The experiment was performed with 420 female Cobb 500 broiler chickens, housed
in 12 floor pens. An experimental unit was formed by one pen, containing 35 birds.
New-born chicks were assigned to one of two dietary treatments differing in starch sources
(six pens per treatment). Another 420 birds from the same batch, which were not used
in this experiment, were housed in the same building. The starch containing feedstuffs
were from the same batches as used in a digestibility trial with broiler chickens (Weurding
et al., 2001a). These feedstuffs were stored at 4 ◦C until the start of the experiment (1
year). In both experiments, the feedstuffs were milled in a hammer mill over a 2.75 mm
screen and diets were supplied as a mash. Therefore, digestion coefficients of starch at
the posterior jejunum and at the posterior ileum of 29 days old broiler chickens were
known for each starch source. Diets were formulated to have equal amounts of ileal digestible
starch (IDS). Diets differed in amounts of rapidly digestible starch (RDS, starch
digested until the posterior jejunum) and slowly digestible starch (SDS, starch digested in
the ileum). Broiler chickens received a diet either high (H) in SDS (52 g/kg) or low (L)
in SDS (7 g/kg). Both diets had the same amount of ileal digestible starch (350 g/kg)