Some rations are balanced using only sodium levels and may result in low chlorine due to the use of buffers. Salt should be provided free choice as well as force fed for most animal groups. Salt should be limited somewhat for springing and dry cows when severe problems are encountered with udder congestion. Low intakes seriously reduce feed intakes and production and may increase the incidence of displaced abomasum. Lack of salt also impairs acid-base balance.
Trace elements play an important role in the diet of dairy cattle.
A lack of these elements may adversely affect production and especially health to an extent equal to the deficiency of either protein or energy. Dairy producers at least should monitor levels of copper, zinc, and selenium by using suitable trace mineral premixes containing other elements such as manganese, iron, cobalt, and iodine in proper proportions. Low intakes of trace minerals can be widespread in young stock and dry cows. Copper and zinc often are lacking in rations for milk cows because levels of the elements are low in homegrown feeds in many areas of the country. Induced copper deficiency may result from high sulfate, molybdenum, iron, and manganese intakes through polluted water or crops.