VFA Responsible for Milk Fat Synthesis

Which Volatile Fatty Acid (VFA) is primarily responsible for milk fat synthesis in ruminants?

Correct Answer: Acetate

Acetate is the primary VFA responsible for milk fat synthesis in the mammary gland. It serves as the main carbon donor for de novo fatty acid synthesis.

Functions of the Three Main VFAs

• Acetate (65%): → Milk fat synthesis. High-roughage diets → high acetate → high milk fat %.
• Propionate (20%): → Gluconeogenesis → milk sugar (lactose) synthesis. High-concentrate diets → high propionate → high milk yield.
• Butyrate (10%): → Converted to β-hydroxybutyrate (a ketone body) by ruminal epithelial cells. Provides energy to rumen epithelium.

Rumen VFA Profile

Acetate : Propionate : Butyrate = 65 : 20 : 10

VFA Absorption Rate

Absorption rate: Butyrate > Propionate > Acetate

Total VFA Production

Total VFA concentration = 80–120 mEq/Litre of rumen liquor. An adult cow produces approximately 4 kg VFA per day.