Topics:
Animal Nutrition, Animal Refresher
Internal Indicators for Digestibility
Internal/natural indicator used in digestibility estimation:
- Lignin
- Silica
- Acid Insoluble Ash (AIA)
- All the above — Correct Answer
Explanation:
Correct Answer: All the above
Lignin, Silica, and Acid Insoluble Ash (AIA) are all recognised internal (natural) indicators used in digestibility estimation. Internal indicators are naturally present in feed and recovered in faeces.
Indicators in Digestibility Estimation
| Type | Examples |
|---|---|
| Internal indicators | Lignin, Silica, Acid Insoluble Ash (AIA) |
| External indicators | Chromic oxide, Ferric oxide, Mg-ferrite, Cr-EDTA, Cerium, Carmine red, Cobalt-EDTA, PEG |
Indicator Method — Key Principle
- Indicator must be: indigestible, not absorbed, not secreted, uniformly mixed in digesta
- Formula: Digestibility% = [1 − (Indicator in feed/Indicator in faeces) × (Nutrient in faeces/Nutrient in feed)] × 100
- Collection period for digestibility: 7–10 days for both ruminants and non-ruminants
- Preliminary/Adjustment period: 10–12 days for ruminants; 7–10 days for horse and swine
Why Other Options Are Wrong
- Lignin alone → internal indicator but incomplete answer
- Silica alone → internal indicator but incomplete answer
- AIA alone → internal indicator but incomplete answer; all three are valid internal indicators
📚 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.
