During the 35 d trial, 80 male broilers of the Ross 308 strain were used. The birds
were raised on wood shaving litter. In a three phase feeding program, the starter, grower and
finisher were offered during 1-20 d, 21-27 d and 28-35 d respectively. Feed and water was
offered for ad libitum consumption. The diets were offered to the birds in meal form and the
chemical composition of the diets is shown in Table 1. Samples of the feed mixture were
ground and analysed according to AOAC procedures.16 There were 4 dietary treatments and
each treatment had 4 replicates with 5 birds per replicate pen. Birds from each pen were
assigned to 1 of 4 treatments that differed in the supplement added to the feed until slaughter
age (35 d): control (CON), 200 mg/kg of thymol (THY), 5 g/kg of tannic acid (TAN) and 5
g/kg of gallic acid (GAL). At 35 d, the birds were killed by cervical dislocation and
exsanguination.