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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Handboek snijmaïs
Schooten, H.A. van; Philipsen, A.P. ; Groten, J.A.M. - \ 2015
Wageningen UR Livestock Research (Handboek / Wageningen UR Livestock Research 27) - 199 p.
voederkwaliteit - maïs - voedergewassen - maïskuilvoer - zea mays - rassen (planten) - rassenlijsten - teeltsystemen - teelt - plantenvoeding - bemesting - rentabiliteit - melkveehouderij - akkerbouw - forage quality - maize - fodder crops - maize silage - varieties - descriptive list of varieties - cropping systems - cultivation - plant nutrition - fertilizer application - profitability - dairy farming - arable farming
Na gras is snijmaïs het belangrijkste gewas voor de melkveehouderij. Dit handboek beschrijft de actuele stand van zaken over teelt, oogst, voeding en economie van snijmaïs.
Low emission feed : opportunities to mitigate enteric methane production of dairy cows
Hatew, B. - \ 2015
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Jan Dijkstra; Andre Bannink; Wilbert Pellikaan. - Wageningen : Wageningen University - ISBN 9789462574458 - 228
melkkoeien - rundveevoeding - methaanproductie - milieueffect - pensfermentatie - voer - zetmeel - maïskuilvoer - graskuilvoer - diervoeding - dairy cows - cattle feeding - methane production - environmental impact - rumen fermentation - feeds - starch - maize silage - grass silage - animal nutrition

As global demand for high-quality food originating from animal production is expected to rise due to an increasing human population and consumer income level, the expected role of ruminants in meeting this demand brings multiple challenges. Ruminant production needs to adapt to environmental changes and, at the same time, reduce its impact on the environment. Ruminants production systems have a major impact on the environment through the emission of greenhouse gases such as methane (CH4), nitrous oxide and carbon dioxide. Microbial fermentation of feeds in the gastrointestinal tract, known as enteric fermentation, is the main source of CH4 emissions from dairy production. Enteric CH4 emission is strongly related to the amount of feed fermented in the rumen, which depends on feed intake, feed composition and rumen fermentation conditions associated to the intrinsic characteristics of these feeds and the characteristics of the whole diet. Important gaps in knowledge remain however. The prime aim of this thesis was to investigate the effects of various feeding strategies to mitigate enteric CH4 emissions of dairy cows.

First experiment was conducted to investigate the effects of type and level of starch in the concentrate. Inclusion of a high level (53%) of starch in the concentrate that accounted for 40% of the total mixed ration dry matter (DM) produced lower CH4 per unit of estimated rumen fermentable organic matter (eRFOM) than a low level (27% of DM) of starch (43.1 vs. 46.9 g/kg of eRFOM). Methane production per kg of eRFOM also was lower for diets based on rapidly fermentable starch (gelatinized maize grain) compared to diets based on slowly fermentable starch (native maize grain) (42.6 vs. 47.4 g/kg of eRFOM). However, inclusion of 53% of starch in the concentrate from both types of starch did not affect CH4 emission intensity (CH4 Ei) (CH4 emission per kg of fat- and protein-corrected milk; FPCM). In a subsequent experiment, maize silage was prepared from whole-plant maize harvested at a very early (25% DM), early (28% DM), medium (32% DM) and late (40% DM) stage of maturity and fed to dairy cows as an alternative to concentrate as starch source. Diet consisted of (on DM basis) 75% maize silage, 20% concentrate and 5% wheat straw. Increasing harvest maturity of maize silage linearly decreased CH4 yield (21.7, 23.0, 21.0 and 20.1 g/kg of DM intake) and CH4 emission as a fraction of gross energy intake (6.3, 6.7, 6.3 and 6.0%). Methane Ei tended to decrease linearly with maturity (13.0, 13.4, 13.2 and 12.1 g/kg FPCM). In another experiment grass silage as roughage source was tested. This experiment was designed to investigate the effects of N fertilisation of grassland and maturity of grass at cutting on CH4 emission in dairy cows. Two N fertilisation rates (65 vs. 150 kg of N/ha) were examined in combination with three stages of grass maturity (early, 28 days of regrowth; mid, 41 days of regrowth; and late, 62 days of regrowth). Diet contained 80:20 ratio (on DM basis) of grass silage (mainly ryegrass) and concentrate. Dry matter intake decreased with N fertilisation and maturity, and FPCM decreased with maturity but was unaffected by N fertilisation. Methane Ei (mean 15.0 g/kg of FPCM) increased by 31% and CH4 per unit digestible OM intake (mean 33.1 g/kg of DOMI) increased by 15% with increasing maturity. Methane yield (mean 23.5 g/kg of DM intake) and CH4 as a fraction of gross energy intake (mean 7%) increased by 7 and 9% with maturity, respectively, which implies an increased loss of dietary energy with progressing grass maturity. Rate of N fertilisation had no effect on CH4 Ei and CH4 yield.

