Staff Publications

Staff Publications

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

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

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

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Versleping in de mengvoederindustrie : inventarisatie en evaluatie van methoden voor het bepalen van bedrijfseigen versleping bij de productie van mengvoeder
    Bikker, P. ; Beumer, H. ; Goeij, E.J. de; Hooglugt, J. ; Wegh, R. ; Egmond, H.J. van - \ 2017
    Wageningen : RIKILT Wageningen University & Research (RIKILT-rapport 2017.003) - 51
    mengvoer - veevoederindustrie - wetgeving - nederland - voedertoevoegingen - compound feeds - feed industry - legislation - netherlands - feed additives
    Mengvoederfabrikanten dienen veilige diervoeders van goede kwaliteit te leveren ter bescherming van de dier- en volksgezondheid en het milieu. Door technische en organisatorische maatregelen moet (kruis)verontreiniging met ongewenste stoffen, toevoegingsmiddelen en diergeneesmiddelen zo veel mogelijk worden beperkt (Verordening 183/2005/EG). Om hieraan te kunnen voldoen schrijven nationale kwaliteitssystemen zoals GMP+ International B.V. (GMP+) in Nederland voor om de versleping van productielijnen van mengvoeders te bepalen en hiermee rekening te houden bij de productie van voeders met kritische stoffen. Een goede procedure en uitvoering van de verslepingstest zijn van belang voor de mengvoederbedrijven en voor de controlerende instanties zoals de NVWA om de doelmatigheid van beheersmaatregelen te beoordelen. Het doel van dit project was daarom: - inventariseren van de methoden die binnen GMP+ gebruikt (mogen) worden voor het bepalen van het bedrijfseigen -verslepingspercentage; - in kaart brengen van de kritische stappen in de methoden en uitvoering ervan; - opstellen van aanbevelingen voor het verbeteren en uniformeren van de verslepingstesten ten behoeve van de betrouwbaarheid en vergelijkbaarheid van de resultaten.
    Low Emission Feed : using feed additives to decrease methane production in dairy cows
    Klop, G. - \ 2016
    Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Jan Dijkstra; Andre Bannink. - Wageningen : Wageningen University - ISBN 9789462578944 - 168
    feeds - emission - feed additives - dairy cows - methane production - nitrates - docosahexaenoic acid - milk composition - voer - emissie - voedertoevoegingen - melkkoeien - methaanproductie - nitraten - docosahexaeenzuur - melksamenstelling

    Research into manipulating methane (CH4) production as a result of enteric fermentation in ruminants currently receives global interest. Using feed additives may be a feasible strategy to mitigate CH4 as they are supplied in such amounts that the basal diet composition will not be largely affected. The latter is relevant because ruminants have the capacity to convert human inedible feedstuffs into human edible energy and protein. However, the application of CH4 mitigation feed additives may be hampered by several negative side effects including trade-offs with other environmental impacts, negative effects on animal performance, and lack of persistency of the mitigating effect. The research described in this thesis addresses both the mitigating effect of feed additives as well as its persistency. The main focus was on investigating additivity of the CH4 mitigating effect of feed additives, on the adaptation of rumen microbes to long term feeding of feed additives, and on exploring the potential of rotational feeding of additives to avoid (or reduce) microbial adaptation.

    In an experiment with lactating dairy cows in climate respiration chambers to study potential interactions between the effects of feeding nitrate and docosahexaenoic acid (DHA; C22:6 n-3) on enteric CH4 production, the effects of nitrate and DHA on CH4 yield [g/kg dry matter intake (DMI)] and CH4 intensity [g/kg fat- and protein- corrected milk (FPCM)], were additive (Chapter 2). Nitrate decreased CH4 irrespective of the unit in which it was expressed, and the average decline in CH4 emission corresponds to 85% of the stoichiometric potential of nitrate to decrease CH4. Feeding DHA had no effect on CH4 yield, but resulted in a higher CH4 intensity, because of milk fat depression. The interaction effect between nitrate and DHA on fiber digestibility indicated that negative effects of nitrate on apparent total tract digestibility of nutrients were alleviated by DHA, probably due to an altered feed intake pattern.

