Effects of dietary defatted olive seed flour supplementation on growth performance, systemic status, and intestinal health in broiler chickens

Abstract

High-growth broilers are prone to gut dysbiosis, oxidative stress, and inflammation. Replacing antibiotic growth promoters with polyphenol- and fiber-rich defatted olive seed flour is a promising strategy. Therefore, this study aimed to evaluate the effects of dietary defatted olive seed flour supplementation on growth performance, carcass traits, serum biochemical profiles, systemic oxidative status, intestinal mucosal cytokine gene expression, the abundance of selected cecal bacterial DNA targets, and ileal histomorphology in broilers. A total of 840 one-day-old male broiler chicks were randomly allocated to five dietary groups (12 replicate pens/group, 14 birds/pen) and received basal mash diets supplemented with 0 (CON), 1 (T1), 2 (T2), 3 (T3), or 4 (T4) g defatted olive seed flour/kg diet for 28 days. Dietary inclusion of defatted olive seed flour (T1–T4) increased final body weight, weight gain, and the production efficiency index and improved feed conversion efficiency ( p  < 0.05); T3 and T4 increased carcass weight and dressing yield ( p  < 0.05). Serum triglycerides and low-density lipoprotein cholesterol were lower at T1 and T2, and total antioxidant capacity was higher and malondialdehyde was lower at T2–T4 ( p  < 0.05). Real-time PCR showed higher cecal Lactobacillus spp. and lower Clostridium spp., Escherichia coli , and Salmonella spp. DNA copy numbers with supplementation ( p  < 0.05). Dietary inclusion at 3 g/kg was associated with greater ileal villus height and villus surface area, along with local transcriptional modulation, characterized by higher IL-10 and IFN- γ transcript abundance. In conclusion, responses across the measured endpoints were generally favorable at 2–3 g/kg, although no single inclusion level consistently improved all outcomes under the conditions of this 28-day study.