Dairy herd health maintained as antimicrobials use cut further

The dairy sector has achieved further reductions of antibiotics usage without compromising on the health and welfare of animals, a new report has found.

The annual Kingshay Antimicrobial Focus Report states there has been a 19% reduction of total antimicrobials usage (AMU) since 2020.

See also: How a Dorset dairy farmer cut antibiotics usage by 80%

Total AMU to March 2024 was 12.7mg for every population-corrected unit (PCU) in the 879 monitored herds, comfortably below the 2024 target of 17.9mg/PCU set by the Responsible Use of Medicines in Agriculture Alliance (Ruma), and down from 13.7mg/PCU in 2023.

In the report launched on Monday (27 January), herd health data collected from Kingshay’s Dairy Manager service has been used for the first time to assess whether the reduction of AMU has caused health issues in livestock.

Dr Tim Potter, Westpoint Farm Vets’ senior clinical director and Kingshay report co-author, says: “We are pleased to report that the latest data suggest that neither herd health nor milk production has been impacted by this reduction in use.

“In fact, as total antimicrobials use has reduced, mastitis rates and bulk somatic cell counts have also reduced, and there hasn’t been a rise in culling for mastitis or an increase in the rate of cows leaving the herd.” 

Westpoint Farm Vets’ senior clinical director and Kingshay report co-author Tim Potter © Tim Potter

Health and welfare trends

“Antimicrobials are a key tool for the treatment of bacterial disease. The overall aim is not zero usage,” Tim says, reiterating that the goal is responsible and sustainable reduction in usage, without compromising on health and welfare.

Mastitis treatment is a key reason for AMU in the dairy sector, but data show there has been a consistent decline in clinical cases of mastitis achieved (see “Improvements in dairy herd health 2019-2024”), alongside a year-on-year reduction in the usage of lactating cow tubes and a reduction from a DCDVet of 0.558 in 2020, to 0.336 in 2024.

Moreover, somatic cell counts have reduced year-on-year since 2020, while the usage of dry cow tubes has fallen from a DCDVet of 0.484 in 2020 to 0.425 in 2024.

Tim says there is still an opportunity where dry cow therapy is concerned, though, with 31% of monitored herds not using teat sealants.

The downward trends in mortality rate, involuntary culling and cows dying on farm (down from 7.2% of cows leaving the farm in 2020 to 6.5% in 2024), enables farmers to make more proactive breeding decisions based on yield, health and fertility, he explains.

The health parameter showing a less consistent decline is lameness, although there is a general downward trend. The data available do not explain why this is.

The highest users

The highest 25% of antimicrobials users account for 50% of the total usage.

Emma Puddy, farm services specialist at Kingshay, who co-authored the report, believes there is room for improvement in this quartile, and says they need to continue to work with vets and advisers to reduce reliance on antimicrobials.

Farms with the highest AMU do not remain the same though. Interestingly, 50% of herds were in a different quartile for total AMU than they were in 2023, reflecting the dynamic use of antibiotics on-farm, dependent on disease challenge.

Oral antibiotics and new vaccines

The 25% of the herds using the most antimicrobials use five times the amount of the remaining 75% of herds when it comes to oral products. These are most likely to be used in the treatment of youngstock diseases such as pneumonia, bacterial scours and cryptosporidium outbreaks, says Tim.

While they are not used at all by many herds in the data sample, they “contribute a significant amount in terms of milligrams”, he says.

One oral product in the tetracycline class of antimicrobials was only used by 47 herds in the dataset but was the fifth biggest contributor to total usage across the year.

Oral administration of antimicrobials, especially to a group of animals, carries a higher risk of antibiotics resistance developing, so is an important area to look at.

“It is important that farms consider alternative disease control strategies, wherever possible,” the report authors write.