Incidence of pecking damage in growing bantams in relation to food form, group size, stocking density, dietary tryptophan concentration and dietary protein source

1. This paper reports 4 experiments with groups of 10 to 20 growing bantams in multi-unit brooders, which investigated effects of certain environmenta l and dietary factors on development of feather pecking damage to 6 weeks o f age. Damage was assessed according to a subjective scoring system. 2. A test of food form (pellets, mash, mash diluted with 100 g/kg powdered cellulose) confirmed that pecking damage tends to be greater with pellets t han with mash but there was no significant difference between the low damag e scores associated with undiluted and diluted mash treatments. 3. A test of group size (10, 20 birds) and stocking density (744, 372, 186 cm(2)/bird) showed that variation in pecking damage was associated with gro up size x density interactions. 4. A test of dietary supplementation with L-tryptophan (0, 10, 20 g/kg) sho wed suppression of pecking damage with the higher (20 g/kg) dose, compared with the control (0 g/kg) treatment. 5. A test of dietary protein source (plant, mainly animal, mainly semipurif ied) showed no difference in pecking damage scores between treatments.