Feeding Monensin to Beef Cows Decreases Intake but Increases Efficiency

by Paul Beck, Oklahoma State University State Extension Beef Cattle Nutrition Specialist, Cow-Calf Corner

This year we are all searching for alternatives that can get our cows through the winter on the least feed and hay, without decreasing the long-term productivity of the herd. Even in “normal” years, feed and pasture is close to 70 percent of variable costs and 50 percent of total costs of maintaining a cowherd.

Economic research has shown that high profit producers had 39 percent lower feed and pasture cost than low profit producers. So, practices that decrease feed costs without affecting productivity have potential to improve profitability.

Ionophores are a class of antibiotics that shift rumen microbial populations to increase energetic efficiency and reduce production of waste molecules such as methane.

The ionophore monensin was approved for used in replacement beef and dairy heifers in 1983 and for beef cows in 1988, but there does not appear to be widespread adoption of its use in the cow-calf industry.

The approval for feeding monensin to beef cows indicates that monensin should be