Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

Current refinement(s):

Records 1 - 20 / 36

  • help
  • print

    Print search results

  • export

    Export search results

  • alert
    We will mail you new results for this query: keywords==ureum
Check title to add to marked list
Refining a model-based assessment strategy to estimate the ammonia emission from floors in dairy cow houses
Snoek, Dennis J.W. - \ 2016
Wageningen University. Promotor(en): Peter Groot Koerkamp, co-promotor(en): Nico Ogink; Hans Stigter. - Wageningen : Wageningen University - ISBN 9789462578852 - 182
dairy cows - stalls - ammonia emission - floors - modeling - mitigation - sensors - ph - temperature - urea - melkkoeien - stallen - ammoniakemissie - vloeren - modelleren - mitigatie - temperatuur - ureum

Ammonia (NH3) emission is still high, and agriculture is still the dominant contributor. In The Netherlands, the NH3 emission from dairy cow houses is one of the most important sources. A lot of research has been conducted to understand and model NH3 emission, to measure it, and to reduce it using identified and developed reduction measures. However, our understanding of how to measure and how to reduce the NH3 emission is still limited. In addition, the set emission ceilings were lowered for 2020.

The objective of this thesis was to refine a model-based assessment strategy to estimate the ammonia emission from floors in dairy cow houses. First the most important input variables and process parameters were identified with a sensitivity analysis in currently available mechanistic NH3 emission models and theory. It was concluded that five puddle related input variables caused the largest variation in NH3 emission estimation, being the puddle pH, depth (Dp), urinary urea nitrogen concentration (UUN), surface area (Ap), and temperature (Tliq). For each input variable the available data was scarce, and it was therefore recommended to measure these five most important variables in practice. However, measurement methods were hardly available. Therefore, sensors were chosen, new measurement methods were developed, and these were combined in a protocol to measure the pH, Dp, UUN, Ap and Tliq of fresh, random and manually created urine puddles in commercial dairy cow houses.

In total 16 commercial dairy cow houses were assessed in a factorial experimental setup based on four floor-management types in two Seasons, with PREclean treatment. PREclean represented intense-floor-cleaning that was compared to on-farm manure scraping. A V-shaped asphalt floor had significantly larger values for both Ap (1.04 m2) and Dp (1.5 mm) than did the slatted and grooved floors (0.76 m2, 0.93 mm). For both Ap and Dp the variation within a farm was large, but was negligible between farms. The Dp values and variation were 3 to 6 times larger than currently assumed. With PREclean treatment the Dp resulted in about 3 times lower values compared to the on-farm scraping. In short, the potential NH3 emission reduction of good floor cleaning is large. Overall mean values were 4.27 kg m-3 for UUN, an initial pH(t=0) of 8.3, both in fresh puddles, and a pH(t=ξ) of 9.0 for random puddles at a random time. For UUN both the variation within and between farms was large, whereas the variation for pH was small. Both the mean UUN and pH showed lower values than currently assumed. In a separate 4 h time series experiment at 3 commercial farms was shown that the pH, on average, quickly increased initially, declined after 1 h and then became stable. The calculated NH3 in kg puddle-1 showed a huge range and was considerably larger than currently assumed for the reference situation.

Compared to the aforementioned sensitivity analysis outcome, the UUN range at farm level is both slightly smaller and shifts to slightly lower values, while for Dp the range and values are both larger. These two variables caused the largest variation in the estimated NH3 emissions, and not the pH. In conclusion, these two variables certainly need to be measured in individual commercial dairy cow houses to estimate the NH3 emission. For Ap, pH and Tair the measured ranges at farm level were less large. The pH turns out to be fairly stable in commercial cow houses and, related to that, it causes less variation in the estimated NH3 emission. Nevertheless, the pH still ranks as the third most important variable, and therefore needs to be measured in individual cow houses. The Ap is fairly stable between farms, but varies within farms and it still has a significant effect on the NH3 emission. The floor design clearly affects the puddle area Ap. Therefore, it is not necessary to measure Ap at each individual farm, but it is sufficient to measure the Ap in only one commercial cow house per floor design. The Tair variable is of limited importance compared to the aforementioned four variables, but it is still significant.

