Magnesium is necessary to maintain normal rumen fermentation, skeletal growth, production, reproduction, and health. Depressed fiber digestibility and impaired reproduction usually occur when rations are not balanced for this element or properly supplemented. Low magnesium intake may result in grass or winter tetany and complicated milk fever cases. Excessive magnesium may depress intake, digestibility, and production. This may result in nutritional scouring or diarrhea.
Sulfur is necessary for the synthesis of essential amino acids by rumen microbes.
Sulfur supplementation is important in rations containing high levels of nonprotein nitrogen since several sulfur-containing amino acids must be made by rumen microbes, notably, cysteine, cystine, and methionine. Low sulfur intake results in an induced protein deficiency, and excessive intake damages liver tissue and function. Forages should be tested periodically and balanced for this nutrient. Potassium is essential for maintaining acid-base balance relationships and allowing transmission of nerve impulses to muscle fibers. It activates or functions as a cofactor in several enzyme systems.