Moreane, NMnisi, CMSumanu, VOFayemi, OEMoonsamy, GhaneshreeKiarie, EGJha, RMlambo, V2026-08-192026-08-192026-122451-943Xhttps://doi.org/10.1016/j.vas.2026.100764http://hdl.handle.net/10204/14898The transition toward antibiotic-free broiler production has intensified interest in precision nutritional strategies that enhance bird resilience under intensive rearing conditions. Hydrolyzed yeast (HY, Saccharomyces cerevisiae) delivers a complex array of bioactive compounds that support gut function and immune regulation; however, the benefits of HY are likely growth-stage dependent, and continuous supplementation may be economically inefficient. This study evaluated the physiological, gut microbial, and meat quality responses of densely stocked Ross 308 broilers to phase-targeted HY feeding strategies: continuous HY supplementation and HY supplementation restricted to the starter, grower, or finisher phase. Growth performance, haemobiochemical indices, carcass and meat quality, and caecal microbiota composition were assessed. Continuous AGP supplementation yielded the highest (P < 0.05) feed intake, body weight gain, and feed efficiency. In comparison, HY feeding strategies did not improve growth performance (P > 0.05) relative to antibiotics, but did influence physiological and meat quality outcomes when applied continuously or in a phased manner. Phase-specific HY supplementation induced distinct physiological responses (P < 0.05), including changes in nitrogen-related and liver-associated blood indices, with negative impacts on carcass or meat quality. Caecal microbial alpha diversity remained unchanged across treatments (P > 0.05), though selective shifts in microbial composition occurred. Overall, few significant differences were detected between phased and continuous HY supplementation across the measured outcomes, suggesting that phased HY supplementation warrants further investigation as a practical nutritional strategy for antibiotic-free intensive broiler production.FulltextenAntibiotic-free systemsStocking densityHydrolyzed yeastCarcass traitsArticlen/a