Performance is the key to success in the cattle business. Good genetics, proper nutrition and top-notch health programs are the all-important ingredients. Regardless of the quality of those programs, however, parasites can steal their effectiveness and cost efficiency.

This special section is the fourth in a series detailing how controlling internal and external parasites pays off in the health and performance of your herd. Earlier versions discussed preweaned and weaned calves, stocker and feeder cattle, and the precalving cow herd. (Dr. Robert Rew, Pfizer Technical Services.)

Washington rancher Everett Cole has run cattle on his Davenport operation for most of his 61 years. Yet, there's always room to learn something new, he says. Last year at this time he was about to embark on a lesson he'll probably never forget.

The story goes like this. Last spring, Cole's ranch manager, Dave Hubbard, purchased 150 head of black baldie cows from their neighbor. The cattle were pretty much identical to Cole's 300 head. They were raised in the same valley - only a barbed-wire fence had separated the two herds for years. They had endured the same droughts and winter storms, and their genetic makeup was almost identical - mostly black baldies with some Simmental influence.

There was one critical difference, however. Prior to turnout, Hubbard decided to deworm all of his newly purchased cows. This was the first week of May, when grass was just starting to grow. Hubbard decided to use a long-lasting, broad-spectrum endectocide. This type of product, he had learned, would give him up to four weeks of protection against internal parasites and, in turn, improve the performance of his cows and calves. Since parasite burdens on pasture are low this early in the year, he was counting on a long-lasting product being the "ounce of prevention" that would give him "pounds of cure" later in the summer.

Cole, on the other hand, decided against deworming his cows. After all, he'd never done it before, so why start now? And even though he typically dewormed his yearling cattle each year, he had never noticed his cow herd having much of a problem with parasites. His pastures were large. The grass looked plentiful. And the semi-arid grasslands of eastern Washington certainly would be less-than-ideal conditions for parasites.

As it turned out, Cole figured wrong. Hubbard's treated cattle came home last fall showing significant differences. His steer calves weaned off their mothers weighing 25 lbs. heavier than Cole's. His heifer calves weighed 14 lbs. more. His cows were 100 lbs. heavier, and their body condition on average was 1 to 2 scores better.

In addition, had it not been for a bull that turned infertile halfway through the breeding season, Hubbard believes his conception rates would have been higher, too. Even so, both herds had a 93% conception rate after a 45-day breeding season.

"It paid to use the dewormer - no doubt about it," says Hubbard, who figures it cost him about $5/head to deworm his cows. "Anytime you can get your cows into this kind of flesh, you know there are other benefits. Even now, nearly a year later, my cows continue to hold their condition better than Everett's. They wintered better. They handled the storms better, and they're going into this spring's grazing and breeding season in better condition."

Cattle producers around the country have observed the same advantages of treating their cattle for parasites - particularly prior to turnout in the spring. Research shows that steps taken at this stage can ensure a more profitable year through better conception rates, better calving percentages and heavier calves at weaning. Parasite control has also been shown to have a positive influence on the overall health of a cow herd. For example, if a cow's immune system is fending off the effects of parasites - both internal and external - she isn't fighting other diseases as effectively as she should. The same is true for her calf.

"The reason we use a long-lasting endectocide is that we want to get all the parasites," says Paul Miller, a cow-calf producer from Alma, KS. "It helps with the worms, but also helps build the immunity system. We're getting improved health, and I'm sure we're getting extra gain."

A secondary benefit of using an endectocide is that it also provides broad-spectrum control - killing everything from brown stomach worms to lice and grubs. This is especially important because parasites can often have a multiplier effect on their host. Simply put, if one type of parasite takes hold, it can make conditions more conducive for other parasites to wreak their own havoc on your cow herd.

For example, brown stomach worms can cause extensive damage to the abomasum, including protein loss and reduced absorption of nutrients. Unabsorbed nutrients passed through the abomasum could be absorbed in the small intestine - if Cooperia or intestinal worms were not present. But these worms impact absorption, furthering the negative effects of the brown stomach worms. If an animal is infected with lice, it eats less feed and its performance diminishes. When these things happen, the parasites not only cause problems for your cow herd, they're also gnawing at your checkbook.

