The role of human presence as social buffer for dairy cattle

This study investigates whether the presence of an unfamiliar human can alleviate stress responses in cows, acting as a social buffer. We assessed behavioral and physiological stress indicators in ten lactating Italian Red Pied cows using the isolation paradigm. Two conditions were tested: Isolation (cow alone) and Social (cow with a human present). Behavioral responses were observed ethologically, and stress levels were also measured via plasma cortisol concentrations before and after each test. We divided the 15-minute test into 30 consecutive 30-second bins, yielding 30 time-series points per behavioral variable. Data were analyzed using Gamma-distributed GLMMs with Condition and Condition×Interval as fixed effects and Subject ID as a random intercept. Separate models were run within each condition to assess time-related trends. Stress-related behaviors were higher under Isolation than Social conditions, with differing temporal fluctuations but no consistent linear trend in either condition. Locomotion was higher in Isolation; both conditions exhibited a significant linear decrease over time, though at different rates. Proximity to human did not differ overall but increased linearly over time only in the Social condition. Exploration showed no condition effect; it declined significantly in Social and marginally in Isolation. Standing showed neither condition differences nor linear time trends. Stranger-directed behaviors, recorded only in Social, increased linearly over time. A significant increase in cortisol levels was observed only in the Isolation condition. Overall, the data suggest that human presence can reduce stress in cows subjected to isolation stress. This study has practical applications for improving animal welfare and productivity in farming systems, for example by reducing stress-related behaviors and enhancing animals’ ability to cope with challenging situations.