News & Advice

BVD Control is all about the PIs

Jun 8, 2017 | Biosecurity, Dairy, Dairy Animal Health & Welfare, Young Stock

Matt Peters, Anexa FVC Rototuna Veterinarian

“I don’t have BVD on my farm. It’s under control. I’m monitoring my Bulk Milk and it’s always OK. Isn’t that enough?” 
Actually, no. Monitoring your bulk milk for BVD is vitally important to tell you if BVD gets into your herd, but it won’t actually prevent BVD from getting in. To control BVD you need to control the PIs. 
PIs, or Persistently Infected cattle, are born with BVD. They do not become PIs when they go out to grazing. They are virus factories shedding huge amounts of virus infecting everyone around them causing massive damage in the time they are alive. Calves exposed to a PI will have depressed growth rates of around 20% and are more likely to get sick. Milking cows exposed to a PI will have a 5% drop in milk production and are more likely to get sick. If PIs are around at mating time they cause conception failure, abortions, birth defects, still births but most importantly they will create a new generation of PIs, amplifying the problem and perpetuating the disease. 
To control BVD we need to control the PIs. We need to cut off the supply of PIs, prevent the creation of new PIs at mating time, and keep them out once gone. To cut off the supply we need to test all replacement calves as early as possible and cull any BVD positive animals. If you wait until they turn up in the herd to find the PIs, it’s too late. Vaccinating cows and heifers pre-mating can help prevent the creation of new PIs, and to keep PIs out ALL incoming stock must be tested. When it comes to BVD all stock are guilty until proven innocent. 
How does AnexaFVC plan to help in the war on BVD? Let us find those PIs by ear-notching all your replacement calves when we come out to disbud them. In this way PIs are removed right at the start. It’s easy; just tick the box on the disbudding form. It’s effective; it’s a new test that allows PIs to be identified at birth. Previously they had to be over 35 days old. It’s cheap; doing it at disbudding time saves cost and the new test is cheaper than the old one. By removing PIs at the start instead of waiting until they reach the herd just the savings in grazing and rearing costs of one PI is likely to cover the cost of testing your calves, and that’s before you take in account all the other benefits of improved growth rates, production, reproduction, and less illness in your other stock. 
Disbudding time not ideal for you? No problem. We can do it at Lepto vaccination time too, but BVD has already started costing you money by then. If there are PIs on your farm, the sooner we find them, the better. 

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