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

Abstract 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 5 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 1 of 6 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 was added to the high ABC-4 diet. From d 0 to 23 and d 0 to 38, increasing ABC-4 increased then decreased (quadratic, P ≤ 0.046) ADG and ADFI. On d 10 and 17, increasing ABC-4 decreased (linear, P ≤ 0.022) fecal DM. From d 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 1 of 5 dietary treatments. Diet 1 was a low ABC-4 diet formulated to 200 and 250 meq/kg in phase 1 and 2, respectively. Two intermediate ABC-4 levels were formulated by either replacing SSPC with ESBM on an 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 d 0 to 24 and d 0 to 38, increasing ABC-4 decreased (linear, P ≤ 0.046) G:F. On d 10 and 24, increasing ABC-4 decreased (linear, P ≤ 0.005) fecal DM. From d 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 d 0 to 10 post-weaning and 250 meq/kg from d 10 to 24 post-weaning 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 performance and fecal DM of weanling pigs.