Behaviour, production and health of organically reared fast-growing broilers fed low crude protein diets including different amino acid contents at start

Abstract

Only fast-growing broilers are available for organic production in Sweden, and due to organic legislations and long rearing periods feed restriction has to be practised. To evaluate the effect on welfare aspects and health, two diets, low in crude protein content, with (LPA) and without amino acid supplements (LP) were fed to 1400 Ross 308 chickens, divided over eight pens in two chicken houses, with access to outdoor pasture. Behavioural observations were conducted at 2, 6 and 10 weeks. In general, birds fed the LP diet used their outdoor pasture more, and showed a higher frequency of behaviours related to feed search, than the LPA birds. The LPA diet resulted in higher live weight, mortality and more leg problems. However, cannibalism outbreaks which are rarely seen in broiler production occurred in the LP birds. This indicates that new problems were introduced that are not beneficial for animal welfare. Furthermore, the behaviour differences related to feed search, changes between behaviours and preening might have indicated a frustration related to the qualitative feed restriction for the chickens given the LP diet.