Investigating the Association Between Salivary Profiles, Production-Related Variables, and Daily Lying Time in Dairy Cows: A Pilot Study

Lying behaviour reflects cattle welfare response. This study aimed to investigate changes in salivary profiles and production variables based on lying time in dairy cows to identify potential biomarkers of rest-related changes. Over a three-month period, lying time was monitored in 15 healthy commercial dairy cows using accelerometric collars. Saliva samples were analyzed for relevant biomarkers. The LMM showed that salivary cortisol (β = 0.481, 95% CI: 0.204-0.758, p = 0.001) and total adenosine deaminase (tADA, β = 0.011, 95% CI: 0.005-0.017, p < 0.001) were positively associated with daily lying time, whereas creatinine kinase (CK) was negatively associated with daily lying time (β = -0.015, 95% CI: -0.030 to -0.001, p = 0.035). Metabolic stress can drive cows to prioritize lying, revealing a coping response to sub-optimal welfare. Increased salivary tADA reflects inflammatory conditions that alter animal behaviour by enhancing lying time. Increasing CK indicates muscle tissue injury, and physical strain may be due to acute restlessness or sustained standing. The findings suggest that changes in lying behaviour may be associated with changes in salivary analytes. The results are encouraging but require validation in larger and more diverse populations before routine application in dairy welfare assessment.