Despite the importance of in vitro gas production technique for evaluating feeds, in vitro study as a stand-alone approach was considered inadequate to fully evaluate the potential effect of feeds and rumen fermentation modifiers on CH4 production, because in vitro studies are frequently performed separately rather than in parallel with in vivo studies. To test this hypothesis, both in vitro and in vivo CH4 measurements were measured simultaneously using cows in the first experiment that were fed (and adapted to) the same dietary material used as a substrate for in vitro incubation, as donor for microbial inoculum. It was found that 24-h in vitro CH4 (mL/g of incubated organic matter) correlated well with in vivo CH4 when expressed per unit of eRFOM (R2 = 0.54), but not when expressed per unit of organic matter ingested (R2 = 0.04). In the same experiment, results showed that incubation of the same substrate with rumen inocula obtained from donor cows adapted to different diets produced a variable amount of CH4 suggesting that it is important to consider the diet of the donor animal when collecting rumen inocula for in vitro incubation. Even though the in vitro technique has limitations to represent in vivo conditions, it is useful for screening of large sets of animal feeds or feed additives to be used as a CH4 mitigation strategy. In this thesis, two in vitro experiments were conducted to examine the effects of variation in structural composition of condensed tannins (CT) in sainfoin accessions collected from across the world on CH4 production, and CT extracts obtained from a selected sainfoin accessions on CH4 production. Results revealed substantial variation among CT in their effect on in vitro CH4 production and this variation was attributed to differences in chemical structure of CT. Condensed tannins evaluated in this thesis showed to have potential to reduce in vitro CH4 production, but require further investigations to fully evaluate their in vivo effects.

In conclusion, results from the research work conducted in this thesis show that changes in the basal diet of dairy cows and in roughage production management can substantially reduce the amount of enteric CH4 produced and thereby influence the impact of dairy production on the environment.

Aandachtspunten voor een betere ruwvoerteelt
Verloop, J. ; Oenema, J. - \ 2015
V-focus 12 (2015)3. - ISSN 1574-1575 - p. 38 - 39.
melkveehouderij - voedergewassen - gewasteelt - ruwvoer (forage) - graskuilvoer - maïskuilvoer - bemesting - dairy farming - fodder crops - crop management - forage - grass silage - maize silage - fertilizer application
Koeien & Kansen-deelnemers besteden in ‘Productieslag’ extra aandacht aan de teelt van gras en mais om een maximale productie te realiseren met de beschikbare meststoffen. Op elk bedrijf zoeken veehouders, samen met hun adviseurs en onderzoekers, naar punten waar verbeteringen mogelijk zijn.
