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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Bringing eggs and bones to light : affecting leg bone development in broiler chickens through perinatal lighting schedules
Pol, Carla W. van der - \ 2017
University. Promotor(en): Bas Kemp, co-promotor(en): Henry van den Brand; Inge Van Roovert-Reijrink. - Wageningen : Wageningen University - ISBN 9789463431422 - 214
broilers - limb bones - biological development - embryonic development - eggs - light regime - incubation - hatching - circadian rhythm - animal pathology - animal health - poultry farming - vleeskuikens - beenderen van ledematen - biologische ontwikkeling - embryonale ontwikkeling - eieren - lichtregiem - broeden - uitbroeden - circadiaan ritme - dierpathologie - diergezondheid - pluimveehouderij

Leg bone pathologies are a common problem in broiler chickens, and they can lead to decreased welfare and poor production performance. It can be speculated that the ae­tiology of some leg bone pathologies lies, to some extent, in suboptimal early life bone development. One factor that can be speculated to affect bone development, and conse­quently leg health, in broiler chickens is application of light. Light has several properties, such as light intensity, color, duration, and schedule. The present thesis focuses on ligh­ting schedules. Aim was to investigate how lighting schedules applied during incubation and in the early post hatch period (the brooding period) affected leg bone development throughout a broiler’s life and leg health at slaughter age.

In 4 studies, effects of eggshell temperature (EST) and lighting schedule during incuba­tion and in the brooding period on leg bone development, leg health, and production parameters were explored. The first study found that an EST of 39.4°C led to lower bone dimensions at hatch than an EST between 37.8 and 38.6°C. It was then decided that incubation experiments on bone development would best be performed at a constant EST of 37.8°C, as this is also an EST that leads to good hatchability and chick quality. In two studies, the effects of circadian lighting schedules during incubation on leg bone development and leg health were investigated. Staining of the embryonic leg bones sho­wed that applying a circadian lighting schedule of 12 hours of light, followed by 12 hours of darkness (12L:12D) resulted in an earlier onset of embryonic ossification of the tibia than continuous light (24L). Compared to 24L, 12L:12D furthermore resulted in higher tibia weight and length, and higher tibial cortical area, cortical thickness, and second moment of area around the minor axis at hatch as revealed by MicroCT scanning. It was furthermore found that 12L:12D resulted in a lower incidence of the leg pathology tibial dyschondroplasia. Continuous darkness (24D) was mostly intermediate. On the other hand, a circadian lighting schedule of 16 hours of light, followed by 8 hours of darkness (16L:8D) did not show the same stimulatory effect on leg bone development, as no dif­ferences in gene expression markers involved in embryonic ossification were found, leg bone dimensions at hatch were not increased, and bone mineral content as determined by DXA scanning was not higher for 16L:8D. It can therefore be speculated that the dark period should exceed 8 hours per day during incubation for increased bone dimensions and ossification. However, incidence and severity of the leg bone pathologies in the form of bacterial chondronecrosis with osteomyelitis and epiphyseal plate abnormalities were lowest for broilers exposed to 16L:8D during incubation, and tibial dyschondroplasia tended to be lower for 16L:8D than for 24D. Interactions between incubation and mat­ching or mismatching post hatch lighting schedules were not found. It was speculated that the endocrine factors (pineal) melatonin, growth hormone, corticosterone, and IGF- 1 were a pathway through which light affected leg bone development, but no evidence was found to support this hypothesis. Production performance was not greatly influen­ced by incubation lighting schedule, but 24L was found to result in higher body weights at slaughter age than 16L:8D and 24D. In the final experiment, lighting schedules were applied during the brooding period from day 0 to 4 after hatching and leg bone develop­ment was measured at day 4 post hatch. 24L led to increased leg bone dimensions, but lower developmental stability of the leg bones than a lighting schedule with 1 or 6 hours of darkness after every 2 hours of light.

The overall findings of this thesis suggest that continuous light during incubation and in the brooding period had a detrimental effect on embryonic and early post hatch leg bone development and health. The involvement of endocrine factors was not clarified from the current results. Applying a light-dark rhythm during incubation may improve embryonic leg bone development and leg health at slaughter age compared to continuous light and continuous darkness, without affecting post hatch production performance, but it appears that the dark period should last longer than 8 hours per day for optimal leg bone development.

