BackgroundSoy protein supplements, with high crude protein and less antinutritional factors, are produced from soybean meal by different processes. This study evaluated the comparative effects of various soy protein supplements replacing animal protein supplements in feeds on the intestinal immune status, intestinal oxidative stress, mucosa-associated microbiota, and growth performance of nursery pigs.MethodsSixty nursery pigs (6.6 ± 0.5 kg BW) were allotted to five treatments in a randomized complete block design with initial BW and sex as blocks. Pigs were fed for 39 d in 3 phases (P1, P2, and P3). Treatments were: Control (CON), basal diet with fish meal 4%, 2%, and 1%, poultry meal 10%, 8%, and 4%, and blood plasma 4%, 2%, and 1% for P1, P2, and P3, respectively; basal diet with soy protein concentrate (SPC), enzyme-treated soybean meal (ESB), fermented soybean meal withLactobacillus(FSBL), and fermented soybean meal withBacillus(FSBB), replacing 1/3, 2/3, and 3/3 of animal protein supplements for P1, P2, and P3, respectively. Data were analyzed using the MIXED procedure in SAS 9.4.ResultsThe SPC did not affect the BW, ADG, and G:F, whereas it tended to reduce (P= 0.094) the ADFI and tended to increase (P= 0.091) crypt cell proliferation. The ESM did not affect BW, ADG, ADFI, and G:F, whereas tended to decrease (P= 0.098) protein carbonyl in jejunal mucosa. The FSBL decreased (P< 0.05) BW and ADG, increased (P< 0.05) TNF-α, andKlebsiellaand tended to increase MDA (P= 0.065) and IgG (P= 0.089) in jejunal mucosa. The FSBB tended to increase (P= 0.073) TNF-α, increased (P< 0.05)Clostridiumand decreased (P< 0.05)Achromobacterand alpha diversity of microbiota in jejunal mucosa.ConclusionsSoy protein concentrate, enzyme-treated soybean meal, and fermented soybean meal withBacilluscould reduce the use of animal protein supplements up to 33% until 7 kg body weight, up to 67% from 7 to 11 kg body weight, and entirely from 11 kg body weight without affecting the intestinal health and the growth performance of nursery pigs. Fermented soybean meal withLactobacillus, however, increased the immune reaction and oxidative stress in the intestine consequently reducing the growth performance.