Calf diarrhoea, or scours, is one of the most common and yet devastating diseases that can affect a calf. Scours can occur due to nutritional reasons, such as a change in composition, volume or timing of milk, or due to an infectious cause.
Viruses, bacteria, and protozoal parasites can all be implicated in scour outbreaks in New Zealand calf sheds.
Scour prevention in calves requires a multimodal approach that focuses on getting high-quality colostrum into calves as soon as possible after birth, vaccination of cows prior to calving, and a plan to manage all of the other factors that can contribute to the incidence of infection, such as feeding routine, pen and equipment hygiene, shed design and overcrowding.
Calves are not born with the ability to fight off disease, they acquire it through passive transfer from the cow via antibodies in colostrum. Unfortunately, the window for acquiring these antibodies is short. From the time a calf is born, the ability of its gut to absorb antibodies rapidly decreases. After 12 hours the calf is already absorbing only a fraction of the antibodies from milk, and after 24 hours the gut can be completely ‘closed’.
Working to ensure that calves get colostrum with the three Qs (Quality colostrum, Quickly and of sufficient Quantity) means that you have set them up for a successful future. Calves will have a stronger immunity and be less likely to catch diseases and more able to fight off disease if they do become infected in the first place.
Vaccination of the cow prior to calving can provide huge benefits in the prevention of calf scours. There are a number of different scour vaccines available now, all of which include protection against rotavirus, coronavirus and E. coli. Speak with your Vetlife vet to find out which of these scour prevention vaccines is best for your farm. Depending on the vaccine, you may need a sensitiser and booster shot in the first season or you may choose one of another type that is effective after just one. Vaccination can help prevent a scour outbreak and also decrease the severity of the outbreak on both an individual calf level and at the farm level by decreasing the amount of virus that infected calves shed and spread.
Vaccines are usually given 3-12 weeks before calving. Splitting the herd into early and later calvers, and jabbing them in two batches can be useful to ensure maximal protection of calves at all stages of the season. We need to focus not just on the heifer replacements coming through at the start of calving, but also on the calves born later in the season when the sheds have been well used and the contamination in pens has started to build up.
Salvexin+B, the salmonella vaccine, is another vaccine that can be useful in preventing calf scours as well. Salmonella is a nasty bacterial infection that is becoming increasingly common on our farms. It is often seen as a scour or abortion outbreak in heifers and adult cows, but it can also affect young calves in the shed. Vaccinating cows at dry off or over the dry period can not only protect cows but also help provide passive transfer of antibodies to calves through colostrum, and this can help prevent an outbreak in the calf shed in spring.
Using these vaccines can help lessen your chance of a significant scour outbreak, but only if the antibodies you inject into your cows actually make it to the calves. Vaccinating means your colostrum feeding becomes even more important. If you invest in vaccination, you need to support that investment in the future of your calves by making sure they are provided with a good immunity via passive transfer.
Vetlife clinics provide an FPT (failure of passive transfer) testing service. Vets or technicians will take a blood sample from calves between 1-7 days of age and test it in-house. The results from this test can determine the level of antibodies a calf has in its system. FPT testing right at the start of the season will either confirm that the systems you have in place for colostrum feeding are working, or provide rapid feedback that changes need to be made.
Regular testing throughout the season is also useful to ensure that your protocols have been followed consistently and you are getting the full value from your vaccination programme.