With Worms, It Pays to Have a Plan
By Nicole Lane Erceg
Effective deworming takes more than a dose of pharmaceuticals, but simple strategic steps can make the process an easy chore.
Odds are, there’s a profit-stealing bandit that has made a home in the front pasture. It’s in the back pasture and probably in your neighbors’ pastures, too. Nestled in the grass the cattle graze daily, this unwelcome guest is poised to eat away at the cow herd that also calls this rangeland home.
What is this pesky pest? Parasites.
Laird Laurence, Merck Animal Health veterinarian, says cattlemen often think about the worms that live inside the herd, wreaking havoc on the cow’s health. However, only 5% of a ranch’s worm population actually lives in the cow — the other 95% is settled in the pasture.
This perfect placement on the grass allows the lucky worms to easily catch a ride from grass stem to cattle stomach without much work. It’s also what leaves them vulnerable to the elements. Laurence says this simple piece of knowledge, knowing where the worms live, can help ranchers strategically rid themselves of parasite problems by planning when and how to deworm based on the weather.
“I always tell people, if it’s cold enough to kill your tomato plants, it’s cold enough to kill 100% of the larvae in the pasture,” says Laurence.
After the first hard freeze in the fall, the larvae preying on cattle in the grass are gone. With 95% of the worm population dead or dormant for the winter, Laurence says it’s the perfect time to attack the leftover worms still living in the cattle. Deworming after the weather turns cold isn’t a permanent solution, as the eggs will survive the winter, but it keeps the cow herd healthy until spring.
Test for worms
Before applying a product, he advises ranchers to always run fecal samples.
“Why deworm if you don’t have to?” he says.
Gathering fecal samples and submitting them for testing (a service that Merck offers free of charge, Laurence adds) will help determine if a dewormer is needed and if so, what type will best eradicate the specific parasite problem on the ranch. Collecting samples for testing pays off twofold; if no dewormer is necessary, it saves time and money and if it is needed, it provides a comparison to make sure the selected product works properly.
“Don’t assume you’re done if you collected samples before deworming,” says Laurence. “Collect and submit them two weeks after a product has been administered, too. If there is not a 90% reduction in fecal egg count, then the product you used did not work and you won’t see the benefits of it.”
The process of collecting fecal samples doesn’t mean a sample from every animal in the herd. Laurence says it only takes 20 samples to make the test statistically significant. This same sample size holds true whether there are 100 or 3,000 cows in the herd.
Product choice
When selecting a product, Laurence says ranchers should select two; an avermectin and a fenbendazole. Using multiple products with both active ingredients ensures that all worms are killed.
For ranchers looking for a low-impact option, Laurence recommends using a feedthrough product like the Safe-Guard® medicated dewormer mineral block.
“What I like about it is that you put it out and you’re done,” says Laurence.
He instructs ranchers using this option to pick up every other mineral supplement and salt block and leave the Safe-Guard® blocks out until they are gone. He says if the blocks are gone within 12 days, then all the cattle have been dewormed. One mineral block will effectively deworm 8,000 lbs. of cattle. The active ingredient fenbendazole is ingested over several days, making sure that all the worms in the intestinal tract absorb enough of the ingredient to be completely terminated. The salt content of the block keeps cattle from over-eating their share and leaving enough for the rest of the herd to receive the medication.
“We did 800 calves recently and it was amazing to me because every calf got its dose,” says Laurence. “We took fecals [fecal samples] every 30 days for six months and the results were amazing.”
Don’t let worms eat the profit
When the weather warms up in the spring, Laurence says it’s time to begin thinking about worms again. The eggs that survived the winter in the pasture will hatch and larvae are ready to begin their new attack on the cow herd.
Laurence cautions ranchers not to deworm at the first signs of spring. He says the most optimal time to begin the process is about six weeks after the first signs of warm days and lush green grass. This gives worms time to mature and the cattle time to pick up the parasites in the pasture.
“This is where the strategic part comes in,” says Laurence. “If you worm them the day the grass is greened up, then it’s no good because you already dewormed them in the fall. With only two days on the coastal grass, they haven’t picked up any parasites yet.”
Watching the weather, taking fecal samples and making good product choices pays off. For ranchers who deploy strategic deworming plans, Laurence says they see an additional 30-40 pounds in gain per calf. Without worms attacking their appetite, immune system and nutrient digestibility, cows are better milk producers, passing on their benefits to the calf.
The added pounds, flesh and health from effective deworming leads to increased profits when selling the calves. Laurence says it’s a low-cost investment with a high rate of return.
“The most common mistake I see cattlemen make is not deworming at all,” says Laurence. “They don’t think they have parasites.”
For ranchers who think that it’s too dry in their area of the state to have worms, Laurence says to think again. There is a high chance that parasites have moved into most Texas pastures. However, with a little planning, worms will no longer be a problem in the cow herd, and ranchers are left with pounds and profit. ❚
“Strategic Deworming” is excerpted from the November 2017 issue of The Cattleman magazine.