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

Abstract Maternal effects have been reported to alter offspring phenotype in laying hens. In this study, we investigated the effects of maternal environment and maternal age on egg traits and offspring development and behaviour. For this, we ran two experiments. First (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 egg composition, yolk testosterone concentration and offspring’s development, anxiety and fearfulness were assessed. In experiment 2 (E2), maternal age effects on offspring's growth and behaviour were further investigated using fertile eggs from commercial breeder flocks at three ages. Results from E1 showed that maternal age affected the majority of measures including egg composition, yolk testosterone, offspring growth, anxiety and fearfulness. Maternal rearing and housing affected fewer measures but included egg characteristics, offspring weight and behaviour. Effects of maternal age were not replicated in E2, possibly due to higher tolerance to maternal effects in commercial breeders. Overall, our research confirms that maternal environment and maternal age affect the offspring of laying hens in a variety of ways. These effects may be mediated by the natural decrease in egg yolk testosterone concentration over time.