Question

Digestible energy minus energy lost in urine and combustible gases is called

• A. Metabolizable energy
• B. Net energy
• C. Gross energy
• D. Heat of increment

Hint:

Remember the energy loss sequence:
GE $\xrightarrow{-\text{Feces}}$ DE $\xrightarrow{-\text{Urine \& Gas}}$ ME $\xrightarrow{-\text{Heat}}$ NE.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
In animal nutrition, the partition of energy describes how dietary gross energy is utilized and lost through different metabolic pathways.
Understanding these energy losses is essential for formulating balanced diets for livestock.

Step 2: Detailed Explanation:
The flow of feed energy through an animal is partitioned as follows:
Gross Energy (GE): The total chemical energy in the feed, measured by bomb calorimetry.
Digestible Energy (DE): Calculated as Gross Energy minus the energy lost in feces:
\[ \text{DE} = \text{GE} - \text{Fecal Energy} \]
Metabolizable Energy (ME): Calculated as Digestible Energy minus the energy lost in urine and combustible gases (such as methane produced during rumen fermentation):
\[ \text{ME} = \text{DE} - \left(\text{Urine Energy} + \text{Gaseous Energy}\right) \]
Net Energy (NE): Calculated as Metabolizable Energy minus the heat of increment (energy lost as heat during digestion and metabolism):
\[ \text{NE} = \text{ME} - \text{Heat of Increment} \]
Therefore, subtracting energy lost in urine and combustible gases from digestible energy yields metabolizable energy.

Step 3: Final Answer:
Subtracting urine and gaseous energy losses from digestible energy yields metabolizable energy.