Raaprobot voor eieren
Vroegindeweij, Bastiaan - \ 2016
raaprobot - eieren - eierraaprobot

Raaprobot voor eieren

Kippen leggen bijna al hun eieren in nesten, maar een aantal eieren belandt ergens in het scharrelstro. Het eieren rapen is nodig, maar tijdrovend. Wageningse onderzoekers ontwikkelden een autonome eierraper die zelfstandig door de stal manoeuvreert. De robot herkent verdwaalde eieren en verzamelt ze. Dat bespaart de pluimveehouder al gauw duizenden euro's per jaar. Bovendien is de robot te voorzien van apparatuur om het stalklimaat te meten of om op zieke dieren te letten. De kippen wennen snel aan de stalgenoot die ze als speelmaatje zien. Zo werkt Wageningen UR aan de kwaliteit van leven.

Are all eggs equal? : embryonic development and nutrient metabolism in chicken eggs of different origins
Nangsuay, A. - \ 2016
University. Promotor(en): Bas Kemp, co-promotor(en): Henry van den Brand; R. Meijerhof. - Wageningen : Wageningen University - ISBN 9789462577749 - 213 p.
eggs - hens - broilers - characteristics - strains - embryonic development - nutrients - metabolism - hatcheries - poultry - nutrition physiology - eieren - hennen - vleeskuikens - karakteristieken - stammen (biologisch) - embryonale ontwikkeling - voedingsstoffen - metabolisme - broedinstallaties - pluimvee - voedingsfysiologie

Hatching eggs, supplied to hatcheries are originating from different origins varying in breed, strain, and breeder age. These hatching eggs can be different in size, composition and eggshell properties, which might influence nutrient and O2 availability and consequently could affect embryonic development and nutrient metabolism. The aim of this thesis was therefore 1) to investigate effects of egg origin on nutrient and O2 availability, 2) to investigate effects of egg origins on nutrient metabolism and embryonic development and 3) to investigate consequences of different egg origins on the incubation process and hatching characteristics. In five studies, effects of different egg origins on nutrient and O2 availability, nutrient metabolism, embryo development and hatching characteristics were investigated. The first and second study focused on breeder age and egg size. The third study on breed; broilers and layers. The fourth study on broiler strain and the fifth study on breeder age, strain and eggshell temperature (EST). The overall findings in this thesis suggest that hatching eggs from different origins are not equal in availability of nutrients and O2. Nutrient availability is altered through variation in yolk size, especially by the effects of breeder age and breed. O2 availability is altered by differences in eggshell properties, which is influenced by especially breed and broiler strain. The availability of both nutrients and O2 plays a role on nutrient metabolism measured as embryonic heat production (HP) and consequently on embryonic development. Between incubation day (E) E7 and E14, both nutrient and O2 availability might affect nutrient metabolism as shown in the results of the broiler and layer comparison. Between E14 and hatching, the availability of O2 becomes the most determinant factor for nutrient metabolism and consequently for embryonic development. An increase in EST from 37.8 to 38.9°C from E7 onward resulted in an acceleration of nutrient metabolism and embryonic development until E16, but thereafter a high EST resulted in reduced yolk free body mass development. Embryos with an accelerated metabolic speed at an early stage of incubation, caused by an increased EST, might reach limited O2 availability at a higher magnitude than the embryos at a normal EST. As a result, nutrient metabolism is restricted and embryonic development is depressed. It can be concluded that not only the HP, but also the availability of O2 is crucial to be taken into account for developing incubator temperature. The principle is to obtain an optimal EST, which could maintain the balance between O2 requirement (driven by nutrient metabolism) and O2 availability for a continuing optimal nutrient metabolism to generate sufficient energy for embryonic development throughout incubation.

