could be diluted at least 200 times without loosing fertilization capacity. Cryopreservation of semen is a valuable tool for selection and conservation of genetic diversity in catfish species.

25 jaar vis à vis de vis
Huisman, E.A. - \ 2001
Wageningen : Wageningen Universiteit - 23
visconsumptie - visserij - visbestand - visteelt - fish consumption - fisheries - fishery resources - fish culture
Rede Wageningen Universiteit, 11 januari 2001
Middelenonderzoek Alternaria dauci in peen, projectjaar 2001
Plentinger, M.C. ; Wilms, J.A.M. ; Huisman-de Lange, M. ; Schepers, H.T.A.M. - \ 2001
Lelystad : Praktijkonderzoek voor de Akkerbouw en de Vollegrondsgroenten
wortelgewassen als groente - alternaria dauci - plantenziekteverwekkende schimmels - penen - root vegetables - plant pathogenic fungi - carrots
In het jaar 2000 werden twee veldproeven uitgevoerd waarin fungiciden werden beproefd tegen Alternaria dauci in peen. De proefvelden werden op het PAV in Lelystad en op het PAV-ZZO in Meterik aangelegd. Het doel van het project was na te gaan of fungiciden die toegelaten zijn in andere gewassen of nog niet zijn toegelaten, werkzaam zijn tegen Alternaria dauci in wortelen. Gewascontrole vond plaats door planten te beoordelen op een bladaantasting door Alternaria dauci. De aantasting werd regelmatig beoordeeld aan de hand van een ziekte-index.
Random regression models in pig breeding
Huisman, A.E. ; Arendonk, J.A.M. van - \ 2001
In: Proceedings 8th Biennal conference on manipulating pig Production, Adelaid, 2001. Vol. 8 - p. 145 - 145.
Genetic parameters for different random regression models to describe weight data of pigs
Huisman, A.E. ; Veerkamp, R.F. ; Arendonk, J.A.M. van - \ 2001
Journal of Animal Science 80 (2001). - ISSN 0021-8812 - p. 575 - 582.
Various random regression models have been advocated for the fitting of covariance structures. It was suggested that a spline model would fit better to weight data than a random regression model that utilizes orthogonal polynomials. The objective of this study was to investigate which kind of random regression model fits best to weight data of pigs. Two random regression models that described weight of individual pigs, one using orthogonal polynomials, and the other using splines, were compared. A comparison with a multivariate model, Akaike's information criterion, and the Bayesian-Schwarz information criterion were used to select the best model. Genetic, permanent environmental, and total variances increased with age. Heritabilities for the multivariate model ranged from 0.14 to 0.19, and for both random regression models the heritabilities were fluctuating around 0.17. Both genetic and phenotypic correlations decreased when the interval between measurements increased. The spline model needed fewer parameters than the multivariate and polynomial models. Akaike's information criterion was least for the spline model and greatest for the multivariate model. The Bayesian-Schwarz information criterion was least for the polynomial model and greatest for the multivariate model. Residuals of all models were normally distributed. Based on these results, it is concluded that random regression models provide the best fit to pig weight data.
Genetic parameters for different random regression models to describe weight data of pigs
Huisman, A.E. ; Veerkamp, J.H. ; Arendonk, J.A.M. van - \ 2001
In: Proceedings EAAP - p. 15 - 15.
A study on internationalization of Bonsai culture (miniature tree art)
Nakano, K. ; Nihei, K. ; Huisman, W. - \ 2001
In: EFITA 2001, Proceedings of the third European Con ference of the European Federation for In formation Technology in Agriculture, Food and the Environment. - Montpellier : J. Steffe, 2001 - p. 245 - 250.
Harvesting and storage of Miscanthus
Bassam, N.E. ; Huisman, W. - \ 2001
In: Miscanthus for energy and fibre / Jones, M., Walsh, M., London : James & James Ltd. - p. 86 - 108.
Harvesting and storage of perennial rhizomatheus grasses
Huisman, W. - \ 2001
In: Proceedings of the 1st world conference on biomass for energy and industry 5-9 june 2000 London : James & James Ltd. - p. 2097 - 2099.
The contribution of farm technology to improving sustainability in the production chain of bioenergy crops
Huisman, W. - \ 2001
In: The first European Conference on Agriculture & renewable energy, 6-8 may 2001. - Amsterdam : emml, 2001
Elucidation of the chemical fine structure of pectic polysaccharides from soybean cell walls
Huisman, M.M.H. ; Schols, H.A. ; Voragen, A.G.J. - \ 2001
In: Pectins and Pectinases, Rotterdam 6-10 May 2001 Wageningen : Wageningen University and Research Centre - p. 21 - 21.
Changes in fatty acid concentrations in tissues of African catfish, Clarias gariepinus, as a consequence of dietary carnitine, lysine and lipid supplements
Ozorio, E.O.A. ; Uktolseja, J.L.A. ; Huisman, E.A. ; Verreth, J.A.J. - \ 2001
The British journal of nutrition 86 (2001)5. - ISSN 0007-1145 - p. 623 - 636.
A study was undertaken to examine the effect of different dietary carnitine (200 and 1000 mg/kg diet) and fat (90 and 190 g/kg diet) supplementation on growth and fatty acid concentrations of fish fed either with a low- (13 g/kg) or a high-lysine (21 g/kg) diet. African catfish (22?7 g/fish), Clarias gariepinus Burchell, juveniles were stocked (sixteen aquaria, twenty-five fish per aquarium) and fed for a maximum of 74 d. Dietary lysine had a clear effect on growth performance and feed conversion ratios, but dietary carnitine supplements had no effect. High-carnitine supplements increased total carnitine content (P<0?0004) and reduced tissue free carnitine: acyl-carnitine ratio (P<0?05) compared with low-carnitine supplements. High-fat supplements decreased liver carnitine concentrations. Clear effects on liver fatty acid concentrations were observed in high-carnitine-fed fish compared with low-carnitine-fed fish. The primary liver fatty acids affected were 18:2n-6 (linoleic acid), 20:5n-3 (eicosapentanoic acid) and 22:6n-3 (docosahexanoic acid). The whole-body fatty acid balance suggested that 20:5n-3 disappeared (apparently by -oxidation) more readily than 18:2n-6 and/or 22:6n-3. From 774 mg 20:5n-3 eaten by high-lysine–high-fat–low-carnitine fish, 58 % was not assimilated into body tissues. High-carnitine-fed fish showed an increase in 20:5n-3 oxidation by 7 % compared with low-carnitine fish. Although dietary carnitine did not improve body growth, these results support the hypothesis that carnitine can enhance the mobilisation of long-chain fatty acids towards oxidation.
