Maternal age and maternal environment affect stress reactivity and measures of social behaviour in laying hens

Abstract

Maternal effects can shape the phenotypes of offspring, but the extent to which a layer breeder’s experience can affect commercial laying hens remains unclear. We aimed to investigate the effects of maternal age and maternal environment on laying hens' behaviour and stress response. In our first experiment (E1), commercial hybrid hens were reared either in aviary or barren brooding cages, then housed in aviary, conventional cages or furnished (enriched) cages, thus forming different maternal housing treatments. Hens from each treatment were inseminated at three ages, and measures of response to manual restraint and social stress were assessed in offspring. In experiment 2 (E2), maternal age effects on offspring's stress response were further investigated using fertile eggs from commercial breeder flocks at three ages. In E1, maternal age affected struggling and corticosterone during manual restraint, feather pecking and pulling and comb wounds. Additionally, maternal rearing and housing in aviary systems showed positive effects on measures of behaviour and stress response in offspring. Effects of maternal age were not replicated in E2, possibly due to methodological differences or higher tolerance to maternal effects in commercial breeders. Overall, we recommend researchers start reporting parent stock's age to increase our understanding of the subject.

Maternal Age and Maternal Environment Affect Egg Composition, Yolk Testosterone, Offspring Growth and Behaviour in Laying Hens

“…In E1, aviary-reared hens had chicks that vocalized more during social isolation and moved quicker out of tonic immobility, indicating higher levels of anxiety but lower fearfulness. As previously reported 16 , the offspring of aviary-reared hens from this same population also showed less displacement preening (an indicator of stress) during a social stress test in comparison with the offspring of cage-reared hens. In addition, E1 showed that aviary-reared hens laid heavier eggs and, consequently, hatched heavier offspring.…”

“…A multifactorial analysis of laying production, production of hatching eggs, and the number of waste eggs showed that layer breeders reared in aviary and housed on litter had better results compared to cage-reared birds 15 . Additionally, our research group reported that maternal environment affected offspring's social behaviour and stress response, with aviary-reared mothers having less emotional offspring, whereas aviary-housed mothers had chicks with a lower stress response 16 .…”

“…Ageing has also been linked to changes in yolk fatty acid pro le 28,29 and late embryonic mortality, hatchability, and body weight in the offspring of broiler breeders 30 . Although the current study is the rst of its kind to assess how ageing affects yolk testosterone concentration in laying hens, a previous publications from our research group reported that maternal age increased both the endocrine and behavioural response of the offspring to manual restraint and affected different aspects of injurious social behaviour in laying hens 16 . Layer breeder ocks typically start producing offspring at around 20 weeks of age and remain in production until around 70 weeks of age, reaching an optimized performance at approximately 44 weeks 31,32 .…”

“…The methodology of this experiment has been described in further detail in Peixoto et al 16 . In short, two consecutive cohorts of 778 Lohmann Selected Leghorn Lite (LSL-Lite) pullets each, were obtained from a commercial hatchery at one day of age and transferred to the University of Guelph's Arkell Poultry Research Station.…”

“…The current study is part of a more comprehensive research project on maternal effects 16,[33][34][35] that aim at investigating how maternal age, maternal rearing experience and maternal adult housing system affect their offspring's behaviour and stress response. For this, we conducted two experiments.…”