BVD Re-Test of Heifer previously tested

hugo29

ok will try to keep this simple

1. purchasing 2 no 20 month old maiden heifers
2. Heifer A, has been BVD tested as a weanling, Heifer B has not
3. am getting Heifer B tested before collecting
4. Should I also get Heifer A re tested as she has been in contact with non tested stock

tanko

I would get them both ear notch tested just for my own peace of mind. It is only a few euros, money well spent imo.

hugo29

tanko wrote: »

I would get them both ear notch tested just for my own peace of mind. It is only a few euros, money well spent imo.

was thinking same, have tags ordered

reilig

There's no need to get one tested that has already been tested - it's not scientifically possible for her to catch BVD. An animal can only become infected with bvd as a foetus in the cow's womb.

She may become transiently infected for a couple of weeks if she is in contact with a bvd positive animal. In this case, I don't think the ear notch test will show that she has a transient infection but it is still safe to buy here, but ensure that you operate an isolation policy for all animals brought onto the farm.

tanko

reilig wrote: »

There's no need to get one tested that has already been tested - it's not scientifically possible for her to catch BVD. An animal can only become infected with bvd as a foetus in the cow's womb.

She may become transiently infected for a couple of weeks if she is in contact with a bvd positive animal. In this case, I don't think the ear notch test will show that she has a transient infection but it is still safe to buy here, but ensure that you operate an isolation policy for all animals brought onto the farm.

I always assumed that the ear notch test will give a positive result if the animal has a transient infection at the time of testing. This is why a second test needs to be carried out a month later to confirm whether the animal is a Ti or a Pi.

Am i wrong about this?

onyerbikepat

tanko wrote: »

I always assumed that the ear notch test will give a positive result if the animal has a transient infection at the time of testing. This is why a second test needs to be carried out a month later to confirm whether the animal is a Ti or a Pi.

Am i wrong about this?

That's correct.

greysides

hugo29 wrote: »

ok will try to keep this simple

1. purchasing 2 no 20 month old maiden heifers
2. Heifer A, has been BVD tested as a weanling, Heifer B has not
3. am getting Heifer B tested before collecting
4. Should I also get Heifer A re tested as she has been in contact with non tested stock

If the BVD test that was done on A was an ear notch test and it was negative then there is no point repeating it as regards checking to see if she's a PI.

greysides

Just for clarification:

reilig wrote: »

There's no need to get one tested that has already been tested - it's not scientifically possible for her to catch BVD become a PI post-natally. An animal can only become persistently infected with bvd as a foetus in the cow's womb.

She may become transiently infected for a couple of weeks if she is in contact with a bvd positive animal. In this case, I don't think the ear notch test will show that she has a transient infection but it is still safe to buy here, but ensure that you operate an isolation policy for all animals brought onto the farm.

The ear notch test would show up positive, but it would be a 'false positive' from the point of showing up a PI.

hugo29

greysides wrote: »

Just for clarification:




The ear notch test would show up positive, but it would be a 'false positive' from the point of showing up a PI.

So the test on A would only be positive for TI , if that was the case then if she was isolated will it pass in a few weeks and could she after say 2 weeks isolation be introduced into a shed full of in calf cows without infecting any of them

J.O. Farmer

hugo29 wrote: »

So the test on A would only be positive for TI , if that was the case then if she was isolated will it pass in a few weeks and could she after say 2 weeks isolation be introduced into a shed full of in calf cows without infecting any of them

That is correct. As somebody said a good isolation policy will save testing her with the added bonus of protection from other infections. PI is all you need to be worried about. These animals are infected in the womb (during the 2nd trimester I think) and never eliminate the virus from the system. TI will carry it kinda like a stomach bug that can be passed on but animals recover.
Depending on the sensitivity of the test method it might not pick up a recent TI.
I have some idea of what I'm talking about as I'm a microbiologist.

greysides

hugo29 wrote: »

So the test on A would only be positive for TI , if that was the case then if she was isolated will it pass in a few weeks and could she after say 2 weeks isolation be introduced into a shed full of in calf cows without infecting any of them

Correct, on the assumption the BVD test mentioned was an ear notch test........ or a blood test for the presence of the virus.

grassroot1

Just out of a matter of interest how long is a TI contagious for?

greysides

grassroot1 wrote: »

Just out of a matter of interest how long is a TI contagious for?

Without checking, probably about 2 weeks.