Understanding Bovine Leukemia Virus (BLV) and it's impact on your homestead's cattle herd.
Hannah, my 10-year-old daughter has been milking our Dexter cows for our family's dairy needs including raw milk, ice cream, cheese, butter, and yogurt. She is also selling the excess but we are hoping to purchase a cow with more capacity so when I saw a Facebook post advertising a Jersey cow for sale at a great price, just an hour away from me the prospect was exciting. It felt like the time and opportunity were just right for adding a quality Jersey cow to our herd.
The cow was being offered at a price that seemed almost too good to be true. The seller was kind and helpful as we discussed their cow. However, as we talked, the seller mentioned something that gave me pause: the Jersey cow had tested positive for Bovine Leukemia Virus (BLV) and that is why they were selling. I've seen the disease mentioned before but knew nothing about it so I started to research the topic. Here's a little of what I found.
The Impact of BLV on Cattle and Herd Management
BLV is a retrovirus that primarily affects the lymphocytes, a type of white blood cell, in cattle. It is of significant concern in the cattle industry due to its impact on long term animal health and breeding productivity. Infected cows can remain asymptomatic carriers, but some may develop conditions like persistent lymphocytosis or, in severe cases, lymphosarcoma—a type of cancer that forms tumors in various organs.
The prevalence of BLV varies widely across herds in the United States:
- Dairy Cattle: Approximately 40-50% of dairy cattle are infected.
- Beef Cattle: The prevalence is generally lower, around 10-20%.
These statistics highlight the importance of regular testing and management practices to control the spread of BLV within herds .
Health Risks and Management of BLV
BLV is primarily transmitted through the transfer of infected blood and bodily fluids, which can occur during veterinary procedures, dehorning, castration, and through biting flies. Calves can also be infected in utero, during birth, or through colostrum and milk from infected dams.
There is currently no treatment or vaccine for BLV, which makes proper management practices crucial. Key strategies include:
- Testing and Culling: Regular testing and culling of infected animals can help control the disease from spreading to the rest of your homestead herd or to neighbor's cattle.
- Biosecurity Measures: Using single-use needles, disinfecting equipment, and controlling biting insects are essential steps to reduce transmission.
The Human Health Debate
While BLV is not considered a zoonotic (transmissible between species) virus and is not known to be transmissible to humans, some studies have suggested associations between BLV and human cancers, such as breast and prostate cancer. These studies have yielded mixed results, and no conclusive evidence exists to confirm that BLV poses a direct threat to human health. Nevertheless, the potential risks have spurred ongoing research in this area and give many homesteaders the added motivation to cull sick cattle.
Making the Right Decision for our Homestead
After a lengthy and honest conversation with the seller, I decided it was in the best interest of my homestead cattle herd and my family’s longterm health to pass on purchasing the Jersey cow, despite the enticing price. This experience reinforced for me the importance of being informed and vigilant about cattle health issues like BLV.
It’s crucial for cattle owners to understand the implications of BLV and take proactive steps to manage their herd health and control spread the spread of disease. Regular testing, fly control, understanding endemic diseases, and staying informed about the latest research can help protect your family's and animals' health.
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References
1. "Prevalence of BLV in Dairy Cattle." Journal of Dairy Science, 2020.
2. "BLV in Beef Cattle: Prevalence and Control." Animal Health Research Reviews, 2019.
3. "Bovine Leukemia Virus and Human Health: Current Research." Journal of Virology, 2021.
4. "Potential Links Between BLV and Human Cancers." Cancer Epidemiology, 2022.
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