Effects of dietary carnitine and protein energy: non-protein energy ratios on growth, ammonia excretion and respiratory quotient in African catfish (Clarias gariepinus) (Burchell) juveniles
Ozorio, R.O.A. ; Eekeren, T.H.B. van; Huisman, E.A. ; Verreth, J.A.J. - \ 2001
Aquaculture Research 32 (2001). - ISSN 1355-557X - p. 406 - 414.
Two separate feeding experiments were carried out to determine the effects of dietary carnitine supplements on growth rates, total ammonia nitrogen (TAN) excretion and respiratory quotient rates (RQ) in the African catfish, Clarias gariepinus (Burchell), juveniles fed various diets differing in protein energy:nonprotein energy ratio (PE:NPE). In Experiment 1, 540 fish (20.9 ± 1.0 g) were evenly distributed into six dietary groups and fed in duplicate aquaria (N = 12 aquaria) to apparent satiation over a 41-day period, until all fish attained an individual final weight of 156.9 ± 10.8 g. Diets were formulated to contain two levels of carnitine (80 and 660 mg kg1) and three levels of PE:NPE (0.7, 0.9 and 1.4). Sampling was divided into two size ranges, according to the predicted individual end-weight of 60 g (days 0-16) and 160 g (days 16-41). In Experiment 2, 240 fish (16.5 ± 0.2 g) were distributed in four 140-L aquaria connected to a respirometer and preconditionally fed twice a day at a restricted feeding level of 24 g kg0.8 day1 for a 25-day period (final weight of 77.5 ± 1.5 g). Four isonitrogenous diets (368 g kg1 crude protein) were formulated to contain two levels of fat (85 and 175 g kg and two levels of carnitine (40 and 600 mg kg1), in a 2 2 factorial design. From days 20-25, three respirometric trials were carried out, during which total ammonia nitrogen (TAN) and RQ were determined over 24 h. In both experiments, carnitine supplemented fish accumulated 2.54 times more carnitine in their tissues than fish fed a basal level (P < 0.05). In Experiment 1, the smallest fish (<60 g) fed 660 mg carnitine showed significantly higher growth rates and lower feed conversion rates than 80 mg carnitine supplemented fish only when the dietary PE:NPE ratio was low (0.7). Additionally, dietary carnitine significantly increased protein:fat ratios in the whole body, suggesting a protein-sparing action. In Experiment 2, high carnitine supplements decreased both TAN excretion and RQ rates in fish <80 g.
The occurrence of internal (1,5)-linked arabinofuranose and arabinopyranose residues in arabinogalactan side chains from soybean pectic substances
Huisman, M.M.H. ; Brüll, L.P. ; Thomas-Oates, J.E. ; Haverkamp, J. ; Schols, H.A. ; Voragen, A.G.J. - \ 2001
Carbohydrate Research : an international journal 330 (2001). - ISSN 0008-6215 - p. 103 - 114.
CDTA-extractable soybean pectic substances were subjected to enzymatic digestion with arabinogalactan degrading enzymes yielding a resistant polymeric pectic backbone and arabino-, galacto-, and arabinogalacto-oligomers. The complex digest was fractionated using size-exclusion chromatography. Monosaccharide composition analysis, HPAEC fractionation and MALDI-TOF MS analysis of the resulting fractions showed that each contained a mixture of oligosaccharides of essentially the same degree of polymerisation, composed of only arabinose and galactose. MALDI-TOF MS analysis was used for molecular mass screening of oligosaccharides in underivatised HPAEC fractions. The monosaccharide sequence and the branching pattern of oligosaccharides (degree of polymerisation from 4 to 8) were determined using linkage analysis and ES-CID tandem MS analysis of the per-O-methylated oligosaccharides in each of the HPAEC fractions. These analyses indicated the presence of common linear (1¿4)-linked galacto-oligosaccharides, and both linear and branched arabino-oligosaccharides. In addition, the results unambiguously showed the presence of oligosaccharides containing (1¿4)-linked galactose residues bearing an arabinopyranose residue as the non-reducing terminal residue, and a mixture of linear oligosaccharides constructed of (1¿4)-linked galactose residues interspersed with an internal (1¿5)-linked arabinofuranose residue. The consequences of these two new structural features of pectic arabinogalactan side chains are discussed
The CDTA-soluble pectic substances from soybean meal are composed of rhamnogalacturonan and xylogalacturonan but not homogalacturonan
Huisman, M.M.H. ; Fransen, C.T.M. ; Kamerling, J.P. ; Vliegenthart, J.F.G. ; Schols, H.A. ; Voragen, A.G.J. - \ 2001
Biopolymers 58 (2001). - ISSN 0006-3525 - p. 279 - 294.
Structural characteristics of pectic substances extracted from soybean meal cell walls (water unextractable solids) with a chelating agent-containing buffer (0.05M 1,2-diaminocyclohexane-N,N,N,N-tetraacetic acid (CDTA) and 0.05M NH4-oxalate in 0.05M NaOAc buffer) were studied. The arabinogalactans present as side chains to the rhamnogalacturonan backbone were largely removed by enzymatic hydrolysis using endo-galactanase, exo-galactanase, endo-arabinanase, and arabinofuranosidase B. The remaining pectic backbone appeared to be resistant to enzymatic degradation by pectolytic enzymes. After partial acid hydrolysis of the isolated pectic backbone, one oligomeric and two polymeric populations were obtained by size-exclusion chromatography. Monosaccharide and linkage analyses, enzymatic degradation, and NMR spectroscopy of these populations showed that the pectic substances in the original extract contain both rhamnogalacturonan and xylogalacturonan regions, while homogalacturonan is absent.
Controlled reproduction of penaeid shrimp: a contribution to its improvement
Alfaro Montoya, J. - \ 2001
Wageningen University. Promotor(en): E.A. Huisman; J. Komen. - S.l. : S.n. - ISBN 9789058084002 - 149
aquacultuur - dierfysiologie - garnalen - penaeus - geslachtelijke voortplanting - gametogenese - schaal- en schelpdierenteelt - aquaculture - animal physiology - shrimps - penaeus - sexual reproduction - gametogenesis - shellfish culture

