Destroying immunity...?

[In the pit]

But have any ever gone down sick?
Farmer i talked of never has had a animal show signs even years after the tests.
Thats the point.
Are we culling animals that don't need culling?
His herd is still going with no losses to johnes despite it being there.

Johnes only tends to show signs when animal get under stress, so beef Sucklers probably won’t show signs.milking cows tend to go downhill at calving but more often when they are bulling
A johnes test is only 50%reliable so a positive animal is a positive animal but one that tests negative could still be positve
Had a cow had 4 test a year for 4 years and never had a high test ,then started scouring ,had a massively high test ,blood and shite test confirmed johnes so sent her down road

 

[Sandpit Farm]

Unfortunately Johne's is not a disease that an animal can become immune to because of the nature of the way the Paratuberculosis works. With something like BVD, the virus is exposed to the immune system at all times so an infected animal can mount an immune response and become immune and no longer infected.

With Johne's they hide inside cells called macrophages so the immune system mounts a response to those that are exposed but those that are 'hidden' maintain the infection so it is incurable. Therefore culling based on 'risk of actually being infected' is a really efficient way to eliminate it. Frequency of testing helps to build a better picture which helps in dairy as we can test the milk easily which is convenient as the cost to the business of 'test and cull' is far greater in dairy than in beef so 'test and manage' becomes effective. Luckily in beef, the cull cow value vs heifer price ratio is much better than dairy so the figures stack up to cull. Pedigree can be a different story though!