Dr Paul Field, BVetMed - Vetora Putaruru
Spring calving is nearly upon us, and before it hits there’s still time to vaccinate your cows to help prevent Rotavirus in your calves.
What is Rotavirus?
Rotavirus is a costly and aggressive cause of calf scours, affecting calves from 3 days – 3 weeks of age. Calves are infected by the faecal-oral route, then the virus attacks the enterocytes (gut lining cells) which causes a haemorrhagic diarrhoea resulting in a sick, dehydrated calf. Outbreaks often have a high mortality, and those that recover often have ‘villous stunting’ meaning that there is less surface area of the gut lining, reducing nutrient absorption and resulting in reduced growth rates for the calf’s life. Also, being viral, no antibiotic works to treat it.
What do I need to do?
Cows vaccinated with Rotavec Corona in the last 12 months can be boosted with Scourguard. Animals vaccinated for the first time will either need 2 injections of Scourguard, 3 weeks apart, or 1 injection of Rotavec Corona.
The injection needs to be timed to be 3 weeks before the planned start of calving, boosting the colostrum for 9 weeks of calving.
How does the vaccine work?
The vaccine is designed to stimulate the cow’s immunity so that she produces lots of antibodies against Rotavirus in her colostrum. This boosted colostrum then is fed to the calf within the first 12 hours of birth, which allows these antibodies to be absorbed by the newborn calf’s gut wall into its bloodstream. This provides an instant immunity for the first 3 months of its life, while it’s own immune system is getting up to speed.
Do I need to vaccinate my heifers?
Yes, any vaccination programme relies on the majority of the population being vaccinated. Even though you may not be keeping calves from heifers as replacements, there will still be a virus challenge to the surrounding environment from them.
What else do I need to do to ensure that it works?
Planning your system so that the calf receives adequate first milking colostrum from vaccinated cows, warm, undiluted and within 12 hours of birth.
Do I need to think about anything else?
Yes, setting up your calf sheds so they are big enough, dry and have good drainage, so that the bugs don’t have the environment to survive and multiply in. If there was Rotavirus last year, make sure all of the old bedding has been removed and the shed disinfected. Hard surfaces can be sprayed with a suitable disinfectant, and limeflour can be put down before shavings.
Make sure calf feeding equipment is clean and disinfected prior to the start of the season. Also, make sure you have Iodine ready to spray or dip calves’ navels with, before you put them up onto the calf trailer.