Gladys Maria Pangga: The Transgenerational Link: Breeder Gut Microbiota and Broiler Progeny Development

This complex and dynamic microbial community performs essential roles in nutrient metabolism, immune system maturation, and protection against pathogen colonisation (Clavijo and Flórez 2018). Preservation of microbiota homoeostasis is therefore critical; however, it is inherently influenced by host genetics, physiology, and environmental factors (Diaz Carrasco et al. 2019). While its importance is well-established in broilers and laying hens, the gut microbiome of breeder hens, despite their foundational role in reproduction and transgenerational microbial transfer (Lee et al. 2019), remains underexplored.

Modern poultry production operates within a highly structured, vertically integrated system designed to maximise efficiency and performance (Dittoe et al. 2019; Siegel 2014). At its foundation are broiler breeder hens and roosters, genetically selected parent stock whose primary role is to produce fertilised eggs (Jong and Emous 2017). While these breeders are not primarily intended for meat production, they serve as the reproductive cornerstone of the broiler industry and are maintained under tightly controlled nutritional and environmental conditions to support optimal egg production and fertility (Jong and Emous 2017). Once laid, eggs are disinfected and incubated in hatcheries, after which newly hatched chicks are transferred to grow-out facilities for meat production, referred to as broilers. These broiler chickens are intensively selected for rapid growth, feed efficiency, and high meat yield, typically reaching market weight within 5–7 weeks (Siegel 2014; Baxter et al. 2021).

Although genetics, nutrition, and husbandry practices have traditionally been viewed as the primary drivers of broiler performance (Dittoe et al. 2019), increasing attention has turned toward maternal influences, particularly the role of the breeder gut microbiota in shaping progeny outcomes. Emerging evidence indicates that vertical transmission of microbial communities from the hen to the chick plays a pivotal role in establishing the early-life microbiome of broiler chickens (Ding et al. 2017; Gao et al. 2025). These maternal microbial inputs have been shown to influence progeny immune function, gut development, and growth performance (Gao et al. 2025). It has also been established that various maternal characteristics, such as age and nutrition, affect progeny outcomes, including embryo villi development, weight and hatchability (Chang et al. 2016; Machado et al. 2020). Consequently, there is growing interest in targeted maternal interventions, including dietary supplementation with probiotics, prebiotics, and phytochemicals to modulate breeder gut microbiota in ways that confer transgenerational benefits (Gao et al. 2023; Wang et al. 2021a; Zhen et al. 2021).

Given the importance of gut microbiome in poultry health and performance and accumulating evidence of the link between the breeder parent and its progeny, maintaining a beneficial gut microbial environment in breeders is therefore essential not only for sustaining their own reproductive performance but also for optimising the development and productivity of their progeny. This review consolidates current knowledge of the breeder gut microbiome, its dynamic nature across the production cycle, and its mechanistic links with broiler progeny performance, with a particular emphasis on the transgenerational impact of microbiota-mediated maternal effects and the potential of microbiome-targeted interventions in broiler breeder management.

2 Development of the Breeder Gut Microbiome

The general chicken microbiome has been characterised extensively in previous reviews (Diaz Carrasco et al. 2019; Clavijo and Flórez 2018; Chica Cardenas et al. 2021; Fathima et al. 2022). In brief, the development of gut microbiota is a dynamic process that begins shortly after hatching, as the GIT is typically sterile at hatch (Fathima et al. 2022). In modern commercial hatchery settings, chicks acquire their microbiota predominantly from environmental sources rather than through direct hen contact, which was the historical method of vertical transmission (Fathima et al. 2022; Aruwa et al. 2021). This colonisation of the gut involves a succession of microbial populations, starting with facultative aerobes, such as coliforms and faecal Streptococcus, which become abundant by day 3 post-hatch (Fathima et al. 2022; Aruwa et al. 2021). Their growth and oxygen consumption create reducing conditions that promote the subsequent colonisation by obligate anaerobes. While the small intestinal microbiota is generally established by around 2 weeks, the caecal microbiota becomes fully established by 6-7 weeks of age, demonstrating an increasing diversity over time (Fathima et al. 2022).

Specifically, in pedigree broiler breeders, the faecal microbiome is dynamic in early life but stabilises after 3 weeks of age, independent of genetic lineage (Díaz-Sánchez et al. 2019). Time-series experiments show that at hatching, the faecal microbial communities are dominated by the phylum Proteobacteria (Díaz-Sánchez et al. 2019). As development progresses, a shift occurs, leading to a community dominated by Firmicutes, with increasing abundances of Actinobacteria and Bacteroidetes (Díaz-Sánchez et al. 2019). In addition, the majority of operational taxonomic units (OTUs) in the gut microbiome persist over host development, becoming common and stable across chickens of the same genetic lineage after 3 weeks of age (Díaz-Sánchez et al. 2019) (Figure 1).

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