Feed-through Parasite Control

With large economic losses attributed to parasites, many forms of parasite control have been developed to target unique operational goals. Treating with feed and mineral supplements has been growing in favor.

By Jason Edmondson

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March 23, 2023 12:37 PM

By Jason Edmondson, Beef Technical Specialist at ADM

Internal and external parasites of beef cattle have long caused frustration for both the cattle producer and the livestock. Recent estimates suggest that parasitism of beef cattle cost the industry in excess of $3 billion annually in lost milk production and calf weight at weaning.1 The effects of parasitism reach every production sector of the industry, from the cow-calf operation to the feedlot. With the large economic losses attributed to parasites, many forms of parasite control have been developed to target unique operational goals. Injectables, pour-ons, rubs, traps, and feed-through options are the most common practices used. Management practices for controlling parasites have advantages and disadvantages and must be evaluated on an operational basis to determine value. Some of the advantages and disadvantages include the logistics of implementation, equipment cost, labor availability, and the cost per head for treatment.

Treating cattle for parasites through feed and mineral supplements has been growing in favor with producers that are experiencing challenges such as lack of labor, working facilities, and/or accessibility of the livestock. The ability to use feed-through insect growth regulators (IGR), repellants, and anthelmintics (dewormers), have created the opportunity for livestock managers to improve the performance of cattle that have previously proven difficult to treat. Successful implementation of feed-through parasite management technologies requires management’s attention to ensure the cattle are receiving an effective dose at the proper time and duration to reach the operational goals for economic benefit.

For instance, feeding an IGR product after flies are present at economically significant levels does not immediately appear to be effective because of how the product is designed to work. IGR products pass through the gastrointestinal tract of the cattle unaltered and end up in the manure on the pasture. The horn fly leaves the host to deposit eggs in the manure and then returns to the host to continue feeding. At this point, the IGR in the manure stops the growth of fly larvae by inhibiting the larvae’s ability to synthesize chitin, a protein that regulates the maturing of fly larvae6, or by disrupting the normal hormonal control of maturation.5 If there is a large quantity of untreated manure on the pasture at the time of the first signs of horn fly infestation, those horn flies will be able to complete their life-cycle until most of the manure on the pasture has a sufficient level of IGR to disrupt the life-cycle of the fly. With no immediate visual reduction in horn flies after introducing the feed-through IGR product, it may appear as a failure of the product. In actuality, starting to feed the IGR product after the fly population has been established is more likely the cause of the delayed results rather than actual product failure. Some of the more common compounds that work through the manure to control larval maturation are s-methoprene, diflubenzeron, and organophosphate.

Another category of parasite control that relies on the ability of compounds to alter the parasite’s feeding behavior is the repellent category. Repellents are a classification recognized by the EPA as behavioral modifiers of pests derived from either synthetic or natural sources. The synthetic repellent category includes DEET, permethrin, picaridin, and other compounds which are mostly used topically. Essential oils and botanical extracts are also recognized by the EPA as insect behavioral modifiers or repellents. Most of the products in this category have active ingredients that have been deemed by the EPA as “Minimum Risk Pesticide Products”, posing little to no risk to the environment.2 Commonly used products in this category are citronella oil, garlic and garlic oil, oil of lemon eucalyptus, cinnamon, mint oil, and clove oil. Most of these compounds are used as topical treatments, but they have limited use as a feed-through option for repelling parasites. They don’t work as feed-through options because they don’t maintain the repellant properties or can present slight toxicity after being broken down in the digestion system. One plant extract that has shown promise in modifying fly, tick, and lice feeding behavior both anecdotally and scientifically without a toxicity challenge is garlic and garlic oil. Two independent field trial studies have shown a reduction in fly and tick populations on livestock when garlic has been added to the diet of ruminants.4 There are many garlic additives available that have different delivery options and concentrations of active ingredients. Be sure to consider this when comparing products.

Regardless of which control strategy is utilized, the management, observation, and timing of the technologies employed to control the parasites is critical for successful implementation. For producers that only gather cattle annually, feed-through options can offer another method of fly control which doesn’t require the extra cost of labor and equipment to gather and treat the cattle. There may also be an advantage to utilize certain control technologies when they are most effective against the parasites in question. It is important to develop a good working relationship with a nutritionist and veterinarian to see how these strategies can be employed to receive the maximum benefit from the advantages that these technologies can bring to the producer.

Jason Edmondson - Beef Technical Specialist at ADM Animal Nutrition

Jason Edmonson is from East Central Alabama and has been in the role of East Region Beef Technical Specialist for ADM Animal Nutrition for nearly two years. His undergraduate and graduate studies were at Auburn University, and he spent almost 15 years on staff at Auburn’s College of Veterinary Medicine helping educate students and producers before coming to ADM Animal Nutrition.

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