What is the primary method through which energy is provided from digestible feed?

The primary method through which energy is provided from digestible feed is through metabolizable energy. Metabolizable energy takes into account the energy from feed that is available for maintenance, growth, reproduction, and other vital functions after accounting for the energy lost in feces, urine, and gases.

When animals consume feed, the energy contained within the feed undergoes digestion and metabolism. While gross energy represents the total energy contained in the feed, it does not reflect how much energy is actually usable by the animal following digestion and absorption. Digestible energy accounts for the energy that remains after subtracting energy lost in feces but still doesn't consider the energy lost in urine and other metabolic processes.

Net energy goes a step further by focusing on what is truly available for maintaining bodily functions and supporting production systems, which is less relevant to the immediate question regarding digestible feed energy. Since metabolizable energy provides the clearest measure of usable energy after accounting for these losses, it is recognized as the standard method for assessing the energy value of feed.