Increasing evidence shows that gut bacteria can influence physiology and behaviour of humans and animals. Whether these gut bacteria can also influence behaviour in a social context is relatively unknown. Identifying these effects is important, especially in farm animals where gut bacteria could contribute to the development of damaging behaviours, such as feather pecking in chickens.
Feather pecking is common in poultry farming and causes welfare problems and production losses. We know that gut bacteria can influence anxiety, activity, stress and the immune system and that these factors are related to feather pecking. However, it is unknown whether a relationship exists between gut bacteria and feather pecking.
To test this, we used chickens bred for high or low feather pecking, resulting in a high and low feather pecking line. The high feather pecking line had more active behavioural responses, a more reactive immune system and differed in bacterial composition from the low feather pecking line. We used this difference in bacterial composition and administered gut bacteria of high or low feather pecking chickens to newly hatched chicks from the high or low feather pecking line. Interestingly, chicks that received gut bacteria from their own line had more active behavioural responses than chicks that received gut bacteria from the other line or a control treatment.