    Using an isotope measurement protocol in the same study, it was demonstrated that effects of nitrate as a CH4 mitigating feed additive on fiber degradation in the rumen can be detected by evaluating diurnal patterns of 13C enrichment of exhaled CO2 (Chapter 3). Feeding nitrate, but not DHA, resulted in a pronounced increase in 13C enrichment of CO2 in the first 3 to 4 h after feeding only. Results support the hypothesis that effects of a feed additive on the rate of fiber degradation in the rumen can be detected by evaluating diurnal patterns of 13C enrichment of CO2. A prerequisite for this detection method is that the main ration components differ in natural 13C enrichment (e.g., C3 and C4 plants), and in content of the nutrients that are expected to be involved in a shift in fermentation (e.g., starch and fiber) or in degradability of a nutrient.

    In a combined in vivo and in vitro trial, the adaptation to CH4 mitigating feed additives, viz. an essential oil blend or lauric acid (C12:0), compared with a control diet was first investigated using the in vitro gas production technique during the period that lactating cows were adapting to certain feed additives (Chapter 4). Rumen fluid was collected from each cow at several days relative to the introduction of the additives in the diets and used as inoculum for the gas production experiment with each of the three different substrates that reflected the treatment diets offered to the cows. The feed additives in the donor cow diet had a stronger effect on in vitro gas and CH4 production than the same additives in the incubation substrate. From day 4 onwards, the C12:0 diet persistently reduced gas and CH4 production, total volatile fatty acid concentration, acetate molar proportion and in vitro organic matter degradation, and increased propionate molar proportion. In contrast, in vitro CH4 production was reduced by the essential oils diet on day 8, but not on days 15 and 22. In line with these findings, the molar proportion of propionate in fermentation fluid was higher, and that of acetate smaller, for the essential oils diet than for the control diet on day 8, but not on days 15 and 22. Overall, the data indicate a transient effect of the essential oils on CH4 production, which may indicate microbial adaptation, whereas the CH4 mitigating effect of C12:0 persisted. It is recommended that this phenomenon is considered in the planning of future studies on the mitigation potential of feed additives in vitro.

    In a follow-up in vivo study, it was investigated whether the alternate feeding of two CH4 mitigating feed additives with a different mode of action (viz. C12:0 and a blend of essential oils) would result in a persistently lower CH4 production compared to feeding a single additive over a period of 10 weeks. The experiment comprised a pre-treatment period and three two-week measurement periods, with two periods of 2 weeks in between in which CH4 emission was not measured. Cows received either continuously the essential oil blend, or both the essential oil blend and C12:0 following a weekly rotation schedule (Chapter 5). Both CH4 yield and CH4 intensity changed over time, but were not affected by treatment. Methane yield and intensity were significantly lower (12 and 11%, respectively) in period 1 compared with the pre-treatment period, but no significant difference relative to the pre-treatment period was observed in period 3 (numerically 9 and 7% lower, respectively) and in period 5 (numerically 8 and 4% lower, respectively). These results indicate a transient decrease in CH4 yield and intensity in time, but no improvement in extent or persistency of CH4 reduction due to rotational feeding of essential oils and C12:0 in lactating dairy cows. However, there were indications that the concept of rotation may be effective and warrants further investigation.

    The additives and concepts tested in this thesis are applied under specific experimental conditions. More mechanistic understanding is required to predict the response of the same additives when supplemented to other basal diets or cows in a different physiological state. Trade-offs in environmental impact, and effects on cow health and performance, and on milk processing parameters and food safety are important aspects to consider in future research on the application of feed additives as CH4 mitigation strategy.

