Selection for low mortality in laying hens affects catecholamine levels in the arcopallium, a brain area involved in fear and motor regulation.
Feather pecking (FP) in laying hens may cause mortality due to cannibalism. Novel breeding methods using survival days of group-housed siblings allow for the genetic selection of laying hens with low mortality (LML: low mortality line) due to cannibalism. Previous studies have demonstrated less fear-related behavior and also less FP in LML hens compared to CL. Selection also caused changes in locomotor behavior in an open field. It is unknown, however, whether selection for low mortality affects central neurotransmitter levels. In this study, brain monoamine levels were measured in the dorsal thalamus, medial striatum, hippocampus and arcopallium of adult laying hens of both LML and CL using HPLC. Brain samples were collected after 5-min of manual restraint. The most prominent line differences were found in the arcopallium. Compared to CL, LML had lower levels of noradrenaline (NA) and 3,4-dihydroxyphenylacetic acid (DOPAC) and tended to have lower levels of dopamine (DA), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA). Levels of serotonin (5-HT), 5-HT- and DA-turnover in this brain area were not affected by line. LML showed less fear-related behavior during the restraint than CL. These findings show that selection for low mortality in hens leads to changes of predominantly the dopaminergic system in the chicken's arcopallium, a forebrain somatomotor area also related to fear. This suggests a relationship between catecholamine functioning in this brain area and FP and cannibalistic behavior in chickens and underpins previously found relationships between FP, fear and high activity.
Utrecht Institute for Pharmaceutical Sciences (UIPS), Department of Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands. Electronic address: m.s.kops@uu.nl.
Marjolein S
MS
Kops
Elske N
EN
de Haas
T Bas
TB
Rodenburg
Esther D
ED
Ellen
Gerdien A H
GA
Korte-Bouws
Berend
B
Olivier
Onur
O
Güntürkün
S Mechiel
SM
Korte
J Elizabeth
JE
Bolhuis
D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D001947:Breeding; D002395:Catecholamines / Q000378:metabolism*; D002645:Chickens / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005786:Gene Expression Regulation; D009026:Mortality; D012149:Restraint, Physical
D002395:Catecholamines
Arcopallium; Cannibalism; Dopamine; Feather pecking; Genetic selection; Laying hens