The impact of chronic, unpredictable social stress, and multi-strain synbiotic supplementation on feather-pecking and liquid consummatory behaviours in domestic laying hens

Feather-pecking is a multifactorial problem that can have detrimental effects on poultry welfare and performance. The aim of the thesis is to examine how nutritional intervention can modulate feather-pecking behaviour in laying hens during exposure to unpredictable chronic stress. Laying hens from high- and low-feather pecking strains are provided with an in-water synbiotic supplementation and exposed to social stress. We examine how liquid consumption, feather-pecking, feather damage, feed consumption, egg production and body weight are impacted. Relative preference to unsupplemented placebo and multi-strain synbiotic-supplemented water is conducted by manual liquid weighing at group-level and monitoring jug visit durations and frequencies using radio-frequency identification technology at individual-level. Group- and individual-level data reveal a significant relative preference for synbiotic-supplemented water compared to the placebo. Severe feather-pecking rates do not increase during stress, indicating that synbiotics may potentially help mitigate an increase in this damaging behaviour.