Abstract
Bovine Viral Diarrhea (BVD) inflicts economic losses on global dairy production. In Thailand, BVD remains outside national control priorities, shifting the burden of disease management entirely to local biosecurity choices. Using a qualitative approach, this study investigated dairy farmers' perceptions and biosecurity practices within Thailand’s certified Good Agricultural Practice (GAP) sector. Semi-structured, face-to-face in-depth interviews and field observations were conducted with smallholders in western Thailand, and the transcripts were analyzed using thematic analysis. The results revealed a profound "biosecurity paradox" driven by salience bias: while farmers showed universal awareness and strictly enforced emergency protocols for highly visible epidemics like Foot-and-Mouth Disease and Lumpy Skin Disease, they exhibited an acute awareness deficit regarding subclinical pathogens like BVD. Crucially, visual animal selection and structural trust routinely led to introducing persistently infected replacement heifers without screening. Furthermore, unstandardized management of reproductive waste was widespread, with most participants discarding infectious tissues into open fields, occasionally commodifying high-risk biological waste into local human food networks. Rigid top-down GAP rules induced intense regulatory fatigue among financially stressed smallholders. Farmers explicitly rejected conventional extension group workshops due to acute labor constraints, preferring decentralized digital micro-learning (mobile short videos and on-farm posters) and clinical interactions with visiting practitioners. This study provides an empirical blueprint for livestock policy to shift from passive, farmer-dependent reporting to government-led active surveillance to protect national dairy herd health.