The effects of food-related environmental complexity on litter directed behaviour, fear and exploration of novel stimuli in young broiler chickens

Stimulation of foraging behaviour during the first weeks of life by increasing environmental complexity such as scattering food items on the litter may be one way of preventing leg disorders, reducing fear and improving broiler welfare. However, studies on effects of access to various food based enrichment are inconclusive. Motivation of animals to search for resources in the litter may be driven by the motivational significance of the provided food resource. This study was conducted to test whether the motivational significance of food enrichment differentially affects activity, litter directed behaviours and fearfulness in broiler chickens. Chickens (120 chickens in three batches of 40 animals) were divided into four groups according to type of food-related enrichment: 1) mealworms (highly attractive), 2) whole wheat (less attractive), 3) wood shavings (no nutritional value), and 4) no enrichment. Enrichment materials were scattered on the litter daily for 12 days starting on day 6. On days 6, 9, 12 and 15 of age the chickens were video-recorded from 10 min before to 30 min after scattering. Duration and frequency of physical activity (time spent on legs), litter directed behaviour (litter pecking and scratching) and leg stretching were analysed from videos in 10-min intervals. All birds were subjected to a tonic immobility test (day 16) and a novel object test (day 17). Mealworm treatment induced a significant increase in activity, litter pecking and litter scratching (p < 0.001) during the first 10 min interval after the treatment. There were no effects on activity, litter directed behaviour, and on any of the parameters in the tonic immobility test and novel object test. In conclusion, motivational significance of the food items scattered on the litter affect litter directed behaviours in broiler chickens. More studies are needed to develop feasible attractive food enrichments and complex distribution methods that would increase time spent in activity.