Topics:
Animal Nutrition, Animal Refresher
ATP Yield from Volatile Fatty Acids
Moles of ATP produced by metabolism of 1 mole of acetate, propionate & butyrate are respectively:
- 10, 17, 25 — Correct Answer
- 17, 10, 25
- 10, 16, 24
- None
Explanation:
Correct Answer: 10, 17, 25
When volatile fatty acids (VFAs) produced during rumen fermentation are completely oxidised in the host tissues, they yield distinct molar quantities of ATP depending on their carbon chain length.
ATP Yield from VFA Oxidation
| VFA | ATP Yield (per mole) | Notes |
|---|---|---|
| Acetate (C2) | 10 ATPs | Enters TCA as Acetyl-CoA |
| Propionate (C3) | 17 ATPs | Gluconeogenic; converted to Succinyl-CoA |
| Butyrate (C4) | 25 ATPs | Converted to 2 Acetyl-CoA units; more energy than acetate |
Comparison with Other Substrates
- Glucose (aerobic) → 38 ATPs
- Glucose (anaerobic) → 2 ATPs
- Glycerol → 22 ATPs
- Palmitic acid → 129 ATPs
- VFAs provide ~70% of ruminant energy needs
Why Other Options Are Wrong
- 17, 10, 25 → swaps acetate and propionate values; propionate gives 17, not acetate
- 10, 16, 24 → off-by-one errors for propionate and butyrate; not standard values
- None → incorrect; these ATP values are established from biochemical pathways
📚 About this Topic — Animal Nutrition
This multiple choice question is from Animal Nutrition, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Nutrition to strengthen your preparation.
