28Mg kinetics in ewes fed normal or tetany prone grass.

Balance studies and a kinetic evaluation of magnesium metabolism with 28Mg were performed on 6 non pregnant ewes, fed first a young normal dried grass, then frozen tetany prone grass. After changing to the tetany prone grass, there was a small drop in blood Mg and a significant urinary decrease of Mg. Mg balance and endogenous fecal excretion were not significantly modified. Total output of Mg from the pool was reduced. The release of Mg from slow exchanging tissues was very low in tetany prone grass fed ewes. The results suggest that hypomagnesemia in ewes fed tetany prone grass could possibly be related to a shift of body magnesium from blood to some other tissue.