It’s equally important, however, to understand what outside factors can have an impact on an animal’s ability to respond to a vaccination.
Stress, nutrition, weather and vaccination timing should all be taken into account to ensure vaccine programs are fully optimized and provide the best result.
Even with all bovine immune system components working to protect an animal from disease, maximum immunity depends on factors such as hydration and nutrition being optimized. Significant amounts of energy and protein are needed to battle a pathogen.
Minerals including copper, selenium and zinc are important for immunity, yet may be deficient if grass, feed or hay is lacking.
If cows have experienced drought in recent years, they may be struggling to stay healthy due to nutritional imbalances that curb immune system response.
Just as the annual time changes associated with daylight savings time cause temporary stress in your body, cattle are stressed by changes in routine or environment.
A Nebraska cattleman vaccinating in sub-zero winter temperatures or a Texas rancher vaccinating in searing, midday July heat will likely see lower immune response.
It’s convenient to vaccinate at weaning, but calves undergo tremendous stress from castration, separation from the cow or commingling with other calves.
Shipping also stresses animals, and some veterinarians advise avoiding vaccination for a week after a major move. Evaluate the potential stress of your handling procedures and the possibility of vaccinating at times of lower stress. The herd veterinarian is always the best source for guidance and can help with recommendations.
Pregnancy is prime time for stress
A cow takes a licking during pregnancy, and it takes a lot to keep her ticking through the changes in her body – even after she’s calved. A swinging pendulum of hormones, ketone bodies and blood calcium levels can all decrease immunity.
After calving, a cow undergoes nutritional stress, and weight loss can be a sign of decreased energy. Cows can maintain a negative energy balance for up to 60 days after calving.
Cows that lose significant body condition while nursing calves will be challenged to respond well to a vaccine. Due to the compromised immune system after calving, most veterinarians discourage vaccinations until at least three to four weeks post-calving.
The cow’s health and nutritional plane during the last 60 days of gestation also impact the calf’s immune system. Calves develop immunity after birth, so high-quality colostrum full of nutrients and antibodies is vital for a calf to get a healthy start.
Keep a watch on handling procedures
Preventive vaccines work like a battery backup when the immune system’s power goes out. Vaccinations are the most effective mechanism to arm the immune system, but you should always start by reading the current label and using vaccines according to guidelines.
Labels can provide guidance about timing, interactions and withdrawal times.
Modified-live vaccines (MLVs) have very specific handling instructions. A disadvantage of an MLV is its vulnerability to sunlight, extreme temperatures and chemical exposure. MLVs must also be used within a short time after mixing, while the organism is live.
Although cattlemen like to conserve every drop, MLVs cannot be saved for future use after they’ve been mixed.
And while some MLVs have been labeled safe in pregnant cows, an increase in abortions is being observed even when the label was followed. Using an inactivated vaccine in pregnant cows can avoid those complications.
Inactivated vaccines are also more stable than an MLV but should never be shaken excessively.
Booster doses are important and should be given if directed. On any given day, for a variety of reasons, 15 percent of vaccinated cattle will not respond as well as others. Boosters catch animals that didn’t respond to the first vaccination and promote a stronger duration response with repeated antigen exposure.
All vaccines should be kept cool, even in the syringe. It’s a good idea to use a cooler by the vaccination chute. Refrigerators used for vaccine storage should be monitored regularly.
Studies from the University of Arkansas, University of Nevada and University of Idaho indicate that up to 75 percent of refrigerators used to store vaccines are failing to maintain proper temperatures. Use a thermometer to monitor temperatures. Discard any vaccines that have frozen or expired.
Needles and syringes can become contaminants. It may be tempting to use the soap on the counter or a disinfectant to clean supplies, but these can leave residues that render a vaccine useless, especially when using MLVs.
Follow cleaning guidelines, which usually suggest rinsing equipment with hot water followed by sterilization with boiling water. Working cattle usually takes a team of family, staff or neighbors. Be sure each person is following proper procedures.
Timing is important
From a time and labor standpoint, it makes sense to vaccinate all your cattle at once, but most vaccines are recommended at specific ages or reproductive cycles. You may want to keep a breeding and calving calendar with scheduled vaccinations.
Remember that immune response takes time to build. For example, it’s best to vaccinate for reproductive diseases at least six to eight weeks before breeding season.
Good immune response is the sum of many moving parts. But the payoff for managing vaccine programs with close attention to details comes in the form of good cattle health and reduced incidence of disease.
Follow instructions, maintain good nutrition and minimize stress to achieve maximum cow herd immunity. 
References omitted due to space but are available upon request. Click here to email an editor.
Douglas Scholz
Director Veterinary Services
Novartis Animal Health U.S. Inc.
