Many mineral deficiencies are noticed only after a prolonged period of underfeeding has occurred. Generally, problems will first be observed in the areas of animal health and reproduction, says J.W. Schroeder, North Dakota State University extension dairy specialist. Although it may take time for clinical symptoms of a mineral deficiency to appear, subclinical deficiencies may have been impairing performance for quite some time.
The ability to meet mineral requirements is complicated by the fact that mineral absorption is lower than absorption of most other nutrients. Mineral absorption varies from one mineral to another and by the form of the mineral. With many minerals, absorption of the mineral decreases as the amount in the diet increases. Older animals also absorb minerals at lower rates.
"Even when we have determined how much of the correct form of a particular mineral to feed, our job is not complete, as there are numerous known interactions between minerals to consider (i.e. high levels of one will decrease utilization of another)," Schroeder says.
Known mineral interactions include copper-molybdenum, sulfur-selenium, calcium-phosphorus, calcium-zinc, calcium-manganese, iron-manganese and potassium-magnesium.
To keep the cost of mineral supplementation down, try to maximize the percent of minerals found in typical feedstuffs. However, remember that the mineral content of feedstuffs is quite variable.
Click here for more information about the use of minerals in dairy cattle diets.
Source: North Dakota State University Extension Service