Topics:
Animal Nutrition, Animal Refresher
Crude Protein Content of Microbial Protein
Microbial protein contains about ______% CP:
- 40
- 50
- 65 — Correct Answer
- 80
Explanation:
Correct Answer: 65%
The microbial mass (bacteria + protozoa) synthesized in the rumen contains approximately 65% Crude Protein (CP) on a dry matter basis. This microbial protein is the primary protein source for ruminants on adequate energy diets and is of high biological value (~70–85%).
Composition of Rumen Microbial Protein
| Parameter | Value |
|---|---|
| CP content of microbial mass | ~65% DM |
| Biological Value (BV) of microbial protein | ~70–85% |
| Digestibility of microbial protein | ~70–80% |
| DCP of microbial protein | ~50–55% |
Factors Affecting Microbial Protein Yield
- Energy supply → more fermentable energy → more microbial growth → more microbial protein.
- N:S ratio → must be 10:1 for sulphur-containing amino acid synthesis.
- Defaunation (removal of protozoa) → increases bacterial protein flow to intestine because protozoa consume bacteria.
- Microbial protein yield = approximately 130–200 g/kg fermentable organic matter.
Why Other Options Are Wrong
- 40% → too low; typical CP of cereal grains, not microbial biomass.
- 50% → the DCP (digestible CP) of microbial protein, not the total CP content.
- 80% → too high; 65% is the established CP content of rumen microbial mass.
📚 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.
