The effect of temperament and responsiveness towards humans on the behavior, physiology and milk production of multi-parous dairy cows in a familiar and novel milking environment.

The objectives of this study were to investigate whether; 1) temperament or 2) behavioral responsiveness to humans, can affect the behavior, physiology and productivity of dairy cows being milked in a familiar and novel milking environment. Temperament of multi-parous cows was defined based on exit time from a restraint device, as High Responders (HR; n=10), Medium Responders (MR; n=10) or Low Responders (LR; n=10). The behavioral response of cows to humans was assessed using four tests: restraint, exit speed, avoidance distance test and a voluntary approach test. Cows were milked according to their established routines in a rotary (familiar) milking parlor and behavioral, physiological and production data were collected over five consecutive days, including heart rate, cortisol and oxytocin concentrations and milk yield. The following week, cows were milked in a novel environment (herringbone parlor within the same farm facility) over five consecutive days, and the data and sample collection program was repeated. Cows were then given an exogenous adrenocorticotropic hormone (ACTH) challenge to measure adrenal responsiveness. Exit time was negatively correlated with the behavioral responses of cows to restraint and human avoidance distance (HAD) in the paddock and arena. The behavioral response of cows to the milking process was greater in MR than LR and HR cows in the familiar and novel milking environments. Milk yields were greater in LR than HR cows in the novel but not the familiar milking parlor. Oxytocin concentrations increased during milking in the novel environment, regardless of cow temperament. In the familiar and novel environments, heart rates were higher in HR than LR cows before and during milking and rMSSD was lower in HR cows during milking in a novel environment. There was no difference in cortisol concentrations between LR and HR cows in response to an ACTH challenge, but HR cows had higher baseline cortisol levels than LR cows. The number of leg lifts cows performed when restrained in the crush was associated with several physiological and milk production measures. These results indicate that cows with different temperaments vary in their basal physiology as well as their behavioral and physiological responses to milking and stress associated with being milked in a novel environment.