Palm kernel cake and decanter cake as broiler feed ingredients: Effects on immunity, gut microbiota, antioxidant gene expression and plasma lipid profile.

The present study examined the impact of feeding broilers diets containing blended palm kernel cake (PKC) and decanter cake (DC) on immune response, cecal microbiota, antioxidant gene expression, and plasma lipid profile in broiler chickens. A total of 1,260 male Ross 308 broiler chicks were reared for 35 days in a completely randomized design (CRD). Birds were assigned to 18 dietary treatments, with seven replicates of 10 birds per treatment. These treatments comprised a basal negative control, single-ingredient positive controls (5% PKC or DC), and PKC:DC combinations at 30:70, 50:50, and 70:30 ratios with inclusion levels of 2-10%. Dietary supplementation with PKC and DC blends significantly enhanced (p < 0.05) secretory immunoglobulin A (sIgA) and immunoglobulin M (IgM) concentrations, particularly at low to moderate inclusion levels, while higher levels showed no additional benefits (p > 0.05). Dietary treatments did not influence (p > 0.05) the concentrations of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), or interleukin-6 (IL-6). In contrast, interleukin-10 (IL-10) expression was upregulated (p < 0.05) in selected PKC and PKC-DC blend treatments. Cecal Lactobacillus populations significantly increased (p < 0.05) with dietary inclusion of PKC and DC, especially in PKC-rich diets. Hepatic glutathione peroxidase 1 (GPX1) expression was elevated (p < 0.05) in birds receiving higher levels of PKC-DC blends. Plasma lipid parameters, including triglycerides (TG), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), high-density lipoprotein (HDL), and total cholesterol (TC), remained unaffected (p > 0.05). Overall, moderate inclusion levels of PKC and DC blends improved IL-10 expression, cecal Lactobacillus populations, and GPX1 gene expression without altering the measured plasma lipid concentrations.