(17)Labelling serves enforcement, traceability and control purposes. In addition, labelling should provide the necessary information to purchasers to enable them to make the optimal choice for their needs, and it should be consistent, coherent, transparent and understandable. As purchasers, in particular livestock farmers, make their choices not only at the point of sale where they can inspect the packaging of the feed, the requirements concerning information provided on the labelling must apply, not only to the labels which appear on the products, but also to other kinds of communication between the vendor and the purchaser. Furthermore, those principles should apply also to the presentation and the advertising of feed.