Digital dermatitis (DD) poses a major animal welfare concern for the dairy industry, with even broader economic implications for the agricultural industry worldwide. The postbiotic, a Saccharomyces cerevisiae fermentation product (SCFP), has had a positive influence on the innate immune system of cattle, which makes it a potential candidate as a feed supplement as part of a prevention strategy for DD. This study investigated the effect of a commercial SCFP feed supplement compared to a control feed supplement on the production of pro-inflammatory cytokines (IL-1β and IL-6) by peripheral blood mononuclear cells (PBMCs) in Holstein Friesian steers experimentally infected with DD. The results showed that SCFP supplementation was associated with an overall reduced IL-1β production (p = 0.005), particularly prior to experimental inoculation with a DD lesion homogenate. However, the results of the analysis suggest that the innate immune system in the SCFP group became prepared to respond more rapidly to DD infection post-inoculation. During active (M2), chronic (M4), and focal flare-ups (M4.1) of DD, SCFP supplementation resulted in a more rapid secretion of IL-1β (M2: p = 0.038; M4/M4/1: p = 0.034). A more rapid response to DD infection for IL-6 was only found for chronic (M4) and focal flare-ups (M4.1) of DD (p = 0.006). These findings emphasize the difference in cytokine response between various stages of DD in the SCFP group compared to the control, highlighting implications for DD prevention and treatment.
Keywords: M-stage; infection model; lameness; postbiotic; pro-inflammatory cytokines.