There is valuable information to be gleaned from a blood test, but different labs use different numbers and your veterinarian, it is hoped, will know how to interpret these.
will not show up on an ear notch test when you are checking for per- sistent infection,” explains Hair- grove. Anyone who keeps bulls for
breeding should be aware of the pos- sible problem that might be caused by vaccination (with modifi ed-live non-cytopathic BVD vaccine) before puberty. “There are some research papers that support this warning. It’s a good idea to work with your veterinarian to know which vac- cines you can safely use on bull calves,” Hairgrove says. When buying a bull, you need
to know the history of the bull. “If you don’t know much about him, you might want to do some tests. When I consult with producers I tell them that they need to talk with their own veterinarians about this. It might pay to do a PCR test on the bull’s semen, for instance, if there are any questions,” says Hairgrove.
IBR This virus is another concern. “IBR is more diffi cult to test for if
tscra.org
you are looking at blood titers,” says Gill. “The animal may have a titer just from vaccination. You are try- ing to build titers (antibody protec- tion) against the disease. Unless the titer is really high, you don’t know whether it’s from natural exposure they’ve recovered from or from vac- cination,” he explains. “To interpret a test for IBR, you
need to know when the bull was vaccinated and with what product and which lab did the test,” says Hairgrove. “There is valuable information
to be gleaned from a blood test, but different labs use different numbers and your veterinarian, it is hoped, will know how to interpret these. IBR always has a potential for future problems. This is a herpes virus that can go dormant and become active again later during a time of stress — similar to shingles cropping up in humans who had chicken pox years earlier,” says Hairgrove.
Anaplasmosis “Some of the problems we’ve
seen in bulls brought into Texas or moved from one region of Texas to another is anaplasmosis,” says Gill. If bulls were raised in an area where this disease is endemic, they may be carriers even if they don’t express any signs of disease. If they are introduced into a cow herd that is naïve to anaplasmosis, there is risk that anaplasmosis will spread through the cows. The reverse is also true. “If a
naïve yearling or 2-year-old bull is put with a herd of cows that carry anaplasmosis, you could lose the bull. Either of these situations can be a serious issue, so you need to know the herd status,” he says. Gill recommends that bulls com-
ing into a herd be tested to see if they do have anaplasmosis. “Most people don’t test the bulls, but we’ve seen more issues these past 3 or 4 years with bulls that have been moved from areas where anaplas- mosis is an issue.” Hairgrove points out that a bull
has more contact with your herd than does any other individual ani-
October 2013 The Cattleman 101
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