To understand the action of enzymes, we can use the metaphor of a lock and key. Imagine a substrate (the molecule on which an enzyme acts) as a kind of lock and an enzyme as the only key which will open it. Put the two together, and a rapid reaction takes place which breaks the substrate into two or more smaller parts. The enzyme key is then removed intact to play its role in another reaction.
Feed enzymes have an important role to play in current farming systems. They can increase the digestibility of nutrients, leading to greater efficiency in the production of animal products such as meat and eggs. At the same time they can play a role in minimizing the environmental impact of increased animal production.