Right Down the Back
Know more about pour-on pesticide and insecticide products to get the most out of them.
By Caitlin Richards
Controlling pests and parasites on livestock is an important task for producers. Effective pest and parasite control keep livestock healthy and keep your bottom line healthy, too.
There are a number of tools out there for ranchers to use — ear tags, larvicide feed-throughs, rubber/oiler, and pour-on products. In most cases, a combination of these methods works best because each method works differently to attack pests and parasites. Understanding how a pour-on works can help ranchers use it, and other methods, to achieve maximum control of pests and parasites.
“There are several kinds of pour-ons,” says Dr. Larry Hawkins, senior technical service veterinarian with Bayer Animal Health. “The kind of pour-on it is will determine how it will work.”
The two most common pour-on products that ranchers encounter are insecticides and endectocides. Insecticides treat external pests, such as flies, ticks, and lice. Endectocides, commonly called dewormers, treat internal parasites like brown stomach worms, lungworms, nodular worms, and barber pole worms.
Producers can confirm the type of pour-on they are using by reading the label. Find detailed information about Bayer products at bayerlivestock.com, but the label is the authority.
Regardless of the pour-on type, they are applied in the same way. A stream of liquid is applied down the middle of the animal’s back with an auto-fill applicator gun or a cup attached to the product bottle, and usually applied to a spot on the poll or face. Even though they are applied in the same way, the body of the animal reacts to the different products in different ways.
Since insecticides are used to treat external pests, many insecticides are not absorbed into the body of the cattle. They stay on the surface of the hide. Hawkins explains that the insecticide works by migrating over the surface of the body through the natural oil layer to provide coverage against external pests.
“Because of the nature of these products, it is important to spread them out when applying them” to the cattle, Hawkins says. “The label of many of these products says to apply a little on the head and then the rest from the withers to tailhead. This helps the product spread over the animal’s body. Think about it; a puddle of product in the middle of the back must migrate a long way to cover the areas affected by flies or lice. Again, how the product is applied can help get the body covered.”
From there, the insecticide protects the cattle from external pests by killing the pests upon contact. Hawkins explains that the insecticide attacks the nervous system of the pest. Essentially, it stops their nervous system from functioning and the pest dies.
Endectocide pour-on products treat internal parasites. Consequently, they are absorbed through the skin and ingested through grooming. Applying this product evenly across the body of the livestock is just as important, Hawkins says, even though the effect of the treatment takes place under the skin.
“If you put it on more areas of the skin, more skin is involved in the absorption of the product,” Hawkins says. “Therefore, more blood vessels take it in and it is absorbed better. That is how they are designed to work.”
Once the endectocide is absorbed into the skin, any parasites present are basically paralyzed. Hawkins explains that the peristalsis action of the intestine then moves the parasites on through the gut to be expelled. Some endectocide products continue controlling parasites after the initial absorption because it remains in the cattle’s system. This is called persistent activity.
“If that animal ingests a parasite’s larvae while grazing, there is still dewormer there,” Hawkins says. “It has the same effect on those larvae as it did on the adult parasites.”
This persistent activity is a key with deworming cattle, Hawkins says. It means that producers can control the parasites in their cattle and defend against future parasites when the cattle ingest them.
Just like aspirin for a headache, the endectocide product has a specific active life within the cattle.
Therefore, the product’s efficacy decreases over time. Cattle owners should check the product’s label to know how long the product is active in the body to treat parasites.
Similarly, the efficacy of insecticides also decreases over time. Since insecticides primarily stay on the surface of the cattle’s hide, their efficacy is affected by sunlight and water.
“They are very soluble and will wash off,” Hawkins says. “The sunlight affects them as well. So once ranchers apply the product on the back of their cattle, from that point on, it starts to decrease in efficacy. When ranchers notice that the flies are back, the product should be re-applied.”
Pour-on products work well because of the ease of application. Even though insecticide pour-ons are subject to deterioration, they provide extra pest control when paired with ear tags and larvicide feed-throughs.
When a fly problem exists, Hawkins says, “if ranchers are putting ear tags in their cows, then I would suggest applying an insecticide pour-on to knock that fly population back and give the ear tag a chance to do its job.”
Insecticide pour-ons can also be used on their own to treat pests and parasites. If cattle owners can easily get their animals gathered into a pen and apply the pour-on product regularly, pour-ons will be very effective at controlling flies for their operation. But expect to re-apply the product in three to four weeks.
“The goal is to get season-long fly control,” Hawkins says, “but the product is going to deplete. Re-applying will be required on an as-needed basis. Typically, we would judge that based on how many flies are on the animals, and what kind of effect the flies are having on them.”
Either way, ranchers should create a plan that fits their operation to achieve some level of pest and parasite control. Keeping the pests and parasites away can mean a healthier bottom line in the end.
“Flies affect the performance of animals,” Hawkins says. “In a research study we did three years ago, when horn flies were controlled, the cows weaned calves 11.8 pounds heavier than the cows where flies were not controlled. That production loss is the reason to do it right.”
Right Down the Back is excerpted from the October 2018 issue of The Cattleman magazine.