The significant improvement of body weight of birds fed CM diets with enzyme supplements is consistent with previous findings of Teves et al. (1989), Pluske et al.
(1997) and Sundu et al. (2004). Interestingly, the effect of enzymes on bird performance was only evidenced when the birds reached five weeks of age (Fig. 1). During the first four weeks, the effects of enzymes were not significantly different. Earlier than that, enzyme addition did not increase body weight significantly. According to Thornton et al. (1956), passage rate of feed in young chicks is faster than in adults. Hence the feed enzymes may not have had enough time to fully attack food in the digestive tract of young chicks or the size of the enzyme digested products of mannan may not have been small enough to aid digestion and absorption in the digestive system of very small chickens and only become of assistance in the larger gut size of birds older than four weeks of age. A small improvement (nonsignificant) was found in the digestibility of the diet when enzymes were included.