Background/Aims: The gut microbiome of breeder hens is crucial for reproduction, egg quality, and offspring development, shaped by genetics, age, diet, and management. While maternal factors can influence progeny intestinal health, the combined effects of breeder environment and age on offspring remain poorly understood. This study evaluated progeny from two breeder farms with similar genetics and ages but contrasting management and productivity (Farm A: high-performing; Farm B: low-performing). Breeder caecal droppings were sampled across seven ages (13–57 weeks; P0–P7). Progeny were obtained from key production timepoints. In each cycle, 4,920 Ross-308 chicks were distributed into 12 pens (410 birds/pen, 6 pens/group) and reared commercially on a maize–wheat diet to day 40. Weekly broiler faecal samples were collected. Performance metrics, including European Poultry Efficiency Factor (EPEF) and Feed Conversion Ratio (FCR), were analysed using generalised linear mixed models. Microbiome composition was assessed via Illumina 16S and ITS rRNA sequencing, processed with Sickle, SPAdes, and QIIME2, and analyzed for alpha/beta diversity using R (phyloseq, vegan). Breeder farm and age significantly affected EPEF (p < 0.05) and corrected 2-kg FCR (p < 0.01), with better outcomes from younger flocks and Farm B. Breeder microbiota diversity was influenced by both factors (PERMANOVA R² = 51%), while progeny diversity depended only on breeder age (R² = 8%). Farm A showed declining diversity with age, whereas Farm B maintained stable evenness. Key taxa included Bacteroides, Synergistes, Ruminococcaceae, and Lactobacillus. Overall, breeder environment and age exert stage-dependent, transgenerational impacts on progeny performance and gut microbiota. Enhancing breeder microbiome stability may improve broiler efficiency across generations.