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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Intraspecific variation in herbivore-induced plant volatiles influences the spatial range of plant–parasitoid interactions
Aartsma, Yavanna ; Leroy, Benjamin ; Werf, Wopke van der; Dicke, Marcel ; Poelman, Erik H. ; Bianchi, Felix J.J.A. - \ 2018
Oikos (2018). - ISSN 0030-1299 - 10 p.
animal behaviour - insect–plant interactions - plant odours - spatial ecology

Chemical information influences the behaviour of many animals, thus affecting species interactions. Many animals forage for resources that are heterogeneously distributed in space and time, and have evolved foraging behaviour that utilizes information related to these resources. Herbivore-induced plant volatiles (HIPVs), emitted by plants upon herbivore attack, provide information on herbivory to various animal species, including parasitoids. Little is known about the spatial scale at which plants attract parasitoids via HIPVs under field conditions and how intraspecific variation in HIPV emission affects this spatial scale. Here, we investigated the spatial scale of parasitoid attraction to two cabbage accessions that differ in relative preference of the parasitoid Cotesia glomerata when plants were damaged by Pieris brassicae caterpillars. Parasitoids were released in a field experiment with plants at distances of up to 60 m from the release site using intervals between plants of 10 or 20 m to assess parasitism rates over time and distance. Additionally, we observed host-location behaviour of parasitoids in detail in a semi-field tent experiment with plant spacing up to 8 m. Plant accession strongly affected successful host location in field set-ups with 10 or 20 m intervals between plants. In the semi-field set-up, plant finding success by parasitoids decreased with increasing plant spacing, differed between plant accessions, and was higher for host-infested plants than for uninfested plants. We demonstrate that parasitoids can be attracted to herbivore-infested plants over large distances (10 m or 20 m) in the field, and that stronger plant attractiveness via HIPVs increases this distance (up to at least 20 m). Our study indicates that variation in plant traits can affect attraction distance, movement patterns of parasitoids, and ultimately spatial patterns of plant–insect interactions. It is therefore important to consider plant-trait variation in HIPVs when studying animal foraging behaviour and multi-trophic interactions in a spatial context.

Boars with balls
Backus, Ge - \ 2018
animal welfare - animal production - pigs - animal behaviour - animal ethics - animal health - castration
Kattenkwaad: in huis poeslief, buiten een moordmachine
Debrot, Dolfi - \ 2018
animal welfare - pets - cats - animal behaviour
Three stars for animal welfare
Bos, Bram - \ 2017
animal welfare - animal production - poultry - fowls - animal housing - animal behaviour - animal health
Code of Practice for the Care and Handling of Rabbits: Review of Scientific Research on Priority Issues
Turner, Patricia ; Buijs, Stephanie ; Rommers, J.M. ; Tessier, Maxime - \ 2017
National Farm Animal Care Council - 69 p.
animal welfare - animal production - rabbits - animal housing - animal nutrition - animal health - animal behaviour
It is widely accepted that animal welfare codes, guidelines, standards or legislation should take advantage of the best available knowledge. This knowledge is often generated from the scientific literature. In re-establishing a Code of Practice development process, NFACC recognized the need for a more formal means of integrating scientific input into the Code of Practice process. A Scientific Committee review of priority animal welfare issues for the species being addressed will provide valuable information to the Code Development Committee in developing or revising a Code of Practice. As the Scientific Committee report is publicly available, the transparency and credibility of the Code is enhanced. For each Code of Practice being developed or revised, NFACC will identify a Scientific Committee. This committee will consist of a target number of 6 scientists familiar with research on the care and management of the animals under consideration. NFACC will request nominations from 1) Canadian Veterinary Medical Association, 2) Canadian Society of Animal Science, and 3) Canadian Chapter of the International Society for Applied Ethology. At least one representative from each of these professional scientific bodies will be named to the Scientific Committee. Other professional scientific organizations as appropriate may also serve on the Scientific Committee. Purpose & Goals The Scientific Committee will develop a report synthesizing the results of research relating to key animal welfare issues, as identified by the Scientific Committee and the Code Development Committee. The report will be used by the Code Development Committee in drafting a Code of Practice for the species in question. The Scientific Committee report will not contain recommendations following from any research results. Its purpose is to present a compilation of the scientific findings without bias. The full Terms of Reference for the Scientific Committee can be found within the NFACC Development Process for Codes of Practice for the Care and Handling of Farm Animals, available at
Project Insecten in pluimvee
Ruis, Markus - \ 2017
animal welfare - poultry - animal nutrition - animal behaviour - animal production
Stressvrij omgaan met varkens
Ruis, Markus - \ 2017
animal welfare - animal production - pigs - animal behaviour - animal health - housing - animal housing
Metabolic status, lactation persistency, and udder health of dairy cows after different dry period lengths
Hoeij, Renny van - \ 2017
University. Promotor(en): Bas Kemp; T.J.G.M. Lam, co-promotor(en): Ariette van Knegsel; Jan Dijkstra. - Wageningen : Wageningen University - ISBN 9789463438070 - 285
dairy cattle - animal health - animal behaviour - dry period - metabolism - energy balance - lactation - milk production - udders - cattle feeding - melkvee - diergezondheid - diergedrag - gustperiode - metabolisme - energiebalans - lactatie - melkproductie - uiers - rundveevoeding

