Controlling parasites in beef cattle

Many beef producers are feeding an uninvited guest each time they feed their herd – parasites – and, according to research done at the Iowa Beef Center, producers could be losing as much as $3 billion on an annual basis.
This cost to producers comes in a variety of forms, according to Dr. Gary Sides, a cattle nutritionist with Pfizer Animal Health Veterinary Operations. When cattle are infected with parasites, it can suppress their appetites, which limits the intake and absorption of nutrients. This comes on top of lost weight gains, poor feed conversions and increased disease levels, since infestations of parasites can mean cattle can’t fight off diseases as easily.
“There is no reason to feed the cow, calf and parasites,” Sides said. “If you deworm, you’re making sure you’re feeding the growing animal and not the parasites. And, if cattle have been grazing on grass, they almost certainly have parasites.”
He noted that, for cows, it’s important to maximize the gains made while on pasture and keep them in good body condition through winter. And for calves, deworming offers the opportunity for significant improvement in productivity.
Cattle should be dewormed in the fall after they come in off pasture, with a broad-spectrum dewormer, Sides said. This should help protect against Ostertagia ostertagi, which is more commonly known as the brown stomach worm, the most damaging internal parasite, plus several other parasites that have the potential to rob cattle of performance and producers of profit.
Producers in this region, if on a parasite program, generally deworm in the fall after cattle have come off pasture. But Myron Andrews, a former professor in the North Dakota State University Animal Science Department, indicated his research work shows there would be a benefit from deworming again in the spring when cattle are going to pasture.
Current deworming products, according to Andrews, will not kill the arrested larvae residing in the gastric glands of the stomach lining or in the lining of the gut. In the spring, these arrested larvae are stimulated to leave their protected positions and develop into active adults in time to produce eggs shortly after the calving season. These newly deposited eggs then infect the newly born calves at their most susceptible age.
Andrews’ suggestion is to medicate the adult animals early in the spring to kill the newly developed adult worms and thereby prevent the rapid increase in pasture contamination early in the spring. This would allow the calves time to stimulate their resistance against worms without undue stress. The time for this spring medication would be between the latter part of March and the time when cattle go on the summer pastures.
Once the decision is made to implement a dewormer program, Sides said producers need to follow five easy steps to get the most out of efforts.
• Read and understand the label: To help ensure the best possible results from deworming products, it is important to be aware of the label indications for the product being used.
“When deworming time rolls around, it is extremely important to read the label every time to ensure you are dosing correctly, reducing the risk for side effects and not creating resistance,” Sides said. “Not giving cattle the full, labeled dose provides parasites the opportunity to become resistant and prevents cattle from reaching their performance potential.”
• Injectable vs. pour-on: The choice of using an injectable or pour-on depends on weather conditions and the different type parasites in the area. Checking with your local veterinarian is a good idea when setting up a deworming program for your herd.
“Injectables really do the best job on internal parasites, but lice control is better with pour-ons,” he said. “I tend to be more concerned with internal parasites, since they can do the most to slow down growth, feed intake and feed efficiency.”
• Store and handle products carefully: Storage and handling can have an effect on product efficacy. Most products list the appropriate temperature range for storage on the product packaging label. It is important to follow label instructions closely to ensure that producers are getting the most bang for their buck, he said.
• Practice proper application techniques: When using pour-on products, it is important to ensure proper application techniques. Avoid applying product onto dirty animals, as it can be absorbed into the dirt rather than the hide. Also, it is possible that general herd behaviors such as rubbing and licking can reduce the amount of effective product on the animal.
“Convenience often has its drawbacks,” he said. “There are some circumstances that keep a pour-on from working as well as it could. Dirt and manure on the animal can reduce the amount of product absorbed into the hide, so it is important to apply pour-on onto animals that are as clean as possible. Rain, snow and sleet can often wash the product from the animal if not given sufficient absorption time, so when possible, plan application around the weather.”
When applying a pour-on dewormer, pour the proper dose down the entire backline of the animal and do not just pour the entire dose to one spot, he added.
Deworm based on geographic location- Deworming times can vary depending on geographic location, but it is generally recommended that producers deworm at green-up in the spring and turn-out in the fall.
“Producers should collaborate with their veterinarian to develop a solid deworming program that is best suited for their herd,” he said. “These factors, as well as numerous other things, can change the recommendation for which products should be used from one herd to another.”
Sides concluded by saying, “Producers need to get the most pounds of gain possible by feeding cattle and not parasites.”


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