Dietary protein, blood pressure and mortality : the value of repeated measurements
Tielemans, S.M.A.J. - \ 2016
Wageningen University. Promotor(en): Marianne Geleijnse; Daan Kromhout, co-promotor(en): Hendriek Boshuizen. - Wageningen : Wageningen University - ISBN 9789462577916 - 169 p.
cardiovascular diseases - blood pressure - dietary protein - mortality - cardiovascular disorders - hypertension - urea - meta-analysis - antihypertensive agents - plant protein - animal protein - hart- en vaatziekten - bloeddruk - voedingseiwit - mortaliteit - hart- en vaatstoornissen - hypertensie - ureum - meta-analyse - antihypertensiva - plantaardig eiwit - dierlijk eiwit

Cardiovascular diseases (CVD) are the main cause of death worldwide. In 2012, about 17.5 million people died from CVD, accounting for 30% of all deaths. High blood pressure (BP) is a major cardiovascular risk factor, which was responsible for 10.4 million deaths in 2013. Diet and lifestyle play an important role in the etiology of hypertension. Maintenance of a desirable body weight, physical activity, and low intake of alcohol and salt are well-known measures to avoid high BP. Whether dietary protein, or more specifically plant and animal protein, could contribute to maintaining a healthy BP is less clear. The association between BP and CVD mortality has been extensively investigated. BP in prospective studies can be analyzed using different approaches, such as single BP (measured at one moment in time), single BP adjusted for regression dilution, average BP, and trajectories of BP. It is not yet clear which of these approaches is to be preferred for CVD risk prediction.

This thesis is centered on BP as a major cardiovascular risk factor. In the first part (Chapter 2, 3 and 4), the relation of dietary protein intake with BP level and change was examined. In the second part (Chapter 5 and 6), various approaches for analyzing repeated BP measurements were compared in relation to CVD and all‑cause mortality risk. The final chapter discusses the main findings and their implications.

Chapter 2 describes the association of 24-h urinary urea excretion, as a biomarker of total protein intake, with 9-year incidence of hypertension. We analyzed data of ~4000 men and women aged 28–75 years, who participated in the Prevention of Renal and Vascular Endstage Disease (PREVEND) study, a prospective cohort study. BP was measured four times during 1997–2009 and participants were followed for hypertension incidence, defined as BP ≥140/90mmHg or use of antihypertensive medication. Urea excretion was assessed in two consecutive 24-h urine collections at baseline and approximately 4 years later, from which total protein intake was estimated. Protein intake based on 24-h urinary urea excretion was not associated with incident hypertension.

Chapter 3 presents findings for long-term total, animal and plant protein intake in relation to 5‑year BP change. Analyses were based on 702 observations of 272 men who participated in the Zutphen Elderly Study. Participants did not use antihypertensive medication and were initially free of CVD. Physical and dietary examinations were performed in 1985, 1990, 1995, and 2000. BP was measured twice at each examination and protein intake was assessed using the cross-check dietary history method. The upper tertiles of plant protein intake were associated with a mean 5‑year change in systolic BP of ‑2.9 mmHg (95% CI: ‑5.6, ‑0.2), compared with the bottom tertile. Total and animal protein intake was not associated with BP.

Chapter 4 describes a meta‑analysis of 12 observational studies and 17 randomized controlled trials (RCTs) of dietary protein, including animal and plant protein, in relation to BP. Protein intake in prospective cohort studies was not associated with incident hypertension. For RCTs that used carbohydrate as a control treatment, the pooled BP effect was ‑2.1 mmHg systolic (95% CI: ‑2.9, ‑1.4) for a weighted mean contrast in protein intake of 41 grams per day. There was no differential effect of animal and plant protein on BP.

