Early-Life Poultry-Derived Lactobacilli Drive Microbial Succession and Gut Immune Modulation in Broiler Chickens.

Area of Science:

• Poultry Science
• Microbiology
• Immunology

Background:

• Probiotic supplementation is recognized for enhancing poultry gut health and immune function.
• Limited research exists on the impact of early-life, specifically embryonic, probiotic administration.

Purpose of the Study:

• To investigate the effects of in ovo, post-hatch, or combined lactobacilli administration on broiler gut immunity and cecal microbiota succession.
• To compare the efficacy of a single in ovo dose versus repeated oral or combined administration.

Main Methods:

• Broiler chickens were administered a lactobacilli cocktail in ovo (embryonic day 18), post-hatch, or both.
• Cecal contents were analyzed over five weeks using 16S rRNA gene sequencing.
• Microbial composition was assessed using MaAsLin2, and immune responses were evaluated via cytokine expression analysis.

Main Results:

• In ovo administration improved hatch rates and modulated early microbial succession, reducing specific pathogenic bacteria and increasing Lactobacillus.
• Shannon diversity increased steadily for three weeks, with community structure stabilizing by week 3.
• Microbiome shifts correlated with reduced expression of pro-inflammatory cytokines (IFN-γ, IL-1β, IL-8) in cecal tonsils.

Conclusions:

• Early-life in ovo probiotic intervention plays a critical role in shaping gut microbial colonization and immune development in broilers.
• A single embryonic dose of lactobacilli can achieve comparable gut health and immune modulation benefits to weekly oral or combined administration strategies.