Abstract: The effect of steam conditioning time and different levels of sodium bentonite (SB) on pellet quality, performance and digestive tract development of growing broilers (11-24 d) fed corn-soybean meal based diet was studied. In a completely randomized design with a 3×3 factorial arrangement of treatments, three SB levels (0.00, 0.75 and 1.50%) and three conditioning times (0, 2 and 4 minutes) were evaluated. Steam conditioning in 2 and 4 minutes increased (P< 0.05) weight gain of the chickens when compared with those of birds in dry conditioning group. Birds fed diets conditioned in 2 and 4 minutes had similar (P> 0.05) weight gains. Addition of different levels of SB had no significant effect on weight gain. Steam and dry conditioning with or without SB had no significant effect on feed intake (P> 0.05). Birds fed the conditioned diet in 2 minutes had lower (P <0.05) feed to gain ratio (FCR) than those of birds fed dry conditioned diet but similar (P> 0.05) to those fed the diet conditioned in 4 minutes. The addition of SB improved FCR and the best FCR was obtained by 1.5% SB (P< 0.05).No significant differences in relative weights of duodenum, jejunum and ileum among treatments were observed. The main effect of conditioning (dry/steam) time was significant (P< 0.05) for relative length of jejunum, ileum and small intestine. However, birds fed pelleted steam conditioning in 2 minutes had shorter jejunum, ileum and small intestine than those of birds fed the pellet diets conditioned in 4 minutes and in dry conditioned. Addition of SB (0.75, 1.5%) decreased relative length of ileum (P< 0.05). Pellet durability index (PDI) and hardness of the diets conditioned in 2 minutes with 1.5% SB were higher than those of other dietary treatments (P< 0.05). Under the condition of this study, it was suggested that steam conditioning improves weight gain and FCR. Steam conditioning and SB improve PDI and hardness.

Keywords