Onderzoek naar betere schatting van de dichtheid van gras- en maiskuilen
Zom, R.L.G. ; Abbink, G.W. ; Schooten, H.A. van - \ 2015
Wageningen : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 872) - 46
graskuilvoer - kuilvoer - maïskuilvoer - dichtheid - voorraden - veevoeder - voedingswaarde - kuilvoerkwaliteit - lineaire modellen - regressieanalyse - grass silage - silage - maize silage - density - stocks - fodder - nutritive value - silage quality - linear models - regression analysis
This report describes the results of a study on the possibilities to estimate the density of grass en maize silages for calculation of the fodder stock more accurately than the current table values. During ensiling the amount of crop of 104 grass silage clamps, 42 maize silage clamps and 108 big bales (54 round and 54 square) were weighted and after ensiling the dimensions were measured and the chemical composition was analysed. For round and square bales a new regression formula was derived, which estimates the density more accurate than the current table values. It is recommended to calculate the density of round en square bales with the following formula: Density (kg/m3) = 994.81 - 0.5335 x dry matter content (g/kg) - 1.196 x crude fibre content (g/kg ds). For grass en maize silage in clamps and bunker silo’s no new model could be derived which estimated the density more accurately than the current table values.
Effect van snijmaissilage als strooiselmateriaal in vleeskuikenstallen op de emissies van ammoniak, geur en fijnstof
Harn, J. van; Nijeboer, G.M. ; Ogink, N.W.M. - \ 2015
Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 845) - 49
emissie - ammoniak - stankemissie - fijn stof - methaan - distikstofmonoxide - vleeskuikens - huisvesting van kippen - pluimveehouderij - maïskuilvoer - emissiereductie - luchtkwaliteit - duurzame veehouderij - emission - ammonia - odour emission - particulate matter - methane - nitrous oxide - broilers - chicken housing - poultry farming - maize silage - emission reduction - air quality - sustainable animal husbandry
This report describes the results of emission measurements of ammonia, odour, PM10, methane and nitrous oxide from broiler houses bedded with white wood shavings (=control), fresh silage maize or pre-dried silage maize.
Enteric methane production, rumen volatile fatty acid concentrations, and milk fatty acid composition in lactating Holstein-Friesian cows fed grass silage - or corn silage-based diets
Gastelen, S. van; Antunes Fernandes, E.C. ; Hettinga, K.A. ; Klop, G. ; Alferink, S.J.J. ; Hendriks, W.H. ; Dijkstra, J. - \ 2015
Journal of Dairy Science 98 (2015)3. - ISSN 0022-0302 - p. 1915 - 1927.
dairy-cows - maize silage - ruminal fermentation - feed-intake - n balance - cattle - emissions - supplementation - digestibility - performance
The objective of this study was to determine the effects of replacing grass silage (GS) with corn silage (CS) in dairy cow diets on enteric methane (CH4) production, rumen volatile fatty acid (FA) concentrations, and milk FA composition. A completely randomized block design experiment was conducted with 32 multiparous lactating Holstein-Friesian cows. Four dietary treatments were used, all having a roughage-to-concentrate ratio of 80:20 based on dry matter (DM). The roughage consisted of either 100% GS, 67% GS and 33% CS, 33% GS and 67% CS, or 100% CS (all DM basis). Feed intake was restricted (95% of ad libitum DM intake) to avoid confounding effects of DM intake on CH4 production. Nutrient intake, apparent digestibility, milk production and composition, nitrogen (N) and energy balance, and CH4 production were measured during a 5-d period in climate respiration chambers after adaptation to the diet for 12 d. Increasing CS proportion linearly decreased neutral detergent fiber and crude protein intake and linearly increased starch intake. Milk production and milk fat content (on average 23.4 kg/d and 4.68%, respectively) were not affected by increasing CS inclusion, whereas milk protein content increased quadratically. Rumen variables were unaffected by increasing CS inclusion, except the molar proportion of butyrate, which increased linearly. Methane production (expressed as grams per day, grams per kilogram of fat- and protein-corrected milk, and as a percent of gross energy intake) decreased quadratically with increasing CS inclusion, and decreased linearly when expressed as grams of CH4 per kilogram of DM intake. In comparison with 100% GS, CH4 production was 11 and 8% reduced for the 100% CS diet when expressed per unit of DM intake and per unit fat- and protein-corrected milk, respectively. Nitrogen efficiency increased linearly with increased inclusion of CS. The concentration of trans C18:1 FA, C18:1 cis-12, and total CLA increased quadratically, and iso C16:0, C18:1 cis-13, and C18:2n-6 increased linearly, whereas the concentration of C15:0, iso C15:0, C17:0, and C18:3n-3 decreased linearly with increasing inclusion of CS. No differences were found in short- and medium-straight, even-chain FA concentrations, with the exception of C4:0 which increased linearly with increased inclusion of CS. Replacing GS with CS in a common forage-based diet for dairy cattle offers an effective strategy to decrease enteric CH4 production without negatively affecting dairy cow performance, although a critical level of starch in the diet seems to be needed.
