A Stealthy Opponent

Take a stand against gastrointestinal parasites this fall.

Story and photos by Kayla Jennings

As the scorching summer sun starts to drop just enough to make a drive in the pasture tolerable, ranchers are out doing one last drive.

Hopefully, a recent rain has kept pastures thriving and green for the grazing cattle that inhabit them. A soft breeze allows the grass to dance back and forth in harmony with calves playing in the background. Along with a melody of katydids in the background, it is the perfect evening. A beautiful sight, indeed.

What is potentially not so beautiful is a silent intestinal parasite discreetly roadblocking the cow's ability to receive maximum nutrition, leaving her depleted in every way. By the time the effects can be seen with the human eye, these stealthy creatures are miles ahead and the producer has serious catching up to do.

"Worms reduce the cow's dry matter intake and that, in turn, reduces the nutrition available," explains Dr. Jacques Fuselier, cattle technical service representative with Merck Animal Health in Louisiana. "The worms cause inflammation, so they reduce the amount of nutrients that can be absorbed through the gut and through the intestine."

At that point, he says the cow's immune system is preoccupied with trying to get rid of worms, so they do not respond as well to other infections - leaving the immune system down and robbing cattle of performance.

Fortunately, this scenario is completely preventable with a proper deworming protocol and herd management. Dr. Wade Nichols, longtime senior technical services manager with Merck Animal Health in Idalou, says keeping ahead of intestinal parasites is essential.

"Being proactive is key," he says. "Getting rid of worms ahead of breeding season and keeping them low is going to help your program tremendously."

A parasite, by definition, is an organism that is detrimental to the host, he says. As a result, worms are to blame for a plethora of problems within a cow herd that impact health as well as long-term profitability.

While some may consider deworming a spring-only strategy, assessing the herd's potential risk and treating parasites as pastures turn dormant can greatly improve the ability to stage off these costly troublemakers.

Know thine enemy

According to Penn State Extension, cattle spend at least two-thirds of their life grazing no matter the production system, so their opportunity to consume worms is high.

The way intestinal parasites infiltrate their host is by the larvae being consumed off blades of grass, laying eggs within the animal and then eventually the animal deposits eggs into the pasture via manure. As the egg count increases, the risk of exposure to worms in the herd increases, as well.

"If it's bad enough, they won't be thrifty," Nichols says. "They'll have a rough hair coat. They can get water jaw. That would be a heavy parasitized animal, but most of the negative outcomes, you wouldn't be able to see until it is too late."

In the case of females, pregnancy rates will plumet, while a bull's fertility could be impacted, and a steer will weigh out significantly lower than their genetic potential.

Yet, there are limited signs of parasites in earlier stages according to Fuselier.

"To be able to look at a herd of cattle and pinpoint which ones are more parasitized is impossible," he adds.

From cow-calf to backgrounding weaned calves and all the way to the feedyard, deworming is a necessary step in the management protocol - even if the cattle are not actively grazing.

Parasite eggs won't mature without grass, meaning there is less concern with livestock in dry lots. However, existing parasites will continue to do damage.

"By deworming, you clear out as much as you can from that individual animal, so you don't reduce any dry matter intake," Fuselier says.

Eradication plan

Since the goal of deworming is to stop the lifecycle of parasites that have a negative impact on the cow herd, producers are advised to deworm regularly as part of their management strategy.

To do this, cattle raisers can work to create an eradication plan. This starts with testing fecal matter from cattle. Nichols notes that the threshold of a normal egg count when a fecal sample is evaluated for parasites can vary.

"The thing to remember is cows will always have lower parasite egg counts in their fecal samples than calves," Nichols says. "The cow has some immunity that builds up, and so they can keep those parasites lower. For example, if you take a cow sample, you're going to be at 30 eggs per gram, where that calf is going to be at 150 to 300 eggs per gram."

Selecting the correct dewormer hinges on a couple of variables - parasite prevalence and management style. By collecting fecal samples to get an egg count, producers can work with veterinarians to identify the best products for treatment. But that is only half the equation.

Management styles and facilities vary greatly across the state, so it is also important to consider practicality and cost when finding the best dewormer for the job. Fortunately, today there are several options available including: an oral drench; pour-on; injectable; and feed through.

By using a combination of treatments, producers can address every kind of parasite. Nichols says it is a great way to keep the parasite load down and the cattle healthy.

"There's enough evidence out there now, enough trials that have been done to show that the combination deworming is your best," Nichols says. "And that also helps with decreasing resistance."

In addition, Nichols recommends producers monitor egg counts throughout the summer months to determine if a non-handling form of dewormer is needed.

The non-handling forms are primarily fed through mineral or cubes. These products work by attacking the worms little by little until they are eventually eradicated. Even if certain cows tend to eat more than others, the product is designed to account for that by building up over the course of several feeding events until the worms are gone.

Drawing from his many years as a practicing veterinarian, Fuselier stresses the importance of dosing properly no matter the product selected.

In a perfect world, giving each animal the recommended dosage printed on the product based on their exact weight would be the way to go. He and Nichols know that is not practical for many producers, but there are still ways to effectively dose the herd.

Within a group of similar weight cattle, Nichols says to dose for the heaviest animal across the board. That way, the heavy animal is sure to receive the correct dose.

All agree underdosing is the larger problem from an efficacy and cost standpoint than overdosing would be.

