Prevention of Milk Fever by Application of Dietary Cation-Anion Balance Concept

Milk fever (hypocalcemia) in dairy cows is caused by an acute deficiency of blood calcium, usually immediately before or after calving. It is often more common in mature cows. Both clinical and subclinical hypocalcemia can seriously affect cow health, including dystocia, retained placenta, prolapsed uterus, displaced abomasum, and left abomasal displacement. Limiting the calcium intake of non-lactating cows by changing forage can help prevent milk fever, but is often not practical. A more practical strategy is decreasing the dietary cation-anion difference (DCAD) in dry cow diets for 10 days to 3 weeks just before calving. DCAD is the sum of the positively-charged ions sodium and potassium minus the sum of the negatively-charged ions chloride and sulfur and can be decreased by adding anionic (sometimes called acidogenic) salts to the diet. Problems to consider are toxicity, palatability, the offsetting effects of other elements of the cow's diet, and avoiding feeding this diet to lactating cows. Supplemented by references, DCAD tables, and formulation instructions. 8 pages