Episode 339- Horn Fly Vaccines: What We Learned from a Summer Study - UMN Extension's The Moos Room

On this spring episode of The Moos Room, Brad dives into the seasonal return of flies and shares results from a recent horn fly vaccine study conducted at the University of Minnesota’s WCROC. Horn flies—common in pasture-based systems—cause significant irritation, blood loss, and production losses in cattle, and their rapid life cycle makes them difficult to control, especially with increasing insecticide resistance.The study evaluated a Medgene horn fly vaccine designed to disrupt the fly’s ability to take a blood meal, ultimately reducing reproduction. Researchers vaccinated about half of the cows and heifers across organic (pasture-based) and conventional (dry lot) systems and tracked fly populations throughout the summer. While no differences were observed for face flies or stable flies—as expected—the vaccine showed promising results for horn flies. There was little effect in conventional cows, but in pasture-based animals, especially heifers, vaccinated groups experienced a consistent 30–40% reduction in horn fly numbers compared to controls.Overall, the findings suggest that horn fly vaccination could be a valuable new tool—particularly for grazing and organic dairy systems—to help manage fly pressure and improve animal well-being over time.Questions, comments, scathing rebuttals? -> themoosroom@umn.edu or call 612-624-3610 and leave us a message!Linkedin -> The Moos RoomTwitter -> @UMNmoosroom and @UMNFarmSafetyFacebook -> @UMNDairyYouTube -> UMN Beef and Dairy and UMN Farm Safety and HealthInstagram -> @UMNWCROCDairyExtension WebsiteAgriAmerica Podcast Directory