Probiotic dosing of Ruminococcus flavefaciens affects rumen microbiome structure and function in reindeer

Area of Science:

• Rumen microbiology
• Animal nutrition
• Microbial ecology

Background:

• Cellulolytic bacteria, like Ruminococcus flavefaciens, are crucial for breaking down cellulose in the rumen.
• Understanding rumen microbiome function is key to improving digestion and nutrient absorption in ruminants.

Purpose of the Study:

• To investigate the impact of dosing reindeer with Ruminococcus flavefaciens strain 8/94-32 on rumen microbiome function and structure.
• To assess the effects on in situ digestion of cellulose and food pellets.

Main Methods:

• Reindeer were dosed with R. flavefaciens strain 8/94-32 during realimentation after starvation.
• Microbiome function was measured by in situ digestion of cellulose and food pellets (percent dry matter disappearance - DMD).
• Microbial community structure was analyzed using 16S rDNA gene sequencing and phylogenetic distance metrics (unweighted UniFrac).

Main Results:

• Probiotic dosing led to decreased digestion of cellulose and food pellets (DMD).
• Microbial community analysis revealed altered rumen structure, with reduced species diversity and evenness.
• While the specific strain was undetectable, Prevotella abundance increased and uncharacterized Bacteroidetes (uBacNR) decreased, showing relationships with pellet DMD.

Conclusions:

• Ruminal dosing of a cellulolytic bacterium can have unexpected negative effects on digestibility.
• Rumen microbiome manipulation requires careful consideration of potential shifts in microbial community structure and function.
• Findings are relevant for other studies aiming to manipulate rumen function in livestock.