Nederlandse handelsbalans eieren
Horne, P.L.M. van; Jukema, G.D. - \ 2016
LEI Wageningen UR (Factsheet / LEI Wageningen UR 2016-012d) - 2 p.
handelsbalans - eieren - export - nederland - balance of trade - eggs - exports - netherlands
In 2014 nam de exportwaarde van consumptie-eieren iets af in vergelijking met 2013. Ook de invoerwaarde is licht gedaald. De handelsbalans kwam eveneens iets lager uit. De verwachting voor 2015 is dat de exportwaarde toeneemt. Voor de Nederlandse pluimveesector is Duitsland een heel belangrijke exportbestemming. Van de in Nederland geproduceerde eieren gaat circa de helft naar Duitsland. Het merendeel is export als consumptie-ei, maar ook veel eiproduct gaat naar onze Oosterburen. De waarde van de export van consumptie-eieren was in 2014 bijna € 380 mln.
Competitiveness of the EU egg industry. International comparison base year 2013
Horne, P.L.M. van - \ 2014
Wageningen : LEI Wageningen UR (Report / LEI Wageningen UR LEI 2014-041) - ISBN 9789086156962 - 36
eieren - landbouwprijzen - handel - markten - eierproducten - productiekosten - europese unie - marktconcurrentie - voedselveiligheid - eggs - agricultural prices - trade - markets - egg products - production costs - european union - market competition - food safety
In this report the impact of reducing or removing import tariffs on the competitiveness of the EU egg sector is studied. The results show that the offer price of whole egg powder in 2013 of some third countries is close to the average EU price. Despite the current import tariffs on whole egg powder, the third countries can be competitive on the EU market. In a scenario with a 50% lower import tariff, all third countries have a lower offer price of whole egg powder compared to the EU egg sector. In a scenario with zero import tariffs, all third countries have a considerably lower offer price of whole egg powder compared to the EU egg sector.
Dioxines en PCB's in eieren van particuliere kippenhouders
RIKILT, - \ 2014
Wageningen : RIKILT Wageningen UR (RIKILT-rapport 2014.012) - 25
eieren - dioxinen - voedselveiligheid - pluimveehouderij - eggs - dioxins - food safety - poultry farming
Dit rapport geeft een eerste beeld van gehaltes in eieren van particuliere kippenhouders en doet een aantal aanbevelingen om de inname van dioxines en dioxineachtige PCB’s door leghennen te reduceren.
Offspring sex ratio bias and sex related characteristics of eggs in chicken
Aslam, M.A. - \ 2014
Wageningen University. Promotor(en): Mari Smits; T.G.G. Groothuis, co-promotor(en): Henri Woelders. - Wageningen : Wageningen University - ISBN 9789462570757 - 192
kippen - eieren - geslachtsverhouding - karakteristieken - nageslacht - toewijzing - polymerase-kettingreactie - hormonen - voedselbeperking - dierveredeling - fowls - eggs - sex ratio - characteristics - progeny - allocation - polymerase chain reaction - hormones - food restriction - animal breeding

Understanding the factors influencing sex of egg and sex ratio in laying chicken may lead to finding potential solutions for the problem of killing of day old male chicks, which is the current practice in breeding of laying hens. In studies described in this thesis, it was investigated if the sex of the chicken egg can be predicted by measurable differences in male and female eggs at unincubated stage and if the female primary sex ratio can be induced in laying chicken using different experimental conditions such as feed restriction and corticosterone feeding. The method of sex determination in unincubated chicken eggs using PCR targeted to CHD1 gene was first developed. This method was subsequently used to study the primary sex ratio bias as well as relationship between egg sex and yolk hormones. No significant relationship of the sex of egg with concentrations of several hormones (testosterone, estradiol, androstenedione, progesterone, dihydrotestosterone) and glucose in yolk as well as of egg parameters (mass, width and length) was found. Effect of feed availability on sex ratio was tested in two separate studies. In one study, the rate of change of hen body mass between day of laying and day of laying minus 2 days (encompass time of meiosis completion) was a significant predictor for the sex of that egg, suggesting meiotic drive as mechanism of sex ratio bias. This relationship was not found in the later study. The difference in results could be due to the reason that hens decreased in body mass much less in the later study as compared to earlier study. Blood corticosterone concentrations were associated with sex ratio per hen in the earlier study. Effect of egg mass on egg sex was studied during the later experiment of feed restriction. The egg sex ratio per hen was negatively associated with the average egg mass per hen in the feed restriction group. Two groups of hens were selected from the feed restriction group i.e. male biased hens with low egg mass and female biased hens with high egg mass for microarray analysis of gene expression in the germinal disc of collected F1 follicle. The results did not show differential expression of genes between the groups. However, gene set enrichment analysis showed that a number of processes related to cell cycle progression, mitotic/meiotic apparatus and chromosomal movement were differently enriched between the groups, supporting meiotic drive as potential mechanisms underlying sex ratio determination. In another experiment, blood circulating levels of corticosterone in hens were increased by feeding corticosterone mixed feed under ad libitum. The blood levels of corticosterone were significantly higher in treated hens but these levels were not associated with sex ratio. Treatment did not affect the overall sex ratio, but affected the sex ratio in interaction with hen body mass. In the corticosterone group, sex ratio, laying rate, and fertility rate per hen were decreased in heavy hens. These results suggest that three parameters (sex ratio, laying rate and fertility rate) are connected at the level of ovarian physiology. Interference with meiosis have been shown to affect these three parameters, suggesting the involvement of meiotic drive as mechanism of sex ratio bias.

