Diet preferences of herbivores at pasture

— Preference is the discrimination among sward components displayed by animals when given free choice. Selection is the removal of certain sward components rather than others. Testing preferences can help to understand diet selection in more complex environments. We can measure these preferences when the animals are offered different swards provided as turves or trays indoors or forming adjacent homogeneous strips at pasture. A number of experiments have recently been con- ducted in this way. In this review, we summarize and discuss what the animals choose to eat given a minimum of constraints. We then focus on how behavioural and vegetation constraints influence diet selection.