Juiste bepaling van kuildichtheden t.b.v. voorraadberekening voor BEX en BEP : samenvatting van het onderzoek
Schooten, H.A. van; Abbink, G. - \ 2014
[Wageningen] : Wageningen UR Livestock Research - 9
wetenschappelijk onderzoek - gewasproductie - graskuilvoer - maïskuilvoer - stikstof - fosfaat - melkveehouderij - scientific research - crop production - grass silage - maize silage - nitrogen - phosphate - dairy farming
De Bedrijfsspecifieke Excretie (BEX) van stikstof en fosfaat en de Bedrijfsspecifieke gebruiksnorm fosfaat (BEP) kunnen alleen goed worden berekend met een nauwkeurige en robuuste schatting van de hoeveelheden geproduceerd, aangevoerd en verbruikt ruwvoer. Dit is een onderzoek uitgevoerd door Blgg AgroXpertus en Wageningen UR Livestock Research, samen met loonwerkers en melkveehouders waarbij de werkelijke ruwvoervoorraden van verschillende praktijkkuilen in kaart zijn gebracht door het wegen van het gewas tijdens het inkuilen. Doelstelling van dit onderzoek is het ontwikkelen van een nauwkeuriger methode voor dichtheidsbepaling van kuilen in de praktijk.
Handboek snijmaïs
Schooten, H.A. van; Philipsen, A.P. ; Groten, J.A.M. - \ 2014
Lelystad : Wageningen UR Livestock Research (Handboek / Wageningen UR Livestock Research 27) - 198
maïs - handboeken - grondbewerking - bemesting - rassenkeuze (gewassen) - zaaien - onkruidbestrijding - plantenplagen - gewasopbrengst - diervoeding - agrarische economie - melkveehouderij - voedergewassen - akkerbouw - teelthandleidingen - maïskuilvoer - zea mays - maize - handbooks - tillage - fertilizer application - choice of varieties - sowing - weed control - plant pests - crop yield - animal nutrition - agricultural economics - dairy farming - fodder crops - arable farming - cultivation manuals - maize silage
Na gras is snijmaïs het belangrijkste gewas voor de melkveehouderij. Een optimale teelt en benutting van dit gewas zijn daarmee van belang voor het rendement van de sector. Een actueel en compleet overzicht van de nieuwste informatie kan daar een belangrijke bijdrage aan leveren. De nieuwe informatie en ontwikkelingen over teelt en gebruik van maïs komen vaak nogal versnipperd en soms beperkt bij de melkveehouders. Dit heeft tot gevolg dat het lastig is voor de gebruiker om de juiste informatie te vinden. Dit handboek beschrijft de actuele stand van zaken over teelt, oogst, voeding en economie van snijmaïs. Jaarlijks wordt het handboek geactualiseerd met de nieuwste informatie.
Extra snijmais goed voor welzijn varkens.
Bracke, M.B.M. ; Aarnink, A.J.A. ; Rotgers, G. ; Vermeer, H.M. - \ 2014
V-focus 11 (2014)6. - ISSN 1574-1575 - p. 34 - 35.
varkenshouderij - vleesvee - vleesproductie - varkensvoeding - dierenwelzijn - proefboerderijen - maïs - maïskuilvoer - varkensstallen - krachtvoeding - varkens - dierlijke productie - pig farming - beef cattle - meat production - pig feeding - animal welfare - experimental farms - maize - maize silage - pig housing - force feeding - pigs - animal production
Vleesvarkens hebben graag een emmer snijmais. Dat blijkt uit praktijkonderzoek op Varkens Innovatie Centrum Sterksel, onderdeel van Wageningen UR. In vergelijking met stro heeft snijmais meer voederwaarde en het leidt minder snel tot verstoppingen in de mestput.
