Question

Which of the following statements is correct for a feed ingredient?

• A. Gross energy $<$ Metabolizable energy
• B. Gross energy $<$ Digestible energy
• C. Digestible energy $>$ Metabolizable energy
• D. Digestible energy = Metabolizable energy

Hint:

Remember the step-down cascade of biological energy: Gross Energy \(>\) Digestible Energy \(>\) Metabolizable Energy \(>\) Net Energy.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Nutritional bioenergetics tracks the flow of energy through an animal. Energy is lost at various stages of digestion, absorption, and excretion.

Step 2: Detailed Explanation:
Gross Energy (GE) is the total potential chemical energy in the feed, measured by bomb calorimetry.
Digestible Energy (DE) is the energy remaining after fecal energy losses are subtracted:
\[ \text{DE} = \text{GE} - \text{Fecal Energy} \] Metabolizable Energy (ME) is the energy remaining after losses in both urine and gill excretions are subtracted:
\[ \text{ME} = \text{DE} - \text{Urinary Energy} - \text{Gill Excretory Energy} \] Since urinary and gill energy losses are always positive non-zero values, Digestible Energy is mathematically greater than Metabolizable Energy (\( \text{DE} > \text{ME} \)).

Step 3: Final Answer:
Digestible energy is greater than metabolizable energy because of subsequent urinary and branchial energy losses.