Journal of Animal Science, Vol 68, Issue 9 2833-2838, Copyright © 1990 by American Society of Animal Science

JOURNAL ARTICLE

Effects of intravenous infusion of high levels of potassium and sodium on mineral metabolism in sheep

S. H. Rahnema and J. P. Fontenot
Dept. of Anim. Sci., Virginia Polytechnic Institute and State University, Blacksburg 24061.

A metabolism trial was conducted with 18 crossbred (Finn x Dorset x Suffolk) wethers, fitted with indwelling jugular catheters and abomasal and ileal cannulas, to determine the effects of high levels of i.v.-infused K and Na on mineral metabolism. The wethers (40 kg) were fed 800 g daily of a 60% concentrate diet in two equal portions at 0800 and 1900. Six wethers were infused randomly with 19 g K+, six with 10.6 g Na+ (chloride salts) and the other six with physiological saline solution (1.2 g Na) per day. Potassium chloride or NaCl infusion had no effects on apparent absorption, retention, flow or partial absorption of Mg, Ca and P in the digestive tract compared with physiological saline infusion. With all treatments, Mg and Ca were absorbed proximal to the abomasal cannula. Magnesium was secreted into, whereas Ca and P were absorbed from, the small intestine. Phosphorus was secreted both in the stomach and large intestinal regions of the digestive tract. Major sites of K and Na absorption were the small and large intestines, respectively. Infusion of K increased (P less than .05) retention of K compared with Na infusion. Infusion of Na increased (P less than .05) excretion and retention of Na compared with K infusion. Serum minerals were not changed by K or Na infusion compared with saline. The results of this experiment indicate that the depressing effects of K on Mg absorption are not attributable to high levels of absorbed K, but rather to K present in the digestive tract prior to the small intestine.