Effects of dietary acidifiers and other low acid-binding capacity formulation strategies on weanling pig growth performance and fecal dry matter

Two experiments were conducted to determine effects of dietary acidifiers and low acid-binding capacity at a pH of 4 (ABC-4) formulation strategies on weanling pig performance and fecal dry matter (DM). In Exp. 1, 300 pigs, initially 6.1 kg, were allotted to 1 of 6 dietary treatments fed in two phases with 5 pigs per pen and 10 replications per treatment. Treatment diets were formulated using four acidifiers to target an ABC-4 of 200 and 250 meq/kg in phases 1 and 2, respectively. The acidifiers included fumaric acid (Primary Products Ingredients Americas LLC, Decatur, IL), Activate DA (Novus, St. Charles, MO), KEM-GEST (Kemin, Des Moines, IA), and ACID-AID (Alltech, Nicholasville, KY) added at 0.36, 0.87, 1.01, and 0.84% of the diet, respectively. The fifth treatment did not contain acidifiers which increased the ABC-4 value of the diet by 40 meq/kg. The last treatment was the same formulation as the diet without acidifiers, but with the addition of pharmacological levels of Zn from ZnO. From d 0 to 24 and d 0 to 38, pigs fed low ABC-4 diets had increased (<i>P </i>≤ 0.020) G:F compared to pigs fed the high ABC-4 diet. In Exp. 2, 725 pigs, initially 5.9 kg, were allotted to 1 of 5 dietary treatments fed in two phases with 5 pigs per pen and 29 replications per treatment. Three treatments were formulated using 0.46% fumaric acid with an additional low ABC-4 formulation strategy to target the same low ABC-4 level as Exp. 1. The three strategies consisted of low Ca levels, 0.6% formic acid (Amasil NA; BASF; Florham Park, NJ), or replacing whey permeate with crystalline lactose. The fourth treatment was formulated to be 100 meq/kg greater than the low ABC-4 diets. The final treatment was the same formulation as the high ABC-4 diet but with the addition of pharmacological levels of Zn. From d 0 to 24 and d 0 to 38, pigs fed the crystalline lactose diet had decreased (<i>P </i>< 0.05) ADFI compared to the other low ABC-4 formulation strategies. Pigs fed low ABC-4 diets had increased (<i>P </i>≤ 0.024) G:F and fecal DM compared to the 100 meq/kg higher ABC-4 diet. From d 0 to 24, pigs fed the diet containing ZnO had increased (<i>P </i>≤ 0.001) ADG and ADFI compared to the high ABC-4 diet without ZnO. In summary, the combination of fumaric and formic acid had the best performance among low ABC-4 formulation strategies, with pigs fed low ABC-4 diets having improved feed efficiency and fecal DM compared to a higher ABC-4 diet when the diets did not contain ZnO.