Effect of Heat-Processed Corn and a Carbohydrase Enzyme in Mash Diets on Nutrient Digestibility, Growth Performance and Ileal Microbial Count in Broiler Chicks During Finisher Period.

Background: Feed processing improves nutrient digestibility by reducing anti-nutritional factors and enhancing starch availability.

Objectives: This study evaluated the effects of heat-processed corn and enzyme supplementation in mash diets on nutrient digestibility, growth performance, intestinal morphology and ileal microbial count of broilers.

Methods: Two trials were conducted. In Trial 1, the apparent metabolisable energy (AME) and apparent total tract retention (ATTR) of corn's nitrogen (N), dry matter (DM), calcium (Ca) and total phosphorus (TP) were determined. In Trial 2, a completely randomised design with a 4 × 2 factorial arrangement was used to assess the effects of processing temperatures (unprocessed or processed at 55°C, 70°C and 85°C) and enzyme supplementation (0 or 0.5 g/kg diet). A total of 480 25-day-old Ross 308 broilers were assigned to 48 experimental units with 8 treatments, 6 replicates and 10 chicks each.

Results: Heat processing at 85°C significantly increased the AME value of corn compared to unprocessed corn or corn processed at 55°C (p < 0.05). Additionally, processing at 55°C improved Ca digestibility compared to unprocessed corn (p < 0.05). Neither processing nor enzyme supplementation significantly affected the AMEn value or ATTR of crude protein (CP), DM or TP during Days 26‒28. Broilers fed diets with corn conditioned at 55°C or 70°C, both groups without enzyme supplementation, showed the lowest feed conversion ratio (FCR) (p < 0.05). Villi height was greater in broilers receiving processed corn compared to those consuming unprocessed corn (p < 0.05). Conditioning corn at 55°C resulted in a lower ileal Clostridium count at 42 d.

Conclusion: Conditioning of corn at 55°C without enzyme supplementation in mash diets improved Ca utilisation, FCR and jejunal villus height while decreasing the ileal Clostridium count in broiler chicks.