How can we prevent calf scours?

Lia Missena, Veterinarian, Anexa Vets Gordonton

Spring calving is almost upon us, and before it starts it is important to prepare! The upside is that most of the spring calving cows are being dried off and spring farmers can get a bit of a well-deserved rest. Unfortunately, this does not mean farmers can completely forget about their dried-off cows. Preparing ahead for calving season means scheduling jobs for the benefit of the calves due to be born e.g. preparing calf pens, colostrum storage facilities and scour vaccinations. Anyone who has had an outbreak of rotavirus calf scours will tell you about the heartbreak and financial losses they endured as this awful disease spread through their calf pens.

Farmers ask us - why does this happen? How can I prevent this? The answer is not so simple.

Newborn calves are born without the protective immunity of antibodies because, in cattle, they are not passed across the placenta to the foetus. Thus, when calves are born in the mud, muck, and rain and then transported to a calf pen they are being exposed to bacteria or pathogens without any protection. Calves need about 2 litres of good quality colostrum within 4 hours of birth - ideally within 1 - 2 hours and 4 litres within 12 hours to get their necessary immunoglobulins. Timing is key! The intestines in calves are filled with little holes that specifically let antibodies through. However, after 12 hours from birth these holes slowly decrease in size and by 24 hours after birth these holes are gone, meaning antibodies won’t be absorbed into the bloodstream anymore. So, it is vital to provide calves with adequate colostrum within 12 hours or their immunity can be compromised.

Another important factor is the quality of colostrum. Using a Brix refractometer reader is an easy way to tell if your colostrum is high-quality. If it’s over 22 percent according to Brix, it’s good enough to feed to newborn calves. Ask your vet more about this if you’re not sure. The refractometer costs less than $100 and will give you a lot of information that will help you set up the essential immune system of your calves.

Finally, you can boost the colostrum quality by using scour vaccines. A single Rotavec injection is given during each pregnancy 3-4 weeks before calving and it boosts the production of antibodies that work against rotavirus, coronavirus (not the one we’ve all been worrying about the last few months), and E. coli K99. Again, it is important to reiterate that once you have vaccinated your cows, colostrum management needs to be top priority. Calves must have 3 to 4 litres of first milking colostrum within the first 6-12 hours of life to absorb the necessary antibodies from the vaccination. If the colostrum is not given on time you will lose the window where calves can absorb the antibodies. Rotavec vaccination is a strategy that needs to be implemented alongside good colostrum management and pen hygiene practices. June is the ideal time to be vaccinating spring calving herds for rotavirus, so book your appointments soon!

Anexa Vets recommend the use of Rotavec to vaccinate cows for rotavirus, coronavirus, and E. coli antigens.

Date Added: Thursday, 29th April 2021