This dissertation deals with controlled reproduction of penaeid shrimp. New knowledge about natural reproductive activity of Penaeus occidentalis in Gulf of Nicoya, Costa Rica, is presented. Since in vitro fertilization of open thelycum shrimp proved unsuccessful, a hypothesis is given to explain experimental results. In P. setiferus , the Male Reproductive Blackening Disease was studied, and bacterial infection was found to be associated with the male's condition. Production of spermatophores in captivity was explored in two species, P. stylirostris and P. vannamei . Adequate husbandry as well as successive ejaculation improved spermatophore quality. Deterioration of spermatophores was observed as part of a normal process for renewal in P. vannamei , without pathological implications. In order to further improve spermatophore quality, the injection of 17-alpha-methyltestosterone and 17-alpha-hydroxyprogesterone at 0.01 and 0.1 µg g -1 body weight was evaluated. 17-alpha-methyltestosterone significantly improved the quality of spermatophores, whereas 17-alpha-hydroxyprogesterone did not. Serotonin injection was evaluated as an alternative to female's eyestalk ablation for induction of ovarian maturation and spawning in P. vannamei . This neurotransmitter induced lower maturation and spawning with 3 doses of 50 µg g -1 body weight, than eyestalk ablation. In other to lay a basis for cryopreservation, penaeid embryos were evaluated in terms of their tolerance to cooling, cryoprotectants, and hypersaline solutions. T. byrdi morulae and advanced embryos (10 h) were tolerant to cooling at 10 °C, but were very sensitive to 0 °C. Embryos showed high tolerance to methanol and intermediate tolerance to dimethyl sulfoxide. Morulae were more resistant to hypersaline treatment at 55 ppt than advanced embryos.

Plasma cortisol and metabolite level profiles in two isogenic strains of common carp during confinement
Ruane, N.M. ; Huisman, E.A. ; Komen, J. - \ 2001
Journal of Fish Biology 59 (2001). - ISSN 0022-1112 - p. 1 - 12.
A rapid increase in common carp Cyprinus carpio plasma cortisol levels was noted, in two experiments, after 30 mins of a 3 h net confinement, which was sustained while the fish were held in the nets. After release from the nets, cortisol levels returned to control values in 1 h. Plasma glucose and free fatty acid levels were elevated by the confinement. Glucose was increased after 30 min but returned to basal levels after 22 h of recovery while free fatty acids were not elevated until 3 h of confinement and remained high for the duration of the recovery period. After confinement for 3 h, plasma lactate levels were reduced and remained low for a further 1 h. No change in either plasma triglyceride or cholesterol levels were found during the study. Confinement had no effect on haematocrit levels but blood haemoglobin levels were reduced. In both experiments hypochloraemia occurred in response to confinement. However, values returned to pre-confinement levels 22 h after confinement. These results show that rearing isogenic carp strains, under identical conditions, results in a reproducable response to an acute stressor and that these carp respond in a similar manner to other teleost species
Cooling, cryporitectant and hypersaline sensitivity of Penaeid shrimp embryos and nauplii larvae
Alfaro Montoya, J. ; Komen, J. ; Huisman, E.A. - \ 2001
Aquaculture 195 (2001). - ISSN 0044-8486 - p. 353 - 366.
The sensitivity of embryos of the penaeid shrimp, Trachypenaeus byrdi, to cooling, cryoprotectant exposure (dimethyl sulfoxide : DMSO, sucrose, methanol and glycerol), and hypersaline treatment was assessed in order to gain basic knowledge for cryopreservation procedures. In addition, cooling and DMSO exposure was evaluated in Penaeus stylirostris and T. byrdi nauplii. Morulae and advanced embryos (setae development stage) showed tolerance to cooling at 10°C, but were very sensitive to 0°C exposure. Methanol exposure at 12°C up to 2 M, was non-toxic for advanced embryos. DMSO toxicity was intermediate; no statistical decrease in survival (P>0.05) was measured at 0.5 M. Sucrose and glycerol were toxic to both embryo stages over 0.25 and 0.5 M, respectively. Morulae were more resistant to hypersaline treatment at 55 ppt than advanced embryos. Nauplii showed a better tolerance to cooling and DMSO exposure than embryos. These findings are being applied to develop a cryogenic protocol for penaeid embryos.
The potential of periphyton-based aquaculture production systems
Ul Azim, M.E. - \ 2001
Wageningen University. Promotor(en): E.A. Huisman; J.A.J. Verreth; M.C.J. Verdegem. - S.l. : S.n. - ISBN 9789058085641 - 219
aquacultuur - visserij - productie - vis - visteelt - aquaculture - fisheries - production - fish - fish culture

Key words : Periphyton; Biofilm; Artificial substrates; Pond productivity; Tropical aquaculture; Monoculture; Polyculture; Fertilization; Proximate composition; Stocking ratio; Stable isotope ratio; Nutrient efficiency; Production economics; Indian major carps; Catla catla ; Labeo rohita ; Labeo gonius ; Labeo calbasu .

