Are your cows immunized or just vaccinated to prevent scours?

Scours has been a menace for decades despite widespread use of pre-calving scours vaccines. Why? For one thing, while vaccine science is sound, studies show that cows don’t always get vaccinated. And just because they’re vaccinated, it doesn’t mean they will experience an effective immune response. Even in perfect conditions, cows respond to a vaccine only 80 percent of the time.

Couple this with farmers having to vaccinate within a specific time frame, plus the dam has to calve within the right time frame to be at peak antibody level when giving colostrum.

There’s a lot of room for error.


Vaccination vs. immune response

Vaccination is not the same as immunization. Just because she’s been vaccinated doesn’t mean she’s protected. We asked an expert about this.

“Often you hear the two words vaccination and immunization used synonymously and they’re not the same thing,” says Dr. Chris Chase, immunology expert and professor in the Department of Veterinary and Biomedical Sciences, South Dakota State University. “If the animal doesn’t respond to the vaccine, it’s not immunized.”

There are a lot of factors that play into not getting a response, such as something going on with the animal related to health, the way the vaccine was handled, and the environment.”

In short, vaccine response varies. Stress, which tends to affect dairy cows more than their beef counterparts, can create variability in response. Timing of the vaccine is also vital to immunization.

Nailing the correct time window

In terms of getting the timing right with vaccination, there are a few factors that can mitigate success:

  • All dam-level scours vaccines require two vaccinations to provide primary vaccination and then one annual booster every year thereafter.
  • Meaningful antibody generation typically takes about seven to 14 days.
  • Because antibodies are not transferred in utero, the only way the calf can absorb them is through drinking colostrum within the first 12 hours of birth.

The upside to a vaccination program is what’s called “memory.” The body remembers the vaccine antigen and is ready for future encounters. But neonatal scours doesn’t attack at multiple timepoints throughout life. Thus memory isn’t useful because we’re only looking at a short period of time required for protection – the first two to four weeks of life. Immediate protection definitely beats long-term memory gains.

Ensuring immunization

Pre-calving scours vaccines are a tradition in our industry, long entrenched as a protocol for preventing scours. But like with many practices, eventually, real competition comes along.

Preformed antibodies, developed through antibody technology similar to that used in human health, have been gaining a foothold on farms for use in scours prevention. These preformed antibodies mimic naturally occurring antibodies, conveying immediate immunity with high levels of protection against specific diseases – without having to stimulate an immune response. Farmers give them directly to the calf at birth around the same time as colostrum.

Developing preformed antibodies begins with the creation of a clean, high-antigen vaccine that has the power to stimulate a good immune response. Think of this vaccine as a starter immunization. It is kicking off the process of stimulating antibody production in the cow’s colostrum.

As part of the development process, the vaccine gets administered to pregnant cows frequently within a precise time frame. After those cows calve, their colostrum gets purified through an extensive pasteurization process. Calving must occur on the targeted calving date for the colostrum to be used.

Then, antibodies get sorted out by molecular weight. Moisture gets removed through a drying process to ensure antibody stability and to create a freeze-dried powder. The powder then gets tested to meet antibody levels proven in third-party studies to protect a calf from E. coli, coronavirus and rotavirus.

Giving preformed antibodies to calves makes a lot of sense compared with vaccines. That’s because immunization, the goal of any vaccination program, occurs immediately, without the need for the animal to do the hard work of stimulating antibody production and a subsequent immune response.

Vaccination is a step to immunization. Why not skip the steps and go straight to immunization?