Negative energy balance (NEBAL)

A cow is in negative energy balance when the energy leaving in milk and used for maintenance is greater than the energy she eats. Nearly every cow is in this state in early lactation and makes up the difference by mobilising body fat.

Moderate fat mobilisation is normal. When it is excessive, the liver is overloaded, ketone bodies rise, and the risk of ketosis, fatty liver and delayed return to cycling goes up.

Written for the 2026 edition of the library.