Chapter 5 describes repeated BP measures and their association with CVD and all‑cause mortality and life years lost in two prospective and nearly extinct cohorts of middle-aged men, the Minnesota Business and Professional Men Study (n=261) and the Zutphen Study (n=632). BP was measured annually during 1947–1957 in Minnesota and 1960–1970 in Zutphen. After 10 years of BP measurements, men were followed until death on average 20 years later. Each 25-mmHg increase in average SBP was associated with a 49% to 72% greater CVD mortality risk, 34% to 46% greater all-cause mortality risk and 3 to 4 life years lost. Four systolic BP trajectories were identified, in which mean systolic BP increased by 5 to 49 mmHg in Minnesota and 5 to 20 mmHg in Zutphen between age 50 and 60. In Zutphen, a 2-times greater CVD and all-cause mortality risk and 4 life years lost were observed when comparing trajectories. In Minnesota, associations were twice as strong. BP trajectories were the strongest predictors of CVD mortality and life years lost in Minnesota men, whereas in Zutphen men, the average BP was superior to other measures.

Chapter 6 presents findings for average BP and BP trajectories in relation to CVD and all-cause mortality, taking into account antihypertensive medication. A total of 762 participants aged ≥50 years of the Rancho Bernardo Study were examined five times from 1984 to 2002 and monitored for cause‑specific mortality from 2002 to 2013. Each 20‑mmHg increment in average systolic BP was associated with 35% greater CVD mortality and 25% greater all-cause mortality risk. We identified four trajectories for systolic BP for which BP increases ranged from 5 to 12 mmHg between age 60 and 70. In individuals who belonged to the higher trajectories, 2‑3 times greater CVD mortality and 1.5-times greater all-cause mortality risks were observed, compared to those who belonged to the lowest trajectory. Long-term systolic BP trajectories and average systolic BP were both significant predictors of CVD and all-cause mortality. The associations were not modified by antihypertensive medication.

As described in Chapter 7, various approaches were used to study the relation between protein intake and BP. Findings from individual studies and a meta-analysis suggest that dietary protein per se does not affect BP within the range of intake generally consumed in the Netherlands. Replacing carbohydrates by protein, however, has a beneficial effect on BP.

Moreover, this thesis showed that BP trajectories are not superior to average BP in predicting CVD and all-cause mortality. A few repeated BP measurements, e.g. three or four, are likely to be sufficient for obtaining a reliable average BP and had a similar predictive value for mortality compared to BP trajectories. Therefore, average BP can be considered the most practical tool for estimating mortality risk.

Stikstofverliezen beter inschatten
Spek, J.W. ; Bannink, A. ; Dijkstra, J. - \ 2013
Veeteelt 30 (2013)17. - ISSN 0168-7565 - p. 20 - 22.
melkveehouderij - stikstofverliezen - excretie - melksamenstelling - ureum - melkveevoeding - voersamenstelling - eiwitgehalte - dairy farming - nitrogen losses - excretion - milk composition - urea - dairy cattle nutrition - feed formulation - protein content
Hoe kan het melkureumgehalte beter worden benut als maat voor stikstofverliezen in de urine? Onderzoekers van WUR concluderen dat stikstofverliezen in de urine beter zijn in te schatten met een combinatie van factoren, zoals het melkureumgehalte en het zout- en eiwitgehalte in het rantsoen.
Variation of milk urea in dairy cattle : a study on factors that affect the relationship between urea concentration in milk and urea excretion in urine
Spek, J.W. - \ 2013
Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Jan Dijkstra; Andre Bannink. - S.l. : s.n. - ISBN 9789461736642 - 156
melkkoeien - melkvee - ureum - melk - concentratie - urinering - excretie - stikstof - meta-analyse - natriumchloride - opname (intake) - diervoeding - rundveevoeding - voedingsfysiologie - dairy cows - dairy cattle - urea - milk - concentration - urination - excretion - nitrogen - meta-analysis - sodium chloride - intake - animal nutrition - cattle feeding - nutrition physiology

