Associations Between Microscopic Balantioides coli Counts and Precision Dairy-Farming Indicators in Clinically Healthy Dairy Cows

Balantioides coli is an enteric ciliated protozoan detected in cattle, but the association between microscopic B. coli counts and precision dairy-farming indicators remains poorly understood. This cross-sectional study evaluated associations between microscopic B. coli counts and behavioral, production and milk-composition traits in 83 clinically healthy Holstein cows in parity 2–4 and 20–100 days in milk. Fecal samples were examinated using sedimentation and modified McMaster methods and abundance was expressed as microscopic counts per field of view. Automated farm systems provided eating and rumination times, daily milk yield, milk fat-to-protein ratio, lactose concentration and somatic cell count. Zero-order correlations between microscopic B. coli counts and all evaluated indicators were weak and non-significant (r = 0.027–0.190). After adjustment for parity and days in milk, a modest positive correlation was observed with lactose concentration (partial r = 0.296, p = 0.007). The remaining adjusted correlations were weak or negligible and statistically non-significant: eating time (r = 0.105), rumination time (r = 0.036), daily milk yield (r = 0.060), milk fat-to-protein ratio (r = 0.064) and log10-transformed somatic cell count (r = 0.015). Overall, microscopic B. coli abundance showed limited association with the evaluated indicators, and the lactose finding should be regarded as exploratory.