Domestication effects on behavioural and hormonal responses to acute stress in chickens

Abstract

Comparative studies have shown that alterations in physiology, morphology and behaviour have arisen due to the domestication. A driving factor behind many of the changes could be a shift in stress responses, with modified endocrine and behavioural profiles. In the present study we compared two breeds of chicken (Gallus gallus), the domestic White Leghorn (WL) egg laying breed and its ancestor, the Red Junglefowl (RJF). Birds were exposed to an acute stress event, invoked by three or ten minutes of physical restraint. They were then continuously monitored for the effects on a wide range of behaviours during a 60 min recovery phase. Blood samples were collected from the chicken at baseline, and after 10 and 60 min following a similar restraint stress, and the samples were analyzed for nine endogenous steroids of the HPA and HPG axis. Concentration of the steroids was determined using validated liquid chromatography tandem mass spectrometry methods. In RJF, an immediate behavioural response was observed after release from restraint in several behaviours, with a relatively fast return to baseline within one hour. In WL, some behaviours were affected for a longer period of time, and others not at all. Concentrations of corticosterone increased more in RJF, but returned faster to baseline compared to WL. A range of baseline levels for HPG-related steroids differed between the breeds, and they were generally more affected by the stress in WL than in RJF. In conclusion, RJF reacted stronger both behaviourally and physiologically to the restraint stress, but also recovered faster. This would appear to be adaptive under natural conditions, whereas the stress recovery of domesticated birds has been altered by domestication and breeding for increased reproductive output.

Is domestication driven by reduced fear of humans? Boldness, metabolism and serotonin levels in divergently selected red junglefowl ( Gallus gallus )

“…In S6 at 28 weeks of age, we assessed plasma corticosterone levels before and after a short period of physical restraint, using methods described in detail earlier [12]. Briefly, each bird (eight males and seven females from the low line; six males and eight females from the high line) was removed from its individual cage, and a blood sample was obtained.…”

Domestication and early experiences in chickens: Behavior, stress and gene expression

“…Many of these traits are consistent with the domestic phenotype. For example, domesticated chickens have a higher growth rate, become sexually mature earlier, show lower fearfulness and display an attenuated hormonal stress response compared to the RJF (Campler et al, 2009;Ericsson et al, 2014;Fallahsharoudi et al, 2015;Kerje et al, 2003;Schütz et al, 2004).…”

“…Domesticated species show an attenuated stress response both behaviorally and physiologically (Ericsson et al, 2014;Gulevich et al, 2004;Künzl and Sachser, 1999;Plyusnina et al, 2011;Trut et al, 2009;Weiler et al, 1998). This effect of domestication is thought to be an adaptation to the captive environment combined with selection pressure for higher reproductive capacity.…”

“…Studies have shown that the chickens of the domesticated breed White Leghorn demonstrate an attenuated peak compared with Red Junglefowl (Ericsson et al, 2014;Fallahsharoudi et al, 2015).…”

Genomics of chicken domestication and feralisation

“…The hypothalamus is a reasonable choice of a measuring point given its involvement in signalling between the central nervous and endocrine systems. Also, several domesticated animals display altered hypothalamo-pituitary-adrenal activity, including chickens (Ericsson, Fallahsharoudi et al 2014) and experimentally domesticated rats and foxes (Harri, Mononen et al 2003;Albert, Shchepina et al 2008). However, choosing a single point of measurement for gene expression must amount to reductive assumption about possible mechanisms.…”