Chitosan-selenium alleviates AFB1-induced growth impairment and immunotoxicity in broilers by suppressing splenic oxidative stress, inflammation and apoptosis.

Introduction: Aflatoxin B1 (AFB1) is a prevalent mycotoxin that severely compromises poultry growth performance and induces immunotoxicity. While selenium is known to mitigate mycotoxicosis, the protective efficacy of chitosan-selenium (Ct-Se), a novel organic formulation, against AFB1-induced splenic immunotoxicity in broilers remains unclear. Methods: 48 one-day-old AA broilers were randomly assigned to four groups: control (CON), AFB1 (0.6 mg/kg), Ct-Se (0.4 mg/kg) and AFB1+Ct-Se groups. Following a 42-day trial, we evaluated growth performance, immune organ indices, oxidative stress, inflammatory cytokines, splenic histopathological lesions and apoptosis. Results: Ct-Se alleviated AFB1-induced growth impairments by improving body weight, average daily gain, and feed conversion ratio. Furthermore, dietary Ct-Se reversed the AFB1-induced suppression of serum IgG and IgM levels, while elevating SOD, GSH-Px, T-AOC activities, and reducing MDA accumulation. Moreover, Ct-Se mitigated AFB1-triggered inflammatory responses by suppressing the expression of pro-inflammatory cytokines and upregulating anti-inflammatory cytokines. Histopathological analysis revealed that Ct-Se effectively attenuated AFB1-induced splenic injury by alleviating lymphocyte loss, red pulp congestion, and vacuolization. Furthermore, Ct-Se significantly suppressed splenic apoptosis by reversing the AFB1-induced upregulation of Bax, Caspase-3, and Caspase-9, while restoring Bcl-2 expression. Discussion: Our findings demonstrate that Ct-Se alleviates AFB1-induced growth impairment and splenic immune dysfunction involving antioxidant, anti-inflammatory, and anti-apoptotic mechanisms, suggesting its potential as a protective feed additive against broiler mycotoxicosis.