Changes in concentrations of certain plasma and erythrocyte minerals associated with hypomagnesaemia in young calves.

Hypomagnesaemia was induced in young calves 1-2 weeks old by feeding them with a diet composed of skimmed milk and barley straw to which urea, potassium chloride and soya-bean oil were added. Blood samples were collected from each calf once a week from the jugular vein until there was a significantly lower (P less than 0.01) plasma magnesium (PMg) concentration in the experimental compared to the control calves receiving MgO instead of KCl. In addition to PMg, the blood samples were analysed for plasma sodium, potassium, calcium, inorganic phosphate and erythrocyte concentrations of magnesium, sodium and potassium and red blood cell counts. The erythrocyte magnesium (EMg) concentration decreased significantly (P less than 0.01) in both groups. The decrease was, however, greater (P less than 0.05) in the magnesium deficient group than in the control group. Erythrocyte sodium (ENa) concentration increased and erythrocyte potassium (EK) concentration decreased in both groups, and the changes did not differ significantly between the two groups. Plasma concentrations of sodium (PNa) and potassium (PK) and red blood cell counts did not change significantly in either group. Significant (P less than 0.05) decreases in plasma calcium and inorganic phosphate concentrations occurred in the magnesium deficient group only.