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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Gezond drinkwater voor vleeskuikens
Ellen, H.H. - \ 2018
Wageningen : Wageningen Livestock Research - 2 p.
animal welfare - animal production - poultry - broilers - animal behaviour - animal health - drinking water - animal nutrition
TerraSea energiezuinig stalconcept voor vleeskuikens
Ellen, H.H. - \ 2018
Wageningen : Wageningen Livestock Research - 2 p.
animal welfare - animal production - poultry - broilers - climate - energy - animal health
Verbetering brandveiligheid oudere veestallen
Bokma-Bakker, M.H. - \ 2018
Wageningen : Wageningen UR Livestock Research - 2 p.
animal welfare - animal production - poultry - broilers - animal behaviour - animal health - animal housing - animal nutrition
Broiler welfare under scrutiny
Jong, I.C. de - \ 2018
Wageningen : Wageningen Livestock Research - 2 p.
animal welfare - animal production - poultry - broilers - animal behaviour - animal health - animal housing - animal nutrition
Is de ‘nieuwe’ supermarktkip gelukkiger dan de omstreden ‘plofkip’?
Jong, I.C. de - \ 2017
Wageningen : Livestock Stories blog, Wageningen University & Research
animal welfare - animal production - poultry - broilers - animal behaviour - animal health - animal housing
Het effect van een verhoogde rustplaats op het gebruik en het gedrag bij opfok vleeskuikenouderdieren
Emous, R.A. van; Gunnink, H. ; Binnendijk, G.P. - \ 2017
Wageningen : Wageningen Livestock Research (Wageningen Livestock Research rapport 1047) - 19
dierlijke productie - pluimvee - vleeskuikens - vleeskuikenouderdieren - huisvesting, dieren - diergedrag - animal production - poultry - broilers - broiler breeders - animal housing - animal behaviour
Bringing eggs and bones to light : affecting leg bone development in broiler chickens through perinatal lighting schedules
Pol, Carla W. van der - \ 2017
Wageningen 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.

First week nutrition for broiler chickens : effects on growth, metabolic status, organ development, and carcass composition
Lamot, David - \ 2017
Wageningen University. Promotor(en): Bas Kemp, co-promotor(en): Henry van den Brand; Peter Wijtten. - Wageningen : Wageningen University - ISBN 9789463430777 - 187
broilers - animal nutrition - poultry feeding - feeds - growth - metabolism - carcass composition - nutrition physiology - vleeskuikens - diervoeding - pluimveevoeding - voer - groei - metabolisme - karkassamenstelling - voedingsfysiologie

During the first week of life, broiler chickens undergo various developmental changes that are already initiated during incubation. Ongoing development of organs such as the gastro- intestinal tract and the immune system may affect the nutritional requirements during this age period. Despite the residual yolk that is available at hatch and that may provide nutritional support during the first days after hatch, the growth performance may be affected by the time in between hatch and first feed intake. Furthermore, it remains largely unknown to what extend nutritional composition of a pre-starter diet, as well as feed availability directly after hatch have an effect on physiological development directly after hatch, but also at later age. The aim of this thesis was to determine the impact of feed availability and feed composition provided during the first week of life on short-term physiological development, as well as potential long-term effects on growth performance of broiler chickens. Especially early hatched chickens were suggested to benefit more from direct feed access compared to midterm and late hatched chickens, as they tended to have a higher body weight gain during the first week after hatch. A delay in feed access for 48 h resulted in lowered body weight gain and feed intake when compared to direct feed access, but so did a short (13 to 26 h) delay in feed access after hatch. In the latter case, delayed feed access resulted in a lower weight to length ratio of the jejunum and ileum at 4 d of age compared with chickens with direct feed access. Although delayed feed access after hatch resulted in lower body weight gain during the first week after hatch and thereafter, it can be discussed whether this is truly an impairment of long-term growth or just a delayed onset of growth. With respect to feed composition, the inclusion of fish oil and medium chain fatty acids in a pre-starter diet had minor effects on humoral immune function. Inclusion of medium chain fatty acids did result in higher body weight gain and lowered feed efficiency during the first week of life, but only during the period it was provided. Feeding increased diet densities during the first week of life, obtained by formulating diets with different dietary fat levels, resulted in an increased gain to feed ratio, whereas body weight gain and feed intake decreased. Despite the shift in dietary energy supply from carbohydrates to fat and the perceived lower fat digestibility in young broiler chickens, nitrogen metabolizability and fat digestibility were not affected in the current study by feeding increased diet densities. The relative crop, liver and pancreas weights decreased when feeding increased diet densities, whereas the length of the entire intestinal tract increased. This suggests that broiler chickens repartition visceral organ development in response to feeding more concentrated diets during the first week of life. Interestingly, protein and fat accretion were not affected. Continued feeding of increased diet densities after 7 d of age resulted in increased BW gain, G:F ratio and metabolizable energy intake, but mainly during the periods that these diets were provided. In summary, even short durations of delayed feed access already impact intestinal development of young broiler chickens. However, a delayed feed access up to 48 h after hatch does not result in impaired growth, but only a delayed onset of growth. Even though digestibility of fats and oils may be suboptimal in young broiler chickens, feeding of these diets does not have to result in lowered performance per se. Young broiler chickens appear to adapt themselves towards high density diets with high fat inclusion levels in the first week of life, enabling them to digest and metabolize these diet types despite a suboptimal capacity for fat digestion. High density diets result in higher growth performance, but only for the period these diets are provided and thus carry-over effects at later age appear to be limited.

