ABSTRACT
Dairymen in the Netherlands have known for many years that cows may develop tetany soon after being turned out from the stall to grass. This condition is known as grass staggers, grass tetany, or lactation tetany. Blood magnesium level falls rapidly within 2 days to 2 weeks after the animals are turned out to grass; the incidence of clinical signs, both with and without hypocalcemia, is high and not necessarily associated with calving. The hypomagnesemic tetany of milk-fed calves and of nonlactating adult bovine animals on poor upland pasture could be attributed to a simple dietary deficiency of magnesium. The magnesium content in pastures in northern Europe is lowest in early spring. Ruminants have a complex 3- or 4-chambered stomach. The rumen is the large first compartment of the stomach of a ruminant from which food is regurgitated for rumination and in which cellulose is broken down by the action of bacterial and protozoan symbionts.