"Underdosing dewormers is one of the main reasons that we have a resistance problem today," Fuselier says. "You're not getting adequate therapeutic levels that way, so giving the proper dose is important."

Protocols in action

Texas & Southwestern Cattle Raisers Association member Austin Adams, of Adams Cattle Co. near Hedley, is diligent in managing parasites within his family's herd and the Angus seedstock herd he manages, Schaefer Farms.

For Adams, who is also the Ranch and Feedlot Operations instructor at Clarendon College, it makes sense in the seedstock herd to deworm right around green-up and again as the forage goes dormant. This allows them to hopefully begin and end the growing season with clean pastures.

"Anytime I have the opportunity, I want to be sure and expose them to the Safe-Guard product to get any internal parasites taken care of," Adams says. "In addition to that, I'll use a rotation of different pour-on insecticides, so the two products can work together to maintain control of both internal and external parasites. The ultimate goal, is to have them free of any parasitic loads setting them up for a good foundation going forward."

In addition to timely deworming like Adams has subscribed to, Nichols and Fuselier encourage producers to take advantage of the free fecal sampling units through Merck Animal Health to formulate a tailored plan with a veterinarian. These tests are easily accessed through many local Extension services, as well.

"Get a random sample from a from a pasture of 20 fresh fecal samples," Fuselier explains. "Then submit those to get an average egg count. By visiting with their veterinarian, producers can get an idea of where the threshold is for their location and formulate a plan for deworming."

To take it one step further, Fuselier says producers can send a follow-up sample after treatment to see how well the products worked. Adams has used these kits, and he says it has been a simple collection with valuable results.

"I have been doing annual fecal samples on our herd in a rotation to make sure that we're maintaining control of our internal parasites," Adams says. "That's one way we are able to make sure that we're doing the best job we can as producers."

Plot twist

Nichols and Fuselier both agree with the old saying, "You can move cattle east to west, but not west to east."

The truth of this saying stems from the normal parasite threshold of cattle in those regions. Parasites exist across the board, but the number is much lower in the more arid Texas Panhandle than in the swamps of East Texas.

In other words, cattle in East Texas are exposed to more parasites throughout their lives, so moving to a place with fewer is a win. For cattle moving east, extra care should be taken to deworm regularly and help them adapt to the new environment.

"Down here in Louisiana, we should deworm our cattle probably three times a year," Fuselier says. "But then you get in a more arid, drier climates, where they have seasons, and it gets cold enough to break that worm lifecycle. They could get by with deworming the herd once a year. Some places they might go twice a year. It's very regional."

Because of irrigation, Adams sees this play out in his own day-to-day even though he lives in a more arid environment. The water delivery system provides the perfect environment for cattle to thrive - and unfortunately parasites, as well. This means if they want cattle to gain maximum value from the available forage, they must take deworming seriously.

"The prevalence of parasites is increased as compared to my neighbors that are across the fence here in the Texas Panhandle, who are relatively dry," Adams says. "Their incidents of parasites are typically less than what our management scheme allows for. I will deworm our cattle twice a year to combat the increase in prevalence of parasites."

Since Adams has taken the initiative to stay on top of parasites, he has seen improvement in calf weights and overall health. He says the return on investment, by way of increased cattle performance, has been positive.

"Looking at our weaning weights year over year, we're looking at around a 28-pound increase just by implementing one product," Adams says. "Over a hundred head, that really can add up, especially with today's prices."

While there is no replacement for deworming products perfectly formulated to target parasites, there are steps producers can take alongside those products to keep worm counts down, too.

In addition to diagnostic testing fecal samples regularly to keep a pulse of how well the deworming protocol is working, Adams rotates pastures to attempt to break the lifecycle.

"When we deworm cattle, I will try to move pastures," he says. "The idea is we are going to remove the parasites in the cows, then we try and clean up the pasture we were in by removing the host of the parasites, in this case the cattle. My goal is to break the lifecycle, whether it be parasites or flies."

Nichols and Fuselier agree rotating pastures keeps cattle from picking up eggs. If the parasite burden is extremely high, Nichols says introducing another species could also help.

"I can run cattle across that pasture and then run the sheep behind them," he says. "They'll pick up the parasites from the cattle. Since parasites are basically species specific, a sheep parasite isn't as detrimental to cattle, and cattle parasites are not as detrimental to sheep."

From his experience, Adams says the investment of time and the dewormer products is non-negotiable. Removing the hindrance of a parasite load in cattle allows them to perform to their fullest potential. In turn, that means higher pregnancy rates and heavier calves at weaning - both big factors in the ranch's bottom-line.

"I need our cattle to look their best all times," Adams says. "If the parasites are onboard, they are robbing the cattle of vital nutrients which is costing us money. If the cattle are having to compete with the parasites, they are more likely to have a rougher hair coat, we can see a decrease in reproductive performance and then, ultimately, all of this culminates to impact our weaning weights and breed back rates negatively."

Fuselier echoes the idea that deworming is a necessary step in a producer's management plan today.

"You're not going to solve all your problems by just deworming cattle, but you're putting a lot of effort into how you're raising them," he reminds. "You're looking at genetics, you're trying to market them the right way and you're trying to pay attention to your pasture. What deworming does, is it helps the animal to make use of all the other efforts that the producer's putting forth to raising this herd."

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Kayla Jennings is a freelance writer from Mason.

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This story first appeared in the August 2024 issue of The Cattleman magazine.

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