BackgroundExtracts derived from the walnut (Juglans regia L.) green husk exhibit a variety of biological activities. This study investigated the effects of walnut green husk polyphenol extracts (WGHPE) on fatty liver hemorrhagic syndrome (FLHS)-related indicators, antioxidant performance, and cecal microbiota modulation in laying hens.MethodsA total of 350 Hy-Line Brown laying hens aged 43 weeks were randomly assigned to five groups with seven replicates per group and 10 hens per replicate. An F