Modification of digesta pH and intestinal morphology with the use of benzoic acid or phytobiotics and the effects on broiler chicken growth performance and energy and nutrient utilization

Two experiments, each consisting of 2 trials, were conducted to investigate the effect of feeding benzoic acid (BA) and turmeric meal (TM) individually or in combination (Exp. 1) or garlic meal (GM) and TM individually or in combination (Exp. 2) on growth performance, digesta pH, gut morphology, and nutrient utilization in broiler chickens. Diets consisted of a nutrient-adequate control diet and the control diet with added BA (2 g/kg), TM (10 g/kg), BA (1 g/kg) plus TM (5 g/kg), and BA (2 g/kg) plus TM (10 g/kg) in Exp. 1. In Exp. 2, in addition to the same control diet as Exp. 1, the control diet with added GM (10 g/kg), TM (10 g/kg), GM plus TM at 5 g/kg each, and GM plus TM at 10 g/ kg each were used. Each treatment had 6 replicate floor pens with 10 chickens per replicate. On d 14, 5 broiler chickens from each floor pen were transferred to metabolism cages and continued on their respective diets. Body weight and feed intake data were collected on d 0 and 21, excreta were collected from chickens in metabolism cages on d 19 and 20, and ileal digesta were collected on d 21. Digesta pH was measured at the crop, proventriculus, jejunum, and cecum. Jejunum sections were collected from chickens in Exp. 1 to study gut morphology. In Exp. 1, only the combination of BA and TM tended (P < 0.10) to improve weight gain but there were no effects on G:F. The combination of BA and TM at both inclusion rates decreased (P < 0.05) digesta pH in the crop, jenunum, and ceca. There were no treatment effects on ileal DM or total tract DM retention, but supplementation of BA or TM alone or in combination increased (P < 0.01) apparent ME (AME) and nitrogen-corrected AME (AMEn) relative to the control diet. In Exp. 2, TM alone or combined with GM improved (P < 0.05) weight gain and G:F compared to the control. Supplementation of TM alone or in combination with GM at the rate of 10 g/ kg each reduced (P < 0.05) digesta pH in the crop, proventriculus, and ceca but had no effect at the jejunum. The combination of GM and TM improved (P < 0.01) ileal DE, AME, and AMEn. In conclusion, BA, TM, and GM individually or in combination with wheat–soybean meal based diets adequate in nutrients and energy selectively improved growth performance, modified digesta pH and intestinal growth,