Which statement best describes NEm?

• A. Energy used for maintenance
• B. Energy available for production
• C. Energy lost as heat
• D. Energy stored in bone

Answer: (A)

The main idea is that NEm stands for the energy required to keep the animal's body functioning at a given size and level of activity. Net energy is what remains after digestion and metabolism, and it splits into energy used for maintenance (NEm) and energy that can go toward production like growth or milk (NEp). So NEm is the energy spent on maintenance of basic body functions—such as heartbeat, respiration, blood circulation, temperature regulation, and ordinary activity. Only after meeting this maintenance energy can the animal use additional energy for production. Energy lost as heat is part of the overall energy expenditure but isn’t what NEm specifically describes, and energy stored in bone isn’t the concept here.