Most of the attention on mineral excesses is typically focused on sulfur and molybdenum.
Less attention is paid to iron, but it should not be ignored.
Iron is found in feed, water, and soil. From the book, Mineral Levels in Animal Health by Robert Puls, he indicates that iron levels between 100 and 500 ppm in the ration is adequate for beef cattle. Levels above 400 ppm can reduce feed intake and it is recommended to keep levels below 1,000 ppm. Levels above 4,000 ppm can be toxic.
Calves are more likely to have an iron deficiency. Symptoms include a reduced immune response and reduced weight gain. It is very seldom for a deficiency to be observed in mature cows.
Issues surface when there is excess iron in a ration. Iron interferes with the absorption of nutrients. Levels above 300 ppm reduce copper absorption. Cobalt, Copper, Manganese, Zinc, and Selenium deficiencies can be induced by high iron levels.
Iron in plants is absorbed from the soil. Depending on soil type and moisture conditions, concentrations are variable. Well water is more likely to have higher iron content than dugout water under normal weather. In the last few years, water recharge and flushing of dugouts has been limited. With evaporation, mineral content in dugout water becomes concentrated which increases problems.
Harvest management can also impact iron content in the feed. Cutting forages close to the ground or scratching the ground with pickup teeth on a baler or silage harvester kicks dirt into the swath. This increases iron content in the harvested crop. Some feed test results I have reviewed contain more than 1,000 ppm iron.
Feed and water testing is needed to establish the concentration of iron and other nutrients. Trace mineral supplement programs need to be adjusted when high iron is present to prevent a reduction in animal performance or deficiencies from occurring.
If you have questions about iron in cattle rations, contact Barry at 403-741-6032 or bjyaremcio@gmail.com.