Topics:
Animal Nutrition, Animal Refresher
Digestibility Coefficient from Hay Intake
A Bull consumed 10 Kg grass hay with 10% moisture and excreted 4 Kg of dung dry matter. The digestibility coefficient will be:
- 44.6%
- 55.6% — Correct Answer
- 66.6%
- 10%
Explanation:
Correct Answer: 55.6%
The bull consumed 10 Kg grass hay with 10% moisture, meaning DM intake = 9 Kg. Faecal dry matter excreted = 4 Kg. Therefore: Digestibility = (9 − 4) / 9 × 100 = 55.6%.
Step-by-Step Calculation
- Given: Hay consumed = 10 Kg; Hay moisture = 10%; Faecal DM = 4 Kg
- Step 1 — Feed DM intake: Feed DM = 10 Kg × (1 − 0.10) = 10 × 0.90 = 9 Kg
- Step 2 — Digestibility coefficient:
- DC = (Feed DM − Faecal DM) / Feed DM × 100
- DC = (9 − 4) / 9 × 100 = 5/9 × 100 = 55.56% ≈ 55.6%
Key Rule
- Always convert feed intake to DM basis (subtract moisture from total weight)
- DC formula: (Intake DM − Faecal DM) / Intake DM × 100
Typical Digestibility Values for Reference
| Feed | Approximate DC% |
|---|---|
| Normal straw | ~46% |
| Urea-treated straw | ~70% |
| Good quality hay | 55–65% |
| Concentrate | 75–85% |
Why Other Options Are Wrong
- 44.6% → would result if 10 Kg (not 9 Kg DM) was used as the denominator: (10−4)/10×100 = 60% — also not matching; 44.6% requires different values
- 66.6% → would mean 3 Kg faecal DM (9−3)/9 = 66.6%; but faeces = 4 Kg in the question
- 10% → far too low; equals the moisture content, not digestibility
📚 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.