Extreem weer remt opbrengst snijmais
Colenbrander, E. ; Groten, J.A.M. - \ 2014
Melkvee Magazine 13 (2014)2. - p. 32 - 33.
zea mays - weer - gewasopbrengst - maïskuilvoer - bemesting - kalium - dosering - weather - crop yield - maize silage - fertilizer application - potassium - dosage
Een opbrengst van 50 ton per hectare. Een dergelijk resultaat is mogelijk als de weersomstandigheden meezitten. Maar het weer wordt extremer en er dreigt kalitekort. Er is ook goed nieuws: er komen telkens nieuwe rassen, die nog beter scoren in opbrengst en voederwaarde.
Topbodem voor topmais
Groten, J.A.M. - \ 2014
Grondig : vakblad voor de cumelasector, specialisten in groen, grond en infra 9 (2014). - ISSN 2210-3260 - p. 52 - 53.
akkerbouw - maïs - zea mays - maïskuilvoer - organische stof - normen - bemesting - groenbemesters - teeltsystemen - wisselbouw - organische stikstof - arable farming - maize - maize silage - organic matter - standards - fertilizer application - green manures - cropping systems - ley farming - organic nitrogen
De organische-stofbalans van een snijmaïsteelt is negatief en de bemestingsnormen liggen inmiddels onder het landbouwkundige advies. Hierdoor neemt de productiviteit van de grond af en daarmee de potentiële maïsopbrengst. Een deel van de oplossing is de teelt van een goed geslaagde groenbemester na de maïsoogst.
Determination of nivalenol in food and feed: an update
Malachova, A. ; Egmond, H.P. van; Berthiller, F. ; Krska, R. - \ 2014
World Mycotoxin Journal 7 (2014)3. - ISSN 1875-0710 - p. 247 - 255.
tandem mass-spectrometry - b trichothecene mycotoxins - lc-ms/ms method - electrochemical detection - fusarium mycotoxins - multiple mycotoxins - quechers procedure - masked mycotoxins - cereal products - maize silage
Based on the recent scientific opinion published by the EFSA CONTAM panel on the risks to human and animal health related to the presence of nivalenol in food and feed, this article provides an update on the determination of this Fusarium mycotoxin. After a brief introduction into the chemistry of nivalenol, chromatographic methods as well as other approaches are being discussed. Methods for the determination of nivalenol are well established and can be applied for the analysis of cereals, food, feed and biological samples. Accurate quantification of nivalenol is mostly carried out by liquid chromatography coupled with (multi-stage) mass spectrometry (MS) often within a multi-analyte approach. Some novel techniques, such as direct analysis in real time (DART) MS and electrochemical methods, have shown potential to determine nivalenol, but applications for routine measurements are not yet available. None of the currently available analytical methods has been formally validated in interlaboratory validation studies. While a certified calibrant for nivalenol is available, no matrix reference materials have been developed. Due to the scarcity of appropriate antibodies also no rapid immunochemical methods specific for nivalenol have become available
Designed enzyme preparations for the hydrolysis of corn silage polysaccharides
Neumüller, K.G. - \ 2014
Wageningen University. Promotor(en): Harry Gruppen; Henk Schols, co-promotor(en): H. Streekstra. - Wageningen : Wageningen University - ISBN 9789462570832 - 150
maïskuilvoer - xylaan - industriële enzymen - hydrolyse - biogas - onderzoek - biomassaconversie - biobased economy - maize silage - xylan - industrial enzymes - hydrolysis - research - biomass conversion
This thesis describes the design of hemicellulolytic enzyme preparations with high activity towards the rather recalcitrant xylan present in corn silage, a major biogas feedstock. Also, recalcitrance factors towards the enzymatic conversion of xylans, varying in type and level of substitution, are addressed.
