Review/Oorsig Volume 22, Issue 05 - Page 22

Oorsig/Review only bet, but this is discussed in the above article. Also sounds like EBL can cause some economic impacts on dairy farms so maybe eradication attempts are worth it either way, but I guess that there are field vets that will have an opinion on this. TC – 10 Nov 2014 I possibly speak on behalf of many KZN dairy vets - and maybe some of you guys will add your pound of flesh. EBL is a disease we live with. The vast majority of our herds are infected and the number of clinical cases is minimal. Having said that we cannot quantify the indirect effect of immunosuppression and reduced productivity, though many of our herds which live with the disease are at the top of our league tables w.r.t. production and reproductive parameters. In a perfect world yes, test (which perfect tests??) and eradicate to achieve negative herd status. It not being a perfect world we concentrate our ruthless culling and management strategies on conditions that are far more serious (in our experience) to dairy economics, and – coward that I am – we CAN get a handle on! Frankly I think the Zim authorities are living in cloud cuckoo land, but I suppose if one is tasked with the job of setting up import protocols, one will dot every i and cross every T. (And thereby miss out on importing some excellent genetics?!) As has been discussed in many forums, the single negative EBL serological result will not necessarily be conclusive, so those beaurocrats are simply “going through the motions.” Like paying your TV licence, it’s the right thing to do. I would be intrigued to know how free the Zim dairy herds are of EBL. From what I recall many countries including many states in the USA have called time-out on EBL eradication and focused on other issues. However, this Ruralvet being an open forum I won’t be offended to receive alternate viewpoints. Even within our practice we have slightly varying opinions. DM - 12 Nov 2014 EBL (Enzootic Bovine Leucosis, caused by Bovine Leucosis Virus or BLV) appears to be a problem in SA dairy herds at the moment. The Department of Production Animal Studies at the Faculty is currently busy with some surveillance work on this disease which may shed some more light, although support from the industry has not been forthcoming. What I understand is that you will find it quite hard to get BLV sero-negative herds nowadays. Please keep in mind: 1. If you find some animals in a herd seropositive to BLV using the AGID test (not the most sensitive test) you can be pretty sure that the virus is in the herd. 2. Serological status is not equal to infection status and is not equal to clinical EBL status: There could very easily be infected animals that have not seroconverted yet, and there are definitely infected, seroconverted cows that will take up to a number of years before they get clinical signs of EBL. For these reasons you should not export ANY animals from the herd because the INFECTION status of individual cows within an infected herd is not detectable with a serological test. 3. The dairy where I am involved is milking >70% BLV positive cows successfully with daily milk yields up to 50kg, some cows being in their 5th and 6th lactations, having been seroconverted for years. I am of the opinion that this is happening in other herds as well, and this fact resulted partly in the ostrich- strategy of the industry. Scientific evidence is not convincing on the impact of the disease Figure 02: Cattle farmers can monitor the incidence of EBL in their herd through co-operation with abattoirs. 22