Effect of feeding different levels of palm kernel cake fermented by Paenibacillus polymyxa ATCC 842 on nutrient digestibility, intestinal morphology, and gut microflora in broiler chickens

•PKC decreased nutrient digestibility in broiler chickens.•FPKC by Paenibacillus polymyxa ATCC 842 improved nutrient utilization.•FPKC improved the gut microflora in broiler chickens.•Both PKC and FPKC did not affect the villi height at 15%. A feeding trial was conducted to investigate the effect of palm kernel cake fermented (FPKC) by Paenibacillus polymyxa ATCC 842 on nutrient digestibility, villi height, and gut microflora. A total of 245 one-day-old broiler chicks (Cobb500) were purchased from a local hatchery and raised in an open house system in the research unit at Universiti Putra Malaysia. The chicks were individually wing-banded, weighed and randomly distributed into seven groups with five replicates (pens) and seven birds per pen. The birds were fed diets containing 0, 5, 10 and 15% palm kernel cake (PKC) and 5, 10, 15% FPKC. All the birds were fed ad libitum during the feeding trial, which lasted 42 days. One bird and two birds per replicate in each dietary treatment were randomly selected at 3 and 6 weeks, respectively. Ileal digesta and small intestinal tissues were collected. The findings showed that feeding of 10% or 15% PKC led to a significant decrease (P