Farm Ireland

Monday 23 April 2018

dairymen taking A far more serious look at herd health

Advances in sampling will give farmers far more information when tackling various diseases

John Donworth

Herd health has moved very close to the top of the list of priorities for dairy farmers. This whole issue is receiving unprecedented attention at discussion group meetings and monitor farm walks in 2010. Indeed, as the year has progressed farmers are asking more and more questions.

They are asking more and more questions because they are getting more and more information through bulk milking sampling. Advances in technology have enabled more accurate and better information to be gleaned from bulk milk samples.

In bulk milk samples, one is usually looking for the presence of antibodies against the presence of the virus. The level of antibodies found gives an indication of how severe the disease threat in their herd.

Many dairy farmers have signed up to various herd health programmes run by service providers to the dairy industry. AI companies are to the fore here. Herd health programmes usually involve taking three bulk milk samples evenly spread throughout the course of lactation. It is important that the samples are spread over the lactation, as antibody levels can vary from some diseases through the year. Taking a minimum of three samples should give you a good idea of the level of viruses circulating in your dairy herd.

Knowing that viruses are circulating in your dairy herd is one thing, but what option do you take on the strength of the information you now have.

The obvious question is do you now vaccinate for the viruses that are circulating in your herd or do you leave well enough alone? Once you start a vaccination programme there is no going back. Vaccines are expensive and they are time consuming when they have to be administered.

So, today in a bulk milk sample, you can test for the presence of antibodies against IBR, BVD, Salmonella, Neospora, Leptospirosis, round worms, lung worms and liver fluke. Rumen (stomach) fluke are identified via a faecal sample.

That's quite a list and it is an indictment of our poor attitude to herd health over the past 15 years. Some countries, particularly the Scandinavian states, have eliminated some of the viruses from their dairy cow population through targeted herd health programmes. Ireland and our friends across the water have done nothing in this regard.

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Today, the IBR virus is circulating in 80-85pc of our dairy cow population. The BVD virus is circulating in 90pc of our cows. Salmonella is circulating in 60pc of our cows. Leptospirosis is circulating in 60pc of our cows. Neospora antibodies are to be found in 40pc of the national dairy herd.

So what do you do with the information once you have all the bulk milk readings in your possession? The chances are your samples are high for IBR, since 80-85pc of the samples contain high levels of antibodies to the virus.

Do you now go out and vaccinate for the disease? There is no doubt that vaccinating for the virus can be considered a public good issue, but vaccinating for IBR should not be done lightly.

Firstly, the vaccine must be given every six months, ie January and July. But before you vaccinate, you should ask yourself the following questions:

  • Are there clinical signs of the disease in the herd, ie have you treated cases of pneumonia in mature cows or have young stock any respiratory problems?
  • Are you on an expansion phase or is herd size static? Increases in herd size will increase stress levels in cows.
  • Do you have any other health issues in the herd, ie high fluke levels?
  • Are there any management changes occurring on your farm? For example, are you now taking ground for heifers?

So, before you go in and vaccinate you should be able to answer the questions I have asked.

If you are remaining static in cow numbers and you are making no obvious changes in your management system, then the necessity to go vaccinating for IBR is greatly diminished.

IBR is like cold sores in the human population. Once cows are infected, they are infected for life. Infected cows may shed three to four times a year and if this shedding of the virus occurs at breeding time or peak performance, then major problems may occur. The IBR virus is transmitted easier than the BVD virus. It can spread through people or it can be airborne.

I have met farmers that have experienced an IBR storm, characterised by cows with high temperatures and milk drop. Action must be taken immediately.

Irish Independent