Leghennenhouderij in diep dal
Horne, P.L.M. van; Wisman, J.H. - \ 2014
Agri-monitor 2014 (2014)june. - ISSN 1383-6455 - 3
pluimveehouderij - hennen - eieren - prijzen - bedrijfsresultaten in de landbouw - rendement - poultry farming - hens - eggs - prices - farm results - returns
De leghennenhouders ontvangen nu al twee jaar eierprijzen fors onder de kostprijs. Vooral scharrelhennenhouders hebben moeite het hoofd boven water te houden. Het perspectief voor het komende halfjaar is niet gunstig.
Authentication of organic eggs by LC fingerprinting and isotope ratio analysis
Ruth, S.M. van; Rogers, K. ; Newton-Smith, E. ; Koot, A.H. ; Alewijn, M. - \ 2012
analytische methoden - massaspectrometrie - vloeistofchromatografie - eieren - biologische voedingsmiddelen - principale componentenanalyse - analytical methods - mass spectrometry - liquid chromatography - eggs - organic foods - principal component analysis
The aim of the present study was to develop and modify fingerprint methodology for the verification of Dutch organic eggs versus conventional (barn/free range) eggs.
Concurrentiekracht van de Nederlandse eiersector
Horne, P.L.M. van - \ 2012
Den Haag : LEI, onderdeel van Wageningen UR (LEI-rapport : Onderzoeksveld Markt & ketens ) - ISBN 9789086155996 - 74
dierlijke producten - eieren - pluimvee - markten - statistiek - prijzen - economische productie - productiekosten - marktconcurrentie - animal products - eggs - poultry - markets - statistics - prices - economic production - production costs - market competition
Het LEI heeft op verzoek van het ministerie van Economische Zaken (EZ) en het Productschap Pluimvee en Eieren (PPE) een onderzoek uitgevoerd naar de concurrentiekracht van de Nederlandse eiersector. Centrale vraag daarbij is of de Nederlandse eierketen concurrerend is. Belangrijk onderdeel van de studie is een vergelijking van de huidige en toekomstige positie van de Nederlandse eierketen ten opzichte van de belangrijkste concurrerende productielanden. In deze studie zijn de productiekosten van eieren in Nederland vergeleken met de productiekosten in het belangrijke afzetgebied Duitsland en met die van enkele concurrerende landen in Noordwest Europa. Ook is een vergelijking gemaakt van productiekosten van eieren met enkele landen buiten Europa.
Competitiveness of the EU egg industry
Horne, P.L.M. van - \ 2012
The Hague : LEI, part of Wageningen UR (LEI-report : Markets & chains ) - ISBN 9789086155989 - 51
eieren - eipoeder - import - heffingen - invoerrechten - landbouwprijzen - prijzen - europese unie - pluimvee - dierlijke productie - hennen - dierenwelzijn - handel - markten - eggs - dried egg - imports - levies - import levies - agricultural prices - prices - european union - poultry - animal production - hens - animal welfare - trade - markets
Egg producers in the EU have to comply with legislation dealing with environmental protection, animal welfare and food safety. From 1 January 2012 keeping hens in conventional cages was prohibited and egg producers had to change to either enriched cages or alternative housing systems. The result of all this legislation is an increase in the cost of producing eggs. At the same time the EU is negotiating with other countries or groups of countries to liberalise trade in agricultural products. These multi- or bilateral negotiations are designed to further liberalise trade by either further reducing import tariffs or removing them altogether. In this report the impact of lowering import tariffs on the competitiveness of the EU egg industry is studied. The results show that the offer price of whole egg powder in 2012 of some third countries is close to the average EU price. Despite the current import tariffs on whole egg powder, the third countries can be competitive on the EU market. In a scenario with a 50% lower import tariff, all third countries have a lower offer price of whole egg powder compared to the EU egg industry.
