Post-pelleting addition of heat sensitive additives is a way to avoid damage to additives. It also contributes to the reduction of carry-over and cross contamination. The use of liquid additives in a post-pelleting application (PPA) may be an alternative technological solution whereby an even dosing of an additive into animal feed can be provided together with a virtually 100% recovery of the additive. This will ultimately benefit the feed manufacturer since it will provide more flexibility in terms of the demand for special custom-build feeds. The implementation of liquid additive systems gives rise to a number of requirements for both feed and equipment. This booklet presents a compilation of the literature associated with the use of liquid additives. It can be used as a ready reference by process engineers, nutritionists, researchers and students who are interested in post-pelleting applications of additives, in the production line and its design.