Delayed posthatch feeding alters stress physiology and skeletal development in on-farm hatched slower-growing broiler chickens.

Early posthatch nutrition is an important factor influencing broiler health and welfare. This study investigated the effects of delayed access to feed on production and health-related outcomes in slower-growing Hubbard Redbro broilers throughout the production cycle. Three treatments were tested: T0 (immediate access to feed), T24 (24 h delay), and T48 (48 h delay). Physiological, morphological, and welfare-related outcomes were assessed through plasma corticosterone (CORTp), bone measurements, skeletal fluctuating asymmetry (FA), gait score, litter moisture, and femur head necrosis (FHN). Delayed posthatch feeding altered CORTp dynamics in a time-dependent manner. On d 2, T48 birds tended to have lower CORTp compared to T0 (P = 0.068) and T24 (P = 0.089), while this pattern reversed on d 3, with T0 birds showing elevated corticosterone compared to both T24 (P = 0.013) and T48 (P = 0.005). Humerus length was reduced in the T48 group (P = 0.002), and the composite FA index followed a non-linear pattern, with the lowest asymmetry in T24 and the highest in T48. No differences were found in gait score, litter moisture, or FHN. Overall, delayed posthatch feeding had measurable short-term physiological and long-term morphological effects, but did not compromise welfare-related indicators by the end of the production cycle.