Exploratory assessment of milk biomarkers during non‑antibiotic treatment in experimental Staphylococcus warneri goat mastitis

Abstract

Conventional milk indicators such as somatic cell count (SCC) and pH have limited specificity for monitoring caprine mastitis, particularly under non-antibiotic treatment protocols. This exploratory study evaluated the temporal behavior of milk N-acetyl-β-D-glucosaminidase (NAGase), SCC, total bacterial count (TBC), pH, and selected electrolyte indicators (Na, K, and Na/K ratio) across sequential non-antibiotic phases, including milk microbiota transplantation (MMT), Resilience (washout), and 7-epiclusianone, in an experimental Staphylococcus warneri mastitis model in goats. Using a paired-udder longitudinal design in six goats, treated udders showed sustained sodium elevation, potassium depletion, and increased Na/K ratio, indicating persistent blood-milk barrier disturbance across phases, whereas pH and TBC showed more variable responses. NAGase activity correlated positively with SCC and sodium and negatively with potassium, consistent with its association with mammary epithelial injury and inflammation. These findings suggest that NAGase, together with Na, K, and the Na/K ratio, may help characterize biomarker dynamics during non-antibiotic treatment. Given the exploratory design and small sample size, these findings require validation in larger studies before routine application.