Apparent Metabolizable Energy Corrected for Nitrogen (AMEN)
True Metabolizable Energy Corrected for Nitrogen (TMEN)
Energy Partitioning in Animal Nutrition
Gross Energy: Total energy of a feed sample measured in a calorimetric bomb.
Digestible Energy (DE): Gross energy minus fecal energy.
Metabolizable Energy (ME): Digestible energy minus energy lost in urine and gases.
Net Energy (NE): Metabolizable energy minus heat increment (HI).
Heat Increment: Energy lost through nutrient metabolization, varies between nutrients (higher in protein, lower in fat).
Ruminants: Fermentation heat increment is significant, hence net energy is often used.
Poultry: Heat increment is low, so metabolizable energy is commonly used.
Detailed Explanation of Metabolizable Energy Types
Apparent Metabolizable Energy (AME)
Formula: AME = (Feed Intake x Gross Energy of Feed) - (Excreta x Gross Energy of Excreta) / Feed Intake
Concept: Measures energy intake minus energy excreted.
True Metabolizable Energy (TME)
Formula: TME = (Feed Intake x Gross Energy of Feed) - (Excreta x Gross Energy of Excreta) + (Excreta from Fasted Group x Gross Energy of Excreta) / Feed Intake
Concept: Accounts for endogenous energy losses using a fasted group to measure excreta from endogenous sources.
Metabolizable Energy Corrected for Nitrogen (AMEN and TMEN)
Reason for Correction: Protein used for other than energy (e.g., feather or muscle protein) needs correction for accurate energy estimation.
Formula for AMEN: AMEN = (Feed Intake x Gross Energy of Feed) - (Excreta x Gross Energy of Excreta) - (Nitrogen Retention x Energy per Gram of Nitrogen)
Formula for TMEN: TMEN = Similar to AMEN but includes correction for endogenous nitrogen in fasted group.
Nitrogen Retention: Consumed Nitrogen - Excreted Nitrogen, accounting for protein turnover and uric acid production.
Notes on Usage
General Reference: If not specified, "Metabolizable Energy" typically refers to AMEN in literature and discussions.
Conclusion
Understanding these various measures of metabolizable energy is crucial for efficient poultry diet formulation.
For questions or further clarifications, interaction within communities (e.g., comment sections) is encouraged.