This trial was conducted to investigate the effects of multi-carbohydrase supplementation on the performance, carcase traits, intestinal histomorphology, caecal microbiota and nutrient digestibility of broiler chickens fed diets with varying energy levels. A total of 400-day-old male chicks were allocated into eight dietary treatments in a 4
2 factorial arrangement with 5 repli- cates per treatment. There were 4 dietary energy levels (the standard breed recommendation and reductions of 50, 100 and 150kcal/kg from the standard) with or without multi-carbohy- drase supplementation. Reducing the energy level by 50 kcal/kg did not significantly impact the measured parameters compared to the standard recommendation while it is reducing by 100 and 150 kcal/kg resulted in significant decreases in the body weight (BW) by levels up to 4.41% and a significant increase in the feed conversion ratio (FCR) by levels up to 4.67%. Enzyme sup- plementation significantly improved the BW and FCR by 3.24% and 2.95%, respectively. Dietary energy lowered by 100–150kcal/kg resulted in a significant decrease in the dressing (up to 2.42%), breast yield (up to 2.82%), fat pads (up to 8.72%), liver (up to 6.30%) percentages and coliform count (up to 28.5%). The digestibility of dry matter, crude protein, ether extract and gross energy was increased due to enzyme supplementation by 4.15, 3.50, 3.35 and 3.72%, respectively. In conclusion, broiler performance and carcase traits can be negatively impacted if the energy density is reduced by 100–150kcal/kg diet. Enzyme supplementation can improve the performance and nutrient digestibility regardless of the dietary energy level.