Extension Spotlight

As the temperatures begin to slowly warm, it is time to start thinking about warm weather parasite control. Controlling external parasites on beef cattle can provide a benefit not only to cattle comfort but also benefit the bottom line. Controlling flies can help prevent decreased gains, added expenses, and prevent disease.

Of external parasites, flies are the most prevalent. Horn flies, stable flies, face flies and heel flies can be extremely harassing and annoying to cattle. When flies become bad, we see cattle bunch up and use group swatting to keep the flies stirred up and off of their bodies. Unfortunately, this also means cattle are not grazing or ruminating comfortably and using energy to combat these pests. This can especially have an adverse effect on weight gain in growing calves and stockers.

Horn and stable flies are blood feeding flies. Horn flies tend to be found on the back, shoulders and belly of cattle. Stable flies tend to be found on the legs. These flies can have a negative impact resulting in calf weaning weights reduced four percent to 15 percent. Stocker cattle and replacement heifers may have weight gains lowered by up to 18 percent.

Although they are not blood feeders, face flies can also cause significant annoyance to cattle. Face flies congregate around areas of animal secretions and can be seen around the eyes, mouth and nose of cattle as well as around in cuts or scratches where blood or fluid is present. Being around the eyes is the most significant issue as face flies can irritate the tissue around the eyes making cattle susceptible to pathogens which cause pinkeye, a contagious inflammation of the cornea and conjunctiva. Treating pinkeye is costly in medication and labor.

Heel flies are not inherently a pest to cattle, but they lay their eggs on the lower legs of cattle. When the eggs hatch, the larvae enter under the skin of the host animal and move through the body. They typically take nine months to migrate through the body until reaching the back of the animal and then cause a wound when they finally exit the body to fall to the ground and pupate.

Fly controls can be used easily and successfully to reduce flies. Beginning with good environmental management, fly numbers can be reduced by eliminating conditions which favor flies. Damp and shaded areas, manure and neighboring cattle with flies can contribute to higher numbers of flies on cattle. Removing them can have a significant impact on fly numbers.

Insecticides can be used in various forms to control flies. The most important two factors for successful fly control are timing of the use of fly controls and rotation of the insecticide to prevent any type of resistance.

Insect Growth Regulators are insecticides that work by eliminating flies in their early stages of life and therefore breaking the life cycle of fly populations. Most IGRs are delivered to cattle in feed or mixed into free choice supplement products.

Fly tags can be used as a passive fly control. Tags are embedded with insecticide and last 60 to 90 days. As cattle congregate and rub on themselves and others the insecticide is spread throughout the herd. Fly tags do require labor to tag cattle and to remove tags later after they have lost effectiveness.

Rubs and oilers can be used to passively deliver insecticide to cattle. Most are placed around an item cattle need and want access to such as water or supplements. As cattle go for the water or supplements, they brush against the rub or oiler and receive insecticide on their hide. Cattle must become conditioned and accustomed to rubs and oilers as at first they are seen as an obstacle to avoid while trying to get to water or supplements.

Fly sprays are some of the oldest forms of insecticide delivery. Many are water based and can be easily sprayed on cattle using hand powered or machine powered sprayers depending on herd size. The down side is many spray products have short durations of effectiveness or can be diluted by rain and wading in water. Time and labor to reapply fly sprays is a major consideration.

Pour-on products deliver insecticides, which are absorbed into and through the skin, with various lengths of effectiveness. Some products deter flies from landing on cattle. Others perform similar to IGR products and can eliminate fly egg viability or kill flies in larval stages. Many pour-on also deliver products to control internal parasites. Producers like these products due to the dual purpose. Pour-on products must be delivered in calibrated amounts based on cattle weight. To do this, handling is required to effectively administer proper dosages to each animal.

As with most animal health management decisions, working with your veterinarian to develop a parasite control plan will give you the most effective and economical options. In the end you will have more productive and less annoyed cattle.