The basis principal to prevent milk fever is to maintain a high plasma Ca level at the time of parturition to overcome the sudden high demand for Ca. For that hormonal therapy and dietary manipulations are successful. Among them, hormonal therapy does not seem to work in the field as it needs an accurate prediction of the date of parturition for the administration of hormones. The dietary manipulation may be the best and easiest way to prevent milk fever in this regard. The supplementation of anionic diet salts brings about a mild acidosis in the body thus increasing the rapid absorption of Ca through intestine and bone resorption.Thus the extracellular level of Ca increases which helps in coping with the demand of Ca particularly in the early lactation. To be more sure of prevention of the disease, anionic salts should be supplemented with high Ca diet so that sufficient amount of Ca is absorbed through intestine. Among the anionic salts, MgSo4 may be used commonly as it is more palatable to the animals and cheap. However, ammonium salts such as NH4Cl and NH4SO4 although effective are less palatable. A useful tool is to measure the urine pH i.e. pH 5.5-6.5 to monitor anion cation balance in diet.