Vaccines for the prevention of calf scours
Over the past two years, the use of vaccines for the control of calf scours has become commonplace on many local dairy farms. They are an important and relatively inexpensive management tool which when used correctly can have significant positive impact on calf morbidity and mortality. In most circumstances, their use translates into significant cost benefit and can greatly reduce the burden on staff and management associated with the treatment and care of sick calves. There is currently some mistruths and misinformation within the industry about the vaccines, and they should not be regarded as a silver bullet for on-farm calf health issues. However, when they are integrated with ordinary farm processes they can be very effective.
There are two adult cow vaccines registered in Australia for the control of calf scours, these being Coopers Rotavec Corona® and Zoetis Ultravac Scourshield®. These vaccines are administered to the pregnant cow who, via her colostrum, passes the immunity developed to her calf. Over recent years we have seen the use of these vaccines grow significantly and when combined with other management practices can help dramatically reduce calf illness and death.
The most common causes of calf scours in South West Victoria include Rotavirus, Cryptosporidium, E. Coli and Coronavirus. It is often claimed that Clostridium perfringens also causes calf scours however it is commonly found in the gut of healthy cattle so a positive sample does not necessarily mean that it was the cause of the scours. Our experience is that this cause has minimal relevance. Both vaccines protect against these common pathogens.
It is critical to understand that for both Ultravac Scourshield and Rotavec Corona to work in your calves they rely on good colostrum management. The vaccines boost the cow’s levels of IgG (immunity) in their blood and, if given at the right time prior to calving, increases the level of IgG in the colostrum that is then fed to your calves. This is an important consideration given recent studies at The Vet Group have shown that approximately 38% of calves do not get sufficient good quality colostrum.
The main reason for vaccine failure is failure of passive transfer of immunity due to incorrect/delayed feeding of colostrum. It is also possible for timing of vaccination to reduce vaccine performance. If the vaccination is given too early or late the increased IgG will not make it into the colostrum. Also, calves are only able to absorb IgG from colostrum in the first 24 hours after birth so if the colostrum is not fed to the calf immediately the calf will not be able to absorb the immunity.
Evidence suggests that both products are similar in their ability to prevent calf scours when administered to cows at the required time(s) pre-calving. But there are some important differences that users should consider as shown below:
The ability to inject the Scourshield vaccine intra muscularly, the greater flexibility in the timing of administration and the longer broach claim (days after opening at which product should no longer be used) make it attractive from a management and cost saving perspective.