How To Prevent Milk Fever

No one knows the cause of milk fever, or hypocalcemia (as it's properly called). The following, however, is known:

[1] The disease occurs primarily in high-milk-production cows that have calved once or twice before.
[2] The symptoms begin to appear—usually—within 72 hours after calving. (First, the afflicted animal shows signs of unsteadiness . . . then she collapses and lies with her head turned to one side, her eyes dull and expressionless. The name "milk fever" notwithstanding, the cow's temperature is usually below-not above-normal.)
[3] The physiological abnormality most consistently associated with the disease is low blood calcium.

Our college dairy herd—a combination of Holsteins and Ayrshires—is relatively high-production by Quebec (Canada) standards and has had its fair share of milk fever. Last year, however, we initiated a new feeding program that has proven 100% effective in preventing milk fever. Here's what we did:

We divided our animals into two equal groups. The first received the usual high-calcium feed prior to calving, while the second got five to seven pounds of low-calcium grain and hay per animal per day for the 10 to 14 days before delivery. (The latter diet provides 100% of the dry cow's energy, protein, and phosphorus needs, but only 60% of her calcium requirements.)

What we observed was that the animals in the "high-calcium" group went on to experience the usual incidence of milk fever after calving . . . while every one of the cows that'd been on the low-calcium diet remained healthy.