Cows traditionally have a 6 to 8 week non-lactating –‘dry period’- before calving and the start of the next lactation in order to maximize milk production in the subsequent lactation. An omitted, compared with a shortened, dry period reduces milk yield and improves energy availability in cows postpartum, but effects on udder health and persistency were unclear. Cows without a dry period fattened and spontaneously dried off due to the improved energy availability. Reducing the energy availability in the feed for cows without a dry period did not affect fattening or lactation persistency in late lactation. Cows with a short or without a dry period did not receive dry cow antibiotics in this study and this did not affect udder health across the dry period or in early lactation, but seemed to impair udder health in late lactation for cows without a dry period.

Light during incubation and noise around hatching aect cognitive bias in laying hens
Rodenburg, T.B. ; Scholten, N.J.T. ; Haas, E.N. de - \ 2017
In: Proceedings of the 51st Congress of the International Society for Applied Ethology (ISAE), 7-10 August 2017, Aarhus, Denmark. - Wageningen : Wageningen Academic Publishers - ISBN 9789086863112 - p. 165 - 165.
animal welfare - animal behaviour
Incubation and hatching conditions can inuence development of laying hens. In commercialconditions, chicks are incubated in the dark and hatch in a noisy environment. €is may a�ecttheir behavioural and cognitive development in a negative way and may have lasting e�ectson their assessment of ambiguous stimuli in a cognitive bias test. €e aim of this study was toinvestigate the e�ects of light during incubation and noise around hatching on cognitive biasin adult laying hens. To meet that aim, eggs were incubated and hatched according to fourdi�erent treatments in a 2×2 cross design: during the .rst 16 days of incubation, they wouldeither be incubated in the dark or in a 12L:12D light schedule. From 17 to 21 days of age, half ofthe eggs from each light treatment would either be incubated in a noisy environment (playbackcommercial incubator noise; 90 dB) or a quiet environment (60-70 dB). Birds were kept ingroups of maximum 10 birds in oor pens separated per treatment from 0 to 35 weeks of age(seven groups per treatment). At 35 weeks of age, 32 hens (eight per treatment) were trainedfor a cognitive bias test, where they had to learn that one side of the test arena was rewarded(mixed grains and mealworms) and the other side was not (smell of feed only). €e rewardedside was varied according to a balanced design. €e experimenter was blind to birds’ treatments.When a bird had learned the task, she was tested with ambiguous cues, where the feeder wouldbe placed in the centre (50%), nearer the unrewarded side (25%) or nearer the rewarded side(75%). €is was done by subjecting each hen to 12 trials, where two rewarded (R) trials andone unrewarded (U) trial (order RRU or RUR, balanced design) were followed by one of theambiguous trials. For all hens, the .rst ambiguous trial was the 50% trial, followed by the 25%trial and the 75% trial. Latency to approach the feeder was analysed using a mixed model withtreatment, trial order and type of cue as .xed factors (including all interactions) and pen nestedwithin treatment as random factor. Over all treatments, birds had a shorter latency to reach thefeeder with the rewarded cue compared to all other cues, and with the 50% and 75% comparedto the unrewarded and 25% cue as expected (F4,360=211.4; P<0.001). €ere was a signi.cantinteraction between treatment and type of cue (F12,360=2.11; P<0.05). Birds from the lightand noise treatment were slower than birds from the other groups in the ambiguous 50% trial(F1,360=3.49; P<0.05), which is interpreted as a more pessimistic response to the ambiguouscue. €e light treatment during incubation may have resulted in a faster embryo development.€is may in turn have resulted in chicks that were more sensitive to the noise treatment thatwas applied around hatching. In conclusion, incubation and hatching conditions in layinghens can a�ect cognitive bias in laying hens. Creating more quiet incubators and could havepositive e�ects on laying hen welfare.
Alternatieve vloeren voor vleeskalveren
Heeres-van der Tol, Jetta ; Wolthuis, Maaike ; Bokma, Sjoerd ; Smits, Dolf ; Stockhofe, Norbert ; Vermeij, Izak ; Reenen, Kees van - \ 2017
