PSVIII-1 - Evaluating the Efficacy of Acidifiers Used in Nursery Diets in Reducing Bacterial Loads in Both Non-inoculated and Inoculated Complete Feed

Abstract: Acidifiers are used in nursery pig diets to reduce the incidence of diarrhea, improve growth performance, and act as a feed preservative. The objective was to evaluate whether acidifiers were able to reduce bacteria presence in non-inoculated feed and reduce bacteria growth in feed inoculated with Escherichia coli and Enterococcus faecium. Each culture media was arranged in a 2×5 factorial with 2 phases and 5 diets. The diets were 1) control – no antibiotics, 2) ZnO (Phase 1: 3,000 ppm Zn and Phase 2: 2,000 ppm Zn), 3) formic acid at 0.7% of the diet (Amasil-NA; BASF Corp. Florham, NJ), 4) glycerol monolaurate – GML at 0.18% of the diet (Natural Biologics, Newfield, NY), and 5) FORMI-3G at 1.0% of the diet (Addcon Gmbh, Bitterfeld-Wolfen, Germany). Non-inoculated feed was plated onto Aerobic Count, E. coli/Coliform, and Enterobacteriaceae petrifilm (3M, St. Paul, MN). Inoculated feed was initially contaminated with E. coli or E. faecium and allowed to incubate prior to plating on MacConkey. There was no difference (P>0.05) in quantity of bacteria for the diets inoculated with E. coli. There was no difference (P>0.05) between the diets inoculated with E. faecium for phase 1; however, the formic acid diet had reduced (P < 0.05) quantities of bacteria compared to control, ZnO, and GML diets. The control and ZnO phase 1 non-inoculated diets had reduced (P < 0.05) quantities of aerobic bacteria, coliforms, and Enterobacteriaceae compared to GML. In phase 2 only the control had reduced (P < 0.05) quantities of Enterobacteriaceae compared to the ZnO and formic acid diets. Formic acid was able to reduce E. faecium quantities in phase 2, while the control and ZnO had decreased overall bacterial loads in phase 1.