Dietary 5-aminolevulinic acid supplementation improves growth performance, nutrient utilisation, iron status and antioxidant capacity of broilers

This study aimed to investigate the effects of dietary supplementation with 5-aminolevulinic acid (5-ALA) on growth performance, blood parameters, iron status, nutrient digestibility, and antioxidant capacity in broilers. A total of 600 one-day-old Arbour Acres broilers were distributed into 5 groups with 6 replicates of 20 birds by a completely randomised design. The birds in the 5 groups were fed the basal diets with 0, 15, 30, 45, and 60 mg/kg 5-ALA, respectively. Dietary supplementation with 60 mg/kg 5-ALA significantly reduced the feed to gain ratio during days 1–21 and days 22–42. Moreover, compared with the control group, dietary supplementation with 30 mg/kg 5-ALA elevated haemoglobin concentrations during days 1–21. Furthermore, dietary supplementation with 45 and 60 mg/kg 5-ALA increased the digestibility of crude protein and decreased serum uric acid levels. At 21 days of age, dietary supplementation with 45 and 60 mg/kg 5-ALA increased liver catalase activity and decreased liver malondialdehyde concentrations, and upregulated the liver mRNA expression of ferritin light chain and nuclear factor erythroid 2-related 2. In addition, the liver mRNA expression of haem oxygenase-1 and divalent metal transporter were upregulated in the 60 mg/kg 5-ALA supplementation group, while the liver mRNA expression of Kelch-like ECH-associated protein 1 was decreased in the 5-ALA supplementation groups. In conclusion, dietary supplementation with 60 mg/kg 5-ALA improved the growth performance, nutrient digestibility, iron status and antioxidant capacity of 21-d-old broilers.Highlights Addition of 60 mg/kg 5-ALA to broiler diets reduced the feed to gain ratio. Addition of 45 and 60 mg/kg 5-ALA to broiler diets improved crude protein digestibility and decreased serum uric acid levels. 5-ALA exhibited antioxidant properties by enhancing the Nrf2 and HO-1 expressio