The aim of this thesis was to increase the applicability of milk urea nitrogen concentration (MUN) as a predictor of urinary urea nitrogen excretion (UUN) by identifying and quantifying factors that can explain variation in MUN that is not related to UUN. A literature study was conducted in order to identify these factors that affect the relationship between MUN and UUN. In this literature review a number of factors were established that affect the relationship between MUN and urinary N-excretion (UN) or UUN, such as dietary crude protein content (CP), intake of dietary salt and water, body weight, diurnal variation in plasma urea nitrogen concentration (PUN), exchange of urea between blood and milk, and heritability of MUN. Results of a quantitative meta-analysis where the effect of various physiological and dietary factors on the relationship between MUN and UN or UUN were studied confirmed the fact that CP affects the relationship between MUN and UUN and showed that by using information on MUN and CP more variation in UUN could be explained compared to using information on either MUN or CP alone. One of the factors established in the literature review that can affect the relationship between MUN and UUN is dietary salt content or drink water intake. In order to quantify the effect of dietary salt on MUN and UUN an experiment was carried out that investigated the effect of four dietary levels of sodium chloride (NaCl) on urea levels in blood plasma and milk and on UN and UUN. The results from this trial clearly showed a negative relationship between dietary NaCl content and MUN whereas UUN was not affected by NaCl intake and UN was slightly increased by increasing NaCl intake levels. The question arose whether the effect of dietary salt on MUN would be similar at high and low dietary protein levels as the renal mechanism of excretion and reabsorption of urea is affected by both dietary protein and salt intake. Therefore, the interaction between dietary salt and protein on UUN was tested in an experiment with two CP levels and two dietary NaCl levels. No interaction between dietary NaCl and CP on MUN was observed. However, the relationship between MUN and UUN was altered by the effect of salt intake. The literature review showed that diurnal variation in PUN and MUN can be substantial, and that this variation depends on factors such as time and frequency of feeding and milking. Insight in the dynamics of urea transport between blood of milk is important in order to model and predict variation in MUN over time under various feeding and milking regimes. To obtain quantitative insight in urea fluxes between blood and milk two experiments were conducted in which urea transport from blood to milk and vice versa was investigated by means of pulse dose injections of labeled [15N15N]urea in milk cisterns at various time intervals before milking. The results showed a rapid distribution of injected labeled urea throughout the milk in the mammary gland and substantial urea transport from milk to blood.

It is concluded that various factors that are discussed in this thesis contribute to variation in MUN that is not related to UUN. Taking these factors into account increases the applicability of MUN as a predictor of UUN.

