Four trials using 312 weanling pigs (average initial wt of 7.2 kg) were conducted to examine the effectiveness of Bifidobacterium globsum a (BGA) on the growth performance, scour scores, humoral and cell-mediated immune response and pH and chloride ion concentration (CIC) of feces and gastrointestinal section contents. The effect of continuous feeding of BGA from weaning to market weight on performance and carcass characteristics was evaluated using pigs from Trial 3 (n=80). Dietary treatments were 0, 5.0 x 104 , 6.7 x 106 and 7.5 x 108 colony forming units (CFU)/d in Trial 1 and 0, 6.0 x 104 , 5.0 x 105 and 5.0 x 106 CFU/d in Trials 2 through 4 and the grower-finisher trial. In Trial 1, ADG was effected quadratically at wk 1-2 and 1-5 (P < .05) and wk 3-5 (P < .01) with pigs fed the medium (6.7 x 106 ) BGA level having higher ADG than control pigs. Quadratic diet effects were also observed for average daily feed intake (ADFI) at wk 1-2, 1-5 (P < .10) and 3-5 (P < .05) with pigs fed the medium level of BGA having greater ADFI than control. / Master of Science