A total of 300 pigs (initially, 6.0 kg) were used to evaluate the effects of altering diet acid-binding capacity-4 (ABC-4) with specialty soy protein sources or acidifiers on nursery pig performance and fecal dry matter (DM). At weaning, pigs were allotted to 1 of 5 dietary treatments. There were 5 pigs/pen and 12 replications/treatment. Pigs were fed experimental diets in two phases with phase 1 fed from d 0 to 10 post-weaning followed by phase 2 from d 10 to 24. A low ABC-4 diet was formulated to 200 and 250 meq/kg in phase 1 and 2, respectively. The low ABC-4 diet utilized 0.38% fumaric acid, 0.36% formic acid, and specialty soy protein concentrate (AX3 Digest; Protekta; Newport Beach, CA) at 9.38 and 7.50% of the diet in phase 1 and 2, respectively. For the first medium ABC-4 diet, specialty soy protein concentrate was replaced with enzymatically treated soybean meal (HP 300; Hamlet Protein; Findlay, OH) on an SID Lys-basis and resulted in an ABC-4 of 290 and 322 meq/kg for phase 1 and 2, respectively. For the second medium ABC-4 diet, acidifiers were removed resulting in an ABC-4 of 271 and 321 meq/kg for phase 1 and 2, respectively. In the high ABC-4 diet, both soy protein replacement and acidifier removal strategies were utilized resulting in ABC-4 values of 362 and 394 meq/kg for phase 1 and 2, respectively. In addition, a control diet was utilized with the same formulation as the high ABC-4 diet but with 3,000 and 2,000 mg/kg of Zn from ZnO in phase 1 and 2, respectively. Following phase 2, all pigs were fed a common diet until d 38 of the study. Increasing ABC-4 decreased (linear, P≤0.043) G:F during the experimental period and overall. Increasing ABC-4 decreased (linear, P≤0.005) fecal DM on d 10 and 24, with no differences on d 17. Pigs fed the medium ABC-4 diet based on specialty soy protein replacement had increased (P=0.003) fecal DM on d 10 compared to the medium ABC-4 diet where acidifiers were removed. Pigs fed diets containing pharmacological levels of Zn from ZnO had increased (P≤0.047) BW, ADG, ADFI, and G:F during the experimental period but decreased (P=0.005) ADG and G:F during the common period, with no differences overall compared to pigs fed diets not containing ZnO. In conclusion, as dietary ABC-4 increased from 200 to 362 meq/kg in phase 1 and 250 to 294 meq/kg in phase 2, growth performance and fecal DM decreased.