Effects of Dietary Recombinant Irisin on Growth Performance, Serum Antioxidant and Immune Indices, and Cecal Microbiota of Broilers

Irisin is a myokine derived from fibronectin type III domain-containing protein 5 (FNDC5) and is involved in energy metabolism, muscle development, and oxidative regulation. Although irisin has been extensively studied in mammals, its potential application in poultry production remains unclear. Enhancing growth performance and physiological resilience is critical for male white-feathered broiler chickens under intensive production systems. This study investigated the effects of dietary irisin supplementation on growth performance and physiological responses in male white-feathered broiler chickens. A total of 180 broilers were randomly allocated to three treatments, with six replicate pens of ten birds per treatment: basal diet and basal diet supplemented with 5 and 10 mg/kg irisin for 42 days. At 42 days, one bird from each replicate pen was sampled for carcass, meat-quality, serum, immune, and microbiota analyses. Dietary irisin supplementation significantly increased final body weight and average daily gain compared with the control group. Feed conversion ratio decreased from 1.51 in the control group to 1.46 in the 5 and 10 mg/kg groups. Carcass evaluation showed higher slaughter yield and breast muscle yield in irisin-supplemented birds, and cooking loss was significantly reduced in both breast and thigh muscles. Serum superoxide dismutase (SOD) activity was elevated in irisin-treated groups. In addition, immunoglobulin Y (IgY) and immunoglobulin M (IgM) concentrations were significantly increased. No significant treatment effects were observed for total antioxidant capacity (T-AOC), catalase (CAT), malondialdehyde (MDA), inflammatory cytokines (IL-6, TNF-α), or immune organ indices (thymus, spleen and bursa of Fabricius). Gut microbiota analysis showed numerical differences in the relative abundance of several major bacterial taxa among treatments. In conclusion, dietary irisin supplementation was associated with improved growth performance and selected carcass, meat-quality, antioxidant, immunoglobulin, and cecal microbiota outcomes in male white-feathered broiler chickens, supporting further investigation of its potential as a functional feed additive in poultry nutrition.