A straight-run flock of one-day-old Cobb 400 chicks (n = 396) was used in a 42 d study. There were 6 dietary treatments
and each treatment had 6 replicates with 11 birds per replicate pen. The birds were raised on saw dust and wood shavings
litter. The mean temperature of the experimental house was maintained at 32–34 ◦C in the first week and at 26–28 ◦C during
the subsequent period. The lighting program was 24 h light for 7 d and 20 h afterwards. The birds were vaccinated against
Marek’s disease (0 d), Newcastle disease (ND live B1 at 7 d and La Sota at 21 d) and infectious bursal disease (14 d). In a three
phase feeding program, the starter, grower and finisher mash were offered during 1–16 d, 17–28 d and 29–42 d respectively.
Feed and water was offered for ad libitum consumption.
The diets were offered to the birds in mash form and were composed of maize and soybean meal and did not contain
any antibiotic growth promoter or exogenous enzymes except the xylanase in the treatment groups (Table 1). However,
Maduramycin was added as a coccidiostat. The experimental diets were formulated in such a way that they were deficient in
AME by 0 (E1), 230 (E2) and 420 (E3) kJ/kg. The E2 diet was energy compromised during the grower and finisher phases only
and was identical to the E1 diet during the starter phase. Energy reduction was accomplished by replacing oil with maize and