Waarde van melkureum als schatter stikstofexcretie : talrijke factoren beïnvloeden relatie tussen melkureum en stikstof
Spek, J.W. ; Bannink, A. ; Dijkstra, J. - \ 2011
Veeteelt 28 (2011)10. - ISSN 0168-7565 - p. 40 - 41.
melkveehouderij - melksamenstelling - ureum - stikstof - excretie - urine - ammoniak - dairy farming - milk composition - urea - nitrogen - excretion - ammonia
Het melkureum gehalte geldt in Nederland als instrument voor het schatten van de stikstofexcretie van melkvee. Wageningse onderzoekers gingen na hoe het melkureumgehalte beter gebruikt kan worden als indicator en hoe een aantal factoren verschillen in melkureumgehalte.
Lammerensterfte, leverbot en ureum bij melkschapen
Verkaik, J.C. ; Smolders, G. - \ 2010
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 417) - 27
biologische landbouw - schapenhouderij - mortaliteit - lammeren - schapen - leverbot - ureum - geboorte - agrarische bedrijfsvoering - quarantaine - eiwitopname - zware metalen - organic farming - sheep farming - mortality - lambs - sheep - liver flukes - urea - birth - farm management - quarantine - protein uptake - heavy metals
The monitored lamb mortality at organic dairy sheep farms is relativly high with big differences. Mortality over 10% is caused by poor management and infectious abortions. Short term improvements needs a structured approach. Treatment of the dairy sheep is limited to the dry period. Avoiding infection by housing ewes in early lactation appears effective. Liver fluke is well predictable on the prognosis and the fluke and grazing history. The time between infection intake and appearance in blood or dung makes these researches risky. Urea appears dependable upon the amount of protein fed. Protein wastage reduces when more energy is fed.
Individueel en gericht stimuleren zorgt voor lager melkureumgehalte
Ham, A. van den - \ 2010
Agri-monitor 2010 (2010)01-04-2010. - ISSN 1383-6455
melkveehouderij - ureum - melkproductie - agrarische bedrijfsvoering - dairy farming - urea - milk production - farm management
Als agrarische ondernemers individueel gestimuleerd worden om bedrijf en milieu te combineren levert dat goede resultaten op voor beide doeleinden. Een voorbeeld is het melkureumgehalte. Het kan vaak en gemakkelijk worden gemeten en kan dienen als snelle signalering, waardoor de melkveehouder beter bij kan sturen.
Ureum als instrument om eiwitvoeding te sturen nog niet betrouwbaar: Kengetal ureumgehalte beter benutten
Spek, J.W. ; Bannink, A. ; Dijkstra, J. - \ 2009
Veeteelt 26 (2009)6. - ISSN 0168-7565 - p. 28 - 29.
melkveehouderij - melksamenstelling - ureum - rundveevoeding - dairy farming - milk composition - urea - cattle feeding
Wat kunnen melkveehouders met het ureumgehalte in melk? Het kengetal zegt iets over de stikstofbenutting, maar is als instrument om de eiwitvoeding van melkkoeien te sturen nu nog onvoldoende betrouwbaar. Wageningse onderzoekers pogen daar verbetering in te brengen
Bladvertering stimuleren is moeilijk, maar helpt
Heijne, B. ; Jong, P.F. de; Kohl, J. - \ 2007
De Fruitteelt 97 (2007)2. - ISSN 0016-2302 - p. 10 - 11.
fruitteelt - boomgaarden - ascosporen - bladschimmels - compostering - stemphylium - ureum - vinasse - plantenziekten - gewasbescherming - toegepast onderzoek - fruit growing - orchards - ascospores - phylloplane fungi - composting - urea - plant diseases - plant protection - applied research
De bestrijding van schimmels met fungiciden in boomgaarden in de herfst is gevaarlijk vanwege resistentieontwikkeling. Vinasse en ureum stimuleren de bladvertering enorm. Bovendien remmen ze de productie van ascosporen. Zo ontstaan er minder schurftschimmel en zwartvruchtrotschimmel. Ook sanitaire maatregelen zoals bladversnippering en poetsen blijken effectief te werken. De praktijktoepassing van sanitaire maatregelen kent nog veel beperkingen en hangt voornamelijk af van een droog moment na de bladvalperiode