The overall objective of this study was to determine the technical and economical performance of periphyton-based aquaculture systems in Bangladesh. It thus addressed one of the key constraints for the poor to benefit from fish culture - limited access to resources such as fertilizers and feeds - while trying to maximize the conversion of these resources into fish. The suitability of four locally available substrates for periphyton growth was evaluated and the optimal fertilization regime determined. The production and growth of four indigenous species, rohu Labeo rohita (Hamilton), catla Catla catla (Hamilton), kalbaush L. calbasu (Hamilton) and gonia L. gonius (Linnaeus), was evaluated under single species and polyculture conditions. The species were selected on the basis oftheir feeding behaviour, ease of culture and high market demand. The periphyton production rate was around 2.5 g of ash free dry matter m -2d -1. Considering the total periphyton substrate area in the pond, this rate can support an estimated fish production of 5,000 kg ha -1y -1. Periphyton production effectively doubled the autotrophic C production, while no trade-off in production between phytoplankton and periphyton communities was observed. The nutritional quality of periphyton was adequate to support the dietary needs of the experimental fish. Nitrogen retention in fish in substrate-based systems was about 1.6 times higher than in control systems without substrate. As periphyton substrate, bamboo ( Bambusa sp.) proved better than hizol branch ( Barringtonia sp.), bamboo side shoot or jute stick ( Corchorus sp.) in terms of nutritional quality and periphyton productivity. Jute stick, however, provided better economical returns.

In single species culture, fish yields of rohu and kalbaush increased on average 80% compared to control systems without substrate, whereas with gonia, no significant production increase was observed. In periphyton-based polyculture systems, 70-180% greater fish production compared to controls was obtained. A three species periphyton-based polyculture technology was developed. Using the 75 m 2experimental freshwater ponds, provided with a substrate surface area approximately equal to the pond water surface area and stocked at the rate of 6,000 rohu, 4,000 catla and 1,500 kalbaush (total 11,500 juveniles) per hectare, a fish production of 2,306 kg was achieved within a 90-days culture period.

A pilot scale trial in an extended number of household ponds, distributed over different agro-ecological zones of the country, has been proposed before dissemination of this technology for wider use as a means of poverty alleviation and nutritional security in Bangladesh and elsewhere in the region.

Dietary L-Carnitine and energy and lipid metabolism in African catfish (Clarias gariepinus) juveniles
A. Ozório, R.O. de - \ 2001
Wageningen University. Promotor(en): E.A. Huisman; J.A.J. Verreth; M.W.A. Verstegen; J.W. Schrama. - S.l. : S.n. - ISBN 9789058084934 - 136
visvoeding - diëten - fish feeding - diets

As the lipid content of the diet increases so does the requirement for certain components involved in lipid metabolism. Carnitine is a normal constituent of animal tissues and plasma, which is required for the transport of long-chain fatty acids (LCFAs) to the site of oxidation. To avoid accumulation of lipids, supplementation of dietary carnitine may be used to stimulate fatty acid oxidation and to regulate lipolysis. Previous studies have demonstrated that responses to carnitine administration were ambiguous. Many reports demonstrated that dietary carnitine supplements improved growth and body lipid oxidation, however, others studies did not observe such effects.

The aim of this study is to assess the effects of dietary L-Carnitine on lipid metabolism in African catfish ( Clarias gariepinus , Burchell).

The working hypotheses of this thesis were the following. Firstly, growth and fatty acid concentrations in fish are positively related to dietary carnitine levels. Carnitine supplementation is expected to increase fatty acid oxidation and as a result the protein:fat ratio in the fish body will increase. Secondly, one may expect that nutritional conditions that result in decreased carnitine synthesis (e.g. dietary lysine deficiency) will enhance the effect of dietary carnitine. Thirdly, the increased lipid oxidation resulting from the extra dietary carnitine may result in a protein-sparing effect (i.e. reduced amino acid oxidation). Fourthly, the carnitine effect will be more pronounced when dietary protein is in shortage, i.e. at a low dietary protein to fat ratio. Finally, extra dietary carnitine may improve the energetic status of the working muscle, thus protecting it against a sudden energy depletion often experienced by fish exposed to prolonged exercise.

The first step of this study aimed to determine whether dietary carnitine effects on African catfish performance is associated to fish size and/or dietary protein to non-protein ratios. Carnitine supplemented fish accumulated 4 times more carnitine in their tissues than fish fed a basal level. The smallest fish (< 60g) fed 660mg carnitine/kg diet showed significantly higher growth rates and lower feed conversion rates than 80mg carnitine supplemented fish, only when dietary PE:NPE ratio was low. Additionally, high dietary carnitine supplements increased body protein:fat ratios and decreased both total ammonia nitrogen (TAN) excretion and respiratory quotient (RQ) rates in fish < 80g.

In Chapter 3 and 4, our working hypothesis was that the effects of dietary carnitine supplements would be measurable only when fish were preconditionally fed to be metabolically incapable to synthesise carnitine endogenously. Therefore, we tested the effect of dietary carnitine and fat supplementation on growth and fatty acid concentrations in fish fed either with a low- (13g/kg diet) or a high-lysine (21g/kg diet) diet. Dietary lysine clearly affected the growth performance and feed conversion ratios, but dietary carnitine supplements had no effect. High-carnitine supplements, however, reduced the tissue free- to acyl-carnitine ratio and showed to increase polyunsaturated fatty acid (PUFAs) transport to the liver. Moreover, carnitine supplements raised the concentration of several amino acids (glutamic acid, aspartic acid, glycine, alanine, arginine, serine and threonine) in muscle tissue. Total amino acid concentration in muscle and liver tissues (dry-matter basis) increased from 506 to 564mg.g -1and from 138 to 166mg.g -1, respectively, when diets were offered with high-carnitine, low-lysine and low-fat levels.

We additionally tested if lipid metabolism in fish tissues (muscle and liver) would respond differently to dietary carnitine when dietary composition and the metabolic state of the fish change. In Chapter 5, we investigated the influence of dietary carnitine and dietary energy sources on lipid metabolism. Plasma carnitine level was increased (7.7 vs. 16.5mmol/ml) and plasma protein level decreased (36.0 v. 32.9 g/L) by high-carnitine supplements in diet. In addition, a decrease in plasma glucose (206.2 v. 61.4 mg d/L), plasma lactate dehydrogenase (944.3 v. 591 U /L) and plasma leptin (16.1 v. 5.2 ng/ml) were also observed in fish fed high-carnitine and high-fat diets.