Eierproductie duurder dan ooit
Vermeij, I. ; Horne, P.L.M. van - \ 2012
De Pluimveehouderij 42 (2012)8. - ISSN 0166-8250 - p. 32 - 33.
eierproductie - pluimveehouderij - eieren - huisvesting van kippen - landbouwprijzen - kosten - berekening - egg production - poultry farming - eggs - chicken housing - agricultural prices - costs - calculation
De hogere voerprijzen laten de kostprijs van consumptie-eieren weer stijgen. Ten opzichte van twee jaar geleden (de vorige berekening) is de kostprijs ongeveer 10 procent hoger.
Exploring ecological sustainability in the production chain of organic eggs
Dekker, S.E.M. - \ 2012
University. Promotor(en): Peter Groot Koerkamp; Imke de Boer, co-promotor(en): Andre Aarnink. - S.l. : s.n. - ISBN 9789461731494 - 175
pluimveehouderij - hennen - eierproductie - eieren - biologische landbouw - milieueffect - ecologische beoordeling - duurzame veehouderij - ketenmanagement - nederland - poultry farming - hens - egg production - eggs - organic farming - environmental impact - ecological assessment - sustainable animal husbandry - supply chain management - netherlands
De visie van de biologische landbouw op duurzaamheid is verwoord door IFOAM in hun doelstelling en in de 4 beginselen van de biologische landbouw en is vertaald in diverse praktische regels voor biologische productie. In dit proefschrift noemen we deze visie het biologisch-ethisch kader. De hoofddoelstelling van dit proefschrift was het vaststellen van het effect van dit biologisch-ethisch kader op de integrale milieubelasting van biologische eierproductie in Nederland. Deze doelstelling werd benaderd vanuit 3 invalshoeken: 1) het vaststellen van het verschil in integrale milieubelasting van eierproductie met en zonder het biologisch-ethisch kader, 2) het identificeren van de belangrijkste milieuproblemen in het bestaande biologische eierproductiesysteem in Nederland en 3) het verkennen van mogelijkheden om de integrale milieubelasting van Nederlandse biologische eierproductie te verbeteren binnen de grenzen van het biologisch-ethisch kader.
Kostprijs bio-ei een derde cent gestegen
Vermeij, I. - \ 2011
De Pluimveehouderij 41 (2011)1. - ISSN 0166-8250 - p. 36 - 37.
biologische landbouw - pluimveehouderij - kosten - landbouwprijzen - eieren - organic farming - poultry farming - costs - agricultural prices - eggs
De kostprijs van een biologisch ei valt in 2010 hoger uit dan in 2009. Door de overgang op het programma LegManager zit in de gebruikte technische kengetallen een kleine trendbreuk.
Op heterdaad betrappen
Ruth, S.M. van - \ 2011
De Pluimveehouderij 41 (2011)6. - ISSN 0166-8250 - p. 24 - 25.
eieren - biologische voedingsmiddelen - pluimveehouderij - biologische landbouw - voedselanalyse - carotenoïden - scharreleieren - eggs - organic foods - poultry farming - organic farming - food analysis - carotenoids - free range eggs
De vingerafdruk van geelpigmenten is geschikt om vast te stellen of een bio-ei echt een biologische herkomst heeft. Voedselveiligheidsinstituut Rikilt heeft de methode ontwikkeld.
Eggspectation : analytische test om biologische eieren te verifiëren
Ruth, S.M. van - \ 2011
Wageningen : Rikilt - Institute of Food Safety
