The effect of a carotenoid-rich diet on immunocompetence and behavioural performances in Moorhen chicks

Carotenoids have attracted the attention of behavioural ecologists because of their modulatory effects on the immune system, colour expression and several physiological functions affecting body conditions. To evaluate whether carotenoid abundance influences growth, behavioural performance, immunocompetence and bill colour, we raised two groups of Moorhen chicks for 1 month with different food intakes (control diet versus carotenoid-rich diet). The two groups did not show significant differences in growth rate, nor in the red or yellow colouration of the bill, although there was a greater immune response in the carotenoid-rich group. Locomotor activity, tested in an open-field apparatus, did not differ between the two groups, but carotenoid-fed chicks showed more intense pecking at a model mimicking the parents. In this experiment, we demonstrated that carotenoid abundance can influence both immune and behavioural responses, with a greater availability of carotenoids being reflected in improved behavioural performance and immunocompetence.