Ask the Expert: Will Johne’s Vaccination Affect Our Ability to Feed Colostrum and Milk to Calves? – Dr. Kevin Ratka and Dr. Owen Mickley, Vita Plus
Question: My herd has a high prevalence of Johne’s, so we’ve been using the Johne’s vaccine in our herd. Will that affect our ability to feed colostrum and milk to calves?
A: For several reasons, Johne’s disease is very difficult to eliminate from a herd, but, with proper management practices, it can be effectively managed to reduce potential exposure and continued spread. This includes a look at how Johne’s vaccination programs affect youngstock feeding protocols. Let’s break down your question into a few different areas.
- Is it 100-percent safe to feed milk from cows vaccinated for Johne’s?
No, you still risk Johne’s transmission even if the cow has been vaccinated. The vaccine doesn’t prevent the cow from becoming infected with Johne’s organisms. That means vaccinated cows could still shed Johne’s bacteria.
The benefit of the vaccine is that it delays the onset of clinical signs and, in some cases, prevents them from becoming clinical. It is basically a “Band-Aid” in herds that have a high level of Johne’s and are culling a lot of cows due to clinical signs of Johne’s. It’s believed that, with the delay of clinical signs, these cows may not shed as early or as much of the bacteria over time. Thus, the level of the exposure in the environment should decline.
The bigger question is whether farms have incorporated strict management practices that are necessary to prevent the continued spread of the Johne’s bacteria in the herd. This will probably have a greater benefit to eliminating Johne’s from the herd than just vaccinating for it.
- Can I feed whole milk if it’s been pasteurized?
Unfortunately, even if the milk has been pasteurized, you run the risk that not all the Johne’s bacteria will be killed. A lot of that depends on just how much bacteria is in the milk at the start of pasteurization.
- Will pasteurizing colostrum eliminate Johne’s bacteria?
Typically, colostrum is heat-treated up to 140 degrees F (rather than the 145 degrees F required for pasteurization). It’s always been thought that heat-treating colostrum reduces the Johne’s bacteria, but it won’t eliminate all of it. We are unaware of any new research to prove otherwise.
A better choice in this case would be to use a colostrum replacer unless you have other health issues in the calves and feel that farm-specific antibodies would aid in managing those issues.
- I want to test the herd for Johne’s to see if we’re making progress. How will I know if cows testing positive indeed have the bacteria or if the vaccine antibody is showing up in the sample?
Any test based on detecting antibodies toward the Johne’s bacteria would give false positives due to the vaccination. We are not aware of a test that differentiates antibodies from vaccination versus antibodies from natural infection.
Instead, you would have to run a test that detects the actual organism, like fecal cultures or fecal PCRs. These tests can be more expensive and, with any Johne’s test, it’s hard to say with 100-percent certainty that a cow is truly negative, even if the test says so. However, if a fecal test comes back positive, you can be very confident the animal is positive for Johne’s. Johne’s is an extremely slow-growing organism, which is why it can take years before enough is shed in the manure for a test to detect it.
Let’s also consider one final clarification. The Johne’s vaccination can only be administered by a certified veterinarian and it is only allowed in certain states. Producers whose herds that have an extremely high prevalence of Johne’s and feel they need to vaccinate for it must get approval from state health officials before they will be allowed to vaccinate. In addition, proper state animal identification and paperwork must be filled out and filed with the state. Calves are vaccinated under 35 days of age in the brisket and administration of the vaccine can leave large, permanent granulomas at the injection site. Veterinarians may use extreme caution when handling the vaccine to avoid accidental injections.
Thanks to Rebekah LaBerge, Ag Partners Co-op calf and heifer specialist, for submitting this Ask the Expert question.
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