The digestive tract of newly hatched poultry is in development in terms of size, structure, immune response, and microbial population. During the first weeks, digestive enzyme secretion and nutrient transport systems also develop, particularly those related to protein digestion. Young animals require highly available proteins for proper growth. Anti-nutritional factors (ANFs), as trypsin inhibitors, present in soybean meal, the most widely used source of protein for poultry, hinder this development. Enzyme-treated soybean meal (ESBM, Hamlet Protein – Horsens, Denmark & Findlay, Ohio, USA), a specialty feed ingredient with low ANFs and high available protein, was evaluated in broiler starter diets. Three hundred 1-day-old Arbor Acres broilers (as hatched) were divided into two groups with ten replicates of 15 broilers each and fed with iso-nutritious diets containing 0 or 5% ESBM from day (d) 1 to 10. Subsequently, both groups were fed the same grower (d11-21) and finisher diets (d22-42). The contents of the duodenum, jejunum, and ileum, and samples of intestinal mucosa, of one bird per repetition, were collected on d10. Blood samples were taken from the wing vein on d10, 21, and 42. The data on growth performance and apparent nutrient digestibility were assessed for statistical significance using ANOVA. The Independent-samples T-test was used for the results of free amino acids (FAA) in blood serum, digesta enzyme activity, and mucosa expression of peptide and amino acid transporters (PAAT), using IBM SPSS 26.0. The outcomes of 5% ESBM during the first 10 days were heavier body weights on d10 and 42 (P < 0.05), with similar feed conversion ratios compared to the control group, enhanced digestibility of dry matter and crude protein, improved proteolytic enzyme activity in the digesta, upregulation of PAAT expression in the jejunum, and FAA in blood serum (P < 0.05, d10). A positive carry-over effect was observed in gut health indicators, as blood endotoxins, diamine oxidase, and malondialdehyde, at d21 and 42 (P < 0.05). Inclusions of consistent protein ingredients with low ANF and highly digestible protein in starter feeds can be used to promote broilers’ early intestinal development and improve long-term performance.

Bible, M., C. Ma, Y. Li, M. Caballero and T. Friis. 2026. Supplementation of enzyme-treated soybean meal during the starter phase improves broiler early intestinal development and performance. 2026 International Poultry Scientific Forum, abstract T222.