Maximizing Immune Response and Health in Dairy Cattle

Maximizing Immune Response and Health in Dairy Cattle

By Heather Smith Thomas

Strong immunity and optimum health are very important in dairy cows. They have huge demands on their body for peak performance in milk production and healthy reproduction, along with ability to produce high-quality colostrum for their calves. The goal in every dairy is to find ways to optimize the health of those animals.

Dr. Dean Elder, Attending Veterinarian at the University of New Hampshire, teaches Pre-Veterinary students and is also the Station Veterinarian for the two university dairies. “In the life of the cow, when we try to maximize health—both short term and long term health—it all starts the moment she is born,” he says.

“We have a lot of research and information regarding colostrum. To try to maximize its benefits to the newborn calf, we’ve done studies here at UNH on different additives that can be placed in colostrum that can increase the average daily gain of that calf,” says Elder.

“We found that by adding nicotinic acid in the feed for pre-fresh cows, we could increase the IgG yield in their colostrum, and their calves were able to absorb those antibodies more efficiently. We found that supplementing with beta carotene would do something similar in terms of increasing growth rate in post-weaned heifer,” he says.

“I am not saying that this is what dairies should do, but there are some products and compounds available that can be added to either the pre-fresh diet or to the colostrum that can actually increase calf-hood health and weight gain, and benefit post-weaned heifers as well,” says Elder.

Colostrum is crucial—getting the appropriate amount and quality into those calves. That’s one of the most important things we can do, as well as trying to keep everything as clean as possible as the calf grows up.

“Research has shown that the calves that are healthier as babies from an immunological standpoint go on to become better cows with longer productive life. Thus the immunological support must start at the moment that calf hits the ground.”

As far as supporting and maximizing immunity, there are two times in a cow’s life that are most important—when they are first born, and in their transition period when they have just calved. During that transition period there are many stressors for that cow. Thus it is important to manage her as best we can in terms of diet and other factors to try to improve her immunity during that time.

“These things can have a direct effect, not only on short term issues a cow might have at that time, like mastitis, metritis, retained placenta, hypocalcemia, etc. but even on how those cows respond and can recover in a shorter period of time, and be healthier in the future,” he says.

All cows go through a stressful period during that transition and we want them to be able to respond immunologically and recover as quickly as possible, rather than linger in continuing immunological upregulation. “For instance, during the transition period, we know that negative energy balance is one of the biggest foes. During negative energy balance there is mobilization of fat for energy. This increases the non-esterified fatty acids (NEFAs) and beta hydroxybuteryc acid (BHB) levels, a condition known as ketosis.

“Studies have shown that elevated NEFAs and BHBs have a direct negative effect on the immune system, inhibiting the immune response; it decreases monocyte counts and neutrophils (the most abundant type of white blood cell) and decreases interferon levels (an immune modifier). This is the time period where we start seeing potential for mastitis, metritis and other issues,” says Elder.

Milk fever during this period has a negative effect on immune response; there are many things we think about with milk fever because the cow is down and we want to get her up, but we are not always thinking about the role calcium plays in multiple body systems. “All of these things are interrelated with the immune system,” he says.

In terms of trying to maximize immune health, a lot of research has looked at ways to try to improve the immune system. One of the main things is to try to avoid or minimize any kind of stress. “Calving is one of the biggest stresses for both the cow and the calf. There are also times we must deal with heat stress or digestive stress—as when transitioning from one silo to another in terms of feed. Changes in diet can create some significant stressors,” he says.

Various aspects of nutrition are important for heifers and young cows. “This includes trace minerals. We need to make sure the diet has optimum balance for calcium but also contains all of the appropriate trace minerals, particularly selenium—which is directly associated with immunological function and reducing oxidative stress that occurs with inflammation. We have a severe problem with selenium deficiency, particularly here in the Northeast, and it must be supplemented either through mineral additives or injectable products, paired with vitamin E. This has been shown to have a definite impact on immune support,” says Elder.

Vitamins A, D, E and C also have important immunological functions. Major minerals like calcium and trace minerals like copper, zinc, and selenium are components of anti-inflammatory immune factors that can help with mastitis and other infections. “Keeping track of vitamins and minerals is important. Studies have shown that folic acid supplementation also helps in mastitis prevention,” he says.

“We do a lot of research here with rumen-protected amino acids, as well. Studies have shown that rumen-protected methionine products have a positive effect on improving anti-inflammatory status of the gastrointestinal system.”

Dairy cattle are asked to do a lot. Beef cattle have the same stress periods such as calving, but then the dairy cow is asked to produce 100 pounds of milk every day. Her body is like a fine-tuned engine, like a race car, requiring the very best fuel. “Recent research has been looking more and more at the micro-nutrients, looking at micro-mineral management and gut promoters. We are using many products like yeast cell derivatives, since they have an impact on gut immunity. These products can help decrease issues with things like E. coli scours in calves, salmonella issues, etc.”

