Do you know which infectious diseases are in your herd, and how many animals have been infected?

According to Animal Health Ireland (AHI) awareness of herd health status becomes even more important when embarking on management changes – regrouping of animals from different management groups or expansion.

According to AHI you can assess the health status of your herd by:

  • Using your farm records.
  • Working with your vet.
  • Testing your cattle.

Use your records

Keeping good records is essential to track changes in herd health over time, AHI says.

According to AHI a production drop (e.g. in milk yield) can be the first sign of a disease outbreak.

Records are particularly important with subclinical infections as you may see poor performance, it says (e.g. high cell counts) before seeing clinical signs of disease.

Records of herd production (e.g. calves reared, weanlings sold, milk yield, slaughter weights), health (e.g. number of antibiotic treatments, deaths, involuntary culls) and fertility (e.g. six-week in calf rate) can be used to assess your herd’s general health status, it says.

AHI advises to analyse records for trends over time.

  • Have you spent more on treatments for infectious diseases in calves and adult stock than last year?
  • Are cell counts higher than last year?
  • Are the cattle taking longer to finish this year?
  • Have more cows aborted (>5% is a problem) than last year?

Talk to your veterinary practitioner

Building a relationship with your veterinary practitioner is important to ensure that they are involved in preventing disease on farm as well as treating disease outbreaks, AHI says.

Your veterinary practitioner is best placed to devise a herd health plan for your farm; AHI says to work with them to prevent, investigate and respond to disease outbreaks by:

  • Discussing and assessing infections present in your herd.
  • Developing an overall herd health plan for your farm.
  • Examining sick cattle.
  • Sampling affected and unaffected animals.
  • Having post-mortem examinations performed on dead animals on the farm or at the laboratory. This will allow you to work together to plan disease control measures specific to your farm.

As well as investigating individual sick cattle and disease outbreaks, your own veterinary practitioner can assess the strengths and weaknesses of your farm and advise on changes required to improve herd health practices and prevent disease outbreaks, it says.

Animal health management should take a structured approach. AHI says to monitor the herd over time even when no clinical disease is present.

Disease impact is much easier to identify when there is baseline data available, it says.

Test your cattle

Tests on the whole milking herd e.g. bulk milk tank (BMT) samples or individual live animals e.g. blood or tissue (ear) samples or dead animals (e.g. post-mortem examination) can tell you about the the specific infections circulating within your herd, AHI says.

Knowing the types of infections present allows you and your veterinary practitioner to plan specific disease control measures and it says that this is particularly important in cases of abortion.

When it comes to BMT testing AHI says that screening tests can be used to establish the exposure of your herd to a range of infectious diseases but there are some limitations to tests and how they are interpreted.

Some tests detect the infectious agent (e.g. the virus) while others detect the animals’ responses to these infectious agents (e.g. antibodies to the virus) – these two results are interpreted differently, it says.

It is particularly important to discuss BMT results with your own veterinary practitioner in conjunction with guidance from the testing laboratory, for example, AHI says that BMT testing is not useful in investigating for Johne’s Disease.