De fokwaarde voor melkureum als maat voor de efficiëntie van de eiwitbenutting door melkkoeien = The breeding value for milkurea as predictor for the efficiëncy of protein utilization in dairy cows
Sebek, L.B.J. ; Riel, J.W. van - \ 2007
Lelystad : Animal Sciences Group (Rapport / Animal Sciences Group 81) - 16
melkkoeien - melkveehouderij - fokwaarde - ureum - eiwit - stikstof - excretie - dairy cows - dairy farming - breeding value - urea - protein - nitrogen - excretion
De fokwaarde voor melkureum kent geen verband met de efficiëntie van de eiwitbenutting. Daardoor is het niet mogelijk om de N excretie van melkkoeien te verminderen via het fokken op melkkoeien met een erfelijk bepaald laag melkureumgehalte
Lager ureumgehalte mogelijk door doelgerichte benadering
Ham, A. van den; Beldman, A.C.G. - \ 2006
Agri-monitor 2006 (2006)2. - ISSN 1383-6455
ureum - ammoniak - emissie - melkveehouderij - urea - ammonia - emission - dairy farming
Het ureumgehalte in de melk is een indicator voor de ammoniakemissie. Melkveehouders van het netwerk 'De toekomst van uw bedrijf' zijn de afgelopen twee jaar bezig geweest met bedrijfsstrategieën voor het verlagen van het ureumgehalte om overheidsdoelstellingen tegemoet te komen. Uit het proces blijkt dat lagere ureumgehaltes mogelijk zijn, mits de ondernemer deze doelstelling expliciet opneemt in zijn strategie
Fokken op lager ureum gehalte : zowel tussen als binnen rassen bestaan duidelijke verschillen in ureumgehalte
Veerkamp, R.F. ; Vuuren, A.M. van; Haan, M.H.A. de - \ 2005
Veeteelt 22 (2005)22. - ISSN 0168-7565 - p. 10 - 12.
melkveehouderij - melkkoeien - dierveredeling - dierlijke meststoffen - samenstelling - ureum - ammoniak - emissie - rasverschillen - heritability - genetische correlatie - dairy farming - dairy cows - animal breeding - animal manures - composition - urea - ammonia - emission - breed differences - genetic correlation
Het ureumgehalte wordt in de nieuwe mestwetgeving belangrijk, zodat een lager gehalte aantrekkelijk is voor veehouders die mest moeten afvoeren. In een onderzoek is daarom gekeken naar de mogelijkheid om het ureumgehalte via de fokkerij te verlagen. Gekeken is hierbij naar verschillen tussen rassen, genetische verschillen binnen een ras, de erfelijkheidsgraad en de genetische correlatie
Ammoniakemissie uit de melkveestal bij beperkte weidegang in relatie tot melkureumgehalte
Duinkerken, G. van; Smits, M.C.J. ; Sebek, L.B.J. ; Vereijken, P.F.G. ; Andre, G. ; Monteny, G.J. - \ 2004
Lelystad : Animal Sciences Group (PraktijkRapport / Animal Sciences Group, Praktijkonderzoek : Rundvee ) - 24
ammoniak - ureum - rantsoenbeweiding - beweidingsintensiteit - ammonia - urea - controlled grazing - grazing intensity
Ammoniak (NH3) ontstaat wanneer ureum uit de urine wordt afgebroken door het enzym urease, dat onder andere aanwezig is in mest. Urine en mest komen met elkaar in contact op stalvloeren en in mestkelders, waardoor een melkveestal een belangrijke bron van ammoniakuitstoot is. Bepalend voor de mate van emissie zijn met name de ureumconcentratie in de urine en de temperatuur. De ammoniakemissie vanuit natuurlijk geventileerde melkveestallen kan met behulp van voedingsmaatregelen worden teruggedrongen. Dit geldt zowel voor bedrijfssituaties met summerfeeding als bedrijfssituaties met beperkte weidegang. Het melkureumgehalte is daarbij een goede indicator voor de emissiereductie. Voedingsmaatregelen die bijdragen aan verlaging van