Question

In monogastric animals, endogenous nitrogen losses are considered for measuring which among the followings?

• A. Nitrogen retention
• B. Protein efficiency ratio
• C. Digestible crude protein
• D. Biological value of protein

Hint:

To remember this concept, remember that "True" biological parameters (True Digestibility and True Biological Value) always add back the endogenous losses (MFN and EUN) to correct for metabolic waste.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Biological Value (BV) is a measure of the proportion of absorbed protein from a feed which becomes incorporated into the proteins of the animal's body.
It measures how effectively the animal can utilize the protein source for growth and maintenance.

Step 2: Detailed Explanation:
To measure the true Biological Value of a protein, we must account for nitrogen losses that do not originate from the current dietary intake.
These unavoidable losses are called endogenous nitrogen losses.
They consist of metabolic fecal nitrogen (MFN) and endogenous urinary nitrogen (EUN).
MFN represents nitrogen from digestive enzymes, sloughed intestinal cells, and bacterial debris.
EUN represents nitrogen from normal tissue breakdown and wear-and-tear of body proteins.
The formula for calculating the true Biological Value of protein is:
\[ \text{BV} = \frac{N_{\text{intake}} - (F_N - \text{MFN}) - (U_N - \text{EUN})}{N_{\text{intake}} - (F_N - \text{MFN})} \times 100 \]
Where \(F_N\) is total fecal nitrogen and \(U_N\) is total urinary nitrogen.
Without accounting for MFN and EUN, we would only calculate the apparent biological value.
Other metrics like Digestible Crude Protein (DCP) and Protein Efficiency Ratio (PER) do not correct for these endogenous metabolic losses in this specific manner.

Step 3: Final Answer:
Endogenous nitrogen losses are considered for measuring the Biological Value of protein.