Ionophores Improve Feedlot Cattle Health Efficiency and Performance

By Andi Anderson

Ionophores are special compounds used in beef cattle diets to improve weight gain, feed efficiency, and control a disease called coccidiosis.

They are classified as antibiotics, but they are not used in human medicine and are not regulated under the veterinary feed directive. In the United States, the three approved ionophores are monensin, lasalocid, and laidlomycin propionate.

Ionophores work by affecting specific rumen bacteria, mainly gram-positive organisms. These compounds disrupt the bacteria’s energy production, reducing their activity and causing a shift in the rumen microbiome.

This shift increases the number of beneficial bacteria that use lactic acid and reduces those that produce lactic acid and methane. As a result, cattle produce more propionate, an efficient energy source, and less methane, which represents lost energy.

Ionophores also help manage protein digestion by lowering bacteria that cause excessive ammonia production. This supports better use of dietary protein in the small intestine.

Research over several decades has shown that ionophores consistently improve cattle performance. Studies have reported increased average daily gain, reduced dry matter intake, and improved feed efficiency.

Early trials in the 1970s and 1980s showed large improvements, while recent studies still show reliable gains of about 2.5 to 3.5 percent in feed efficiency with modern genetics and feeding systems. Ionophores also shift the rumen volatile fatty acids toward more efficient energy use.

In addition to performance benefits, ionophores such as monensin and lasalocid act as coccidiostats, helping control coccidiosis in young calves. This disease causes diarrhea and reduced appetite, leading to poor growth.

Including a coccidiostat in milk replacer or starter feed can help protect calves until weaning.

The economic return from feeding ionophores is strong. Based on typical feedlot diets and expected improvements in growth and efficiency, cattle fed ionophores may return about $37 more per head.

The return on investment is estimated at nearly 5 to 1, making ionophores a cost-effective tool for producers. When combined with improved health and disease prevention, ionophores offer valuable benefits for modern feedlot systems.

Photo Credit: gettyimages-ahavelaar