A comparison of a selective dry cow therapy and a non-antibiotic dry cow protocol in Irish dairy farms: a controlled field study

<title>Abstract</title> <p> <bold>Background</bold> Reducing antimicrobial use in dairy systems is a key priority due to concerns over antimicrobial resistance. Although selective dry cow therapy (SDCT) is widely used, evidence for non-antibiotic alternatives remains limited. This study compared SDCT with a non-antibiotic protocol (NAP) in commercial Irish dairy herds. <bold>Methods</bold> A controlled, non-randomised field study was conducted on four Irish dairy farms involving 155 cows allocated to either a NAP or a reference group managed under SDCT principles. Outcomes assessed during the subsequent lactation included somatic cell count (SCC), milk production, clinical mastitis incidence and pathogen detection using optimised real-time PCR assays. <bold>Results</bold> No significant differences were observed between the NAP and SDCT groups for SCC, milk yield, fat yield, protein yield or clinical mastitis incidence (P &gt; 0.05). Molecular screening detected low levels of mastitis-associated pathogens overall, with no consistent differences between groups. <bold>Limitations</bold> The relatively small sample size, inclusion of only four herds and non-randomised group allocation may have limited the ability to detect subtle differences between protocols. <bold>Conclusion</bold> The non-antibiotic protocol performed similarly to SDCT-based management under the conditions of this study. These findings suggest that non-antibiotic dry cow management strategies warrant further investigation as part of antimicrobial reduction programmes. </p>