Comparative Effects of Different Dietary Acidifiers on Growth Performance and Intestinal Health in Weaned Piglets

This study evaluated the effects of conventional benzoic acid (BA), a benzoic acid formulation containing 97% benzoic acid and 3% Permeabilizing Complex™ (NBA), and a compound acidifier containing formic, acetic, propionic, and citric acids (CA) on growth performance, nutrient digestibility, intestinal morphology, serum parameters, and fecal microbiota in weaned piglets. A total of 128 piglets were assigned to four dietary treatments for 42 d: a basal diet without supplemental acidifier (CON), 0.5% BA, 0.3% NBA, or 0.3% CA. The acidifier products were evaluated at their respective manufacturer-recommended inclusion rates; therefore, the study represents a practical comparison of acidification strategies rather than an equal-benzoic-acid-dose comparison. BA increased final body weight (BW) compared with CON and increased average daily gain (ADG) during days 15-42 and 1-42 compared with CON and CA, while also increasing average daily feed intake (ADFI) compared with all other treatments (p < 0.05). NBA also increased ADG compared with CON (p < 0.05), with a numerical response intermediate between CON and BA. CA increased the apparent total tract digestibility of crude protein, ash, and gross energy compared with CON, BA, and NBA (p < 0.05), and increased dry matter digestibility compared with BA and NBA but not CON; however, these improvements were not accompanied by greater final BW or ADG. NBA increased serum IgM, whereas CA increased IgM and total antioxidant capacity but decreased IgG relative to CON (p < 0.05). Intestinal morphological responses were segment-specific. NBA increased duodenal villus height and villus height-to-crypt depth ratio and reduced ileal crypt depth while increasing the ileal ratio, but also increased jejunal crypt depth and reduced the jejunal ratio (p < 0.05). NBA and CA reduced fecal microbial richness, while dietary treatment significantly affected fecal microbial community membership. In conclusion, conventional BA produced the clearest feed intake and growth response, whereas NBA increased ADG relative to CON and produced segment-specific effects on intestinal morphology, and CA primarily increased apparent nutrient digestibility.