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| Now is an excellent time to plan ahead for the upcoming weaning of
the spring born calves. Plan now to give the calves the best opportunity
to achieve excellent immunity to infectious diseases. According to
Dr. Ron Shultz, (in 1993 AABP proceedings) "One of the most important considerations
in designing a vaccination program, after the specific vaccines have been
selected, is timing. When should the vaccine be administered?
Incorrect timing of vaccination is the greatest cause for vaccines failing
to immunize. Timing includes such considerations as: 1) the effects
of maternal antibody on active immunization, 2) the period of time between
injection of vaccines that require multiple doses, 3) the age of the animal
at which the disease most often occurs, and 4) the competence of the immune
system, especially as it may be affected by age and stress."
It is the last point that is worthy of discussion. Vaccines given during the stress of the weaning process may be compromised. The stress of weaning a calf from its mother can be physiologically and pyschologically draining to the calf. Often short term dehydration and fasting occurs as the calves learn to eat and drink from sources other than the udder of the dam. During these first few days after weaning calves often contract some disease organism that their immune system is actively fighting. Therefore this is not the best time to solicit a new immune response to the introduced antigen in the vaccine. Two to four weeks before weaning is an excellent time to vaccinate calves for the respiratory diseases such as IBR, PI3, and BVD. Giving the vaccine and returning the calves directly back to the herd should allow them to start to develop the immunity desired while under minimal stress. Boosters, if required, can then be given at weaning time. In addition to the improved immune response, there is an added bonus. Calves vaccinated before weaning should begin to have protection from the respiratory diseases and be less prone to sickness while undergoing the weaning process. In some cases, clostridial, and leptospirosis vaccines may also be given at the vaccination time prior to weaning. Remember some vaccines are not labeled for use on calves being returned to nurse pregnant cows. Be sure to visit with your local veterinarian about the vaccines of choice for your herd. Another fall vaccination that requires prior planning are those recommended for fall-born replacement heifers. Replacements that are to go into their first breeding season this fall should be immunized at about 12 months of age. This should be about one month before the start of the heifer breeding season. Replacement heifers would best benefit from a modified live IBR-BVD vaccine. This vaccine is sometimes given with the 5 way leptospirosis bacterin as a diluent. This vaccination should give long term protection against IBR-BVD infections. Again, be sure to visit with your local veterinarian about the vaccines of choice for your herd. An excellent source of more information about Immunizations for Oklahoma Cow Herds can be found in OSU Fact Sheet 9123 .
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