Feed Lot

JUN 2018

Feedlots and cow/calf operations in the beef industry who feed 500 or more has annually on grains and concentrates; maintain 500 or more beef cows; backgrounder, stocker/grower, preconditioner; veterinarian, nutritionist, consultant

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able to reproduce. In other words, these products prevent flies from breeding. Because of this mode of action, larvicides generally are not species-specific, and thus target more than one species of fly. As a result, larvicides target not only horn flies, but also face flies and stable flies. Because of their differences, it is important to make sure that you are using the correct product to achieve your goals for fly control – and similarly, meet your expectations. For example, occasional situations arise where an IGR is being used, but the producer does not believe it is working because they still see flies. Since that product is intended to control horn flies, do not expect it to reduce pressure from face flies or stable flies. This often results in mistakenly assuming that the prod- uct is not working, when in fact it is. In this or similar situations, the issue has been a lack of understand- ing in what the specific product is Feed-through fly control has without doubt become one of the most popular types of feed addi- tives utilized in beef production systems. As a result, many floor- stocked free-choice mineral sup- plements and other feed products containing one of these technol- ogies will soon become available for the upcoming grazing season. Feed-through fly control can be a valuable component of a com- prehensive fly control program, however its misuse often results in lost opportunities and limited return on investment. Thus, it is important to understand the sci- ence behind these products and how they should be used in order to maximize their efficacy. One thing that all feed-through fly control products have in com- mon is that they have no direct effect on the animal – rather they have their effect in the animal's manure. While they are consumed by the animal, they move through its digestive tract relatively un- changed, and are deposited in the animal's manure. This is where they wage their war against flies. Although they are delivered to the manure in a similar manner, their differences lie in mode of action. As such, these additives generally fall into one of two cat- egories: insect growth regulators (IGR), or larvicides. Insect growth regulators are compounds that typically interfere with the progression of normal fly development. In other words, these products work through inhibiting or delaying the progression of fly larvae from one stage of develop- ment to the next. Because of this, IGR products are generally spe- cies-specific, and thus target only a single fly species. Most commonly available IGR products are only effective on horn flies. In contrast to IGR, larvicides elicit a structural change in the fly that leads to death before it is PEST AND PARASITE CONTROL BY DR. JASON SMITH, ASSISTANT PROFESSOR, UT BEEF CATTLE EXTENSION SPECIALIST FEED-THROUGH FLY CONTROL Fly Life Cycle A feed through works by interrupting the fly's life cycle rather than through direct toxicity. An IGR is ingested with the cattle's mineral or feed. As they graze, cattle disperse the IGR via their manure, where female flies lay their eggs. The eggs hatch into larvae, and after three to five days they molt into pupae. At this point, however, the active ingredient in the IGR disrupts the development of the fly by naturally mimicking the biochemicals that are responsible for insect development. The fly life cycle is effectively ended here. GRAPHIC COURTESY OF CENTRAL LIFE SCIENCES 14 FEED•LOT June 2018 This Year Consider ing

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