At the end of the experimental phase of this study we investigated the interaction effect between diet composition and exercise on the energy state of the fish (Chapter 6). High-energy phosphates [adenosine triphosphate (ATP) and phosphocreatine (PCr) levels], adenilate energy charge index (AEC) and ammonia concentrations in white muscle were affected by the carnitine-fat-exercise interaction. Exercise caused a decrease in the PCr level, followed by a decrease in the ATP level (p<0.05). At the same time, a drastic increase in the iosine monophosphate (IMP) level was observed. Carnitine supplements showed to be effective to improve the recovery of the high-energy phosphates.

In conclusion, carnitine biosynthesis by the animal may be sufficient to maintain growth during standard husbandry conditions. Nevertheless, extra dietary carnitine altered the non-protein energy metabolism, body protein:fat rate, and decreased postprandial ammonia synthesis and ammonia excretion. These effects are conditioned by nutritional factors, such as the natural carnitine content and fat in the feeds. In addition, the presence of factors that modulate the action of dietary carnitine, including size-related metabolic differences, high metabolic state, and their interactions have been shown. In such cases, an extra dietary requirement for carnitine was observed.

Optimization of stocking ratios of two Indian major carps, rohu (Labeo rohita Ham.) and catla (Catla catla Ham.) in a periphyton-based aquaculture system
Azim, M.E. ; Wahab, M.A. ; vam Dam, A.A. ; Beveridge, M.C.M. ; Huisman, E.A. ; Verdegem, M.C.J. - \ 2001
Aquaculture 203 (2001). - ISSN 0044-8486 - p. 33 - 49.
Evaluation of protein quality in microbound starter diets made with decapsulated cysts of Artemia and fishmeal for fish larvae
Garcia-Ortega, A. ; Huisman, E.A. ; Sorgeloos, P. ; Verreth, J.A.J. - \ 2001
Journal of the World Aquaculture Society 2001 (2001). - ISSN 0893-8849 - p. 317 - 329.
Unexpected anthropophagic behaviour in Anopheles quadriannulatus
Pates, H.V. ; Takken, W. ; Curtis, C.F. ; Huisman, P.W. ; Akinpelu, O. ; Gill, G.S. - \ 2001
Medical and Veterinary Entomology 15 (2001). - ISSN 0269-283X - p. 293 - 298.
Nitrogen transformations and fluxes in fish ponds: a modelling approach
Jiménez-Montealegre, R.A. - \ 2001
Wageningen University. Promotor(en): E.A. Huisman; J.A.J. Verreth; M.C.J. Verdegem. - S.l. : S.n. - ISBN 9789058084019 - 185
visteelt - aquacultuur - visvijvers - stikstof - stikstofretentie - stikstofkringloop - stikstofmetabolisme - visvoeding - modellen - fish culture - aquaculture - fish ponds - nitrogen - nitrogen retention - nitrogen cycle - nitrogen metabolism - fish feeding - models

Nitrogen is a key element in aquatic environments, and in Aquaculture it is an important pond management variable. In current aquaculture research two important goals are to maintain the water quality within the system, and to improve the retention of nutrients applied to the system in order to minimize the discharge. The principal objectives of this study were to integrate the information available of nitrogen processes in fish ponds into a predictive model, and to investigate further the nitrogen dynamics between the water, the sediments and the biota present in this systems. First, a nitrogen balance in fish ponds was followed along a growing cycle; by combining estimates of the deposition rates of uneaten feed, faeces and dead phytoplankton with measurements of nitrogen accumulation in the sediment, the rate of decomposition of organic matter in the sediment was evaluated. The cumulative recovery at the end of the experiment was almost 100%, meaning that the nitrogen budget in the system studied can be fully explained without any consideration of nitrogen volatilisation, due to either denitrification or ammonia volatilisation. The interactions between various N-species are complex and difficult to integrate. A model that calculates the amounts of various N-compounds in the water column and in the sediment was constructed, and used to gain insight into the relative importance of transformation processes between the various N-compounds. The model was divided into three modules: fish, phytoplankton and sediment-water.

All concentrations of the various N-species present were simulated well except the N retained in organic matter in the sediment. To improve our understanding of the bottom organic matter dynamics, and make the model a more comprehensive predictive tool, an estimation of the principal sources of organic matter that accumulate in fish pond bottoms was assessed. Organic matter accumulation in fish ponds was quantified, and the data was used to construct, to calibrate and to validate a dynamic simulation model of organic matter deposition/decomposition in fish ponds. Besides, the rates of sedimentation and resuspension were measured along a growing cycle, following the influence of nutrient input, water parameters, fish biomass and fish size on these processes. Using a dilution analysis method to differentiate between sedimented and resuspended particles, sedimentation and resuspension rates were calculated. The rate of material collected in sediment traps increased from 88.5 to 330 g/m 2 per day along the growing cycle, but the relative resuspension did not change significantly, being always in the range of 42 to 47% of the total collected material. The processes of sedimentation of organic matter and resuspension were included in the original model. The proportion of three principal sources of organic matter that accumulate in the pond bottom were also included as parameters of the sedimentation process. A logistic equation relating the rate of resuspension and the fish biomass was calculated; and seepage, as a potential loss of nitrogen from the system, was also considered. The additions to the model represented a substantial improvement to model simulations.

