Effects of encapsulated sodium butyrate and arginine on the growth performance and gut health of broiler chickens, with or without enteric challenge

The experiment evaluated the effects of encapsulated sodium butyrate and arginine on the gut health of broiler chickens from 1 to 22 days of age, with or without exposure to an enteric challenge. The experiment was carried out in the vivarium of the Federal University of Paraná, Brazil. Seven hundred and sixty-eight one-day-old male Cobb 500® broiler chicks were used. The birds were randomly assigned to eight treatment groups with six replicates each (48 experimental units with 16 birds per replicate) in a 4 × 2 factorial design (four diets, with and without enteric challenge). The four diets were: 1) 113% standardised ileal digestibility (SID) arginine:lysine ratio; 2) 113% SID arginine:lysine ratio + encapsulated sodium butyrate; 3) 130% SID arginine:lysine ratio; 4) 130% SID arginine:lysine ratio + encapsulated sodium butyrate. At 15, 16, and 17 days of age, the birds in the challenged groups received 15 mg of amoxicillin per kilogram of live weight, inoculated into the ingluvium. At 19 days of age, the same birds received an inoculum containing Escherichia coli (ATCC® 8739™, 109 colony-forming units/bird). The results show that from 1 to 14 days of age, birds that received combined arginine and encapsulated sodium butyrate had better weight gain. Enteric challenge increased the production of short-chain fatty acids and reduced the depths of the crypts and the absorption area of the ileal mucosa. Arginine and encapsulated sodium butyrate supplementation effectively improved performance in the second week of life, but did not interact with the enteric challenge model. (Submitted 13 September 2025; Accepted 30 January 2026; Published 13 February 2026)