Evaluation of dietary acid-binding capacity level on nursery pig growth performance and fecal dry matter.

Two experiments were conducted to evaluate dietary acid-binding capacity-4 (ABC-4) level on weanling pig performance and fecal dry matter (DM). In both experiments, there were five pigs per pen and 12 replications per dietary treatment fed in two phases. In Exp. 1, 360 barrows, initially 5.9 kg, were allotted to one of six treatments. Five treatments were formulated with increasing ABC-4 ranging from 150 (low ABC-4) to 312 meq/kg (high ABC-4) in phase 1 and 200 (low ABC-4) to 343 meq/kg (high ABC-4) in phase 2. The low ABC-4 diet was formulated with specialty soy protein concentrate (SSPC; AX3 Digest, Protekta, Newport Beach, CA) and a combination of dietary acidifiers. Increasing ABC-4 was achieved by progressively replacing SSPC with enzymatically treated soybean meal (ESBM; HP 300, Hamlet Protein, Findlay, OH) on a standardized ileal digestible (SID) Lys basis and decreasing acidifiers. Diets were formulated to contain 100 mg/kg of Zn. For the sixth treatment, pharmacological levels of Zn from ZnO were added to the high ABC-4 diet. From day 0 to 23 and day 0 to 38, increasing ABC-4 increased then decreased (quadratic, P ≤ 0.046) ADG and ADFI. On days 10 and 17, increasing ABC-4 decreased (linear, P ≤ 0.022) fecal DM. From day 0 to 23, pigs fed the diet containing ZnO had increased (P ≤ 0.009) BW, ADG and ADFI compared to the high ABC-4 diet without ZnO. In Exp 2, 300 pigs, initially 6.0 kg, were allotted to one of five dietary treatments. Diet 1 was a low ABC-4 diet formulated to 200 and 250 meq/kg in phases 1 and 2, respectively. Two intermediate ABC-4 levels were formulated by either replacing SSPC with ESBM on a SID Lys basis (diet 2) or removing acidifiers (diet 3). Diet 4 was a high ABC-4 diet formulated by replacing SSPC and removing acidifiers to increase ABC-4. Diet 5 was diet 4 but with pharmacological levels of Zn from ZnO. Diets 1 through 4 contained 110 mg/kg of Zn. From day 0 to 24 and day 0 to 38, increasing ABC-4 decreased (linear, P ≤ 0.046) G:F. On days 10 and 24, increasing ABC-4 decreased (linear, P ≤ 0.005) fecal DM. From day 0 to 24, pigs fed the diet containing ZnO had increased (P ≤ 0.047) BW, ADG, ADFI, and G:F compared to the high ABC-4 diet without ZnO. In conclusion, an ABC-4 of 200 meq/kg from day 0 to 10 postweaning and 250 meq/kg from day 10 to 24 postweaning improves pig growth performance and fecal DM for compared to higher ABC-4 diets. In diets without ZnO, low ABC-4 diet formulation can improve the performance and fecal DM of weanling pigs.