    Immuunsysteem sturen met voer
    Have, H. ten; Smits, M.A. - \ 2015
    V-focus 12 (2015)4. - ISSN 1574-1575 - p. 20 - 21.
    varkens - varkenshouderij - diergezondheid - varkensvoeding - voedertoevoegingen - immuunsysteem - antigenen - darmen - pigs - pig farming - animal health - pig feeding - feed additives - immune system - antigens - intestines
    Het onderzoeksprogramma Feed4Foodure werkt aan een meetlat om te voorspellen wat het vermogen is van een dier om adequaat te reageren als het wordt blootgesteld aan ziekteverwekkers. Dit wordt de immuuncompetentie van het dier genoemd. Deze immuuncompetentie is te beïnvloeden door onder andere diervoeding en voederadditieven, vertelt onderzoeker Mari Smits van Wageningen UR.
    Biological processes induced by ZnO, Amoxicillin, Rye and Fructooligosaccharides in cultured Intestinal Porcine Epithelial Cells : VDI-4; In-vitro tests 2013-2014
    Hulst, M.M. ; Hoekman, A.J.W. ; Wijers, I. ; Schokker, D. ; Smits, M.A. - \ 2015
    Wageningen : Wageningen UR Livestock Research (Livestock Research report 882) - 42
    in vitro - bioassays - epithelium - livestock - feed additives - genes - immunology - in vitro - biotesten - epitheel - vee - voedertoevoegingen - genen - immunologie
    The objective of this study was to develop an in-vitro bioassay using cultured Intestinal Porcine Epithelial Cells (IPEC-J2) and evaluate the capability of this assay to predict enterocyte-specific physiological and immunological processes induced by nutrients/additives in the intestines of farm animals. Responses to five nutrients/feed-additives, similar to those studied in animal trials, performed in the Feed4Foodure framework, were measured by gene expression analysis of IPEC-J2 cells either under stressed (Salmonella) or non-stressed conditions. Response genes were analysed using bioinformatics web-tools in order to identify dominant biological processes induced by these nutrients/feed-additives and to predict key-genes/proteins important for regulation of these biological proc
    Copper in diets for weaned pigs : influence of level and duration of copper supplementation
    Bikker, P. ; Baal, J. van; Binnendijk, G.P. ; Diepen, J.T.M. van; Troquet, L.M.P. ; Jongbloed, A.W. - \ 2015
    Wageningen : Wageningen UR Livestock Research (Livestock Research report 830) - 38
    varkens - biggen - spenen - koper - diervoedering - minerale supplementen - groei - dunne darm - voedertoevoegingen - biggenvoeding - pigs - piglets - weaning - copper - animal feeding - mineral supplements - growth - small intestine - feed additives - piglet feeding
    This study was conducted to determine the influence of level (15-160 mg/kg voer)and period (2-8 weeks) of supply of a Cu-supplement on growth performance and expression of Cu absorption-related genes in different segments of the small intestine of weaned pigs.
    Algae cultivation profitable by 2025
    Wijffels, R.H. - \ 2014
    voer - diervoedering - diervoeding - voedertechnologie - maling - voedertoevoegingen - ingrediënten - markten - statistiek - veevoederindustrie - voedermiddelbewerking - feeds - animal feeding - animal nutrition - feed technology - milling - feed additives - ingredients - markets - statistics - feed industry - feed processing is tailored towards the information needs of the international feed business community and is complementary to our print publications Feed Tech and Feed Mix. The site offers the worldwide feed industry: news, industry opinions, a newsletter, article archives, market information, and statistics, and much more
    Versleping in de mengvoederindustrie : inventarisatie van de huidige (technologische) situatie
    Hooglugt, J. ; Sterrenburg, P. ; Spiegel, M. van der; Egmond, H.J. van; Bikker, P. ; Beumer, H. - \ 2014
    Wageningen : RIKILT Wageningen UR (RIKILT rapport 2014.003) - 49
    mengvoer - veevoederindustrie - coccidiostatica - wetgeving - nederland - eu regelingen - voedertoevoegingen - sectorale analyse - compound feeds - feed industry - coccidiostats - legislation - netherlands - eu regulations - feed additives - sectoral analysis
