Aflatoxin contamination of poultry feed is still a major concern worldwide and leads to huge economic losses due to poor growth, immunosuppression, hepatotoxicity, and oxidative stress, as well as food safety concerns. The search for effective, safe, and natural countermeasures is therefore urgent. This study evaluated an organic acids-enriched filtrate (OAF) of Aspergillus niger isolate as a dietary supplement in broilers challenged with aflatoxin (250ppb aflatoxin B₁ for 28 days). HPLC analysis of OAF revealed the presence of citric, oxalic, succinic, gluconic, malic and fumaric acids as the major organic acids. The filtrate showed dose-dependent (25-400mg/kg) antimicrobial activity against Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus, and aflatoxigenic fungi, Aspergillus flavus and Aspergillus parasiticus, with MICs ranging from 62.5 to 250µg/mL, as well as it showed strong antioxidant activity against DPPḢ with IC₅₀ of 85.3µg/mL. In vivo, OAF was tested at 50, 100 and 200mg/kg, in comparison to an antibiotic and combination group (OA 200+antibiotic). Aflatoxin challenge resulted in reduced body weight gain, increased feed conversion ratio and mortality (18%), impaired carcass traits (lower dressing and breast percentages, higher liver weight and abdominal fat), anemia and leukocytosis, increased liver enzymes and uric acid, decreased immune markers (IgG, IgM, lymphocyte proliferation, phagocytic index), induced oxidative stress (increased malondialdehyde, decreased superoxide dismutase/catalase/reduced glutathione), and disturbed cecal microbiota (higher Escherichia coli and total bacterial count, total yeast and molds, lower Lactobacillus). OAF (200mg/kg) significantly mitigated all these changes, restoring performance, immunity, antioxidant status, and microbial balance to levels close to controls, with efficacy comparable to antibiotic treatment. The combination OAF 200+ antibiotic showed additive benefits resulting in complete enhancement. In conclusion, organic acid filtrate of A. niger is a promising natural agent for the amelioration of aflatoxicosis in poultry.

To Cite This Article: Bouqellah NA, 2026. Effects of Aspergillus niger organic acid filtrate on growth, immunity, oxidative balance, and gut health in aflatoxin‑challenged broiler chickens. Pak Vet J, 46(6): 1452-1462. http://dx.doi.org/10.29261/pakvetj/2026.138