Retrospectieve analyse van standaard vastgelegde data in de vleeskuikenproductieketen
Jong, I.C. de; Riel, J.W. van - \ 2017
Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 1013) - 32
vleeskuikens - vleeskuikenproductie - pluimveehouderij - prestatiekenmerken - gegevens verzamelen - gegevensanalyse - nederland - dierenwelzijn - dierlijke productie - broilers - broiler production - poultry farming - performance traits - data collection - data analysis - netherlands - animal welfare - animal production
Risicobeoordeling waterverstrekking aan vleeskuikens en vleeskuikenouderdieren
Jong, I.C. de; Koene, P. ; Ellen, H.H. ; Emous, R.A. van; Rommers, J.M. ; Brand, H. van den - \ 2016
Wageningen Livestock Research - 62 p.
animal welfare - animal production - poultry - broilers - animal nutrition - drinking water - animal health
This report describes the methods of water provision in the current housing and management of broilers and broiler breeders and the possible impact of these management practices on animal welfare (including animal health). It provides an overview of drinking behavior of chickens, the physiology of water intake and factors affecting water consumption in broilers and broiler breeders. Based on scientific literature and expert opinion it is estimated that the current methods of water provision to broiler chickens do not have an effect on welfare. The current methods of water provision to broiler breeders are estimated to affect broiler breeder welfare, but evidence from scientific literature is lacking. It is described which management methods can be applied to reduce the welfare impact of water provision to broilers and broiler breeders. Finally, recommendations for further research are provided
Ontwikkeling van een rekentool om de ammoniakemissie uit vleeskuikenstallen te kunnen voorspellen
Aarnink, Andre ; Harn, Jan van; Banken, Klaas ; Ogink, Nico - \ 2016
Wageningen : Wageningen Livestock Research (Livestock Research rapport 990) - 73
vleeskuikens - ammoniakemissie - modellen - pluimveehouderij - broilers - ammonia emission - models - poultry farming
Phytate degradation in broilers
Krimpen, M.M. van; Emous, R.A. van; Spek, J.W. ; Kwakernaak, C. - \ 2016
Wageningen : Wageningen Livestock Research (Wageningen Livestock Research report 978) - 50
broilers - phytic acid - digestibility - poultry feeding - vleeskuikens - fytinezuur - verteerbaarheid - pluimveevoeding
Actualisering geuremissiefactor vleeskuikens
Ogink, N.W.M. ; Ellen, H. ; Mosquera, J. - \ 2016
Wageningen : Wageningen Livestock Research (Livestock Research rapport 960) - 25
vleeskuikens - pluimveehouderij - stankemissie - regelingen - nederland - broilers - poultry farming - odour emission - regulations - netherlands
The aim of this study was to advice on the update of the odour emission factor for broiler houses that is used in the national regulation to control nuisance from odour from livestock (Rgv) in the Netherlands. The update was based a statistical analysis of odour emission data from field studies carried on 28 broiler barns between 1996 en 2014. The main conclusion drawn from this analysis was that the odour emission under current management conditions is higher than the so far used odour emission factor in the Rgv-regulation. The current odour emission factor in the Rgv assigned to broiler houses without additional air cleaning techniques amounts 0.24 OUE/s per placed bird. It is advised to adjust this factor to 0.33 OUE/s per placed bird.
Gezonde vleeskuikens - Een goede start: belang van voer en water : Kennisclip
Ruis, M.A.W. - \ 2016
Dierenwelzijnsweb
dierenwelzijn - dierlijke productie - diergezondheid - antibiotica - pluimvee - vleeskuikens - animal welfare - animal production - animal health - antibiotics - poultry - broilers
Een gezond kuiken kan onder optimale omstandigheden zijn voordeel doen van directe beschikking over voer en water. Het kuiken kan de dooierrest dan beter benutten voor ontwikkeling, immuniteit en groei. De juiste temperatuur van de omgeving is hierbij een zeer belangrijke factor, want als kuikens het koud of te warm hebben eten ze niet en zal van een goede start geen sprake zijn.

