Dr. Joe Hogan
Coliform mastitis vaccines have been commercially available throughout the US for several years. These vaccines are based on the immunization of cows with Gram-negative bacteria that have common core-antigens naturally exposed whereby the cows can mount immune responses that will cross-react with a large number of bacterial strains. Most of these vaccines use either Escherichia coli J5 or Salmonella typhimurium Re17 as the antigens. While these vaccines are generally considered safe and effective, a large number of questions have arisen concerning the proper administration and expected results from using these vaccines.
Q: What improvements will I see in the herd?
A: The most common change seen in herds using these vaccines are fewer clinical cases at calving and during the first month of lactation. The proper use of Gram-negative core antigen vaccines reduces the incidence, severity, and duration of clinical signs due to intramammary infections caused by coliform bacteria. These vaccines will not prevent intramammary infections, but enhance the ability of cows to fight the infections once bacteria enter the gland.
Q: Will I have to vaccinate each dry period or will one series of injections last the life of a cow?
A: Unfortunately, cows have little immunological memory toward these vaccines. The protective antibodies in blood return to pre-vaccination concentrations within a couple of months after the last immunization. Cows should be vaccinated during each dry period to maximize protection at calving and during early lactation.
Q: Will the Gram-negative core antigen vaccines reduce all types of mastitis?
A: Most labels of Gram-negative core antigen vaccines specify efficacy against only Escherichia coli. Data from field trials suggest that these vaccines also reduce clinical cases of mastitis by Klebsiella spp., Pseudomonas spp., Serratia spp., and Proteus spp. These vaccines have no effect on mastitis cause by staphylococci, streptococci, or other Gram-positive bacteria.
Q: Should I use a product that requires two injections or a product with three injections?
A: Some products instruct the use of two immunizations during the dry period while others direct the use of two injections during the dry period and a third at calving. The three injection protocol does elevate antibodies in blood at 30 days after calving compared to the two injection regime. Whether the increased antibody titers relate to a decrease in clinical cases during early lactation is currently unknown.
The timing of the first two injections is constant among products and crucial to the success of the Gram-negative core vaccines. The first injections should be given at the time of drying off with a booster injection given 28 to 30 days later. This will maximize protection during the weeks around calving in cows averaging a 60-day dry period. A vaccination regime that does not protect cows is to vaccinate only at drying off and at calving. The lapse of time between injections is too great for animals to adequately respond to the vaccine.
Q: Can I treat clinical mastitis with the vaccine?
A: Treating clinical cases of mastitis with Gram-negative core antigen vaccines is not recommended. The average duration of an E. coli intramammary infection is less than two weeks. The blood and milk antibody responses to vaccination is maximum 28 days after immunization. Therefore, the infection has almost certainly been eliminated by the cow?s own defenses before the vaccine has an opportunity to affect the disease. These bacterins act as preventative vaccines, not therapeutic drugs.
Q: Will vaccination cause my cows to abort?
A: Controlled trials have shown no adverse effects of these vaccines on pregnancy, feed intake, or milk production. The concern voiced by some experts was that the endotoxin in these vaccines might cause elevated temperatures in cows. Administering the vaccines according to label direction should not affect animal health during pregnancy.
Q: When starting my herd on a Gram-negative core antigen vaccine, should I immunize the whole herd at once or only as cows enter the dry period?
A: Vaccinating cows during lactation is not recommended. The time of greatest susceptibility to coliform mastitis is during the weeks surrounding calving. Label directions for use of the vaccines are intended to maximize protection during this time of greatest risk. As lactation progresses, risk of coliform mastitis greatly diminishes. The use of these vaccines in lactating cows will probably have little beneficial effects and not be cost effective.
Q: Will the use of coliform mastitis vaccines in first calf heifers be beneficial?
A: A trial recently completed in Ohio showed that the advantages seen in vaccinated cows also were realized in first lactation animals that received a primary injection 60 days prior to calving, a booster 30 days later, and a third injection within 24 hours after calving.