By: Brandi B. Karisch, Extension Beef Cattle Specialist, Mississippi State University
Beef producers have many options available to include in beef cattle diets that can offer many benefits in a small package. These feed additives can function to improve production, feed efficiency, and even animal health. Although most typically think feed additives are used in feedlot operations, their usefulness in grazing cattle, both stocker and cow calf is well documented. For cattle on pasture, the most commonly used feed additives function to improve feed efficiency and growth or to reduce the incidence of bloat, illness, or parasites. It is extremely important that label directions are followed explicitly for medicated feed additives, and withdrawal times are strictly adhered to. Feed additives can be classified into several broad categories: rumen fermentation modifiers, animal health products, and direct-fed microbials.
Ionophores fall into the category of rumen fermentation modifiers, and actually function to modify the microbial population in the rumen. These antimicrobial compounds function to inhibit some microbes in the rumen, thereby selecting for those microbes which are more efficient or produce products that are more efficiently used by the animal. By altering this microbe profile, the type of volatile fatty acid produced in the rumen is altered, and less methane is produced. This results in an improved feed efficiency and improved production. In addition to these benefits, ionophores also can reduce the incidence of coccidiosis, acidosis, and bloat. Specifically in stocker cattle, the use of ionophores has been show to increases ADG by 5–15% and improves feed efficiency by 8–12% (Lawrence and Ibaruru 2008; Elam and Preston 2004). Currently there are several commercially available options (monensin-Rumensin®, lasalocid-Bovatec®, laidlomycin propionate-Cattlyst®) that are often purchased pre-mixed into minerals or supplements.
Feed additives that affect animal health can be further split into several categories: antibiotics, fly control, and parasite control. Antibiotics can be utilized in 2 methods. They may be fed at continuous low levels and included in a mineral or feed supplement to cattle on pasture. These sub-therapeutic doses function to improve growth or feed efficiency. When fed at higher levels, antibiotics may be used to treat or prevent scours, coccidiosis, shipping fever, anaplasmosis, foot rot, and liver abscesses. This simply results in healthier cattle with improved productions. Chlootetracycline (CTC) is one popular choice for antibiotics in feed.
Feed through fly control products can be included in a feed or mineral supplement for cattle on pasture. These may be referred to as insect growth regulators or IGR technology. With this method, an insecticide designed to prevent larvae from reaching maturity is mixed into a feed or mineral source for the cattle to consume, and typically works best if it is fed before the adult flies begin to emerge. The major benefits of the feed through option are attributed to its application method. Since the fly control is present in the feed or mineral cattle would already be consuming, there is little extra labor or stress involved for the cattle. Some disadvantages of this option include consumption, the product is not effective if cattle do not consume it in adequate amounts, and fly transfer, if cattle are near other animals not treated for flies, and it is likely that adult flies will transfer to the treated herd. It is important to remember that these feed through products reduce fly counts by interrupting the life cycle of the fly, not by killing adult flies.