Handboek snijmaïs
Schooten, H.A. van; Philipsen, A.P. ; Groten, J.A.M. - \ 2013
Lelystad : Wageningen UR Livestock Research (Handboek / Wageningen UR Livestock Research 27) - 196
melkveehouderij - zea mays - maïs - maïskuilvoer - teelthandleidingen - voedergewassen - akkerbouw - handboeken - onkruidbestrijding - plantenziekten - plantenplagen - gewasbescherming - dairy farming - maize - maize silage - cultivation manuals - fodder crops - arable farming - handbooks - weed control - plant diseases - plant pests - plant protection
Na gras is snijmaïs het belangrijkste gewas voor de melkveehouderij. Dit handboek beschrijft de actuele stand van zaken over teelt, oogst, voeding en economie van snijmaïs.
Juiste bepaling van de dichtheid van ingekuild ruwvoer voor de voorraadberekening van BEX en BEP = Determination of silage density to estimate roughage supplies for BEX and BEP
Zom, R.L.G. ; Abbink, G.W. ; Schooten, H.A. van - \ 2013
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 677) - 19
graskuilvoer - maïskuilvoer - ruwvoer (roughage) - voorraden - grass silage - maize silage - roughage - stocks
This report describes the results of a desk study on opportunities to improve the determination of the density of grass and maize silages. It is concluded that it is possible to develop a model (based on feed parameters) which estimates the density more accurate than the current tablebased method. Therefore, it is recommended to develop new calibration datasets based on silage densities as measured in common practice.
Grain filling, starch degradation and feeding value of maize for ruminants
Ali, M. - \ 2013
Wageningen University. Promotor(en): Paul Struik; Wouter Hendriks, co-promotor(en): John Cone. - Wageningen : Wageningen UR - ISBN 9789461738196 - 177
maïs - zea mays - groeifasen, rijp - genotypen - zetmeelvertering - pensvertering - voedingswaarde - herkauwersvoeding - korrels (granen) - maïskuilvoer - kuilvoerbereiding - gewasfysiologie - voedingsfysiologie - maize - maturity stage - genotypes - starch digestion - rumen digestion - nutritive value - ruminant feeding - kernels - maize silage - silage making - crop physiology - nutrition physiology

Keywords; Maize (Zea mays L), Genotypes, Grain filling, Growth temperature, Kernels, Gas production, Starch degradation, Oven-drying, Silage, Ensiling temperature, Ensiling duration, Feeding value, Lactating cows

Maize (Zea mays L.) is a major component in the ration of dairy cows in many parts of the world. The currently increasing economic importance of maize has highlighted the need to determine its nutritional value, and to assess the factors influencing its nutritive value. Genotypic make-up (especially differences in starch and endosperm), growing conditions, maturity stage at harvest, and post handling processes, like oven-drying, can influence nutritive value of maize kernels. Similarly, ensiling temperature and duration can affect feeding value of maize silage. This thesis is divided into three parts; the first aim was to characterize the dry matter (starch) accumulation of maize different genotypes in different environments under controlled (glasshouse) and on different locations (sand and clay) in field conditions. Maize genotypes used were different in starch structure and composition, and in type of endosperm. Starch structure refers to amylose and amylopectin; and composition refers to their proportions, whereas type of endosperm defines levels of vitreousness. The vitreousness is the ratio of vitreous (hard) to floury (soft) endosperm. Six maize genotypes, differing in amylose content and vitreousness, were grown under three contrasting day/night temperature regimes during grain filling and harvested at different maturity stages from two greenhouse experiments. Similar investigations were carried on another set of genotypes grown on sandy and clay soils and with different sowing times under field conditions. Water contents and dry matter (starch) accumulation were significantly influenced by growth temperature, genotype, soil type and sowing time (P<0.0001). The second aim of thesis was to establish a relationship between rumen in vitro starch degradation (feeding value) of maize kernels and different factors, like genotype, growth temperature during grain filling, and maturity stage. Oven-dried kernels of six maize genotypes, from the two greenhouse experiments mentioned before were investigated. Starch content was measured using an enzymatic method