    De Food en Veterinary Office van de EC heeft in 2010 geconstateerd dat de Nederlandse mengvoederindustrie niet voldoende deed om versleping te voorkomen. Dit heeft er toe geleid dat het Ministerie van EL&I behoefte had aan een inventarisatie van de huidige situatie m.b.t. versleping. In dit rapport worden de resultaten van deze inventarisatie gepresenteerd.
    Literatuurstudie en in vitro onderzoek naar antibacteriële werking van voeradditieven ter vermindering van de Streptococcus suis problematiek = Desk study and in vitro analysis of antibacterial effects of feed additives to reduce Streptococcus suis in the field
    Smith, H.E. ; Greeff, A. de; Faber, I. ; Peet-Schwering, C.M.C. van der; Kluivers-Poodt, M. ; Troquet, L.M.P. - \ 2014
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 760) - 8
    varkenshouderij - varkensziekten - varkensvoeding - voedertoevoegingen - antibacteriële eigenschappen - streptococcus suis - dierziektepreventie - pig farming - swine diseases - pig feeding - feed additives - antibacterial properties - streptococcus suis - animal disease prevention
    In opdracht van het Productschap Vee en Vlees en het ministerie van Economische Zaken is een literatuurstudie uitgevoerd naar voeradditieven waarvan beschreven is dat zij een direct bacteriedodend effect hebben, bij voorkeur tegen Streptococcus suis. De top 5 voeradditieven, die uit deze studie naar voren kwam, te weten oregano, knoflook, kaneel, laurinezuur en monolauraat zijn vervolgens in vitro getest op de bacteriedodende werking tegen verschillende Streptococcus suis stammen van serotype 2 en 9.
    Effects of herbal products in vitro and in vivo
    Groot, M.J. ; Pikkemaat, M.G. ; Driessen-van Lankveld, W.D.M. ; Eerden, M.E. van; Klis, J.D. van der - \ 2013
    diervoeding - geneeskrachtige kruiden - voedertoevoegingen - antimicrobe-eigenschappen - anti-infectieuze middelen - diergezondheid - animal nutrition - herbal drugs - feed additives - antimicrobial properties - antiinfective agents - animal health
    The aim of the study was to examine the antimicrobial action of herbal feed additives and the relation between this antimicrobial action and performance data in vivo and gut histology (villus/crypt ratio) as parameter for gut health.
    Carry-over in compound feed production : interpretation of EU legislation concerning sampling and control strategies for carry-over of coccidiostats
    Spiegel, M. van der; Sterrenburg, P. ; Egmond, H.J. van - \ 2013
    Wageningen : RIKILT Wageningen UR (RIKILT report 2013.014)
    wetgeving - europa - bemonsteren - statistische steekproeftechnieken - controle - bestrijdingsmethoden - analytische methoden - voedertoevoegingen - coccidiostatica - antiprotozoaire middelen - nederland - legislation - europe - sampling - statistical sampling techniques - control - control methods - analytical methods - feed additives - coccidiostats - antiprotozoal agents - netherlands
    The objective of this study is to give recommendations to the Dutch Ministry of Economic Affairs and the Dutch Food and Product Safety Authority on the interpretation of the EU legislation with respect to sampling and control of carry-over in coccidiostats in feeds in the Netherlands. To this end, relevant EU legislation has been listed and it has been examined how the Netherlands and seven other EU Member States interpret the law regarding sampling and evaluation of analytical results of the flushing charge.
    Versleping in de mengvoederindustrie : interpretatie van de EU wetgeving met betrekking tot bemonsterings- en controlestrategieën voor coccidiostatica versleping
    Spiegel, M. van der; Sterrenburg, P. ; Egmond, H.J. van - \ 2013
    Wageningen : RIKILT Wageningen UR (Rapport / RIKILT 2013.013)
    mengvoer - voedertoevoegingen - coccidiostatica - protozoa - bemonsteren - voederkwaliteit - voersamenstelling - locatie - wetgeving - gemeenschappelijk landbouwbeleid - Nederland - compound feeds - feed additives - coccidiostats - protozoa - sampling - forage quality - feed formulation - location - legislation - cap - Netherlands
