Effects of Post-Hatch Delayed Feed Access on Growth Performance in Broiler Chickens: An Age-Stratified Meta-Analysis

The immediate post-hatch period is a critical physiological transition in broiler production, and delayed access to feed may affect early nutrient utilization and subsequent growth performance. This meta-analysis evaluated experimental evidence on post-hatch delayed feed access in broiler chickens, with body weight and feed conversion ratio (FCR) prioritized as primary pooled outcomes. Searches of PubMed, Web of Science, and Scopus identified 262 records; after deduplication, 169 unique records remained, and 58 full-text reports were assessed. Thirty-four reports were considered quantitative extraction candidates, of which 15 studies contributed at least one primary BW/FCR effect to the final analytical dataset. Clean delayed-access versus immediate/early-access contrasts were extracted when treatment definitions, means, variation estimates, and sample sizes were available without unresolved co-intervention confounding. Mean differences (MDs) were pooled using DerSimonian–Laird random-effects models stratified by age window, with Hartung–Knapp–Sidik–Jonkman (HKSJ) confidence intervals used to assess the robustness of the statistical inference. Delayed feed access was associated with lower body weight across all age windows: 0–7 d (k = 9; MD −17.87 g; P