Development of physical activity levels in laying hens in three-dimensional aviaries

Levels of physical activity are known to be associated with a number of health and welfare parameters in laying hens, such as stronger bones. Despite this, we presently lack insight into the development of physical activity throughout the life of the laying hen. To close this knowledge gap, we measured physical activity levels of four different strains of laying hens (LSL-lite, Hyline Brown, Dekalb White, Lohmann Brown; 3 groups of 10 chicks per strain, n = 120) throughout three age classes (10–16, 17–24 and 25–37 weeks of age) using tri-axial accelerometers to record 120 min of activity per bird per week. Using these data, we were able to predict low- (e.g. small postural movements), moderate- (e.g. walking) and high- (e.g. aerial ascent) intensity physical activity with 98% accuracy (verified using video recordings). Throughout all age classes, birds allocated their time towards moderate-, low-, and high-intensity physical activity in descending order. Young pullets expressed the greatest level of high-intensity physical activity, which declined with increasing age (p < 0.0001). The least low-intensity physical activity was observed in birds entering the laying (17–24 weeks of age) period (p = 0.007). Overall, brown-feathered birds allocated less time towards low-intensity physical activity levels compared to white-feathered birds (p < 0.0001). Accelerometers and their prediction model proved useful for objectively measuring physical activity budgets in domestic birds. Future research should focus on the application of accelerometers in commercial settings to identify relationships between low-, moderate- and high intensity physical activity levels and the incidence of injury within aviaries.