    De doelstelling van dit onderzoek is om aanbevelingen te geven aan het Ministerie van Economische Zaken en de Nederlandse Voedsel en Waren Autoriteit voor de interpretatie van de EU-wetgeving m.b.t. de bemonstering en controle voor versleping van coccidiostatica in mengvoeders in Nederland. Hiervoor wordt m.b.v. een enquête de relevante EU-wetgeving geïnventariseerd, en wordt onderzocht hoe Nederland en 7 andere EU-lidstaten de huidige wetgeving wat betreft monstername en analyseresultaten van de spoelcharge interpreteren.
    Nitraat voeren effectief tegen methaanemissie
    Vegte, D.Z. van der; Sebek, L.B. ; Hilhorst, G.J. ; Verloop, K. - \ 2013
    V-focus 10 (2013)4. - ISSN 1574-1575 - p. 30 - 31.
    melkveehouderij - herkauwersvoeding - melkveevoeding - nitraat - voersamenstelling - voedertoevoegingen - methaan - emissiereductie - mineralenboekhouding - dairy farming - ruminant feeding - dairy cattle nutrition - nitrate - feed formulation - feed additives - methane - emission reduction - nutrient accounting system
    Nitraat is niet alleen een waardevolle kunstmest, maar kan ook als voeradditief gebruikt worden om de methaanemissie uit de pens van herkauwers te verminderen. Voor een klimaatneutrale melkveehouderij kan het een belangrijk middel zijn om de doelstelling te verwezenlijken. Daarom heeft Knowledge Transfer Centre De Marke in een pilotexperiment onderzocht of het voeren van nitraat past in het management van het melkveebedrijf en of er risico’s voor de diergezondheid zijn. Ook is onderzocht wat het effect van deze extra stikstofbron is op de N-kringloop van het bedrijf. Als de vermindering van de methaanemissie gepaard gaat met meer verliezen uit de N-kringloop (nitraatuitspoeling, ammoniakemissie en lachgasemissie) dan is het middel misschien erger dan de kwaal.
    Feed additives : annual report 2012 of the National Reference Laboratory
    Driessen, J.J.M. ; Beek, W.M.J. ; Zuidema, T. ; Jong, J. de - \ 2013
    Wageningen : RIKILT Wageningen UR (Report / RIKILT Wageningen UR 2013.008) - 15
    voedertoevoegingen - toevoegingen - conserveermiddelen - versterkers (enhancers) - voer - mycotoxinen - feed additives - additives - preservatives - enhancers - feeds - mycotoxins
    This report of the Dutch National Reference Laboratory (NRL) for feed additives (RIKILT Wageningen UR) descreibes the activities employed in 2012. The main tasks of the NRL are: providing assistance to the European Union Reference Laboratory (EURL) on their request, as well as providing advice and support to the competent authority, which is the Dutch Ministry of Economic Affairs - Department 'Plantaardige Agroketens en Voedselkwaliteit'.
    Feed additives : annual report 2011 of the National Reference Laboratory
    Driessen, J.J.M. ; Beek, W.M.J. ; Jong, J. de - \ 2012
    Wageningen : RIKILT Wageningen UR (Report / RIKILT Wageningen UR 2012.006) - 15
    diervoeding - veevoeder - voedertoevoegingen - jaarverslagen - animal nutrition - fodder - feed additives - annual reports
    This report describes the activities employed by RIKILT regarding the functions as: - the National Reference Laboratory (NRL) for feed additives; - advice regarding temporary use exemptions, other advice and support of EL&I. This report also presents the activities by the NRL to keep up expertise on the analysis of feed additives like participation in proficiency tests and presenting (posters, abstracts, publications)analytical research.
    Effecten van voeding op darmgezondheid van leghennen = Effects of nutrition on intestinal health of laying hens
    Veldkamp, T. ; Krimpen, M.M. van - \ 2012
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 548) - 27
    diergezondheid - pluimveevoeding - pluimveehouderij - hennen - spijsverteringskanaal - darmen - voersamenstelling - voedingsrantsoenen - voedertoevoegingen - biologische landbouw - dierenwelzijn - animal health - poultry feeding - poultry farming - hens - digestive tract - intestines - feed formulation - feed rations - feed additives - organic farming - animal welfare
