Abstract Acids are utilized in young nursery pig diets to enhance nutrient digestibility and support gut health by lowering gastric pH and limiting pathogenic bacteria growth. Traditionally, acids are only used in the early nursery phase, but there has been interest in whether a step-down acidification program into late nursery has additional benefits. Therefore, this study evaluated the interactive effects of in-feed acidifiers in early and late nursery on growth performance and survival of nursery pigs. A total of 4,833 pigs (PIC 337 × L42, initial BW = 5.7 kg) were used in a 38-d trial, placed in pens with 34 or 35 mixed-sex pigs. Pens were blocked by initial BW and randomly allotted to 1 of 9 dietary treatments with 15 or 16 replicates per treatment. Two acid blend (AB) products were evaluated in this study: AB1 (ABC-4 = -4,699 mEq/kg) and AB2 (ABC-4 = -4,487 mEq/kg). Dietary treatments were arranged in a 3 x 3 factorial treatment structure. During early nursery (d 0 to 17), pigs were fed diets with 0.235% AB1, 0.245% AB2, or 0.50% AB2. In late nursery (d 17 to 38), each early treatment was subdivided to receive 0, 50, or 100% of the early nursery acidifier levels. Early nursery diets were fed in pellet form and were corn, soybean meal, and oats based with 1.38% SID Lys and pharmacological levels of Zn and Cu (3,000 and 200 ppm, respectively). Late nursery diets were fed in mash form and consisted of corn, soybean meal, and 10% DDGS diet with 1.30% SID Lys. Pigs and feeder were weighed on d 0, 17, and 38 to calculate ADG, ADFI, and G:F. ). Data was analyzed using the PROC GLIMMIX of SAS (v 9.4) using pen as the experimental unit.No evidence for interactive effects between early and late nursery acidification (P 0.10) was found. From d 0 to 17, there was a tendency for lower ADG (P = 0.083) when pigs were fed 0.50% AB2, which was driven by a numerically lower (P = 0.14) ADFI. From d 17 to 38, there were no statistical differences in ADG, ADFI, or G:F. Overall, there was no evidence statistical differences in health outcomes. However, pigs that received AB1 followed by 50% rate in late nursery had numerically lower mortality and higher full value pigs. Our findings suggest that feeding weaned pigs a diet containing an acidifier during early nursery followed by a step-down program in the late nursery improves growth performance and may improve survivability.
Hart et al. (Wed,) studied this question.