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The need to know your herd health status

Charlie Carslake BA BVSc MRCVS, Molecare Veterinary Services

Why do I need to know my herd health status?

Knowing your herd health status means taking steps to find out which bovine infectious diseases are affecting your herd. Bovine infectious diseases cause significant production losses in UK beef and dairy systems. Depending on the disease involved, your herd’s prior immunity and your system, losses can range from reduced growth and milk yield to severe outbreaks involving multiple animals, abortions and even deaths.

Knowing your herd health status means you can take steps to limit the impact or even eradicate infectious disease, helping you avoid future losses.

How can I find out my herd health status?

The main infectious diseases we deal with are BVD, Johnes, IBR, Leptospirosis and Neospora. Testing involves taking samples from some or all of your cattle depending on the disease you are looking for and working with your vet to interpret the results. The table below summarises some of the main infectious diseases on farm, their clinical signs as well as the tests we routinely carry out to look for them on farm.

Disease: Clinical signs: Surveillance Testing:
  • BVD virus infection may lower immunity to other infectious diseases particularly in young calves
  • Infection during early pregnancy causes reproductive problems, weak/premature calves, and live persistently-infected (PI) calves that shed the BVD virus
  • Young stock screening: Check exposure to BVD in 5 unvaccinated calves from each management group (9-18months)
  • Tag and test all calves born on farm
  • Diarrhoea, poor milk yield and weight loss in cattle three to five years-old
  • May continue for several months with the animal becoming emaciated, and then culled for economic/welfare reasons
  • 30-cow screen as a start point to assess status
  • Test all individual animals over 2 years of age through blood or milk testing
  • Dramatic drops in milk yield may be first sign
  • Difficulty breathing, coughing, red eyes and deaths
  • Abortions
  • Young stock screening
  • Bulk milk tank monitoring
  • Abortion, between 3 and 9 months of pregnancy (particularly 5 to 7 months)
  • Stillbirth or premature calves (occasionally with brain disease at birth)
  • Blood test aborted animals
  • Submit aborted foetuses for testing
  • Routinely test the whole herd
  • Drop in milk yield
  • Colostrum-like secretions or blood-tinged milk in all quarters
  • Lethargic and stiff cows with a fever and reduced appetite
  • Abortions
  • Weak Calves
  • Bulk milk tanks monitoring

Monitoring means you can work with your vet to establish a plan to limit the impact (through vaccination or targeting culling) and in some cases eradicate the diseases that are on your farm. Monitoring still needs to be done in vaccinating herds to ensure vaccination is effective and necessary. Relying on results that may be several years old is very unreliable and a sure way to expose your herd to future losses!

Thinking about buying in?

As you will be well aware new animals bring new diseases with them. Testing is complex and it is essential to consult your vet on this! For example, animals that have tested negative to Johnes may still be harbouring the disease even if they come from a regularly tested and low level accredited herd. Vaccination does not always mean that the animal is free of a disease. One South Devon farm inadvertently introduced BVD by purchasing in-calf heifers from a herd with an unknown BVD status. The heifers had tested negative to the ear-tag test and were vaccinated but had been exposed to a persistently infected (PI) animal at breeding before they were vaccinated. Several of the heifers subsequently produced PI calves that went on to infect other animals. Working with your vet to evaluate the disease status of the animals you are buying in will help guard against this.

Why might disease accreditation be a good idea?

Disease accreditation provides proof to buyers that your herd is either free of/or working to control certain infectious diseases by verifying that your herd has been through a specific testing regime and meets specific biosecurity criteria. It can boost the value of your stock and provides a structure for regular testing as well as discounts for certain tests. It is important to think about how accreditation can add value to your stock and complement whatever testing you might already be doing. Depending on your needs you can accredit for one, two or all of the main diseases. Costs vary depending on the number of diseases and animals you wish to accredit for.

Please feel free to contact us to discuss disease accreditation and all your disease testing requirements.

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