Effects of dietary calcium levels on concentration and solubility of macro minerals in the digestive tract of sheep.

Digesta samples were collected from rumen, omasum, abomasum, upper small in tes t ine , middle small intestine, lower small intestine, cecum and colon to study the effects of dietary calcium levels on the concentration and solubility of minerals in the digestive tract of sheep. Ca lc ium c o n c e n t r a t i o n s in d ige s t a and supernatant increased and calcium solubilities tended to become lower with the elevation of dietary calcium level. In comparison with the concent ra t ions of calcium, magnes ium and potassium, the concentrations of phosphorus and sodium in digesta and supernatant were higher in the rumen and the omasum. A net absorption of calcium appeared to occur in the upper small intestine and that of phosphorus in the middle and the lower small intestine. Similar to calcium, a decrease in phosphorus solubility was found in the lower small intestine when high ca lc ium r a t i o n s were given. S u p e r n a t a n t concen t ra t ions of magnes ium, sodium and potassium increased in the upper small intestine and decreased in the middle and lower small intestine. Although calcium, phosphorus and m a g n e s i u m c o n c e n t r a t i o n s in d ige s t a and supernatant did not decrease in the cecum and the colon, sodium and potassium lowered in these sites. ( K e y W o r d s : D i e t a r y C a l c i u m , M i n e r a l Concentrations, Digesta, Sheep.)