Aronia melanocarpa pomace enhances egg production and quality in late-laying hens via modulating gut microbiota and lipid metabolism.

1. This study investigated the effects of Aronia melanocarpa pomace (AP) supplementation on serum variables, egg quality, laying performance, nutrient utilisation and gut microflora in late-stage laying hens.2. A total of 288 Hy-Line Brown hens (60 weeks old) were randomly allocated to one of four groups: a control (basal) or the basal diet supplemented with either 1% AP (APL), 2% AP (APM), or 3% AP (APH) for 20 weeks. Each group contained six replicates of 12 hens.3. Egg production, egg mass and shell thickness increased with AP supplementation, peaking in the 3% AP group (p < 0.05). The AP supplementation significantly reduced serum total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and aspartate aminotransferase (ALT) concentrations, with the greatest reductions observed in the 3% AP group (p < 0.05). Linear decreases in TG, TC and LDL-C were more pronounced in the 2% and 3% AP groups (p < 0.05). Linear improvements in calcium metabolism were observed in AP groups compared to the control group (p < 0.05).4. Crypt depth decreased in the duodenum, jejunum and ileum (p < 0.05), while the villus height-to-crypt depth ratio increased in the duodenum and ileum (p < 0.05), with a similar trend for the jejunal samples (p = 0.092). The AP supplementation increased beta diversity of caecal microbiota. At the genus level, Megamonas and Olsenella spp. abundance rose (p < 0.05), while Barnesiella spp. decreased (p < 0.05).5. Supplementation with 3% AP enhanced laying performance and egg quality in late-stage hens by improving lipid metabolism, calcium utilisation and gut microbiota composition. These findings highlighted AP as a functional feed additive for sustainable poultry production.