There are a lot of feed additives available that work specifically on gut health and immunity. “We are finding—with a lot of animal studies—that gut health and the microbiome of the gut is very important for dairy cattle. What we choose to feed them in terms of nutrition and supportive care has a very direct impact on overall immunity. Gut immunity has a big impact on immunity for that animal,” says Elder. The GI tract is a huge organ that plays a huge role, yet many people don’t think about the importance of the gut in the immune system.

The basics of optimizing immune health include good colostrum and trying to decrease disease burden when calves are young. “In terms of trying to maximize immunity, we always go back to vaccination. Having an appropriate vaccine protocol for a dairy is extremely important to enhance immunology as a whole, but there are many management protocols that can help the animals during these times of stress.”

When it comes to vaccination, most dairies tend to give vaccines to certain groups at certain times, such as at dry-off—not only for the health of the cow but to prime her immune system to add important antibodies to the colostrum. Calf-hood vaccinations at appropriate times are also important. “These are the building blocks and the foundation for the immune system, and we work from there with proper nutritional support and in decreasing environmental stress, keeping on top of disease risk,” he says.

Dr. Rob Lynch (Dairy Herd Health Extension Specialist at Cornell University PRO-DAIRY, a statewide Dairy Extension program) says vaccinations at dairies revolve around production cycles, though some disease risks can be seasonal. “Dairies working with their veterinarian go through a risk assessment to identify diseases of concern and then look at the bigger picture of to prevent them or lower the exposure. This includes biosecurity practices, hygiene and general management that could lower those risks. Then we determine if there are vaccines for the diseases we are concerned about, and where we can fit that into the existing vaccination protocol,” says Lynch.

“The American Association of Bovine Practitioners (AABP) developed vaccine guidelines for veterinarians, similar to the approach in equine medicine; core vaccines are those that every animal should receive. Others are risk-based vaccines. Core vaccines cover diseases that are prevalent everywhere.” Nearly every animal on a farm could be at some risk of being exposed to bovine diseases like BVD, IBR, BRSV, etc.

“Most vaccination protocols include some type of respiratory vaccine and some reproductive vaccines. We commonly include some of the clostridial vaccines in dairy programs—to include blackleg, malignant edema, and sometimes tetanus and Clostridium perfringens.” These bacteria typically live for long periods of time dormant in the soil.

“Risk-based vaccines include some that are in addition those core vaccines. Some herds use mastitis vaccination, particularly coliform mastitis. Some herds incorporate scours vaccines,” he says. These scour vaccines administered to the calves or to their dams prior to their expected calving date to boost colostral antibodies.

Day-to-day farm management is also important. “Is it a closed herd with no animals coming and going? Closed herds have less risk of exposure to animals with unknown health status. With an open herd, the risk is higher—if you bring in new animals or have some animals leave the farm (such as go to a calf ranch or heifer development program) and then coming back after they’ve mingled with other cattle. In those situations we may utilize vaccines more aggressively,” he says.

“We want to make sure these protocols are doable—not too complicated or hard to follow—or theywon’t get done consistently. It might depend on what kind of handling facilities and how many people are available to get tasks done, in a year-round production setting. Vaccinations need to happen on a weekly, every-other-week or monthly basis, year round, so we need to make sure we have the ability to get this task done easily and correctly,” says Lynch.

We all know that cortisol (the stress hormone) has an adverse effect on the immune system, and the overall health and welfare of the cow makes a difference. Short-term stress is usually handled by a healthy cow, but it may be harder to alleviate some of the more major stresses such as during the transition period. “Transition is very stressful, and if it’s not managed properly it can turn into a big problem,” says Elder. If a cow ends up with ketosis, metritis, retained placenta, mastitis or displaced abomasum at this time, it can become a long-term problem. If a cow doesn’t have a good immune system she won’t be able to handle these stressors and may end up getting culled early in her career.

Nutrition is basic, but there are also some macronutrients and micronutrients that can help improve immunology as a whole. “An immunologically sound cow will be able to get back to normal within a shorter period of time. Others may end up with chronic illness, chronic inflammation, and immunological stress that continues out, and this group also has an increase in cull rate,” says Elder.

Most people think about pathogens, but the immune system is not only working against pathogens, but also the inflammatory responses associated with these time periods. “A good immune system quickly recruits ways to combat inflammation, pathogens, etc. and goes to an appropriate level to fight whatever is going on. It then returns back to normal in a short time. Where we have issues are either in cows that do not respond appropriately immunologically (they don’t put up a proper response) or the response is too much, or continues going on without returning back to normal,” he says.

Managing and supporting the immune system is what we can do to help the cow help herself, to respond appropriately to infections or inflammation, and then get back to normal. “As time goes on, research will give us a lot more information about very specific immunological responses with our cows that will help us manage each cow at a more specific level rather than just at the herd level. We can look at very specific things and be more able to support or treat one cow versus another, with more individual attention.”

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