In the light of increasing awareness of public health risks from livestock-sourced antimicrobial resistance, antimicrobial use in animal agriculture is facing increased regulations around the world. The most recent and sophisticated addition is the Danish Yellow Card Initiative, which imposes quantity restriction on therapeutic antibiotic use. Using a panel m-order conditional efficiency analysis, this article provides one of the first empirical estimates of the association between the Danish Yellow Card Initiative and the economic efficiency of pig farms. The research design enables us to establish associations rather than causal relationships but the results suggest a small reduction (0.15 percentage points for the average farm) in revenue efficiency and a small reduction (0.03 percentage points) in cost efficiency in the short run after imposing restrictions to antibiotic use.