Magnesium depletion and repletion effects on magnesium, calcium and potassium in bone, muscle, cerebrospinal fluid and plasma of sheep

The major objectives of this experiment were to evaluate the effect of magnesium depletion and subsequent repletion upon the mineral levels (Mg, CS; and K) in bone, skeletal muscle, cerebrospinal fluid and plasma in yearling and mature wethers. Two separate identical trials were conducted using 12 yearling wethers (trial I) and 12 mature wethers (trial II). The animals were divided into a control group of four wethers fed a magnesium supple-mented diet, and a treatment group of eight wethers fed first a magnesium deficient diet, and then, at the point of magnesium depletion, switched to a magnesium supplemented diet (repletion). Four times during each trial, biopsy samples of bone, skeletal muscle, cerebro-spinal fluid and plasma were taken from each wether. Records of feed consumption, fecal excretion; and urine excretion were recorded and samples of each were collected from each animal. The yearling treatment wethers were depleted of bone magnesium more rapidly and to a lower level than the mature wethers, which showed a similar decreasing trend. Repletion had no immediate effect on the magnesium level in the bone in either trial. The plasma magnesium level of treatment wethers in both trials dropped rapidly during depletion, and increased rapidly during repletion. There was no significant effect found in either trial on the mineral status of skeletal muscle or cerebrospinal fluid due to magnesium depletion or repletion. However, the skeletal muscle of the treatment wethers in trial I showed a slight decreasing trend in magnesium level.