Microbial inoculum effects on the rumen epithelial transcriptome and rumen epimural metatranscriptome in calves

Area of Science:

• Rumen microbiology
• Animal science
• Transcriptomics

Background:

• Early-life manipulation of the rumen microbial ecosystem can influence dairy cow productivity.
• Understanding the impact of microbial interventions on the rumen epithelium and its associated microbiome is crucial for calf development.

Purpose of the Study:

• To evaluate the effects of three distinct microbial inocula (autoclaved rumen fluid, bacterial-enriched, and protozoal-enriched) on the rumen epithelium (RE) transcriptome and rumen epimural metatranscriptome (REM) in dairy calves.
• To identify host gene expression and microbial community changes induced by different early-life microbial dosing strategies.

Main Methods:

• Holstein bull calves were orally dosed weekly with different rumen inocula from 3 to 6 weeks of age.
• Rumen epithelium tissues were collected at 9 weeks of age for transcriptome and metatranscriptome analysis.
• Gene ontology, KEGG pathway analysis, and microbial diversity and correlation analyses were performed.

Main Results:

• Different inocula altered the RE transcriptome and REM, with protozoal-enriched inocula showing more significant gene upregulation compared to controls.
• Microbial communities differed among treatments, with lower alpha diversity observed in the control group.
• Specific microbial genera correlated with host gene expression changes, and inocula impacted KEGG modules related to metabolism and biosynthesis.

Conclusions:

• Artificial dosing with microbial inocula in early life significantly alters the rumen epithelium transcriptome and the rumen epimural metatranscriptome in dairy calves.
• Protozoal-enriched inocula demonstrated a notable impact on host gene expression and microbial functions, indicating potential for modulating rumen development and performance.