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Domestication effects on behavioural and hormonal responses to acute stress in chickens
Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology. (AVIAN Behavioural Genomics and Physiology Group)
Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology. (AVIAN Behavioural Genomics and Physiology Group)
Uppsala University, Sweden.
Uppsala University, Sweden.
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2014 (English)In: Physiology and Behavior, ISSN 0031-9384, E-ISSN 1873-507X, Vol. 133, 161-169 p.Article in journal (Refereed) Published
Abstract [en]

Comparative studies have shown that alterations in physiology, morphology and behaviour have arisen due tothe domestication. A driving factor behind many of the changes could be a shift in stress responses,withmodifiedendocrine and behavioural profiles. In the present study we compared two breeds of chicken (Gallus gallus), thedomesticWhite Leghorn (WL) egg laying breed and its ancestor, the Red Junglefowl (RJF). Birds were exposed toan acute stress event, invoked by 3 or 10 min of physical restraint. Theywere then continuouslymonitored for theeffects on a wide range of behaviours during a 60 min recovery phase. Blood samples were collected from thechicken at baseline, and after 10 and 60 min following a similar restraint stress, and the samples wereanalyzed for nine endogenous steroids of the HPA and HPG axes. Concentration of the steroids was determinedusing validated liquid chromatography tandem mass spectrometry methods. In RJF, an immediate behaviouralresponse was observed after release from restraint in several behaviours, with a relatively fast return to baselinewithin 1 h. In WL, somebehaviourswere affected for a longer period of time, and others not at all. Concentrationsof corticosterone increasedmore in RJF, but returned faster to baseline compared toWL. A range of baseline levelsfor HPG-related steroids differed between the breeds, and they were generally more affected by the stress in WLthan in RJF. In conclusion, RJF reacted stronger both behaviourally and physiologically to the restraint stress, butalso recovered faster. This would appear to be adaptive under natural conditions, whereas the stress recovery ofdomesticated birds has been altered by domestication and breeding for increased reproductive output.

Place, publisher, year, edition, pages
Elsevier, 2014. Vol. 133, 161-169 p.
Keyword [en]
Corticosterone Recovery Restraint White Leghorn Red Junglefowl
National Category
Biological Sciences
URN: urn:nbn:se:liu:diva-107167DOI: 10.1016/j.physbeh.2014.05.024ISI: 000340315100022OAI: diva2:722560

Funders: Swedish Research Council (VR) [621-2011-4731]; Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) [221-2011-1088]; ERC (project Genewell) [322206]; Swedish Centre of Excellence in Animal Welfare; ARUP Institute for Clinical and Experimental Pathology

Available from: 2014-06-09 Created: 2014-06-09 Last updated: 2016-04-05
In thesis
1. Stress in chickens: Effects of domestication and early experience on behaviour and welfare
Open this publication in new window or tab >>Stress in chickens: Effects of domestication and early experience on behaviour and welfare
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Stress hos höns : Effekter av domesticaring och tidig stress på beteende och välfärd
Abstract [sv]

The domestication is the process where animals have adapted to human conditions. A prerequisite for domestication is tame behaviour towards humans and subsequently, selection for other desirable traits took place which led to changes in several behavioural and physiological parameters. The domestication of chickens (Gallus gallus) was initiated around 8000 years ago, and today we see clear phenotypic and genotypic alterations when comparing domestic breeds with the wild ancestor. Our modern domestic production breeds have been selected for, and still undergo heavy selection for high meat and egg yields. Beside obvious morphological changes, studies investigating behavioural differences between the ancestral Red Junglefowl and domestic breeds show, for example, differences in fearfulness, foraging strategies, exploratory behaviour and sociality. The modern production environments are intense and already from hatch chicks are exposed to harsh conditions. From an animal welfare perspective, the production environment contain many stressful aspects. The shift in stressor types between wild and captive conditions have likely contributed to alterations in stress tolerance when comparing domestic breeds to the wild ancestors. Previous research on mammalian models have underlined that early-life stressor exposure can induce negative consequences both immediately and in adulthood, but can also affect the offspring in a transgenerational fashion. The effects observed are for example disturbance of normal brain development, a hyper-reactive hypothalamic-pituitary-adrenal (HPA) -axis, decreased immune function and increased risk of developing cognitive dysfunction and abnormal behaviour. In chickens, the long-term effects of stress during the chick phase and during puberty are not well-investigated, and further, conflicting data has been presented on the hatchling HPA-axis reactivity.

In this thesis, results from four projects are presented, which all concern stress and welfare at different ages in chickens. The development of the HPA-axis and how chicks respond to early stress both on the short- and long term was investigated. Furthermore, an experiment on the effects of stress exposure a different ages during puberty was conducted, in search of particularly stress-sensitive periods. Two papers address domestication effects on the stress response.

