|Nelsen Terry C,|
|Calvert Corlette, - USDA, RETIRED|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 5, 1994
Publication Date: N/A
Interpretive Summary: The amounts of minerals in digesta, whether they are in a form to be absorbed by the body, and interactions of minerals with dietary fiber are of interest to scientists concerned with recommending healthy diets. This study used pigs as model animals because their digestive system is similar to that of humans. The pigs were fed diets, mineral supplemented and not supplemented, that contained 10% corn bran as the added dietary fiber source. The total amounts of seven minerals in retrieved digesta, the amounts free to be available for absorption by the digestive tract and the amounts of calcium and potassium associated with the corn bran were measured. Only a small amount of calcium was captured by the corn bran, so that in diets containing adequate minerals, moderate amounts of added corn bran should not interfere with mineral metabolism. In mineral supplemented diets, higher concentrations of calcium, zinc and copper were available for absorption in the small intestine. This information is useful to nutritionists and animal scientists.
Technical Abstract: The intent of this work was to measure total and free minerals in pig digesta and to test the practicality of using energy-dispersive X-ray methods to determine concentrations of minerals in corn bran retrieved from digesta. Concentrations of Na, K, Ca, Mg, Zn, Fe and Cu, total and free to pass through a 1000 MW ultrafilter, were measured in digesta recovered from five gastrointestinal tract locations in pigs. A mineral-supplemented basal diet containing (by weight) about 10% dry-milled corn bran, 20% soybean meal and 67% degermed corn grits, was fed to six pigs. Another group of six pigs was fed the diet without mineral supplementation. Mineral concentration ratios, free/total, over the GI tract were not significantly different as a function of diet. Free concentrations (mM) over the GI tract with mineral supplemented diets were: K=222, Na=426, Ca=52, Mg=62, Zn=.32, Cu=.08, Fe=.09; with diets not mineral supplemented, K=243, Na=431, Ca=28, Mg=74, Zn=.16, Cu=.06, Fe=.05. Free concentrations of Ca, Mg and Zn were highest in the stomach: free concentration of Cu was highest in the upper GI tract. Significant differences, supplemented vs. not supplemented diets, in free Zn (.12 vs. .04 mM) and Cu (.032 vs. .015 mM) were measured in samples retrieved from the jejunum and ileum. Total concentrations were higher in the lower GI tract, except for Na, which was highest in the jejunum and ileum. Energy-dispersive X-ray analysis was used to measure the K and Ca contents of retrieved corn bran, wherein concentrations were proportional to free concentrations. The calcium content of retrieved bran was always higher than the initial content.