    Intestinal health is of vital importance for health and welfare of laying hens and nutrition may have a significant contribution. Insoluble non-starch polysaccharides (NSP) and feed additives such as herbs, phytogenic material, probiotics and prebiotics, organic acids and enzymes may have a beneficial effect on intestinal health.
    Inkuilen van eendenkroos als veevoer met verschillende additieven = Ensiling Duckweed for feed with different additives
    Hoving, I.E. ; Schooten, H.A. van; Holshof, G. ; Houwelingen, K.M. van; Geest, W. van de - \ 2011
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 528) - 30
    waterplanten - lemna - vochtgehalte - droging - kuilvoerbereiding - voedertoevoegingen - kuilvoerfermentatie - aquatic plants - lemna - moisture content - drieration - silage making - feed additives - silage fermentation
    Ferment duckweed as silage is a cheap and sustainable alternative for drying. Without an additive, no satisfying preservation result was reached. Molasses gave a good preservation result and is relatively cheap and practical. Common methods of forage ensilaging are not suitable for duckweed as they have too little product structure to facilitate wrapping. The use of an airtight container or silo may lead to good preservation results, and prevent losses.
    Invloed van kunstmelk en voersamenstelling na spenen op energieopname en Streptococcus suis infecties bij biggen = Effect of milk intake and feed composition after weaning on energy intake and Streptococcus suis infection in piglets
    Peet-Schwering, C.M.C. van der; Dirx-Kuijken, N.C.P.M.M. ; Binnendijk, G.P. ; Raymakers, R. - \ 2011
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 529) - 34
    varkenshouderij - biggen - biggenvoeding - kunstmelk - speenleeftijd - energieopname - streptococcus suis - spenen - voedertoevoegingen - voersamenstelling - pig farming - piglets - piglet feeding - filled milk - age at weaning - energy intake - streptococcus suis - weaning - feed additives - feed formulation
    At Swine Innovation Centre Sterksel it was investigated whether the supply of milk during six days after weaning and the supply of an optimized pre-starter diet can increase the energy intake of the piglets after weaning and reduce the number of weaned piglets with clinical signs of an infection with Streptococcus suis. The results are described in this report.
    Sturen in melkproductie en melksamenstelling : verkennende studie naar de effecten van Clinoptiloliet
    Verwer, C.M. ; Eekeren, N.J.M. van - \ 2011
    [S.l.] : Louis Bolk Instituut (Biogeit rapport / Louis Bolk Instituut 23) - 25 p.
    geitenhouderij - clinoptiloliet - voedertoevoegingen - melkproductie - melksamenstelling - biologische landbouw - goat keeping - clinoptilolite - feed additives - milk production - milk composition - organic farming
    In dit Biogeit rapport wordt een praktijkonderzoek beschreven naar de effecten van Clinoptiloliet op de melkproductie en melksamenstelling van geiten. Voor het onderzoek zijn 50 nieuwmelkte geiten gebruikt. De geiten werden verdeeld over 2 groepen; een controle-groep en een Clinoptiloliet-groep. Clinoptiloliet werd verstrekt nadat alle dieren minimaal 6 weken in lactatie waren. Gedurende 6 maanden zijn om de 6 weken melkmonsters genomen om per individu de melkproductie, vetgehalte en eiwitgehalte te bepalen. Bij de start van het onderzoek en aan het einde van het onderzoek is ook het celgetal per geit bepaald. Clinoptiloliet had geen (neven)effect op de melkproductie en het eiwitgehalte van de melk. Clinoptiloliet had een positief verhogend effect op het vetgehalte van de melk met ongeveer 0.1-0.4 %.
    Dietary strategies to reduce methane emissions from ruminants
    Zijderveld, S.M. van - \ 2011
    Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Jan Dijkstra; Walter Gerrits. - [S.l.] : S.n. - ISBN 9789461730220 - 132
    rundvee - diervoedering - melkkoeien - voedertoevoegingen - methaanproductie - cattle - animal feeding - dairy cows - feed additives - methane production

