Cutting antibiotic use in calves offers major opportunity, experts say

Figures released by RUMA at the end of 2025 show that calf oral antibiotic sales more than doubled in 2024, rising from 1.92 mg/kg defined daily dose for animals (DDDvet) to 4.03 mg/kg DDDvet.   

RUMA has now introduced a new target to reduce calf oral antibiotic use by 10% year on year, underlining the importance of addressing antibiotic use in youngstock. 

Supporting this, the latest Kingshay results covering 967 dairy herds across 136 veterinary practices show that while average total antimicrobial usage has continued to decline, falling to 12.2 mg/kg PCU in 2025, down from 12.7 mg/kg PCU in 2024 and 15.7 mg/kg PCU in 2020, usage remains heavily concentrated within a subset of farms. 

The data revealed that herds ranking in the highest quartile for antibiotic use accounted for 50% of total antibiotics used, with oral products, often administered to calves for respiratory disease and scour, making up 13% of total antibiotic use within these higher-using herds. 

While Kingshay data showed calf oral antibiotic usage fell from 1.38 mg/kg PCU to 1.05 mg/kg PCU between 2024 and 2025, the contrasting RUMA figures highlight that oral antibiotic use in calves remains a key area of focus for the industry. 

Increase in overall antimicrobial usage

Emma Puddy, Kingshay farm services specialist and report co-author, said the use of oral antibiotics in calves can significantly increase overall antimicrobial usage. 

“If you use oral antibiotics within calves, you will see that your usage is significantly higher than maybe the group average, and I think that is really highlighted in our report. 

“Oral antibiotics tend to really increase your overall antimicrobial usage. Injectable treatments are for just one animal and involve only a small amount of product, whereas if you’re treating a whole pen of calves because 5% of them are getting sick and you want to stop the rest, that’s when oral antibiotics tend to be used more,” she continued. 

Kingshay training consultant and vet Michael Head said that a strong starting point for reducing antimicrobial use is monitoring disease incidence through an effective herd health plan, with vaccination forming a key part of that approach. 

“Effective vaccination strategies form part of this because people can tend to reach for antibiotics, but the benefits of strong immunity, genetic advances and good nutrition mean cattle are better able to resist disease and, in turn, reduce the need for antimicrobials,” he added. 

Despite this, the latest AHDB vaccine report shows that fewer than 50% of calves are vaccinated against respiratory disease, while only around a quarter of producers vaccinate for calf enteritis (calf scour). 

Mr Head believes the introduction of two vaccines, Bovilis Cryptium for protection against calf scour caused by cryptosporidiosis and a vaccine for Mycoplasma bovis, could make a meaningful difference. 

“Their use is certainly increasing at pace, and I’m already hearing farmers recommending the use of vaccines to other farmers,” he said. 

The expert also highlighted the longer-term consequences of disease in calves. “Calf diseases have significant onwards consequences with regard to the future health of those animals, their longevity and their disease resistance.” 

Vital role of vaccinations

Dr Kat Baxter Smith, a vet at MSD Animal Health, added that the Kingshay findings underline how oral antibiotic use in calves can quickly influence overall farm figures and why prevention through vaccination and management changes could provide a low-hanging fruit for farmers to reduce overall antibiotic use in their youngstock. 

“Respiratory disease and scours remain two of the most common reasons antibiotics are used in young calves. By tackling these challenges earlier through vaccination and good management, farmers can significantly reduce the need for antimicrobial intervention. 

“Scours caused by cryptosporidiosis can be particularly difficult to manage, and while some antibiotics don’t always treat the underlying cause, they are often used to manage secondary infections. There have also been reports of some resistance to paromomycin4 in E.coli K99, a commonly used antibiotic for treating E.coli K99 infections and is also licensed for use against cryptosporidiosis,” she said.  

Dr Baxter Smith added that vaccination can play an important role in reducing disease pressure. 

“Using vaccines such as Bovilis Rotavec Corona for rotavirus, coronavirus, and E. coli and Bovilis Cryptium for Cryptosporidium parvum is one of the most effective ways to reduce the incidence of neonatal diarrhoea.  

“Vaccination used alongside good management such as housing, ventilation and colostrum management not only helps aid calf health but also supports better lifetime performance, resilience and productivity within the herd,” she concluded. 

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