Vitamins and minerals were supplemented to meet or exceed the estimated nutrient requirements for nursery pigs as recommended by the NRC (1998). Diets also contained 3.0 g/kg of chromic oxide as an indigestible marker. The analyzed composition of the experimental diets is shown in Table 2.Pigs were housed in individual pens in an environmentally controlled room (26◦C, 70% humidity). A feeder and a nipple drinker were installed in each pen. Body weight was recorded at the beginning and at the end of each period. Feed allowance was equivalent to 40 g/kg of BW and divided into 2 equal meals fed at 0800 and 1700 h each day. Water was available at all times throughout the experiment. Each period consisted of a 5-d adaptation period followed by 2-d collection of ileal digesta from 0800 to 1700 h. A 200 ml plastic bag was attached to the open cannula using a cable tie. Bags were removed
whenever they were filled with digesta, or at least every 30 min and stored at −20◦C to prevent bacterial degradation of AA in the digesta.