During the initial phase, 1-28 days, eighty broiler chicks aged one-da
y, 40 males and 40 females, were kept in a brooder battery containing
10 birds per division. The chicks received diets with 2,500, 2,800 and
3,100 kcal ME/kg and 20% of crude protein. The birds had free access
to the three different diets (self-selection). In the final phase, bet
ween 29-49 days of age, 22 birds (11 males and 11 females) selected at
random, were weighed and kept in individual cages. During this phase
the crude protein content was changed to 18% and the diets were also o
ffered by self-selection. In both phases, the intake of the different
diets and weight gain were weekly measured. The birds during the whole
experimental period had preference to the diets containing higher ene
rgetic densities (3,100 and 2,800 kcal ME/kg). The energy intake was 2
89,90 kcal ME/bird/day.