Topics:
Animal Physiology, Animal Refresher
Absorption of VFA in Ruminants
Absorption of VFA occurs in ruminants by:
- Active transport
- Facilitated transport
- Passive diffusion — Correct Answer
- None of the above
Explanation:
Correct Answer: Passive diffusion
Volatile Fatty Acids (VFAs) — acetate, propionate, and butyrate — produced by microbial fermentation in the rumen are absorbed primarily through passive diffusion across the rumen wall (epithelium).
How VFA Absorption Occurs
- VFAs are weak acids. At rumen pH (~6.5–6.8), they exist mostly in undissociated form (lipid-soluble).
- Undissociated, lipid-soluble VFA molecules diffuse passively through the lipid bilayer of the rumen epithelial cells.
- Rate of absorption follows the order: Butyrate > Propionate > Acetate (butyrate is most lipid-soluble → fastest absorption).
Destination of VFAs After Absorption
- Acetate: Used for energy in peripheral tissues; major precursor for milk fat synthesis in mammary gland.
- Propionate: Goes to liver → primary gluconeogenic precursor in ruminants (converted to glucose via gluconeogenesis).
- Butyrate: Largely metabolized by rumen epithelial cells themselves → converted to ketone bodies (β-hydroxybutyrate).
📚 About this Topic — Animal Physiology
This multiple choice question is from Animal Physiology, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Physiology to strengthen your preparation.