Wageningen : Wageningen Livestock Research (Wageningen Livestock Research rapport 1056) - 103
dierenwelzijn - dierlijke productie - vleeskalveren - huisvesting - diergedrag - diergezondheid - animal welfare - animal production - veal calves - housing - animal behaviour - animal health
Monitoring verduurzaming veehouderij 1.0 : een eerste proeve van een Monitorings-systematiek voor de 15 ambities van de Uitvoeringsagenda Duurzame Veehouderij, met initiële resultaten voor drie diersectoren en een aantal keteninitiatieven
Bos, A.P. ; Puente-Rodríguez, Daniel ; Reijs, Joan W. ; Peet, G.F.V. van der; Groot Koerkamp, Peter W.G. - \ 2017
Wageningen : Wageningen Livestock Research (Wageningen Livestock Research rapport 1045) - 113
dierenwelzijn - dierlijke productie - melkvee - varkens - pluimvee - huisvesting, dieren - diergezondheid - diergedrag - animal welfare - animal production - dairy cattle - pigs - poultry - animal housing - animal health - animal behaviour
In 2013, the governance network UDV formulated fifteen ambitions towards a sustainable livestock production. In this way, the UDV’s stakeholders defined the long-term goals of an integrated and sustainable livestock production. To what extent have these 15 ambitions been achieved? And, how substantial is the contribution of supra-legal initiatives to this process? In this report, we present the first elaboration of a monitoring system that enables the visualization of the progress made. Moreover, it also enables comparing the different livestock production systems and creates the basis for a comparison between conventional animal production and supra-legal initiatives. In this concept-report the system is applied initially to the three larger livestock production sectors in the Netherlands (i.e., dairy, pigs, and poultry) and –as far as enough data is available– to four supra-legal initiatives. The system is currently under construction. Particularly because it involves interpretation and a number of value-laden choices that –notwithstanding their current support by arguments and references to the literature– should become shared and supported by (at least) the UDV stakeholders in the near future.
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
Elearning Cursus mens-dier interactie in de varkenshouderij
Ruis, M.A.W. - \ 2017
Wageningen : Wageningen Livestock Research - 2 p.
dierenwelzijn - dierlijke productie - varkens - diergedrag - diergezondheid - huisvesting, dieren - varkenshouderij - gedrag - behandeling - animal welfare - animal production - pigs - animal behaviour - animal health - animal housing - pig farming - behaviour - treatment
Hoe ervaart een varken de omgeving? En waarom is het van belang om hierbij stil te staan? Deze cursus richt zich op het belang van een goede mens-dier relatie, waarbij onder andere gekeken wordt naar de manier waarop een varken de wereld ervaart. Dit geeft inzicht in de manier van omgang, met als gevolg minder stress voor dier én mens. Het doel is een win-win situatie; het bevorderen van dierge - zondheid en dierenwelzijn dat onder andere zorgt voor meer werkplezier en meer benutting van het productie potentieel van het varken.
Systeemomschrijving “Plateau 2.0”
Hoofs, Anita - \ 2017
Wageningen : Wageningen Livestock Research - 5
dierenwelzijn - varkens - huisvesting, dieren - diergezondheid - diergedrag - animal welfare - pigs - animal housing - animal health - animal behaviour
En varkenshok met plateau is een hok waarin varkens vrij beschikken over twee verblijfsniveaus, één op de begane grond en één op het plateau. Varkens kunnen gemakkelijk het plateau op - en aflopen via een trap. Bij toepassing van een plateau, dat voldoet aan de systeemomschrijving, mag het beschikbare vloeroppervlak van het plateau als beschikbaar vloeroppervlak meegerekend worden.
Simulating pigs : Understanding their motivations, behaviour, welfare and productivity
Boumans, Iris - \ 2017
University. Promotor(en): Imke de Boer, co-promotor(en): Eddy Bokkers; Gert Jan Hofstede. - Wageningen : Wageningen University - ISBN 9789463432122 - 200
pigs - pig farming - sustainability - motivation - animal behaviour - behaviour disorders - animal welfare - simulation models - animal production - varkens - varkenshouderij - duurzaamheid (sustainability) - motivatie - diergedrag - gedragsstoornissen - dierenwelzijn - simulatiemodellen - dierlijke productie