In paper I, the results show that the HPA-axis is fully functioning at hatch, resulting in elevated corticosterone levels at exposure to stressful conditions. Breed differences indicate domestication effects on the reactivity and development of the HPA-axis; the Red Junglefowl displayed a lower corticosterone baseline and a lower stress response on day one, compared to a domestic breed, whereas the results were the opposite on day 23. Similar results were seen in paper IV, conducted on adult birds, where the Red Junglefowl had a more pronounced reaction to acute stress but a faster recovery period, both with respect to behaviour and physiology. In commercial hatcheries, chick are exposed to multiple potential stressors on their first day of life. In paper II, chicks who had experienced the potentially stressful environment in a commercial hatchery was compared to a quietly treated control group. The hatchery managed birds displayed a reduced growth pattern and tendencies towards altered vigilance and reduced locomotion was seen as an effect of stress in adulthood.

In paper III, it was demonstrated that one week of stress exposure at different ages during the chick phase and puberty affect long-term behaviour and physiology, however depending on age of stress exposure, different parameters were affected. The early stress also induced transgenerational effects, most clearly on HPA-axis reactivity, and showed some overlapping differentially expressed genes.

In summary, domestication has altered the acute stress coping behaviours as well as the development and reactivity of the HPA-axis both in young and adult birds. Furthermore, puberty can be regarded as an equally stress sensitive period as the chick stage and affect various behaviours, stress physiology and gene expression. The outcome can vary depending on timing and nature of stressor.

Abstract [en]

I denna avhandling presenteras resultat från fyra studier där alla har effekter av stress hos höns som gemensam nämnare. Vi har främst tittat på hur stress tidigt i livet påverkar beteendet och mängden stresshormoner i blodet på kort och lång sikt, men även hur den tidiga stressen kan påverka avkomman. I två av studierna undersöks också effekterna av domesticering.

Domesticeringen, processen där vi avlat djur på tamhet och andra önskvärda anlag, har anpassat djuren till våra mänskliga förhållanden. Förfadern till alla våra domesticerade raser, det Röda djungelhönset, finns fortfarande kvar i vida populationer i Sydostasien där de lever i skogar. Detta är en stor fördel då man vill studera domesticeringsprocessen och vilka förändringar som uppkommit, eftersom man kan göra studier mellan raser och sedan direkt jämföra skillnader och likheter. Domesticeringen av höns inleddes för ca 8000 år sedan. Man tror att högre tolerans mot stress kan vara en bidragande faktor i domesticeringsprocessen eftersom tamhönsen har fått anpassa sig till miljöer och förhållanden som egentligen är kan betraktas som onaturliga för en höna, till exempel mycket stora flockar, trånga utrymmen och inomhusvistelse.

Ägg och kyckling är viktiga livsmedel i stora delar av världen och bara i Sverige kläcks många miljoner höns till kött- och äggproduktion varje år. På kläckerier utsätts kycklingar för en rad av potentiellt stressande situationer och behandlingar och man har varit osäker på om detta påverkar kycklingarna negativt. Forskning visar att stress tidigt i livet kan störa utvecklingen av bl.a. hjärnan och stressystemet, som kontrollerar utsöndringen av stresshormoner. Negativa erfarenheter tidigt i livet kan ge upphov till bl.a. beteendestörningar, sänkt immunförsvar och påverka kognitiva beteenden på senare i livet. Det innebär att det kan vara mer allvarligt att utsättas för stress när man är liten jämfört med när man är äldre. Vid stress ökar mängden stresshormoner i blodet. Detta leder till att beteendet förändras och vissa kroppsfunktioner minskar i aktivitet för att energin istället behövs i musklerna. Kroppen förbereder sig på att försvara sig mot det potentiella hotet genom kamp eller flykt. Genom att ta blodprov kan man mäta mängden stresshormoner.

I ett projekt undersöktes välfärd hos nykläckta kycklingar och huruvida hanteringen på kläckerier kan bidra till fysiologiska och beteendemässiga förändringar hos djuren. Vidare har vi undersökt hur stressystemet utvecklas tidigt i livet, om det finns skillnader i hur Röda djungelhöns och domesticerade värphöns reagerar. Vi har också undersökt om stress vid olika åldrar under kycklingstadie och pubertet kan ge effekter i vuxen ålder och slutligen har vi undersökt hur akut stress hos vuxna djur påverkar beteende och en rad olika hormoner.

Resultaten visar att kycklingstadiet och puberteten kan anses som stresskänsliga perioder och ge upphov till kort- och långsiktiga effekter på beteende, genexpression och stressfysiologi. Även avkomman kan i vissa avseenden påverkas. Vi har också kunnat bekräfta att kycklingar har en fullt fungerande stressrespons redan från dag ett efter kläckning. De potentiellt stressande upplevelserna på kläckerier har en påverkan på hur vissa gener kopplade till stress uttrycks i hjärnan. Hanar i vuxen ålder verkar påverkas mer av den tidiga hanteringen än vad honor gör. Vidare visar vi att domesticeringen har påverkat hur höns reagerar på stress både tidigt i livet och i vuxen ålder.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2016. 44 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1755
National Category
Behavioral Sciences Biology
urn:nbn:se:liu:diva-126236 (URN)10.3384/diss.diva-126236 (DOI)978-91-7685-796-0 (Print) (ISBN)
Public defence
2016-06-03, Planck, Fysikhuset, Campus Valla, Linköping, 09:00 (English)
Swedish Research CouncilSwedish Research Council Formas
Available from: 2016-04-05 Created: 2016-03-21 Last updated: 2016-04-28Bibliographically approved

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