“Ionophores in the Cow Herd”
by Chris Reinhardt, feedlot specialist
Use of ionophores in the feedlot industry is commonplace, but they are still a relative novelty in the cow/calf sector. It may help clarify the function and value of ionophores by starting with a refresher course on how the cow’s rumen works.
We often say “the cow feeds the bugs, and the bugs feed the cow.” Rumen bacteria and other microbes break down the complex carbohydrates that are the major components of forage consumed by the cow, and in the process release much smaller compounds that the cow can use for energy. Some types of bacteria create byproduct compounds which have greater total energy value to the cow and produce less energetically wasteful byproducts, such as methane, than other types of bacteria.
Ionophores function by selectively killing certain types of bacteria in the rumen, which produce the less efficient fermentation, improving rumen environment for other bacteria that produce a more useful and efficient fermentation. By shifting the rumen population, the cow can get about 10% more useful energy out of a given feedstuff.
There are 2 ways to use this extra value. Since rumen volume and intake are limited by how much forage cows can consume, thin cows or heifers can get 10% more energy out of the same amount of forage, in order to put on body condition. But equally valuable is that we can actually reduce the forage needs for fleshy cows by 10% while still maintaining body condition.
It’s up to the manager to decide how to make best use of the added efficiency, but given the current situation, it’s nice to have these kind of choices.
