Pecking behaviour studies commenced at 10 weeks of age.
Pecking at a red cube : During the first 5 days of life, chicks were allowed 60 min daily to peck at a red plastic cube (l3x3x3 cm).
Pecking behaviour : The same test was repeated but, after food deprivation, the red cube was placed in the bottom of the feed hopper with no feed provided.
The peak force (measured in grams) of a bird pecking at the food was recorded during the first 3 min after being placed in the cage.
Pecking behaviour and peak pecking force (measured in grams) at a red disc attached to the pressure transducer were measured.