For Larry Wickstrum, who runs a 1,500-head cow-calf operation and a 5,000-head-capacity feedlot near Westmoreland, KS, his biggest concern is biting and sucking lice.

"If you don't treat your cattle, they don't do as well as they should," he says. "Their hair coats look rough, and they spend all their time scratching and rubbing. This really takes it out of them. The cattle we treat just rest and eat more. They do better."

In most cases, subclinical parasitism is what U.S. producers have in their cow herds. That means it's often hard to tell whether you have a problem or not. But even if you can't see a problem, the parasites you do have can eat your cattle from the inside out, resulting in lighter weaning weights, reduced gains for stocker cattle, lower conception rates and calving percentages and reduced body scores - without you even knowing it.

Most importantly, however, is that effective parasite control programs can help producers achieve improved returns on their most valuable asset: their pastures. Simply put, if you're not getting the most from your grass, then you're losing ground financially. By using a long-lasting endectocide, producers lower the burden of parasite contamination - not just this grazing season, but for years to come. A treated cow herd cleans up the pasture by ingesting infective larvae and killing them, rather than allowing them to go full circle and re-infest your pastures.

In fact, treated cows and calves act as "vacuum cleaners" on your pasture. And, because an endectocide works for a long period of time, the persistence pays in better performance and improved profitability.

Parasite populations on pasture typically are minimum in the spring in northern climates, and in fall in the southern states. That makes this the optimum time to deworm with a long-lasting product.

For northern producers, a key to understanding parasites is realizing that winter really has limited impact on their population in years with good snowpack. Once the weather warms and grass begins to grow, parasites must find cattle to infect quickly. These infective larvae increase through most of the grazing season, so protecting your cows and controlling parasites early in this time period is critical.

Keep in mind, too, that tough winters don't do much to kill parasites. And, if you think the big snowstorm you had last winter should have killed off the parasites, think again.

Mike Hildreth, a parasitologist for South Dakota State University, recently studied the impact of snowpack on winter soil temperatures. He found that even when air temperatures fell well below zero and there was good snow pack, soil temperatures generally remained in the 20-30 degrees F. range.

"That's ideal for parasites," Hildreth says. "It's like storing them in your refrigerator. We realized that whether you have a mild winter or a tough one you're going to have a parasite challenge next spring."

The problem with parasites, adds Bert Stromberg, a University of Minnesota veterinary parasitologist, is that if producers do nothing to control them during grazing season, cows and calves become parasite production factories, further contaminating your pastures for the following year.

Stromberg recently researched two herds of cattle - one treated for parasites and one that was not. Both groups were managed under identical grazing conditions. He found that during the course of a typical five-month grazing season, a cow and her calf produce about 3 tons of feces. A cow that is not dewormed will produce between 2 to 15 eggs/gram of feces toward the end of the grazing season, or about 29.2 million eggs total during the grazing season. By summer's end, an untreated calf will produce about 160 eggs/gram of feces, or 21.5 million eggs total. All told, the pair produces about 50 million eggs during a single grazing season. Half will live to re-infect your pasture.

But when Stromberg compared these numbers to cattle that were treated, he found substantial reductions in the numbers of parasite eggs.

Cows treated with a short-acting, drench dewormer at turnout and then again during the first week of July put out 8.4 million eggs total. Calves treated at mid-summer with a short-acting drench dewormer in July shed 8.5 million eggs onto the pasture during the grazing season total. All told, the pair produced 17.1 million eggs.

In a similar trial, cows treated with a long-lasting endectocide shed only 1.7 million eggs during the course of the grazing season. Calves treated with a long-lasting endectocide produced only 1.6 million eggs during a grazing season. The total was just 3.3 million eggs - about a 90% reduction from the non-treated group.

