Broiler chickens’ responses to a diet incorporating fermented or unfermented palm kernel cake on intestinal morphology, antioxidant indices, caecal microbiota composition, and liver metabolomic profiles

This study evaluated the effect of feeding broiler chickens a diet incorporating fermented or unfermented palm kernel cake (PKC) on their intestinal morphology, antioxidant indices, caecal microbiota composition, short-chain fatty acids, and liver metabolomic profiles. 240 broiler chicks (3–day-old male Arbour Acres) were divided into 4 groups, with 10 chicks/replication and 6 replications/treatment. These groups were the control, PKC (10% unfermented PKC), LPKC (10% fermented PKC), and the MPKC (20% fermented PKC) groups. The chickens received the basal diet in the control group, while those in the MPKC group consumed the basal diet with a 20% substitution of fermented PKC and the basal diet with a 10% substitution of either unfermented PKC (PKC group) or fermented PKC (LPKC group). A combination of <i>Lactobacillus plantarum LY19</i>, <i>Bacillus natto NDI</i>, and hydrolysis enzymes was used to ferment the PKC at 37 °C and pH 4.8 for 48 h. The findings demonstrated that fermented PKC increased the intestinal morphology, tight junction (<i>Claudin-1</i>), and total antioxidant capacity more than the control group (<i>p</i> &lt; 0.05). All PKC treatments did not change the caecal microbiota diversity (α-diversity, β-diversity at the phylum level, and most genera at the genus level) or short-chain fatty acids compared to the control group (<i>p</i> &gt; 0.05). The LPKC group upregulated certain metabolites associated with amino acid metabolism or carbohydrate metabolism more than the control group, while it downregulated some metabolites related to lipid metabolism more than the control, PKC, or MPKC groups (<i>p</i> &lt; 0.05). Considering our findings, the PKC, LPKC, and MPKC (particularly LPKC) should be better alternatives to the shortage of corn and soybeans for broiler chicken production. Fermented PKC could be incorporated into broiler chickens’ feed up to 20%;Fermented PKC improved broiler chicken’s intestinal morphology, tight junction, and total antioxidant capacity;Feeding broiler chickens with a diet incorporating unfermented or fermented PKC impacted the liver metabolism. Fermented PKC could be incorporated into broiler chickens’ feed up to 20%; Fermented PKC improved broiler chicken’s intestinal morphology, tight junction, and total antioxidant capacity; Feeding broiler chickens with a diet incorporating unfermented or fermented PKC impacted the liver metabolism.