    Ruminant products form an important part of the human diet. The demand for ruminant products is expected to increase due to the increase in the size of the human population and its increasing wealth. The production of ruminant meat and milk is associated with a relatively large environmental impact when compared to other animal products. This is, for a large part, caused by the fact that ruminants produce enteric methane, a greenhouse gas, during the digestion of their feed. Many dietary strategies have been proposed to lower methane production in ruminants, although most of these have only been tested in vitro. In this thesis, a number of dietary strategies, that had been proven effective in vitro, were evaluated for their in vivo efficacy in methane reduction. A mixture of lauric acid, myristic acid, linseed oil and calcium fumarate lowered methane production by 10% in lactating dairy cows. However, fat and protein corrected milk production was negatively affected by feeding this mixture. Despite the methane reduction, energy balance was unaltered in this study. Diallyldisulfide, yucca powder, calcium fumarate, an extruded linseed product and a mixture of capric and caprylic acid did not affect methane production in lactating dairy cows, although their efficacy had been demonstrated in vitro. The addition of nitrate and sulfate to sheep diets lowered in vivo methane emissions (-32% and -16%, respectively), presumably by acting as a hydrogen sink in the rumen. No negative side-effects of feeding nitrate or sulfate were observed in this study. The use of nitrate in methane mitigation was further evaluated in a long-term study with dairy cows. Dietary nitrate persistently lowered methane production by 16% in dairy cows over the 89-d experimental period. Despite this reduction in methane production, milk production or energy retention were not improved. Methemoglobin levels in blood were slightly elevated, when nitrate was fed to dairy cows. Further analysis of the efficacy of nitrate in methane mitigation demonstrated that the efficacy of nitrate in methane mitigation decreased with increasing dose of nitrate (expressed in g nitrate/kg 0.75 per day). The conversion of metabolizable energy gained from a lowering of methane production may be less efficient than is commonly assumed. This could originate from a shift from methane to hydrogen emissions, when methane is specifically inhibited, or from erroneous assumptions made in the calculation of heat production during indirect respiration calorimetry. Dietary fat addition may be an effective strategy to lower methane production from ruminants, although the fatty acid profile of the added fat does not appear to have additional effects on methane production from ruminants. When assessing the environmental impact of ruminant products, it is generally overlooked that ruminants are capable of transforming feed not accessible to humans into human food.

    Dose-response relationships between dietary copper level and growth performance in piglets and growing-finishing pigs and effect of withdrawal of a high copper level on subsequent growth performance
    Jongbloed, A.W. ; Bikker, P. ; Thissen, J.T.N.M. - \ 2011
    Lelystad : Wageningen UR Livestock Research (Report / Wageningen UR Livestock Research 483) - 18
    varkenshouderij - varkensvoeding - biggenvoeding - koper - voedertoevoegingen - groeianalyse - pig farming - pig feeding - piglet feeding - copper - feed additives - growth analysis
    This study showed a clear optimum level at approx. 150 mg added Cu per kg feed on growth performance of pigs from 5 to 25 kg. Reduction of a high to a low Cu dose in the feed may hamper overall growth performance compared with the negative control group.
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