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Rotavirus is a costly disease that causes the majority of diarrhoea or scours in newborn calves.
In a Zoetis New Zealand rotavirus webinar update, Massey University’s School of Veterinary Science Doctor Laryssa Howe provided an update on findings from the 2025 Rotavirus Surveillance Study on calf faecal samples submitted by veterinary clinics across the country.
The study showed that while the G6 strain of rotavirus is the most prevalent, 10% of farms had a G10 strain component present, highlighting the risk of cross infection.
Research shows rotavirus is present in 70% of New Zealand farms and is responsible for up to 62.5% of scours cases in calves. The disease can result in high death rates, reduced weight gain and long-term productivity loss, and increased veterinary treatment costs, not to mention the emotional toll on those caring for them.
Newborn calves are not able to mount their own immune response to rotavirus, which is why protection passed on from their mothers is so crucial. Vaccination of the cow is a key tool in the proactive management of rotavirus in vulnerable youngstock.
Zoetis veterinary technical advisor, Karley DeFrees, explains that the Zoetis ScourGuard 4K vaccine is the only vaccine on the market in New Zealand that contains both the G6 and G10 rotavirus strains.
“ScourGuard 4K is a proven, tissue-friendly vaccine that offers the broadest spectrum protection as it covers calves for G6 rotavirus, G10 rotavirus, Coronavirus and E. coli.”
Cows are vaccinated two to 12 weeks before calving to give them time to mount an immune response, she says. Vaccination results in an increased antibody pool in the dam, which is passed on to her offspring through the all-important colostrum.
Howe emphasises the dynamic nature of rotavirus, and its vaccines. Rotavirus has the ability to be variable, re-assort and make changes to its genetic material.
Aside from vaccination, control and prevention of rotavirus rests on three main factors: environmental, pathogen and calf.
“Vaccines are a tool and need to be used in context of the broader picture of how to control the environment and do the best by the calves,” she explains.
“We are not preventing infection; we are minimising disease. It’s about how the immune system is managing it, so calves do not become sick.”
Environmental factors include stocking density, hygiene and temperature/humidity. Pathogen factors are virulence, survival time in the environment and treatment. Calf factors include the quality and quantity of colostrum received, vaccination and nutrition intake.
DeFrees says that while vaccination is important, other factors outlined by Howe must be addressed as well.
“Calves need antibodies and the first 24 hours is crucial. Even if vaccine has been used, farmers still need to ensure a calf has had enough colostrum. If it is in a cold, damp environment, rotavirus could also show up more severely, for example.”
Vaccine Choice
Howe outlines three factors to consider when assessing vaccine suitability:
- Does it elicit the correct type of immune response - are we getting a response that's going to work?
- Does it reduce shedding/environmental contamination?
- Does it provide cross protection if needed?
“Studies show the use of a vaccine decreases the amount of rotavirus being shed. Although there is a reduction, it’s not zero and these viruses are incredibly effective at getting in. Vaccination does not mean that the environmental control tools are not useful or needed. We need to do other things, as well as vaccinate, to help protect our calves and manage the disease.”
DeFrees sees vaccination as a key tool in proactive best practice animal health on dairy farms.
“Healthy calves are the building blocks of your future dairy herd. Everything we can do to set calves up to gain weight and get in calf early, is all related to what ends up in the vat. Prevention is about being proactive.”
Vaccination offers a form of ‘insurance policy’ by raising the levels of antibodies needed to protect calves and build an immune system to give them the best start to life, which will later be repaid in the form of milk production.
Article provided by Zoetis
