Combating Milk Fever,

Parturient paresis is a metabolic disease which is associated with parturition and initiation of lactation. It is characterized by low total serum calcium and inorganic phosphorus. Failure of the calcium homeostatic mechanism at parturition is associated with: (1) advanced age of cattle—older cattle absorb less dietary calcium and may have less exchangeable bone calcium; (2) too great an intake of calcium, over 100 to 125 g/ day; (3) reduced intake at parturition, greater in older cattle; (4) overconditioned cows which appear to go off-feed easily; and (5) increased hormones, estrogen, and glucocorticoids at parturition which may reduce serum calcium. Attempts to prevent failure of this mechanism include: (1) feeding prepartal diets low in calcium; (2) adjustment of the dietary calcium-to-phosphorus ratio; (3) feeding acidic diets, mineral acids, or ammonium chloride prepartum; (4) short-term administration of 90 to 100g of calcium chloride daily; (5) feeding massive doses of vitamin D prepartum; (6) prepartum administration of 25-hydroxycholecaIciferol, a metabolite of vitamin D 3 . While much is known, the real cause of failure in the calcium homeostatic mechanism remains unanswered.