In de kuikenbroederij komen kuikens niet allemaal tegelijk uit. De kuikens die het eerst uit komen, moeten wachten totdat alle kuikens uit zijn, en dat kan nog wel een dag duren. Daarna worden de kuikens verwerkt en geteld, en worden ze naar de boerderij gebracht. Zo kan het wel 36 uur duren voordat de eerst uitgekomen kuikens voer en water krijgen.

Innovaties in de pluimveehouderij richten zich op vroege voeding als pluspunt onder optimale omstandigheden: direct verstrekken van water en voer in de uitkomstkast, en het laten uitkomen van broedeieren in de stal.

In opdracht van Wageningen UR Livestock Research en het Ontwikkelcentrum, project 'Naar gezonde kalveren en kippen' (BO-20-011-032). Meer informatie over diergezondheid en dierenwelzijn: www.dierenwelzijnsweb.nl
Gezonde vleeskuikens - hygiëne troef: een beetje preventie is geen preventie : Kennisclip
Ruis, M.A.W. - \ 2016
Dierenwelzijnsweb
dierenwelzijn - dierlijke productie - diergezondheid - antibiotica - pluimvee - vleeskuikens - animal welfare - animal production - animal health - antibiotics - poultry - broilers
Ziekteverwekkers bij vleeskuikens kun je indelen in virussen, bacteriën en parasieten. Antibiotica werken alleen tegen bacteriën. De voornaamste bacteriën bij vleeskuikens zijn E-coli en enterococcen. De meest voorkomende virussen zijn ademhalingsvirussen. Van de parasieten komt de darmparasiet Eimera veelvuldig voor, veroorzaker van coccidiose.

Ziekteverwekkers kunnen op een bedrijf en in de stal worden binnengebracht door personen, voertuigen, het pluimvee zelf, voer, water, ongedierte, materialen en de lucht. Ze kunnen ook al aanwezig zijn in de stal. Er moet dus aandacht besteed worden aan zowel bedrijfshygiëne (externe biosecurity) als stalhygiëne (interne biosecurity).

In opdracht van Wageningen UR Livestock Research en het Ontwikkelcentrum, project 'Naar gezonde kalveren en kippen' (BO-20-011-032). Meer informatie over diergezondheid en dierenwelzijn: www.dierenwelzijnsweb.nl
Gezonde vleeskuikens - Schoon en smakelijk: belang van goede kwaliteit drinkwater : Kennisclip
Ruis, M.A.W. - \ 2016
Dierenwelzijnsweb
dierenwelzijn - dierlijke productie - diergezondheid - antibiotica - pluimvee - vleeskuikens - animal welfare - animal production - animal health - antibiotics - poultry - broilers
Goede kwaliteit drinkwater is essentieel voor een gezond vleeskuiken. Niet alleen aan de bron, maar ook daar waar de dieren het water opnemen: bij de nippel dus. Goed drinkwater is niet alleen belangrijk voor optimale bedrijfsresultaten, maar ook voor voedselveiligheid en diergezondheid.

Van onderzochte watermonsters uit de drinknippel bleek bijna 8 procent ongeschikt en bijna 20 procent minder geschikt als drinkwater voor pluimvee! De kwaliteit van drinkwater wordt vooral beïnvloed door de mogelijke aanwezigheid van biofilm aan de binnenzijde van de drinkleiding. Deze bestaat uit micro-organismen die groeien op afzettingen van vuil en mineralen.

