The vaccines available to help control respiratory disease include IBR, PI3, BVD, BRSV, Pasteurella and Hemophilus. Some of the newer pasteurella products show promise of improved value but must be given well in advance of weaning to have time to stimulate any immunity by the time of stress. One new product requires only one injection, but this must be given with a generous lead time to be of value. Replicated virus from modified live virus vaccines for IBR can be transmitted to other cattle and some may have caused abortions. Don’t use these vaccines on pregnant cows nor on calves which will be commingled with pregnant cows. There are other vaccines available which are safe for use in those situations.
It is critical for producers to remember that vaccines which call for a second (or booster) dose will usually NOT stimulate a protective level of immunity in that animal until 10–14 days after the second injection. The initial dose merely primes the immune system but gives very little protection. Producers continue to ignore that fact. The use of poorly timed vaccination programs, result in a severely reduced level of herd immunity.
Four alternative timing schedules will be described for the use of vaccines.
1. At branding and weaning:
With this system the calves are vaccinated at branding (1–2 months of age) and again at weaning. It eliminates extra handling but there is a real potential for a lack of immune response. Young calves do not respond as well to vaccines, there is a long period between the initial and second dose, and the time between the weaning dose and exposure is so short the calves may have almost no immunity from the vaccinations.
2. Prior to and at weaning:
The vaccines are given at 3–4 weeks prior to weaning and again at weaning. This provides the proper spacing of the initial and booster dose. But it doesn’t allow any more time for development of immunity after the second dose and does require handling the animals one extra time.
3. Prior to weaning (two doses):
This requires that calves be handled twice in addition to weaning. The vaccines are given at approximately 6 and 3 weeks prior to weaning and then only the minimal handling for separation is actually done at weaning. The cattle must be relatively accessible if this is to be practical. Other procedures such as castration, dehorning and implanting can also be performed at these vaccination times.
4. Vaccinate at weaning (and perhaps again at 7 days later) with MLV (modified live virus) products:
This schedule has been used extensively in Kansas with good success. The calves are vaccinated at weaning and if the calves have been especially stressed, the MLV vaccinations are repeated again 7 days later. Most producers use only the intramuscular injections but some have used both the intramuscular and the intranasal form of IBR/PI3 at entry and then give just the IM form for the second dose at 7-10 days later.
Many producers have some fear of using MLV vaccines at the time of weaning stress and have even greater fears of working the calves again after 7 days. But, the use of these vaccines and this schedule on large numbers of calves in Kansas has shown no problems from either of these “feared” procedures.
The pasteurella or hemophilus vaccines are not used in this timing system because there is not sufficient time for the calves to develop protective immunity before they are into the high stress period.
In the fall of 1993, a trial was conducted at USU which compared alternatives two and four. There was no significant difference in the measures used to evaluate the health effects for the two vaccination systems. This and the experiences from Kansas and other areas should help producers and veterinarians to feel greater freedom in applying the system that will best fit their production and handling methods.
Whatever vaccine and timing schedule is used, it is critical that vaccines be handled properly. Read and follow directions for refrigeration, reconstitution, equipment sterilization, and avoiding sunlight and heat. Don’t mix vaccines together that are not directed for mixing. Remember to observe guidelines to reduce injection site lesions. Use the subcutaneous route whenever possible and if the intramuscular route is needed, use the neck; don’t inject into the top of the rump.
For a successful weaning, implement a good general management program and utilize a sound vaccination system as part of that management program.
Source: Clell V. Bagley, DVM, Extension Veterinarian, UtahStateUniversity