Combined in ovo and post-hatch choline supplementation enhances growth and muscle development in goslings

This study evaluated how embryonic choline supplementation (ECS) via in ovo injection and gosling choline supplementation (GCS) via diet jointly influence embryonic development, endocrine status, growth performance, and muscle development. A total of 1,250 hatching eggs were allocated to five ECS treatments: non-injected control (E_NC), sham-injected control (E_PC), and 0.5 mL of choline chloride at 0.5 (E_0.5), 1.0 (E₁), and 1.5 (E_1.5) mg/mL. Following hatch, 720 female goslings (144 per ECS group) were randomly assigned to three GCS levels: 0 (G₀), 200 (G₂₀₀), and 400 (G₄₀₀) mg/kg. ECS significantly increased embryo weight and relative embryo weight (embryo weight as a percentage of initial egg weight) at embryonic day 18 (DE18; P < 0.001) and DE27 (P = 0.005), while no significant effects were observed at DE20 (P > 0.05). Circulating growth hormone (GH), adrenocorticotropic hormone (ACT), and corticosterone (CORT) responded to choline in dose-dependent patterns (P < 0.001). Post-hatch body weight was significantly affected by the ECS × GCS interaction throughout the post-hatch period (P ≤ 0.016 at 7, 14, 21, and 28 days of age). GCS at 400 mg/kg significantly improved 28-day body weight (P < 0.001) and feed conversion ratio (P < 0.001). Pectoralis and leg muscle myofiber diameter and cross-sectional area were enhanced by higher choline supply (ECS: P ≤ 0.041; GCS: P < 0.001), accompanied by reduced pectoral fiber density (P < 0.001). Notably, myofiber hypertrophy occurred without changes in myogenin (MyoG), myogenic regulatory factor 4 (MRF4), or myogenic factor 5 (Myf5) expression (P > 0.05). Instead, choline exerted treatment-dependent modulation of IGF-1 and MSTN primarily in the pectoralis (P < 0.001), indicating that choline promotes muscle growth via the IGF-1/MSTN axis. For growth rate and feed efficiency, E₁G₄₀₀ is preferable; for muscle yield, E_1.5G₄₀₀ offers additional fiber gains; for immune organ development, E₀G₀ is preferable given the increased bursa weights at lower supplementation. These findings provide a scientific basis for targeted choline nutritional strategies in goose production systems.