biologische voedingsmiddelen - voedselanalyse - eieren - analytische methoden - carotenoïden - testen - organic foods - food analysis - eggs - analytical methods - carotenoids - testing
Binnen het onderzoeksinstituut RIKILT (Wageningen University & Research Centre) is een methode ontwikkeld om de identiteit van biologische eieren te kunnen verifiëren. De fingerprint van de geelpigmenten (carotenoïden: carotenen en xantofyllen) in eieren worden hierbij gebruikt om onderscheid te maken tussen biologische en reguliere eieren.
Verkenning van dierlijke tussensegmenten in onze buurlanden; Duurzaam varkensvlees, pluimveevlees en eieren
Oosterkamp, E.B. ; Bremmer, B. ; Hoste, R. ; Greef, K.H. de - \ 2011
Den Haag : LEI, onderdeel van Wageningen UR (LEI-rapport 2011-028) - ISBN 9789086155255 - 105
dierenwelzijn - dierlijke productie - duurzaamheid (sustainability) - duurzame veehouderij - varkensvlees - pluimveevlees - eieren - landen van de europese unie - overheidsbeleid - animal welfare - animal production - sustainability - sustainable animal husbandry - pigmeat - poultry meat - eggs - european union countries - government policy
Bij de ontwikkeling van het segment tussen biologisch en gangbaar, het tussensegment, voor dierlijke producten is het Verenigd Koninkrijk een voorbeeld voor Nederland. Het marktaandeel van het tussensegment is daar hoog en het land heeft een vergelijkbare aanpak voor de verbetering van dierenwelzijn. In die aanpak zijn standaarden voor dierenwelzijn ontwikkeld en kan de consument onderscheid tussen producten maken. Vergeleken met Nederland staat de overheid daarbij meer op afstand. In Frankrijk is de aanpak anders en garandeert de overheid de kwaliteit van producten via de wet. Cultuurverschillen tussen landen spelen hierbij een rol.
Eggspectation : organic egg verification tool
Ruth, S.M. van; Hoogenboom, L.A.P. - \ 2011
The Organic Standard 2011 (2011)118. - ISSN 1650-6057 - p. 3 - 4.
voedselanalyse - biologische voedingsmiddelen - testen - analytische methoden - eieren - certificering - food analysis - organic foods - testing - analytical methods - eggs - certification
In 2009 RIKILT conducted a study on about 2,000 eggs to evaluate three different analytical verification methods: carotenoid profiling, fatty acid profiling and isotope ratio mass spectrometry. The eggs were collected from about 50 Dutch farms. The selection was based on the farms’ location and size, and production methods: organic, free range and barn raised. Carotenoid profiling showed a 100% correct prediction of the identity (organic vs. conventional) for the organic eggs in this ‘training set’.
De ideale biologische leghen…
Leenstra, F.R. ; Niekerk, T.G.C.M. van; Reuvekamp, B.F.J. - \ 2011
biologische landbouw - hennen - pluimveehouderij - eieren - organic farming - hens - poultry farming - eggs
Poster met informatie over onderzoek naar de ideale biologische leghen.
Pluimveehouderij: inkomens lager
Wisman, J.H. - \ 2010
Agri-monitor 2010 (2010)dec. - ISSN 1383-6455 - p. 1 - 3.
pluimveehouderij - bedrijfsresultaten in de landbouw - inkomen van landbouwers - eieren - vleeskuikens - landbouwprijzen - agrarische handel - poultry farming - farm results - farmers' income - eggs - broilers - agricultural prices - agricultural trade
De Pluimveehouderij had in 2010 te maken met teruglopende inkomens, vooral vanwege de gestegen voerkosten. In de legsector droegen daarnaast de lagere eierprijzen bij aan een lager saldo. Dit geldt met name voor de kooibedrijven.
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