EFFECT OF MAGNESIUM SUPPLEMENT AND HOUSING ON SERUM TRANSAMINASE ACTIVITIES IN BEEF-COWS

Eighteen groups, each containing 4 pregnant Shorthorn beef cows, were used to determine the effect of magnesium supplementation on serum tra nsaminase activities. Three mineral supplements (no magnesium, 8% magn esium as magnesium oxide, and 0.8% magnesium as sequestered magnesium) were offered to 6 groups throughout the experiment. Six groups, 2 on each mineral supplement, remained indoors throughout the summer; the o ther 12 groups were turned out to pasture on May 25 and continued rece iving the appropriate mineral supplement. Cows on pasture had greater (P < 0.05) activities of both serum glutamic-oxaloacetic transaminase (SGOT) and serum glutamic-pyruvic transaminase (SGPT) starting about 1 0 d after turn out to pasture than cows housed in the barns. Supplemen tation of magnesium either as magnesium oxide or as sequestered magnes ium had no significant effect on serum transaminiase activities of cow s and calves. Cows on pasture had significantly higher transaminase ac tivities than cows housed in the barn. The SGPT activity of carves wer e initially less than those of cows, but by September their levels wer e similar to those of the cows.