Phase-specific and continuous hydrolyzed yeast (Saccharomyces cerevisiae) supplementation elicits similar physiological and meat quality responses in densely stocked broiler chickens
The 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, oxidative status, carcass and meat quality, and caecal microbiota composition were assessed. Continuous antibiotic supplementation yielded the highest feed intake, body weight gain, and feed efficiency. In comparison, HY feeding strategies did not improve growth performance relative to antibiotics but produced comparable physiological and meat quality outcomes when applied continuously or in a phased manner. Phase-specific HY supplementation induced distinct physiological responses, including changes in nitrogen-related and liver-associated blood indices, without negatively affecting carcass or meat quality. Caecal microbial alpha diversity remained unchanged across treatments, though selective shifts in microbial composition occurred. Generally, phased HY feeding elicited responses similar to continuous supplementation, maintaining physiological health, microbial stability, and meat quality, supporting its use as a cost-effective, practical alternative to antibiotics in intensive broiler production.