When to vaccinate
Once you have decided to vaccinate, the question is when. The cost of vaccines is usually only a small part of the overall cost. The expense of mustering and handling stock usually means that many vaccination programs have to coincide with routine husbandry procedures.
There are several opportune times in a normal calendar when this occurs, such as at branding, weaning, or (more usually) to coincide with pregnancy testing. While weaning is an ideal time to start vaccination programs, the other times when vaccination opportunities arise are at selection of heifer replacements and at bull testing. It does not make a lot of sense to do a full Bull Breeding Soundness Examination but fail to protect the investment with a vaccine against three-day sickness, vibriosis and other preventable diseases.