In opdracht van Wageningen UR Livestock Research en het Ontwikkelcentrum, project 'Naar gezonde kalveren en kippen' (BO-20-011-032). Meer informatie over diergezondheid en dierenwelzijn: www.dierenwelzijnsweb.nl
Gezonde vleeskuikens : goed ter been: belang van een goede strooiselkwaliteit : Kennisclip
Ruis, M.A.W. - \ 2016
Dierenwelzijnsweb
dierenwelzijn - dierlijke productie - diergezondheid - antibiotica - pluimvee - vleeskuikens - animal welfare - animal production - animal health - antibiotics - poultry - broilers
Voetzoollaesies zijn aantastingen van de voetzolen van vleeskuikens. Bij een milde laesie is er sprake van een oppervlakkige aantasting (verkleuring, verdikking) van de huid van de voetzool. Bij een ernstige laesie is de opperhuid aangetast tot in de diepere huidlagen en is er sprake van onderhuidse ontstekingen. Deze ernstige voetzoollaesies zijn pijnlijk, en zijn een risico voor diergezondheid.

Voetzoollaesies bij vleeskuikens worden veroorzaakt door een slechte strooiselkwaliteit: nat en plakkerig strooisel. De strooiselkwaliteit wordt door veel factoren beïnvloed, zoals het klimaat, de voersamenstelling en ziekten. De aanpak ervan verschilt van bedrijf tot bedrijf. In de Nederlandse regelgeving is een norm voor voetzoollaesies opgenomen die van toepassing is voor de hoogste bezettingsgraad (39-42 kg/m2).

In opdracht van Wageningen UR Livestock Research en het Ontwikkelcentrum, project 'Naar gezonde kalveren en kippen' (BO-20-011-032). Meer informatie over diergezondheid en dierenwelzijn: www.dierenwelzijnsweb.nl
Gezonde vleeskuikens - Campylobacter de baas – belang van het weren van vliegen : Kennisclip
Ruis, M.A.W. - \ 2016
Dierenwelzijnsweb
dierenwelzijn - dierlijke productie - antibiotica - pluimvee - vleeskuikens - animal welfare - animal production - antibiotics - poultry - broilers
Campylobacter is de meest voorkomende bacteriële veroorzaker van voedselinfecties in Nederland. 20-30% van de Campylobacter-besmettingen van de mens wordt veroorzaakt door consumptie van ongaar of onhygiënisch bereid pluimveevlees. De dieren zelf worden er na besmetting niet ziek van.

Vliegen zijn een belangrijke besmettingsbron op pluimveebedrijven. Het weren van vliegen is daarom een belangrijk aandachtspunt, maar moet gecombineerd worden met een goede biosecurity. Momenteel wordt onderzocht wat het effect is van het plaatsen van vliegennetten, zodat pluimveestallen vliegenvrij zijn.

In opdracht van Wageningen UR Livestock Research en het Ontwikkelcentrum, project 'Naar gezonde kalveren en kippen' (BO-20-011-032). Meer informatie over diergezondheid en dierenwelzijn: www.dierenwelzijnsweb.nl
Disentangling the domestic contract : understanding the everyday-life construction of acceptability -or non-acceptability- of keeping and killing animals for food
Nijland, Hanneke J. - \ 2016
Wageningen University. Promotor(en): Cees van Woerkum; Noelle Aarts. - Wageningen : Wageningen University - ISBN 9789462578296 - 325
meat - vegetarians - vegetarianism - vegetarian diets - killing of animals - meat animals - meat production - households - environmental impact - sustainability - animal welfare - animal production - animal ethics - food - dairy cattle - beef cattle - pigs - poultry - broilers - hens - vlees - vegetariërs - vegetarisme - vegetarische diëten - doden van dieren - slachtdieren - vleesproductie - huishoudens - milieueffect - duurzaamheid (sustainability) - dierenwelzijn - dierlijke productie - dierethiek - voedsel - melkvee - vleesvee - varkens - pluimvee - vleeskuikens - hennen

When we were children learning the names of animals, farm utensils and food products from picture books, talking about farming animals and related food products appeared simple. However, the intricate realities of modern-day farming practices differ momentously from this primary reference - the picture books. The topic brings about polarized responses, both rationally and emotionally, reflecting very diverse outlooks on the world. This dissertation reports on a research, set in the Netherlands and Turkey, that was designed to improve our understanding of the everyday-life construction of the acceptability -or non-acceptability- ofkeeping and killing animals for food, or in other words: to disentangle the domestic contract.