How fish benefit from floodplain restoration along the lower River Rhine
Grift, R.E. - \ 2001
Wageningen University. Promotor(en): E.A. Huisman; A.D. Buijse. - S.l. : S.n. - ISBN 9789058084880 - 205
vissen - rivieren - herstel - ecologie - aquatische ecosystemen - uiterwaarden - fishes - rivers - rehabilitation - ecology - aquatic ecosystems - river forelands

The objectives of this study were to test the beneficial value of newly created secondary channels and reconnected oxbow lakes along the lower River Rhine for fish and to give advice on position, shape and character of future water bodies. These water bodies should contribute to the rebuilding of the population of rheophilic cyprinids that are endangered due to embankment and normalization of the Rhine. The functions these water bodies fulfil during the life cycle of distinct fish species, were inferred from the description of patterns of presence of fish in time and space in 25 floodplain water bodies (secondary channels, oxbows, lakes). In all water bodies, depth, flow velocity and the presence of vegetation determine the fish community present. Secondary channels and reconnected oxbow lakes do have a beneficial value for the riverine fish community. They function as nursery areas for all rheophilic cyprinids (e.g. Barbus barbus , Leuciscus idus and Gobio gobio ). Secondary channels probably also function as spawning areas for L. idus and G. gobio but not for lithophilic species ( B. barbus , Leuciscus leuciscus ) since suitable substrate lacks. Eurytopic species ( Abramis brama , Rutilus rutilus and Stizostedion lucioperca ) use all types of floodplain water body to reproduce. For A. brama , isolated turbid clay-pits form important source areas from which juveniles recruit to the main channel during floods. The dominance of eurytopic species in the lower Rhine is caused by the large area of suitable spawning and nursery areas for these species relative to those of rheophilic species. For limnophilic species ( Tinca tinca , Rutilus erythrophthalmus ) suitable habitat (vegetated lakes) is also scarce and should be preserved. Within plans on flood protection, floodplain management should focus on increasing the number of secondary channels and on restoring the natural interaction between the river and its floodplains.

The impact of the dietary electrolyte balance on growth performance, energy metabolism and acid-base balance: a comparison between African catfish (Clarias gariepinus) and pigs
Dersjant-Li, Y. ; Verreth, J.A.J. ; Schrama, J.W. ; Huisman, E.A. ; Verstegen, M.W.A. - \ 2001
Aquaculture Research 198 (2001). - ISSN 1355-557X - p. 293 - 305.
Comparison of bale storage systems for biomass
Huisman, W. ; Jenkins, B.M. ; Summers, M.D. - \ 2000
In: Proceedings of the 1st world conference and exhibition on biomass for energy and industry London : James & James Ltd. - p. 241 - 244.
Enzymatic and mass spectrometric studies of complex xylans from various sources.
Schols, H.A. ; Huisman, M.M.H. ; Kabel, M.A. ; Voragen, A.G.J. - \ 2000
In: 2nd European symposium on enzymes in grain processing. : VTT symposium, Espoo 2000 Espoo : Technical Research Centre of Finland - ISBN 9789513857066 - p. 21 - 30.
Metabolic costs of changing the cation-anion difference in the diet of juvenile African catfish Clarias gariepinus (Burchell)
Dersjant-Li, Y. ; Verreth, J.A.J. ; Tijssen, P.A.T. ; Booms, R. ; Verstegen, M.W.A. ; Huisman, E.A. - \ 2000
Aquaculture Nutrition 6 (2000). - ISSN 1353-5773 - p. 39 - 45.
The influence of dietary cation-anion difference (CAD, Na K - Cl, mEq kg1) on energy metabolism and nitrogen losses in juvenile African catfish Clarias gariepinus (Burchell) was examined in fish exposed to different dietary CAD levels (-146, 116, 497, 713 and 828 mEq kg1 diet). The experiment was conducted in open circuit balance respiration chambers over a 3-week period. Five 24-h monitoring periods were carried out at 3-day intervals during the experimental period with O2 consumption, ammonia and nitrate nitrite (NOx) and CO2 production being measured at 5-min intervals for each chamber. The negative dietary CAD (-146 mEq kg1) resulted in the highest energy expenditures (83 kJ kg0.8? d1). With increasing dietary CAD levels, heat loss gradually decreased to minimum values of 56 kJ kg0.8 day1 at a dietary CAD level of 713 mEq kg1. Consequently, metabolizable energy utilization efficiency (MEU, percentage of retained energy over metabolizable energy) quadratically (P < 0.05) increased and reached a maximum at a dietary CAD of 713 mEq kg1.
Impact of dietary cation anion difference in fish and pigs: a comparative study
Dersjant-Li, Y. - \ 2000
Agricultural University. Promotor(en): M.W.A. Verstegen; E.A. Huisman; J.A.J. Verreth; J. Schrama. - S.l. : S.n. - ISBN 9789058082978 - 169
vissen - varkens - diervoedering - diervoeding - zuur-base-evenwicht - ph - groei - energiemetabolisme - voedingsfysiologie - fishes - pigs - animal feeding - animal nutrition - acid base equilibrium - ph - growth - energy metabolism - nutrition physiology

Dietary cation anion difference (CAD, Na + K - Cl, mEq kg -1 ) determines the pH and acid base status of a diet, consequently affecting the acid base balance in the body compartments of animals. After feeding, a low dietary CAD will contribute more acids to the animals than a high dietary CAD. An optimal dietary CAD will increase the acid buffer capacity of a diet and this will help animals to compensate for metabolic acidosis. It is hypothesized that with an optimal dietary CAD, less energy will be needed for acid base regulation, indirectly improving feed intake and growth of animals. In the present study the effect of dietary CAD on growth performance, energy metabolism, acid base balance in the blood and in the digestive system were investigated in African catfish and pigs. The study consisted of 3 parts. Part 1 dealt with the growth response to dietary CAD and dietary Na/K ratio. Part 2 dealt with the energetic response to dietary CAD. Parts 3 dealt with the acid base balance in the blood and in the digestive system in response to dietary CAD. A negative dietary CAD (-100 mEq kg -1 ) resulted in a low feed intake and growth in both African catfish and young pigs. In African catfish, increasing dietary CAD from -100 to 700 mEq kg -1 led to a linear increase in growth.

