Unfolding dairy farmers' behaviour, goals and drivers in mastitis control: reference-point stability through goal-means instrumentality.

Effective mastitis control in dairy production requires not only adherence to preventive measures but also understanding the motivations underlying farmers' decision-making in response to udder-health indicators. This study examined how Swedish dairy farmers select and adapt mastitis-control measures in response to perceived changes in bulk milk somatic cell count (BMSCC), a key indicator of udder health. Drawing on Goal System Theory and Tri-Reference Point Theory, we employed a three-stage exploratory observational study design combined with the means-end chain approach and laddering interviews to analyse how farmers' goals, values, and perceived outcomes influence mastitis-control decisions. Thirty Swedish dairy farmers participated in telephone interviews using a structured three-stage exploratory scenario design in which they responded to rising, persistently high, or decreasing BMSCC levels. For each scenario, farmers identified control measures they would implement, explained the expected consequences for herd health and production, and described the underlying goals guiding their choices. Farm economic performance and animal welfare consistently emerged as dominant goals, but the selected measures and reasoning patterns varied across scenarios. Decision-making became more focused and intervention-oriented when BMSCC increased, whereas declining BMSCC prompted farmers to prioritise maintaining effective routines. Across scenarios, the interviews showed that farmers selected multifinal means, actions serving multiple goals, and adjusted their strategies in response to performance feedback. The findings suggest that farmers' self-defined BMSCC reference points influenced how the interviewed farmers reasoned about intended mastitis-control decisions. Advisory strategies that acknowledge farmers' individual motivations, goal structures, and intervention thresholds may facilitate discussions around preventive measures and support herd-health management that is better aligned with farmers' decision-making processes.