het melkureumgehalte, dragen tevens bij aan een verlaging van de ammoniakemissie uit de stal. Voorbeelden van dergelijke emissieverlagende maatregelen zijn: verlaging van het N-bemestingsniveau op grasland, later inscharen in weidepercelen en het bijvoeren van energierijke en eiwitarme voeders op stal (denk aan snijmaïs). De ammoniakemissie vanuit de natuurlijk geventileerde ligboxenstal met roostervloer kan voor bedrijfssituaties met beperkte weidegang goed worden voorspeld met een emissiemodel met buitentemperatuur en tankmelkureumgehalte als verklarende variabelen. Uit dit model blijkt dat de stalemissie stijgt met ca. 2,6% bij toename van de buitentemperatuur met 1°C en dat de stalemissie exponentieel stijgt bij een toename van het tankmelkureumgehalte. Bij een niveau van 20 mg ureum per 100 g melk stijgt de stalemissie met ca. 2,5% bij stijging van het melkureumgehalte met 1 mg/100 g. Bij een niveau van 30 mg ureum per 100 g melk stijgt de stalemissie met ca. 3,5% bij stijging van het melkureumgehalte met 1 mg/100 g
Lager ureumgehalte door scherp voeren
Thomassen, I. ; Poelarends, J.J. ; Smolders, E.A.A. - \ 2003
Nieuwsbrief Koeien & Kansen 2003 (2003)12. - p. 2 - 2.
melkveehouderij - melkveevoeding - voersamenstelling - ammoniakemissie - melksamenstelling - melkkwaliteit - ureum - milieueffect - dairy farming - dairy cattle nutrition - feed formulation - ammonia emission - milk composition - milk quality - urea - environmental impact
Om te weten of een sterk milieugerichte bedrijfsvoering gevolgen heeft voor de diergezondheid en vruchtbaarheid worden deze aspecten op Koeien & Kansen bedrijven onderzocht. Bij een sterk milieugerichte bedrijfsvoering is het ureumgehalte in de tankmelk een belangrijke graadmeter. Uit onderstaand onderzoek blijkt dat de ureumgehaltes in de tankmelk van K&K-bedrijven lager zijn dan op referentiebedrijven, wat betekent dat ze inderdaad met meer aandacht voor het milieu werken.
Goede diergezondheid mogelijk bij scherp voeren
Smolders, G. ; Poelarends, J. - \ 2002
Praktijkkompas. Rundvee 16 (2002)3. - ISSN 1570-8586 - p. 6 - 7.
melkveehouderij - agrarische bedrijfsvoering - diergezondheid - dierziekten - rundveeziekten - melkkwaliteit - celgetal - ureum - mastitis - vruchtbaarheid - voortplantingsstoornissen - benen - klauwen - hoeven - voetziekten - hoefontsteking - botziekten - melkvee - melkkoeien - dairy farming - farm management - animal health - animal diseases - cattle diseases - milk quality - somatic cell count - urea - fertility - reproductive disorders - legs - claws - hooves - foot diseases - laminitis - bone diseases - dairy cattle - dairy cows
De eerste indruk is dat ook bij scherp letten op stikstof en fosfaat de diergezondheid goed kan zijn.
Vloeibare meststoffen hebben incidenteel meerwaarde
Clevering, O.A. - \ 2001
PPO-bulletin akkerbouw 5 (2001)4. - ISSN 1385-5301 - p. 10 - 13.
plantenvoeding - kunstmeststoffen - vloeibare kunstmeststoffen - stikstofmeststoffen - stikstof - fosformeststoffen - fosfaat - stikstoffosformeststoffen - kaliummeststoffen - ammoniummeststoffen - ammoniak - ureum - toepassing - toedieningswijzen - spuiten - injectie - plaatsing (van meststoffen) - gebruiksefficiëntie - gebruikswaarde - efficiëntie - gewasopbrengst - bemesting - plant nutrition - fertilizers - liquid fertilizers - nitrogen fertilizers - nitrogen - phosphorus fertilizers - phosphate - nitrogen-phosphorus fertilizers - potassium fertilizers - ammonium fertilizers - ammonia - urea - application - application methods - spraying - injection - placement - use efficiency - use value - efficiency - crop yield - fertilizer application