In pigs, the optimal dietary CAD was observed to be between 200 and 500 mEq kg -1 . The optimal dietary Na/K ratio in formulating dietary CAD was 1.5 to 2.5 (mol/mol) for African catfish. The lowest maintenance cost was observed at a dietary CAD level of 700 mEq kg -1 for African catfish. In pigs, dietary CAD of 200 mEq kg -1 tended to increase energy requirement for maintenance compared with dietary CAD of -100 mEq kg -1 , at restricted feeding. In pigs, a -100 mEq kg -1 CAD diet resulted in low blood pH, oxygen and HCO 3- content (mmol L -1 ) compared to a 200 mEq kg -1 CAD diet. During the postprandial period, however, pigs maintained a relative constant pH level in both portal and arterial blood within each CAD group. African catfish fed 700 mEq kg -1 CAD diet showed higher stomach digesta pH than fish fed -100 mEq kg -1 CAD diet both 0.5 and 3 h after feeding. However, no difference in pH of small intestine digesta was observed. In pigs, dietary CAD levels of -100 and 200 mEq kg -1 did not affect either stomach or small intestine digesta pH 2.5 h after feeding. The possible mechanisms of dietary CAD effect on feed intake and growth were discussed.

Recent advances in the chemistry and enzymology of (glucurono)arabinoxylans
Voragen, F. ; Huisman, M. ; Kabel, M. ; Laere, K. van; Broek, B. van den; Schols, H. - \ 2000
In: Proceedings 10th International Symposium Plant Polysaccharides 2000 : 10th International Symposium Plant Polysaccharides 2000, Wageningen, 2000 Wageningen : Wageningen University and Research Centre - p. 16 - 16.
Selective breeding for stress response in common carp (Cyprinus carpio L.) using androgenesis
Tanck, M. - \ 2000
Agricultural University. Promotor(en): E.A. Huisman; E.W. Brascamp; J. Komen. - S.l. : S.n. - ISBN 9789058083470 - 185
cyprinus - karper - selectief fokken - androgenese - stressreactie - genetica - hydrocortison - cyprinus - carp - selective breeding - androgenesis - stress response - genetics - hydrocortisone

The aim of the thesis was to explore the genetic background of stress response in common carp ( Cyprinus carpio L.) and produce homozygous and heterozygous isogenic strains with divergent stress responses. As stressor a rapid temperature decrease (= cold shock) was used. As a preparatory step, a number of experiments were carried out to 1) investigate the validity of the cold shock as a stressor, 2) investigate the possible influences of environmental factors on the stress response, and 3) define a selection criterion for the selection experiment. The stress response of common carp was studied by evaluating plasma cortisol, glucose and lactate after single or multiple rapid temperature drops (ΔT: 7, 9 or 11 °C). All three amplitudes used induced a significant rise in plasma cortisol levels. Peaks occurred within 20 min after onset of the cold shock. No stress-related related secondary metabolic changes were observed in any of the experiments described: plasma glucose levels remained unaffected and plasma lactate levels dropped. Carp of 60 days old showed a significant stress response, although plasma cortisol levels were lower than those observed in carp of 120 days. Furthermore, fish that had experienced multiple cold shocks showed an overall lower cortisol response than fish experiencing a single cold shock, indicating that habituation to this stressor occurred. Based on these results, the plasma cortisol concentration at 20 min after onset of the cold shock was set as selection criterion in our selection experiment and fish were tested at a minimal age of 100 days post hatching.

The first step in the actual selection experiment was the formation of the base population. This base population was an F 1 cross between six sires from a wild strain originating from the Anna Paulowna (AP) polder and a highly domesticated homozygous E4 dam already present in our laboratory. The six sires, caught in the water system surrounding the Anna Paulowna (AP) Polder in The Netherlands, were characterised using allozyme and microsatellite markers. At the sMDH-A1,2* loci an allele was found, which was previously only found in wild River Rhine and wild Vietnamese common carp. Microsatellite allele frequencies showed that these AP carp were significantly different from a group of carps originating from several different domesticated strains. Based on both allozyme and microsatellite data, the AP carp most likely originated from a wild or feral self-sustaining population.

Thirty-three randomly picked sires from these six E4 × AP full-sib families (F 1 ) were androgenetically reproduced to create the F 2 generation, which thus consisted of 33 doubled haploids (DH) progeny groups. These 33 DH progeny groups (566 individuals) were subjected to the 9 °C cold shock, enabling us to estimate heritabilities for weight, length, condition factor (K), and plasma cortisol, glucose and lactate concentrations using Gibbs sampling and an animal model. Estimated heritabilities for the morphological traits weight and length were 0.09 (90% Highest Posterior Density range: 0.03 - 0.17) and 0.11 (0.04 - 0.21), respectively. The condition factor (K), showed a medium heritability of 0.37 (0.20 - 0.62). Heritabilities for basal plasma glucose and lactate were 0.19 (0.10 - 0.33) and 0.56 (0.33 - 0.85), respectively. For stress-related cortisol increase a high heritability estimate of 0.60 (0.37 - 0.90) was found. Although the height of this cortisol heritability has to be regarded with some reservation, due to confoundedness of some environmental effects with sire effects, the estimated heritability clearly shows that the stress response due to a cold shock is hereditary in the carp population used.

Because the model used to estimate the h2 assumed a complete homozygous state of the DH individuals and to ensure that only homozygous individuals would be used for subsequent reproduction, all individuals within the 33 DH androgenetic progeny groups were analysed using 11 microsatellite markers to: 1) verify the homozygous status of the 566 androgenetic DH individuals, 2) analyse the microsatellite allele segregation, and 3) study possible association of microsatellite alleles with the phenotypic traits recorded. In total, 92% of the androgenetic DH individuals proved to be homozygous at all 11 loci. Forty-three out of the 47 heterozygous individuals were heterozygous at a single locus only. This heterozygosity was probably due to DNA fragments caused by UV-irradiation of the eggs, although the maternal origin of the fragments could not be proved beyond doubt. Screening with 11 microsatellites also revealed two linkage groups, a segregation distortion at two microsatellite loci and possible association of some microsatellites with weight, length, stress-related plasma cortisol levels and basal plasma glucose levels. The success of the linkage and association study could be explained by a low recombination frequency due to high chiasma interference. This would imply a relatively short genetic map length for common carp.

