The influence of the diet with different magnesium content on chosen chemical and physical properties of bones of young rats was investigated. In the first part of the work the influence of the calcium level in the diet on the content of magnesium and some other mineral constituents in bone was also studied. The investigations were carried out on growing Wistar rats weighing 96-100 g. During 21 days the animals were fed the following semi-synthetic diets: a) with different content of calcium: 0,214, 0,418, 0,610, 0,815% Ca and the same level of magnesium (av. 554 ppm Mg), b) with different content of magnesium and the same level of calcium (av. 0,614% Ca). The content of phosphorus was the same (0,440%) in all the diets. The control diet contained: 0,610% Ca, 0,44% P and 550 ppm Mg. After 21 days of experiment the animals were killed by anesthesia and the femurs and humeri were isolated. They constituted the material for investigations. The results of the investigations showed that the variable level of calcium (from 0,214% to 0,815%) in the diet with the same level of magnesium did not influence the content of magnesium and phosphorus in dry fat-free weight of bones. The body weight of rats fed the diets with different content of calcium was very similar to the control group. On the contrary the weight of femurs and calcium content in dry fat-free weight of bones of rats fed the diet with the lowest level of calcium (0,214%), were smaller than in the control group. In the group of rats fed the diet with 60 ppm Mg the visual symptoms of magnesium deficiency appeared after 7 days of the experiment. After 21 days the body weight and length of bones in this group were smaller than in the control group. Also the content of magnesium and phosphorus in dry fat-free weight of bones, breaking strength, and the strength of twisting destroying moment of bones were lower in this group of rats as compared with the control one (for most indices p less than 0,01). The group of rats fed the diet with 120 ppm Mg differed from the control group only by smaller content of magnesium in dry fat-free weight of bones. There was no statistically significant difference in the group of rats fed the diet with 2060 Mg regarding all indices except for the phosphorus from the control group.
Animals Bone and Bones