Samenstelling en eigenschappen van vloeibare meststoffen (stikstof-, fosfaat- en kalimeststoffen), en resultaten van onderzoek naar de toepassing van vloeibare urean, ureum, ammoniak, ammoniumwater en NP-meststoffen in verschillende soorten akkerbouwgewassen. Toedieningsmethoden (verspuiten, injecteren), toepassing (basisgift, startgift, bijbemesting, rijenbemesting), effecten op de opbrengst, en mogelijkheden voor verlaging van de mestgift worden besproken. In normale jaren werken vloeibare meststoffen niet beter dan vaste; de iets hogere efficiëntie weegt niet op tegen de kosten
Sturing melkureumgehalte op dierniveau via de voeding
Zom, R.L.G. ; Remmelink, G.J. ; Duinkerken, G. van - \ 2001
Lelystad : Praktijkonderzoek Veehouderij (Rapport / Praktijkonderzoek Veehouderij 215) - 24
melkvee - melksamenstelling - ureum - diervoeding - rundveevoeding - voer - samenstelling - voedingsrantsoenen - concentraten - eiwitbalans - eiwitten - dairy cattle - milk composition - urea - animal nutrition - cattle feeding - feeds - composition - feed rations - concentrates - protein balance - proteins
Het Praktijkonderzoek Veehouderij voerde in de winterseizoenen van 1997-1998 en 1998-1999 een viertal voederproeven uit die antwoord moesten geven op de vraag of er variatie bestaat in het optimale melkureumgehalte tussen individuele dieren en in welke mate het melkureumgehalte van individuele dieren valt te sturen door middel van de voeding.
Ammoniakemissie fors lager na voermaatregelen
Duinkerken, G. van; Smits, G.A.M. - \ 2001
Rundvee praktijkonderzoek 14 (2001)2. - ISSN 1569-805X - p. 13 - 15.
melkveehouderij - rundveevoeding - eiwit - ammoniak - emissie - melk - samenstelling - ureum - dairy farming - cattle feeding - protein - ammonia - emission - milk - composition - urea
De ammoniakemissie vanuit melkveestallen is aanzienlijk terug te dringen door de eiwitvoeding aan te scherpen. Via het melkureumgehalte is goed in beeld te brengen in welke mate de emissie afneemt.
De fysiologische basis voor de minimale onbestedig eiwit balans in melkveerantsoenen
Vuuren, A.M. van; Tamminga, S. - \ 2001
CVB - 22
melkveehouderij - melkkoeien - melkveevoeding - stikstof - stikstofmetabolisme - pensmicro-organismen - pensvertering - stikstofkringloop - ureum - pens - dairy farming - dairy cows - dairy cattle nutrition - nitrogen - nitrogen metabolism - rumen microorganisms - rumen digestion - nitrogen cycle - urea - rumen
In dit rapport komen de volgende onderwerpen aan de orde: - systematisch inzicht in de stikstofstromen, die van belang zijn voor een adequate stikstofvoorziening van pensmicroben; - beschrijving van deze factoren en van de kwantitatieve rol, die zij spelen bij de stikstofvoorziening van pensmicroben. Hierbij zal met name de recycling van stikstof naar de pens aandacht krijgen; - fluctuaties in stikstofvoorziening over de dag.
Weten is wegen . . . . : Ureumgehalte melk bevestigt noodzaak goede voerweging
Teenstra, E.D. - \ 2000
Nieuwsbrief Koeien & Kansen 2000 (2000)1. - p. 4 - 4.
melkveehouderij - dierlijke meststoffen - fosfaat - stikstofbalans - ureum - monitoring - dairy farming - animal manures - phosphate - nitrogen balance - urea
Afgelopen jaar is veel tijd en energie gestoken in het uniformeren van de gegevensstroom. Vrijwel alle deelnemers beschikken nu over weegapparatuur waarmee ze nauwkeurig de voeropname van het vee kunnen registreren. Voor de berekening van de stikstofbenutting van het vee levert dit belangrijke informatie. Het ureumgehalte blijkt hiervoor een goede graadmeter. Dit artikel geeft een indruk voor de weideperiode van 1999.
Check title to add to marked list
<< previous | next >>

Show 20 50 100 records per page

Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.