Selection of individual fish from the 33 DH progeny groups based on the response at 4 months was not possible. Therefore, three DH progeny groups with a high (H1-3) and three with a low (L1-3) mean plasma cortisol concentration were selected. The 154 DH fish in these six groups were individually tagged, mixed and subjected to a second cold shock at an age of 15 months. For each individual fish, a breeding value was estimated (EBV 15 ) for stress-related cortisol using an animal model with a fixed h 2 of 0.60. Two homozygous sires (two high and two low) and dams (high and low) were selected based on their EBV 15 and used to produce four homozygous (HomIso) and eight heterozygous isogenic (HetIso) strains. These were used in two separate experiments to examine the genetic background of the stress-related cortisol response. In both experiments, the strains were subjected to the 9 °C cold shock at an age of 5 months. The ranking in plasma cortisol levels of the HomIso strains was identical to the ranking in EBV 15 of the sires and the maximal difference of 350 nmol.l -1 was similar to the expected difference based on these EBV 15 's. Differences between the HetIso strains were smaller than expected, and influence of non-additive genetic effects could not be detected ( PD×S = 0.14). Estimated breeding values based on the performance of the androgenetic progeny (EBV 5 ) in experiment 1 and general combining abilities (GCA) of the sires and dams calculated in experiment 2 were positively correlated with the EBV 15 ( r not significantly different from 1), providing no evidence that the stress response at 5 and 15 months are different traits.

Apart from the isogenic strain used in the first experiments, no complete profiles of the cortisol, glucose and lactate dynamics had been examined in other isogenic strains. Therefore, an additional experiment, parallel to the selection experiment, was carried out to investigate the 'complete' cortisol, glucose and lactate dynamics during the cold shock in four, readily available, isogenic at two different ages. The experiments showed that stress-related cortisol response patterns can differ consistently between genotypes of common carp. Significant dam and sire effects on the total amount of cortisol measured during the cold shock were found, but no significant dam × sire interaction effect. Although no significant difference was found between the cortisol response dynamics at 5 or 7 months, the results justify further research into that field. The observed differences in plasma glucose and lactate dynamics between control and shocked fish were most likely temperature related. Age did not have any apparent influence on either plasma glucose or lactate dynamics in both control and shocked fish.

Based on the results of the experiments described in this thesis, it can be argued that the best method to change the stress response of common carp would be through selective breeding (exploiting additive genetic effects) rather than through crossbreeding (exploiting non-additive genetic effects). The selection and the 'parallel' experiments resulted in several isogenic strains of common carp with at least two types of cortisol stress responses. Type I showed a relative short cortisol response with either a high or low peak at 20 min after onset of the shock. Type II showed a similar cortisol level at 20 min but no significant decrease in this level during the cold shock. These different isogenic strains will be valuable tools in future research into the stress response itself and its effects on other traits like growth, reproduction and health. This way, some of the problems related to the use of stress response as selection criterion in commercial breeding programmes in fish could be solved in the near future.

Residual heterozygosity was demonstrated to occur in androgenetic progenies, most likely due to maternal DNA fragments induced by the UV irradiation of the eggs. Improved control measures were implemented in the androgenesis procedure, but androgenetic progenies destined for further reproduction purposes should be screened for residual heterozygosity. Androgenetic reproduction proved to be a useful tool for dissection of phenotypic variance and heritability estimations for traits, especially in combination with selection experiments aimed at development of isogenic strains for this trait. Androgenesis might result in reduced fertility in female progeny, but the advantages are such that inclusion of androgenetic reproduction within larger commercial breeding programmes for faster dissemination of genetic progress and product protection should be considered as a promising option.

Options for co-management of an Indonesian coastal fishery
Pet-Soede, C. - \ 2000
Agricultural University. Promotor(en): E.A. Huisman; M.A.M. Machiels. - S.l. : S.n. - ISBN 9789058081841 - 135
visserij - visserijbeheer - kustwateren - indonesië - fisheries - fishery management - coastal water - indonesia

Perceptions of fisheries authorities and fishers on the status of the fisheries and fish stocks in Spermonde Archipelago, a coastal shelf off SW Sulawesi, Indonesia, seem to concur. However, constraints imposed by the administrative and physical environment and by the weak contrasts in fishery outcome within Spermonde cause these partners cannot find realistic arguments for a causal relation between catch and effort from their experiences. Therefore co-management for fisheries in this area is not yet viable. More informative use of fisheries data by standardising the unit of effort, accounting for the fast developments in motorization, and combining data on fisheries and ecological grounds rather than on administrative grounds will increase the management value of already available official data. Exchange of experiences between local fisheries authorities and fishers from districts or provinces with highly contrasting levels of fishing intensity will facilitate discussions on the need and benefits of effort regulations.

Effects of dietary L-carnitine supplements on the fatty acid and amino acid metabolism of African catfish (Clarias gariepinus) fed low-lysine diets
Ozorio, R. ; Huisman, E.A. ; Verreth, J.A.J. - \ 2000
In: Proc. IX Int. Symp. on Nutrition and Feeding of Fish, June 2000, Japan
Interactions between fisheries and birds in IJsselmeer, The Netherlands
Mous, P.J. - \ 2000
Agricultural University. Promotor(en): E.A. Huisman; M.A.M. Machiels; A.D. Rijnsdorp. - S.l. : S.n. - ISBN 9789058081834 - 205
visserij - vis - vogels - ijsselmeer - fisheries - fish - birds - lake ijssel

IJsselmeer, a eutrophic, shallow lake (mean depth 4 m) of 180,000 ha, is heavily exploited by a fishery that catches dfl 11 million worth of eel Anguilla anguilla , perch Perca fluviatilis , pikeperch Stizostedion lucioperca and of the small zooplanktivorous smelt Osmerus eperlanus, the main prey for perch and pikeperch and for the piscivorous birds of IJsselmeer. The population of cormorant Phalacrocorax carbo affects the fisheries through its predation on perch and pikeperch, whereas black tern Chlidonias niger and black-headed gull Larus ridibundus are affected by the availability of smelt in IJsselmeer. The spatial distribution of prey fish and piscivorous birds was described as a function of spatial scale, water transparency and water depth. The carrying capacity of IJsselmeer for the production of prey fish was assessed, and a dynamic simulation model was constructed to predict consequences of fishery management measures on the fisheries and on the food availability for piscivorous birds.

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