The transition towards sustainable pig production systems is receiving increasing attention nowadays. Pig behaviour plays a central role in sustainability, as it is an important indicator for pig welfare and can also affect other sustainability issues. Understanding behaviour and related welfare consequences requires to understand motivations underlying behaviour. The two aims of this thesis were: 1) to assess the use of agent-based modelling for understanding pig behaviour and underlying motivation, and 2) to apply agent-based modelling for increasing our understanding of pig behaviour, and related animal welfare and productivity performance.

We first explored the use of agent-based modelling with tail biting behaviour in pigs as a case study. An agent-based model was developed to understand the causation of tail biting behaviour. Subsequently, we developed a mechanistic and dynamic simulation model to gain more understanding of feeding behaviour and internal (physiological) factors. The model integrates knowledge from physiology and ethology, and combines growth with a behavioural decision model based on motivation. This model included motivations underlying feeding behaviour and various feeding patterns of an individually housed growing pig. To deepen our understanding of mechanisms underlying feeding patterns of pigs within 24 hours, hormonal circadian rhythms were included in the model in a follow-up study. The circadian rhythms of cortisol and melatonin explained the alternans pattern, a small peak of feed intake at the beginning of the day and a larger peak at the end of the day, of feeding in pigs. Next, an agent-based model of feeding and social interaction in commercially group-housed pigs was developed to deepen our understanding of the complex interaction between internal physiological factors and external social factors. Social factors (e.g. competition level and social facilitation) and behavioural strategies (e.g. avoidance and approach) affected social interactions among pigs and feeding behaviour. The causation of variation among pigs was further explored in this model. Pig characteristics were important in various feeding, social interaction and growth patterns in pigs.

In general, agent-based modelling proved to be a useful method to understand animal behaviour and underlying motivations. It contributed to further understanding of tail biting, feeding and social behaviour in pigs. Furthermore, agent-based modelling showed to be a novel method to find and assess behaviours as welfare indicators, and to contribute to understanding trade-offs and synergies between sustainability issues, such as animal welfare and productivity.

Big uit groepsstal groeit beter
Nieuwamerongen, Sofie van - \ 2017
animal welfare - animal production - animal housing - animal behaviour - animal health
Can minor, easily applied alterations of routines during the rearing period reduce fearfulness in adult laying hens?
Brantsæter, Margrethe ; Tahamtani, Fernanda M. ; Nordgreen, J. ; Sandberg, Ellen ; Hansen, Tone Beate ; Rodenburg, T.B. ; Oppermann Moe, Randi ; Janczak, A.M. - \ 2017
In: Proceedings of the 51st Congress of the International Society for Applied Ethology (ISAE), 7-10 August 2017, Aarhus, Denmark. - Wageningen : Wageningen Academic Publishers - ISBN 9789086863112 - p. 198 - 198.
animal welfare - animal behaviour
Exaggerated fear-reactions are associated with injuries, smothering, feather pecking and other events that compromise laying hen welfare. Provision of litter during the rearing period may reduce fearfulness. The aim of this study was to test the hypothesis that chicks with access to litter during the first five weeks of life would be less fearful as adults compared to birds reared without access to litter. The hypothesis was tested in 23 commercial aviary layer flocks in Norway. Five rearing farmers divided the pullets into two groups within their rearing houses. During the first five weeks of life, paper substrate, on which food and other particles could accumulate, covered the wire mesh floor in the treatment group, whereas the control group was reared on bare wire mesh. The egg producers were instructed to follow their normal management procedures. At 30 weeks of age, 23 layer flocks (11 control flocks and 12 paper reared flocks) were visited. A stationary person test and a novel object test were conducted to test fearfulness of the adult hens. In addition, data on provision of environmental enrichment was collected as a binary yes/no variable. Provision of environmental enrichment to adult birds tended to reduce the latency to approach within 2 m of the stationary person (P=0.08). For birds without environmental enrichment as adults, access to litter during rearing increased the number of birds that approached the novel object compared with birds reared without paper (P=0.04). For birds with access to environmental enrichment during production, the access to litter during rearing had no effect on the number of birds that approached the novel object as adult (P=0.99). These results indicate that both providing chicks with paper substrate from the first day of life and providing them with environmental enrichment as adults, are practical and simple alterations of management that reduce fearfulness in laying hens.