Effects of temperature and CO2 during late incubation on broiler chicken development
Maatjens, C.M. - \ 2016
Wageningen University. Promotor(en): Bas Kemp, co-promotor(en): Henry van den Brand; I.A.M. van Roovert-Reijrink. - Wageningen : Wageningen University - ISBN 9789462578258 - 196 p.
broilers - embryonic development - temperature - carbon dioxide - incubation - animal physiology - broiler performance - artificial hatching - hatcheries - poultry farming - vleeskuikens - embryonale ontwikkeling - temperatuur - kooldioxide - broeden - dierfysiologie - vleeskuikenresultaten - kunstmatig bebroeden - broedinstallaties - pluimveehouderij

Incubation conditions need to be adjusted to meet embryonic requirements to obtain optimal chick quality and hatchability. Eggshell temperature (EST) can be used as a non- invasive method to determine embryo temperature. A high EST of 38.9°C during the second or third week of incubation negatively affects chicken embryo development and survival compared to a constant EST of 37.8°C during that period. These negative effects of high EST might be due to a dis-balance between metabolic rate and oxygen (O2) availability. However, effects of lowering EST, which might restore the balance between metabolic rate and O2 availability, are largely unknown. Besides EST, the carbon dioxide (CO2) concentration during late incubation also seems to affect embryo development and might even interact with EST. Based on the potential effects of (lower) EST during the last week of incubation and of CO2 during only the hatching phase, the following three aims are derived: 1, to investigate effects of EST during the last phase of the incubation process, with special attention for EST below the general accepted optimal EST of 37.8°C, 2, to examine from which day of the incubation process onward EST should be changed from 37.8°C, and 3, to investigate whether CO2 concentrations are interacting with EST during the hatcher phase.

Time until hatch was longer when an EST of 35.6°C was applied during the last week of incubation, followed by 36.7, 37.8, and 38.9°C, which is probably caused by the lower metabolic rate at an EST below 37.8°C. Hatchability of fertile eggs was not affected at low EST, and EST did not affect time between internal pipping (IP) and hatch. An EST of 35.6 and 36.7°C, resulted in a higher yolk-free body mass (YFBM) at hatch compared to 37.8 and 38.9°C, and residual yolk weight was higher at hatch at 38.9°C compared to all other EST treatments. An EST of 35.6°C resulted in higher hepatic glycogen concentration and amount at IP and hatch compared to all other EST treatments. The proposed mechanism involved is that at lower EST, metabolic rate is reduced, which prevents the embryo from O2 limitation and ensures that fatty acid oxidation from the yolk can be maintained, resulting in energy production to be invested in growth and development. At an EST of 38.9°C, metabolic rate is high, resulting in a relative O2 shortage for the embryo. Consequently, lipid oxidation is reduced, which forces the embryo to switch to alternative energy sources, such as glycogen. Because glycogen storage is very limited in the egg and embryo, alternative energy sources such as amino acids obtained from muscles might be used. A clear interaction between EST and start day of treatment was found for relative heart weight. Relative heart weight was higher at an EST of 35.6°C and decreased with increase in EST. The differences among EST became larger when the EST treatment started earlier.

Effects of CO2 on embryo physiology, embryonic organ development, and chick quality were marginal. EST interacted with CO2 mainly before IP, but effects were minor at hatch. Interactions between EST and CO2 were found at an EST of 36.7 and 37.8°C, but remained absent at an EST of 38.9°C, which might indicate that physiological systems are already challenged due to the higher metabolic rate, which limits the capacity to cope with high CO2 of the embryo.

No effect of start day of treatment was indicated for embryonic organ development and chick quality found at hatch, which suggests that EST affected these parameters only in the last phase of incubation, e.g. from E19 onward. However, first week post-hatch performance was affected by start day of treatment. The beneficial effects of a lower EST of 35.6 and 36.7°C applied during the last week of incubation found at hatch, might contribute to an enhanced development during the first week post-hatch as body weight, carcass weight, and gain to feed ratio were increased.

In conclusion, results of this thesis show that an EST below 37.8°C during late incubation is beneficial for embryo development, organ growth during incubation, and growth performance during the first week post-hatch. In addition, start day of treatment did not affect chick quality and organ growth, except heart weight, at hatch, which implies that effects of EST occur during the hatching phase, e.g. from E19 onward. Although, an effect of start day of treatment was found on first week post-hatch performance, it remains to be investigated whether an EST below 37.8°C leads to improved later life quality characteristics.

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