By Dr Stephen Jagoe

vaccinationIn the last Vetchat we had an article of the types of vaccines used in our dairy herds. This article concentrates on how to get the best response and best herd immunity from your investment in vaccines.

There are a number of factors influencing how an animal responds to a vaccine. Vaccines aim to sensitise the cow’s immune system to specific infections so that it produces antibodies and recruits infection fighting white cells to remove the infection, without the animal showing disease signs.

The following is a checklist of important factors which influence the success of a vaccine program in a cattle herd.

Stress

Any stressful event around the time of vaccination will reduce response to vaccines:

  • Weaning or dehorning without sedation and pain relief: vaccinate before undertaking procedures or wait 10 days before vaccinating animals after these procedures; dehorning with sedation and pain relief results in lower levels of stress hormones and this results in a better immune response to vaccination.
  • Transportation: don’t move cattle for 10 days after vaccination, or allow at least 24 hours before vaccination after transporting cattle;
  • Don’t vaccinate cows for at least 14 days after calving.

Temperature

Animals are at risk of an adverse reaction to vaccination if it the daytime temperature exceeds 29°. Do not vaccinate animals if the night time temperature doesn’t go below 23°.

Vaccination Timing

Vaccines need to be given from an early age to fully protect animals from disease. Always follow labels to determine when the first vaccination should be given, and the correct interval to booster vaccinations. As vaccination is an insurance policy against disease, it should be timed to coincide with periods of greater risk. For example 7 in 1 should be given to young calves (according to label directions) then timed to be given prior to first joining and then just prior to entering the herd. Annual boosters can then be given during the dry period up until two weeks before calving.

Timing of Calf Scour Vaccination

The first shot should be given at least 5 weeks before calving. The second dose (or annual booster dose) should be given 2-6 weeks before calving which corresponds to the time of maximum colostral antibody production.

Vaccination Combinations

Gram negative bacteria in vaccines increase the risk of adverse reactions. Gram negative bacteria are present in calf scour and salmonella vaccines. As a general rule, salmonella vaccines should be given by themselves. t is also possible to overload an animal’s immune system, so it is best not to give more than two vaccines to cattle on the one day. If more than one vaccine is given on a day separate vaccine sites by at least 15cm, or give on opposite sides of the body. In bulls vibrio vaccine and lepto vaccine (in 7 in 1) should be separated to reduce the risk of reaction, and a reduction in bull fertility.

Vaccination Efficacy

Some vaccines for the same diseases are better than others. One of the reasons why cattle are vaccinated with 7 in 1 is to protect human health against lepto. Lepto is a debilitating disease in humans, and is a cause of reproductive loss in cattle. Only one vaccine, Ultravac 7 in 1, has a registered claim to prevent urinary shedding of lepto, which is the main source for human disease. When given at the correct times, vaccinated animals challenged by lepto bacteria will not shed lepto in their urine. Urinary shedding in incorrectly vaccinated animals, or vaccines that do not prevent this, can occur for the life of the animal.

There are also differences between the calf scours vaccines and at Warrnambool Veterinary, based on scientific evidence, we consider Ultravac Scourshield to be a more effective vaccine with better dosing flexibility.

Vaccine Handling

Most vaccines are designed to be refrigerated so that do not lose their potency, or risk creating adverse reactions. Therefore when being given to cattle they should be refrigerated until just before use. Keep vaccines in an esky or chilly bin so they remain chilled until use.

With most vaccines once the container is opened all the contents should be used, or any remaining vaccine be disposed of within 12hours of use.

However some vaccines have a ‘broaching’ claim. This means they can be used up to a certain time period after the bottle is opened as long as they are stored correctly.

For example Scourshield has a 63 day broaching claim which allows unused vaccine to be used for booster purposes.

Other factors to consider are:

  • Is the vaccine gun delivering the correct dose?
  • Is the correct vaccine being used (for example salmonella vaccines should contain the salmonella types found in your herd);
  • Are all necessary booster vaccines being given at the correct time?
  • Is there a record of which animals have been given what vaccines and when they are given?

Vaccination is integral to disease prevention strategies in cattle herds. A fully integrated vaccination program is a significant cost so it is important to use the appropriate vaccines correctly so that you get the best return on your investment.

As each vaccine program needs to be tailored to individual herds, talk to one of our vets about what is the best vaccination protocol for in your herd.