Abstract
The gut microbiome of breeder hens plays a pivotal role in reproductive efficiency, egg quality, and progeny development. Its composition is shaped by host factors such as age and genetics, as well as environmental influences, including diet and management practices. Importantly, the breeder gut microbiome is not only dynamic but also responsive to targeted interventions that can enhance intestinal health, metabolic function, and laying performance. Vertical transmission of maternal microbes through the cloaca and egg components provides offspring with a foundational microbial community, with the yolk sac serving as a critical reservoir for early colonisers that influence gut maturation, immunity, and growth. Emerging evidence further demonstrates that maternal nutritional strategies can programme the gut microbiota of progeny and intestinal development, highlighting the breeder microbiome as both a determinant and mediator of transgenerational performance. These insights underscore the potential of microbiome-focused approaches to improve reproductive success and sustainability in poultry production.