On the first day of the experiment (7 d of age
and with a mean BW [BWm] of 152 g), 4 birds from
the general group were selected at random, killed by
cervical dislocation, and stored in a freezer at –20°C
for analysis. The rest of the chicks were individually
weighed and sorted, and the lightest and the heaviest
were discarded. Each of the 64 pens had a solid floor
with an area of 0.4 by 0.4 m that was covered with
clean wood shavings.