Phenolab: ultra-wide band tracking shows feather pecking hens spent less time in close proximity compared to controls
Haas, E.N. de; Eijk, J.A.J. van der; Mil, B. van; Rodenburg, T.B. - \ 2017
In: Proceedings of the 51st Congress of the International Society for Applied Ethology (ISAE), 7-10 August 2017, Aarhus, Denmark. - Wageningen : Wageningen Academic Publishers - ISBN 9789086863112 - p. 176 - 176.
animal welfare - animal behaviour

Hens which feather peck can cause multiple victims in a group. As a result pen-mates could keep a greater distance from feather peckers. Our aim was to relate time spent in close proximity between birds selected divergently on feather pecking. Automatic ultra-wide band location data was obtained by using an active sending tag (UbisenseR) placed in a backpack on the birds. A group of birds was then placed for 15 minutes in a barren test-room equipped with four receiving beacons. We used 37-week old White Leghorn laying hen lines selected for high (HFP) or low feather pecking (LFP), and an unselected control (CON) line (n=76 in total, 5-7 hens per pen; 4 pens per line). Hens were habituated to the backpacks four weeks prior to observations, and were tested for 5-min to the test-room individually one week prior to group testing. Sample rate of tags was set to twice per second, detecting location of each tag separately and simultaneously. Location data was provided by TrackLab software (Noldus, Wageningen, The Netherlands) and compared between tags by Excel calculations. Percentage of time in close proximity was defined as being less than 25 cm apart from another tag, calculated for each bird and averaged per group. Behavioural sampling of feather pecking of 2×20 min at 28-29 wks of age was included on pen-level and used for identification of peckers (>2 bouts/20 min). Percentage of time in close proximity was correlated to feather pecking (pearson correlation), tested to differ between peckers and average of the group (t-test of groups with peckers) and tested to differ between lines (ANOVA including the number of animals per pen as covariate). Feather pecking on pen-level was not correlated to proximity measures (r=-0.28, P>0.10), but birds spent less time in close proximity of the feather pecker as opposed to time spent on average with other pen-mates (17.6・}1% vs 21.6・}1.2, t16=-1.18, P=0.04).

