Question

A measure of the proportion of the absorbed nitrogen retained by the body is

• A. Ideal protein value
• B. Biological value
• C. Digestible crude protein value
• D. Protein efficiency ratio

Hint:

Remember the fundamental difference:
1. Net Protein Utilization (NPU) = Nitrogen retained Nitrogen intake
2. Biological Value (BV) = Nitrogen retained Nitrogen absorbed

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The quality of dietary protein can be measured by assessing how well its amino acid profile meets the physiological maintenance and growth requirements of an animal.

Step 2: Key Formula or Approach:
The biological value (BV) is calculated using the following nitrogen retention index:
\[ \text{Biological Value (BV)} = \frac{\text{Nitrogen Retained}}{\text{Nitrogen Absorbed}} \times 100 \]

Step 3: Detailed Explanation:
- Biological Value (BV): Directly quantifies the fraction of absorbed nitrogen that is retained by the body for protein synthesis.
- Protein Efficiency Ratio (PER): Relates body weight gain to the weight of protein consumed.
- Digestible Crude Protein (DCP): Simply measures the fraction of dietary protein that is absorbed by the digestive tract, without accounting for how much of it is retained or excreted in urine.
- Ideal Protein Value: Refers to a conceptual amino acid ratio designed to match the animal's requirements precisely.

Step 4: Final Answer
The precise metric measuring the proportion of absorbed nitrogen retained by the body is the Biological value.