"The use of the endectocide effectively turned off the egg shedding," says Stromberg. "We believe that if you use a long-lasting endectocide, you will substantially reduce parasite pressure on your pastures, and prevent future re-infections from taking place."

So what's the best management strategy for controlling parasites in the spring? It depends on where you operate, says Jim Williams of Louisiana State University.

(c) Producers in the South should consider deworming their cows a few weeks prior to calving - typically in November and December, Williams advises. Once their calves start to grow and graze, it's good to get the entire cow herd back in and deworm everything around the first of June.

This isn't a typical practice for many southern producers, but it does have its benefits. For example, many parasites, such as the brown stomach worm go into arrested development during the summer months. That means they burrow within the walls of the abomasum inside the cow and calf, where they wait out the hot summer months until conditions turn cooler in the fall. Then th ese inhibited worms re-emerge to re-infect your pastures.

By deworming your cattle during the first week in June, with a product that gets this inhibited form of brown stomach worm, you can effectively kill all parasites hibernating inside your cattle - and have a cleaner pasture by summer's end. "This will reduce your overall parasite populations," Williams says. "A treatment in June really knocks back the brown stomach worms."

(c) Producers in the North should follow the lead of Cole and Hubbard. Few things work better than giving your cows a treatment of endectocide right before they're turned out on pasture. This protects your cow herd and cleans up your pastures when parasite populations are highest. This also gives your calves a boost when they start grazing by mid-summer.

"By treating your cattle at turnout you can reduce the pasture contamination significantly," says South Dakota State's Hildreth.

When possible, it may be a good idea to get those cattle back in around the first week of July, adds Stromberg, and treat them again. Because calves at this time are beginning to graze, they're becoming infected, too. And, according to the research discussed earlier, they'll shed many more parasite eggs than their dams by the end of the grazing season if left untreated.

That line of thinking holds true for stocker cattle, too. In a 161-day study conducted in Louisiana in 1995-96, stocker cattle treated twice (at Day 0 and at Day 84) out-gained untreated cattle by 64%. They gained an average of 2.16 lbs./day compared to the 1.32 lbs./day for the non-treated cattle.

"If I could convince people to do this, I think they'd find that there's certainly an advantage to deworming cows and calves in the middle of summer," says Stromberg. "That can be a tough request in terms of management, but it will suppress the egg shedding from the cows, and do the same for the calves."

For Everett Cole, who decided against deworming his cows a year ago, the bottom line of his experience is cut and dried. This spring, he says wholeheartedly, his cows are getting the treatment.

"This was a pretty good lesson for us," Cole says. "We learned that this program is not just good for your cows. It's good for your pastures, and it puts more dollars in your pocket. Dave (Hubbard) got better gains from his calves, more money out of his cull cow sales because his cows weighed more, and his cows held their condition better than mine through the winter.

"We derive 100 percent of our income from our cow herds. If we're not getting all that we can out of our cattle and our pastures, we're not as profitable as we need to be," Cole says.

Effective parasite control can result in more than just improved reproductive efficiency, better gains and sale-day weights. By improving these areas, you can also increase returns on your investment and lower costs of production.

A recent study conducted by Cattle-Fax, the Denver-based market analysis firm, shows that cow-calf producers who increase their weaned calf crop by 10% can reduce their breakeven price by $6.01/cwt. That equates to an increase of $26.81/cow in return.

In addition, a 10% increase in weaning weight can mean a reduction of $5.03/cwt. in breakeven price, and an increase of $22.45/cow in return. These are the two largest factors affecting the profitability of a cow-calf operation - greater than feed cost and equal to calf price (also $22.45) - and both can be improved through parasite control.

Stocker operations that increase average daily gain by 10% can reduce their breakeven price by $1.80/cwt. and improve their returns by $12.61/head. This is the largest, controllable factor for stocker operators - except for sale and purchase prices - to improve the profitability of their operations.

Parasite control, like few other management practices, can help your cattle gain the way they should, and make more efficient use of your feed resources.