New Zealand Veterinary Guidance Will Tighten Dry Cow Therapy
New Zealand’s dairy farmers have increasingly moved towards selective dry cow therapy (DCT), but some farms still give antibiotics to every cow at drying-off. From January 1st 2027, updated guidance from the Veterinary Council will place greater emphasis on showing that antimicrobial treatment is justified for each individual animal.
Matt Buckley, a veterinary technical adviser at MSD Animal Health, said selective DCT was not a new practice. The change, he said, was the stronger backing for it and the availability of technologies that can provide more information about individual cows. “The thresholds and guidelines have been there for quite a while. The difference now is that vets have much stronger backing to say, ‘show me the evidence that this cow needs antibiotic dry cow therapy.’”
Analysis by DairyNZ found that blanket DCT provides a benefit only in herds where bulk milk somatic cell count exceeds 250,000 cells per millilitre and increases by more than 50,000 cells per millilitre during the final three months of the season. DairyNZ estimates that fewer than 5% of New Zealand herds are likely to satisfy both conditions. For other herds, its recommended approach is antibiotic treatment for qualifying cows, together with an internal teat sealant for every cow to help prevent new infections during the dry period.
The guidance is intended to reduce unnecessary antimicrobial use while retaining treatment for animals that need it. The issue is also linked to antimicrobial resistance. Mr Buckley said responsible use meant preserving the effectiveness of antibiotics for people and animals. “We want antibiotics to work when we genuinely need them. This isn’t about not treating cows that need treatment – it’s about the right treatment, for the right cow, at the right time.” DairyNZ says New Zealand farmers already rank among the lowest users of antibiotics internationally.
Selective treatment requires farmers and veterinarians to assess cows individually. Relevant evidence can include clinical mastitis records and individual-cow somatic cell counts. A 2024 study in the Journal of Dairy Science examined 1,544 cows across four predominantly pasture-fed New Zealand herds. It found that somatic-cell-count data gathered through SenseHub Dairy In-Line Somatic Cell Count during the final 12 weeks of lactation produced results similar to conventional herd-testing data when identifying major intramammary infections at drying-off.
The researchers concluded that in-line data could be used to select cows for either antimicrobial DCT or an internal teat sealant. Continuous individual-cow records can also show rising cell counts earlier in the season and help identify possible mastitis problems before drying-off. Farmers already use herd-test results, mastitis records and drying-off dates to produce lists of cows that meet treatment criteria. Technology can additionally assist with separating cows assigned to different treatments, while milk-volume data can help determine when an individual cow should be dried off.
Veterinarians will remain responsible for helping set the relevant thresholds and treatment strategy, taking account of each herd’s mastitis situation. Mr Buckley advised farmers who have traditionally used blanket DCT to discuss their 2027 approach with their veterinarian, including the criteria for antibiotic treatment and whether they have sufficient individual-cow information to support the decisions.
