A study was conducted to evaluate the effects of a multi-strain Bacillus subtilis-based direct-fed microbial (DFM) on growth performance and apparent nutrient digestibility of nursery pigs. Eighty pigs, of equal number of barrows and gilts (initial BW: 7.0 ± 0.60 kg), were weaned at 21 ± 1 d and randomly allotted to one of sixteen pens, with five pigs per pen. Two dietary treatments were implemented, a basal control (CON) and a control plus DFM (DFM). Both diets were corn, soybean meal, and

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... illers dried grains based. Diets were fed for 42 d and growth performance measures were recorded weekly. On d 21 and 42 of the experiment, one pig per pen, with equal number of males and females, was randomly selected and euthanized. Digestibility of nitrogen (N), amino acids (AA) and energy were evaluated within the duodenum, jejunum, ileum, ascending and distal colon. Relative to CON, DFM tended to increase ADG during wk 2 (P = 0.08), and significantly increased ADFI during wk 2 (P = 0.04) and wk 3 (P = 0.02). In addition, DFM decreased G:F during wk 6, relative to CON (P = 0.04). Within the jejunum, pigs fed DFM had greater digestibility of tryptophan (P = 0.04) and cysteine (P = 0.04), and tended to have greater digestibility of lysine (P = 0.07), methionine (P = 0.06), and threonine (P = 0.08), relative to CON. The content pH in ascending colon did not differ between DFM and CON. Compared to CON, apparent total tract digestibility (ATTD) of energy of DFM did not differ while ATTD of nitrogen of DFM was lower (P = 0.05). The addition of a multi-strain Bacillus subtilis-based DFM appears to impact growth performance, AA and N digestibility depending upon location in the gastrointestinal tract, with primary AA differences occurring within the mid-jejunum.