Topics:
Animal Nutrition, Animal Refresher
Calculation of Hemicellulose
NDF - ADF represents:
- Cellulose
- Hemicellulose — Correct Answer
- Lignin
- Silica
Explanation:
Correct Answer: Hemicellulose
In the Van Soest Detergent Method, NDF − ADF = Hemicellulose. NDF (Neutral Detergent Fibre) includes hemicellulose + cellulose + lignin + silica. ADF (Acid Detergent Fibre) includes cellulose + lignin + silica. Their difference (NDF − ADF) therefore = Hemicellulose.
Van Soest Fibre Fractionation
| Fraction | Calculated As | Components |
|---|---|---|
| NDF | Direct measurement | Hemicellulose + Cellulose + Lignin + Silica |
| ADF | Direct measurement | Cellulose + Lignin + Silica |
| Hemicellulose | NDF − ADF | Hemicellulose only |
| Cellulose | ADF − ADL (Acid Detergent Lignin) | Cellulose only |
| Lignin (ADL) | Direct (permanganate oxidation) | Lignin only |
Nutritional Significance
- NDF strongly correlates with voluntary feed intake — higher NDF → lower intake.
- ADF strongly correlates with digestibility — higher ADF → lower digestibility.
- Hemicellulose is partially fermentable by rumen microbes; cellulose is fermentable; lignin is indigestible.
Why Other Options Are Wrong
- Cellulose → calculated as ADF − ADL (Acid Detergent Lignin), not NDF − ADF.
- Lignin → measured directly (ADL); it is a component of ADF.
- Silica → inorganic; measured as Acid Insoluble Ash (AIA); a component of ADF.
📚 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.
