Normal VFA Level in Rumen Liquor

Normal level of VFAs in the rumen liquor is:

Correct Answer: 80–120 mEq/L

The normal level of Volatile Fatty Acids (VFAs) in rumen liquor is 80–120 mEq/L.

VFAs in Rumen Physiology

• VFAs are the primary end products of ruminal fermentation.
• VFA ratio: Acetate : Propionate : Butyrate = 65 : 20 : 10
• VFAs provide 70% of ruminant energy needs.

Functions of Individual VFAs

• Acetate: Responsible for milk fat synthesis; high roughage diet → high acetate → high milk fat%
• Propionate: Gluconeogenic (precursor of glucose); responsible for milk sugar synthesis; high concentrate diet → high propionate → high milk yield
• Butyrate: Converted to β-hydroxybutyrate (ketone body) by ruminal epithelial cells; high butyrate → risk of ketosis

In Severe Grain Engorgement

Excess grain → excess lactic acid from amylolytic bacteria → rumen pH drops to ≈ 4 → severe ruminal acidosis.