Horn fly control in grazing cattle can be aided with the use of a mineral with MTH, or methoprene. These are generally added into a mineral and called IGR's. IGR stands for intake growth regulators. The IGR's break the cycle of the fly, whereas the second hatch of flies after IGR's are introduced in the cow's mineral will never make it to the adult stage to reproduce. In laymen's terms, it is birth control for flies. Most commercial feed manufacturers offer a product line with MTH included in the mineral. The cost is minimal, when you consider the amount of time your cattle are standing together, swatting flies off of each other, intead of foraging for grass. Purina Mills offers are large line of "wind and rain" minerals that are specific for your needs, such as fescue type minerals and lower phos/cal ratios for areas that have land applied chicken manure. You can also get these with CTC (chloratetracycline) levels for pinkeye, footrot, and potential anaplasmosis control. When considered on a cost per head per day vs. fly tags, time to spray cattle, equipment necessary to spray, and potential pinkeye/ footrot problems. it is a very inexpensive piece of arsenol to have. You can feed this to "show" cattle as well through a mineral feeder, or dumping a little in a pan in their pens seperate from their feed. We put about a coffee can out in the cement bunks for the few calves that are at the house, then put more out when they ear it, and put out loose mineral in the pastures for the cattle. There is no withdraw time for MTH, or an identified LD50 (it's pretty safe). The product that we use is a complete, where no added salt is necessary, so it's simple, which I dig.
