Administration of the Postbiotic Substance 412 to Slovak Warm-Blooded Horses: A Pilot Experiment

Antimicrobial proteinaceous postbiotic substances (PS) and/or bacteriocins can beneficially influence animal health, as previously shown with enterocins from non-autochthonous enterococcal strains. Therefore, the effectiveness of PS 412, produced by our beneficial autochthonous strain Enterococcus faecium EF 412, was assessed in horses. In the pilot experiment, PS 412 was administered to 12 horses of various ages and breeds for 21 days via a small feed ball. Sampling was performed on days 0/1, 21, and 42 (after a 3-week cessation of PS 412). The horses served as their own controls. Although the number of horses was limited, the microbiological analysis showed significant decreases in enterococci, other lactic acid bacteria, and campylobacters (p < 0.05; p < 0.001). Staphylococci decreased slightly. Coliforms, aeromonads (p < 0.001), and pseudomonads also decreased. In next-generation sequencing at the phylum level, 15 phyla were detected at higher abundance, with Bacteroidota (35.38%) and Bacillota (32.25%) the most abundant. After PS 412 (activity 51,200 AU/mL), the relative abundance of several phyla decreased. On day 21, phagocytic activity was higher (69.00 ± 3.91%). The metabolic profiles and hematologic values were mostly within the reference range. Although continued testing is necessary, postbiotics appear to be a tool for supporting equine health.