Current Progressive Dairy digital edition
Advertisement

Vaccination 101: Set your animals up for success

Jenna Hurty-Person for Progressive Dairyman Published on 07 August 2017

You vaccinate your cows and heifers, but are they immunized? Not necessarily. To get a good immune response, you need to set your animals up correctly.

During his presentation at the 2016 American Association of Bovine Practitioners Conference, Chris Chase, a professor at South Dakota State University, shared some insight into setting cattle up for immunization success.

advertisement

advertisement

The immune response

To begin, Chase clarified that vaccination does not equal immunization. Vaccination, he said, is merely the act of receiving a vaccine, whereas immunization is the appropriate immune response. For a vaccine to be effective and have an appropriate immune response, the host must be set up properly for it.

In other words, they must be under as little stress as possible, have adequate nutrition and be well hydrated.

To be successful, the vaccine must first activate the innate immune response.

“When it comes to the vaccine response, whether we’re giving a mucosal vaccine or whether we’re giving a perineal, we have to breach the barrier one way or another and get the attention of the innate immune system,” Chase said.

Innate immunity, Chase said, is like a smoke alarm: It detects an incoming or potential threat, initiating a response action by recruiting white blood cells and triggering the full immune response.

advertisement

When an inflammatory response occurs in a lymph node, two things happen:

1. Blood circulation increases by 50 percent – so more cells enter the lymph node.

2. The efferent lymphatic (the outgoing-exit lymphatic) begins shutting down, causing the lymph node to swell. T cells, white blood cells responsible for cell-mediated immunity, and B cells, white blood cells responsible for producing antibodies, are trapped there, increasing the chances of seeing their antigen.

Vaccine types and how they work

While the number of T cells (the vaccine-specific cells) is fixed, the antigen-presenting cell is a variable that can be controlled by the type and location of the vaccination. The goal is to trigger a large enough immune response to generate immunity.

“If we do a good job, we generate memory,” Chase said. “As we generate memory, we get to a point where we have enough memory we sort of break the threshold. The thing is, once you break the threshold of memory, those cells aren’t going anywhere.

If you do a good job in terms of vaccination and get a good memory response, those memory cells are going to, depending on the antigen, be there at the very least several months or years – or maybe even the lifetime of the animal.”

advertisement

Vaccine principles

A vaccination program is designed to build up herd immunity against a specific disease by elevating the immune response of each animal. However, not every animal will respond strongly enough to the vaccine to achieve immunization. In fact, it is impossible to achieve a 100 percent immunization response.

On any given day we give a vaccine, not every animal will respond (genetics, stress all play a role), but it is still possible to achieve herd immunity without a 100 percent immunization response.

Herd immunity is influenced by the animal’s environment. This includes stocking density and the level and type of disease agent present. For most common pathogens, such as infectious bovine rhinotracheitis virus and bovine viral diarrhea, herd immunity can be achieved if 70 to 80 percent of individual animals respond to the vaccine. While individuals may become ill, the herd itself should be protected.

It is important to administer the booster at a time interval to maximize animals’ immune response. It takes 17 to 21 days to achieve a full mature immune response. In addition, the immune system may make mistakes, requiring it to take time to cull cells, selecting only the best of the best cells.

For this reason, studies show giving a booster – even if it’s more than 21 days later or even a few months after the initial vaccine – still boosts the animal’s immunity.

Chase recommended using a modified live vaccine and boosting with an inactivated vaccine when possible, saying studies show that method is better than two doses of modified live vaccines. The effectiveness of using an inactivated vaccine followed by an inactivated booster, which previously had a poor response, has improved with the addition of an adjuvant system.

Keep in mind administering a booster won’t increase the immunity of the animals that already had a good immune response to the initial vaccine. However, it will boost those that previously had a mediocre response, increasing herd immunity.

When to vaccinate

Since the cow’s antibody levels will be high just prior to parturition, Chase suggested taking advantage of this and vaccinating cows during the dry period rather than waiting until after she calves, when her immune system will likely not be capable of mounting a good immune response.

“The postpartum cow is an immunological wreck. She’s got immune suppression,” Chase said. “She’s early into lactation. Ketosis and acidosis both suppress immune responses.”

Although not ideal, if you do need to vaccinate the cow postpartum, wait until at least three weeks after parturition to give the cow a chance to recover.

When shipping or commingling cattle, vaccinate them 30 days prior for best results. Studies show morbidity will not increase, but there is a 40 percent decrease in the number of cattle that will need to be revaccinated.

If the animal is dehydrated, it is much more difficult for these cells to move, thereby limiting the animal’s immune response. For this reason, Chase does not recommend vaccinating cattle right after shipping or any other time where they will likely be dehydrated.

“When it comes to the immune response, the animal doesn’t lie to us. In other words, if we’ve got the immune system’s attention, we can expect we’re going to have an inflammatory response,” Chase said. “We can expect there’s going to be some side effects, particularly on the primary vaccination.”

These side effects include some drop in intake, some loss of appetite and maybe a little droopiness – droopy ears and listlessness – similar to people after they get a flu or a tetanus shot. If you see a poor response or no response, then the animal probably also had a poor immune response.

However, the immune response can also go too far the other way. Too much of an immune response could result in such things as an allergic reaction or a sick animal.

Chase said with lactating cows, producers should not see a drop in production after a vaccination, but research shows they may see a drop in milk quality because the immune system needs protein to mount an immune response.

The bottom line is: Achieving herd immunity is a balancing act. Work with your veterinarian and nutritionist to develop the vaccination program best for your herd and one in which each animal is set to achieve successful immunization.  end mark

Jenna Hurty-Person
  • Jenna Hurty-Person

  • Field Editor
  • Progressive Dairyman
  • Email Jenna Hurty-Person

Guidelines For Immunization Success

  • Provide good nutrition: Minerals, vitamins, protein and energy are critical to a good immune response.

  • Reduce stress: Increased stress due to things like commingling, dehydration, nutritional intake, parturition, lactation or heat stress can lead to a poor immune response.

  • Good gut health: A healthy gut and the microbiota within the gut are imperative for a good immune response.

  • Hydration: Dehydration can make it harder for the immune system to react, leading to a poor immune response.

  • Multiple vaccines: If you need to administer more than one vaccine, do it on different sides of the neck to activate different lymph nodes.

LATEST BLOG

LATEST NEWS