Two experiments were conducted to test whether young pigs are capable of discriminating against a feed based on its nutrient balance (or protein value) and/or the presence or absence of anti-nutritional factors and whether there is an order of preference. In each experiment 48 Large White X Landrace female pigs weighing 16.5 ±1.50 kg were randomly allocated to one of either 12 dietary treatments (Experiment 1) or 14 dietary treatments (Experiment 2) and kept on the treatment diets for four weeks. In Experiment 1 there were four single feed control treatments, four two-feed choice treatments and four three-feed treatments. The choices were between Soyabean Oilcake vs Cottonseed Oilcake as the main dietary protein source, and between diets that have a higher (balanced) versus lower (unbalanced) proportion of amino acids compared with the balance of amino acids in ideal protein. Experiment 2 had similar choices to Experiment 1 but also included treatments with 1% added tannin. The results showed that when young pigs were given a choice of diets their preference was firstly against potentially harmful substances in the feed (e.g tannin) or an anti-nutritive factor (e.g cottonseed oilcake), and then for better-balanced or higher protein-value feeds.