A longitudinal study conducted by an Auburn University research team demonstrated that age plays a major role in cecal microbiome development in broilers.
The microbiota community in the ceca changes rapidly as broiler chickens grow. Additionally, these microbes play a major role in digestion, nutrient use and bird health. However, earlier studies of the cecal microbiome described only broad bacterial groups.
The study’s authors emphasized that species-level resolution is important because genus-level analysis can miss biologically important differences among organisms within the same genus. Having species-level data provides better biological resolution for identifying potentially beneficial, neutral or harmful taxa in broiler ceca, they added.
The researchers followed male and female broilers from hatch to market age to better understand how these gut microbes develop over time.
Study design
The research team used 70 Ross YP × 708 broilers, separated by sex, and sampled cecal contents on days 0, 14, 28 and 42. At each time point, six birds per sex were euthanized for cecal sample collection. Birds were fed a maize-soy diet formulated according to Aviagen recommendations.
The microbiome was analyzed using full-length 16S rRNA sequencing, enabling species-level identification of bacteria.
The researchers also analyzed alpha diversity to assess the bacterial species diversity and beta diversity to determine the similarities and differences between samples.
Microbiome findings
The results showed that age was the strongest factor shaping the cecal microbiome. Newly hatched chicks had a much simpler microbial community, but major changes occurred within the first 2 weeks of life. After that, the microbial population became more stable, particularly between 28 and 42 days of age.
Importantly, the types of bacteria present in the gut changed as birds matured. Some bacteria were more common immediately after hatch, while others became more abundant later in life, suggesting that the gut environment becomes more complex and better established with age.
Alpha diversity increased rapidly after hatch. Day 0 had significantly lower diversity than later ages in both males and females, while diversity at days 14, 28 and 42 was generally more stable.
Core microbiome richness plateaued early. Shared species richness stabilized at roughly 330 to 350 species from day 14 onward, suggesting early establishment of a relatively stable core cecal microbiome.
Although males and females differed in dominant bacterial species, their overall gut microbial diversity was similar at the same age.
Dominant species changed with age and differed somewhat by sex. On day 0, Enterococcus faecalis was dominant in both sexes. By day 42, females had more Romboutsia ilealis, while males had more Negativibacillus massiliensis.
Early colonizers differed from later stable taxa. Species such as Clostridium celatum, C. disporicum, C. jeddahitimonense and C. saudiense were enriched on day 0, whereas later ages had higher abundance of species such as Bittarella massiliensis, Turicibacter bilis and Turicibacter sanguinis.
Key takeaways
The results suggest that earlylife is the most important windowfor shaping the gut microbiome, meaning that management practices or nutritional strategies such as probioticsmayhavethegreatestbenefitwhenappliedsoonafterhatch.
Overall, this work improves our understanding of how the broiler gut microbiome develops and may inform future approaches to improving poultry health and productivity.
What does this mean for producers?
- The first 2 weeks are the most dynamic window for microbiome
- Day 0 to 14 is likely the key period for interventions like probiotics, feed additives or management changes.
- Microbiome interventions may be most effective early in life, before the community stabilizes.
- Environmental and management factors likely shape the broiler cecal microbiome more strongly than sex as birds
- Later microbiome differences appear more related to shared environment than to sex
The full paper, titled “Longitudinal analysis of broiler cecal microbiome: unraveling the species level dynamics across age and sex,” can be found in Poultry Science and online here.
Interpretative Summary by Deepak Subedi, The University of Sydney, can be found online here.
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