and the gas production technique was used to assess starch degradation in rumen fluid of dairy cows. The extent of starch degradation at different incubation times was calculated from measured gas production data (6, 12 and 20 h, respectively) and a published equation. At each maturity stage, whole kernel and starch degradation in rumen fluid depended on the genotype (P<0.0001), growing conditions (P<0.0001), starch content (P<0.0001) and starch amount (P<0.0001) in the kernels. The same but fresh (not oven-dried) maize kernel samples were investigated using gas production technique to determine the impact of oven-drying on rumen in vitro starch degradation of maize kernels. Oven-drying significantly (P<0.0001) influenced the rumen in vitro starch degradation in maize kernels various incubation times, with more starch being degraded in the fresh than in the oven-dried maize kernels, although the differences were small. There was a consistent and highly significant (P<0.009 to 0.0002) interaction between oven-drying and genotype, with the high-amylose genotype showing larger effects of oven-drying than the other genotypes. The third aim of thesis was to investigate effect of ensiling temperature and duration on feeding value of maize silage. Samples of maize whole plants (dry matter 33%) were collected from the medium vitreous endosperm cultivar, grown in different seasons on sandy soils. Maize plants were chopped and ensiled in mini silos at three different temperatures. Samples from the silos were taken after 0 (not ensiled, i.e. control), 4, 8 and 16 weeks of ensiling. The gas production technique was used to evaluate the influence of the ensiling temperature and duration of ensiling on the degradation of the fresh ground silage samples in rumen fluid. The final pH of the silages and the gas production was significantly influenced by ensiling temperature in both seasons (P<0.0001). Gas production and pH decreased with an increase in ensiling duration (P<0.0001). The relationship between pH and gas production was quadratic and depended on the ensiling temperature (P<0.002). It was found that ensiling temperature and ensiling duration determine the rate of change and final pH, and play a significant role in feeding value of maize silage. The finding of thesis can be used to determine the exact feeding value of maize kernels and silage, and also can be used as a tool to revise the current feeding evaluation systems i.e. shift from oven-dried to fresh samples.

Concentrations of n-3 and n-6 fatty acids in Dutch bovine milk fat and their contribution to human dietary intake
Valenberg, H.J.F. van; Hettinga, K.A. ; Dijkstra, J. ; Bovenhuis, H. ; Feskens, E.J.M. - \ 2013
Journal of Dairy Science 96 (2013)7. - ISSN 0022-0302 - p. 4173 - 4181.
conjugated linoleic-acid - lactating dairy-cows - fed fish-oil - extruded soybeans - calcium salts - food sources - rumen biohydrogenation - maize silage - supplementation - profile
Weekly samples representative of Dutch milk were analyzed for concentrations of n-3 and n-6 fatty acids (FA). Concentrations of the n-3 FA a-linolenic acid (ALA), eicosatetraenoic acid, eicosapentaenoic acid, and docosapentaenoic acid were 0.495 ± 0.027, 0.041 ± 0.004, 0.067 ± 0.005, and 0.086 ± 0.008 g per 100 g of fat, respectively, whereas docosahexaenoic acid was absent or present in concentrations lower than 0.020 g per 100 g of fat. Concentrations of the n-6 FA linoleic acid (LeA), ¿-linoleic acid, dihomo-¿-linoleic acid, and arachidonic acid were 1.428 ± 0.068, 0.070 ± 0.007, 0.066 ± 0.004, and 0.089 ± 0.004 g per 100 g of fat, respectively; adrenic acid was present in concentrations lower than 0.020 g per 100 g of fat, whereas docosapentaenoic acid was absent in all samples. The concentrations of ALA and LeA were significantly higher in spring and summer, compared with autumn and winter. The concentrations of all other ALA- and LeAderived n-3 and n-6 FA were not significantly different between seasons. The contribution of milk fat to the daily intake of eicosapentaenoic acid, docosapentaenoic acid and docosahexaenoic acid was calculated for human consumption levels in different countries. Milk fat contributed between 10.7 and 14.1% to the daily intake of eicosapentaenoic acid and between 23.5 and 34.2% to the intake of docosapentaenoic acid; whereas docosahexaenoic acid contribution was marginal. Arachidonic acid from milk fat contributed between 10.5 and 18.8% to the human intake of n-6 FA.