If you give the pig a choice: suckling piglets eat more from a diverse diet
Middelkoop, Anouschka ; Choudhury, R. ; Gerrits, W.J.J. ; Kemp, B. ; Kleerebezem, M. ; Bolhuis, J.E. - \ 2017
In: Proceedings of the 51st Congress of the International Society for Applied Ethology (ISAE), 7-10 August 2017, Aarhus, Denmark. - Wageningen : Wageningen Academic Publishers - ISBN 9789086863112 - p. 101 - 101.
animal welfare - animal behaviour
Stimulating solid feed intake in suckling pigs is important to ensure a successful weaning transition, exemplified by the correlation between pre- and post-weaning feed intake. In nature, piglets begin to sample food items in a playful manner when only a few days old. In pig husbandry, contrarily, suckling pigs are not encouraged to forage, whereas we hypothesize that this is crucial to increase piglet robustness via improved intestinal and gut microbiota development. One approach to familiarize pigs with solid feed at an early age ight be by providing feed in a variety of forms, using diversity or novelty to stimulate the pigs’ foraging behaviour. We studied the effect of dietary diversity (i.e. offering two diverse feeds simultaneously) vs novelty (i.e. regularly hanging the flavour of one feed) on the foraging behaviour and feed intake of suckling pigs. We also hypothesized that piglets, rather than sampling from one feed only, would prefer a diverse diet. Piglets received ad libitum feed from 2 days of age in two feeders per pen. In treatment 1 (T1, n=10 pens) pigs were given feed A and feed B which differed in size, flavour, composition, smell, texture and colour. In treatment 2 (T2, n=9) pigs received feed A plus feed A to which additional novel flavours (4 different ones) were added from day 6 in a daily sequential order. Feeding behaviour was studied by weighing feed remains (d6, 12, 16, 22) and by live observations (4-min scan sampling, 6 h/d; d10, 15, 22; n=6 pens per treatment). Observations were also used to determine ‘eaters’ (i.e. pigs scored eating at least once). Data were analyzed using mixed models. Piglets did not prefer feed A(d2-22: 196±16 g/pig) or B (152±13) within T1 and did not have an overall preference for feed A with (d6-22: 78±4 g/pig) or without flavour novelty (66±6) within T2. In accordance, just a few piglets (T1: 1.5% and T2: 3.2% out of all eaters per treatment) were observed eating only one of the feeds throughout lactation. Interestingly, T1-pigs (d2-22: 327±28 g/pig) ate muchmore than T2-pigs (147±9; P<0.0001) and explored the (feed in the) feeders 2.6 times more at d15 (P=0.001). This also implies that feed A, the common feed provided in T1 and T2, was more consumed in T1 (d6-22: 152±13) compared to T2 (68±5; P<0.0001). The percentage of eaters within a litter did not differ over time between T1 (d10: 26%, d15: 78%, d22: 94%) andT2 (20, 71 and 97%). In conclusion, our results suggest that piglets like to eat a varied diet instead of preferring one feed over the other. Dietary diversity by providing two feeds at the same time different in flavour, size, composition, smell, texture and colour stimulated the feed intake and feed-related exploratory behaviour of suckling pigs more than dietary diversity via novel flavours only, but did not elicit pigs to start eating earlier. Further research is needed to explore the most effective dietary diversity to stimulate early feeding.
Nesting behaviour of broiler breeders
Oever, Anne van den; Rodenburg, T.B. ; Bolhuis, J.E. ; Ven, L.J.F. van de; Kemp, B. - \ 2017
In: Proceedings of the 51st Congress of the International Society for Applied Ethology (ISAE), 7-10 August 2017, Aarhus, Denmark. - Wageningen : Wageningen Academic Publishers - ISBN 9789086863112 - p. 110 - 110.
animal welfare - animal behaviour
Broilers have been selected for growth related characteristics, which are negatively correlated to reproductive traits. This genetic background creates challenges in broiler breeders, as the hens do not make optimal use of the nests provided leading to dirty and cracked eggs. Despite the economic importance of this problem, little research has been done on nesting behaviour in broiler breeders. This project aims to investigate which factors are involved in nest site selection of broiler breeder hens and to create practical improvements in housing design. The first experiment focuses on nest design preferences, where three alternatives to a standard nest will be offered to groups of hens. This preference will then be related to the personality traits sociability and fearfulness, measured with density related permanence and tonic immobility tests. The second experiment will compare two genetic strains on leg health and social interactions. The effect of introducing perches at an age of 20 weeks on leg health, measured by scoring for footpad dermatitis and gait, will be investigated. Leg health will furthermore be related to mobility, fertilisation and production. Social interactions amongst females and between females and males are expected to influence nest site selection as well. Dominant females might attract submissive females to certain nests, but can also prohibit submissive females access to the nests. Feral males are known to escort females to suitable nest sites, although it is unknown whether this holds true for domestic chickens. By scoring social interactions and nest site, these possible relations can be studied. A final field experiment will be conducted at a commercial farm, fitted with nests designed according to the preferences of the first experiment and with or without perches as proven optimal according to the second experiment. Productivity, fertilisation, leg health and behaviour will be recorded to measure the performance of this improved system.

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