They were fed 2 diets in a 2-period crossover design so that eachpig received 2 different diets over a period of 2 wk rotation with 6 pigs per dietary treatment. The diet was formulated to contain 200 g/kg of EFM protein ingredient as the only AA source. A N-free diet was also included to determine the basal endogenous losses of CP and AA. The formulation of the N-free diet (Table 2) was adapted from Stein et al. (2007). 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.