Passage kinetics of 13C-labeled corn silage components through the gastrointestinal tract of dairy cows
Warner, D. ; Dijkstra, J. ; Hendriks, W.H. ; Pellikaan, W.F. - \ 2013
Journal of Dairy Science 96 (2013)9. - ISSN 0022-0302 - p. 5844 - 5858.
rumen degradation characteristics - marker excretion patterns - maize silage - milk-production - perennial ryegrass - nutritional-value - concentrate type - digestive-tract - grass maturity - sampling sites
Fractional passage rates form a fundamental element within modern feed evaluation systems for ruminants but knowledge on feed type and feed component specific passage rates are largely lacking. This study describes the use of carbon stable isotopes (13C) to assess component-specific passage kinetics of 6 intrinsically 13C-labeled corn silages varying in quality (2 cultivars × 3 maturity stages) in a 6 × 6 Latin square design using 6 rumen-fistulated lactating dairy cows. An increase in maturity increased starch and decreased neutral detergent fiber and acid detergent fiber contents of corn silages. Passage kinetics were assessed for an external (chromium mordanted fiber; Cr-NDF) and an internal marker (13C isotopes) collected in feces and omasal digesta. The best fit was obtained with a deterministic multicompartmental model compared with stochastic Gn and GnG1 models with increasing order of age dependency (n = 1 to 5) for both sampling sites. The Cr-NDF marker yielded higher rumen fractional passage rates (K1) than did 13C in the dry matter (13CDM) in feces (0.042/h vs. 0.023/h). Omasal marker excretion patterns support the conclusions based on conventional fecal marker excretions. Component-specific passage was assessed for acid detergent fiber (13CADF) in feces and for starch (13CST) in omasal digesta. The fractional passage rate based on fecal 13CDM and 13CADF did not differ. Omasal 13CST provided higher K1 values (0.042/h) than omasal 13CDM (0.034/h) but lower values than omasal Cr-NDF (0.051/h). Fractional passage rates from the proximal colon-cecum (K2) based on fecal marker concentrations showed trends similar to K1, with Cr-NDF providing a value (0.425/h) more than twice as high as that of 13CDM (0.179/h) and 13CADF (0.128/h). Total mean retention time in the gastrointestinal tract was approximately double for 13CDM (64.1 h) and 13CADF (77.6 h) compared with Cr-NDF (36.4 h). Corn silage quality did not affect any of the estimated passage kinetic parameters. In situ fractional degradation rates did not differ among corn silages, except for a decreased fractional degradation rate of starch with advancing maturity. Results indicate that isotope labeling allows assessment of component-specific passage kinetics of carbohydrate fractions in corn silage.
Rumen fermentation profile and intestinal digestibility of maize and grass silages
Ali, M. - \ 2013
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): John Cone; Gert van Duinkerken. - S.l. : s.n. - ISBN 9789461736581 - 157
melkkoeien - maïskuilvoer - graskuilvoer - pensfermentatie - verteerbaarheid - darmfysiologie - chemische samenstelling - diervoeding - voedingsfysiologie - dairy cows - maize silage - grass silage - rumen fermentation - digestibility - intestinal physiology - chemical composition - animal nutrition - nutrition physiology

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

Effect van koolzuurgas en stikstofgas toevoegen in geopende gras- en maïskuilen op aerobe stabiliteit = Effect of addition of carbon dioxide and nitrogen gas in opened grass and maize silage on aerobic stability
Wikselaar, P.G. van; Schooten, H.A. van - \ 2013
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 697) - 14
maïskuilvoer - graskuilvoer - kooldioxide - stikstof - veehouderij - maize silage - grass silage - carbon dioxide - nitrogen - livestock farming
This report describes the results of research on the effect of adding carbon dioxide and nitrogen gas in opened grass and maize silages on the aerobic stability.The study was carried out with mini silos.
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