Effects of dietary potassium and sodium on magnesium utilization in sheep.
Two metabolism trials were conducted to determine the effect of altering dietary Na and K on Mg availability. Three dietary treatments (normal K-normal Na, high K-normal Na and high K-high Na) were imposed upon nine crossbred wether lambs in a randomized block design. Each trial consisted of a 5-d diet adjustment, a 10-d preliminary period and a 5-d collection of feed, feces and urine. Increasing K and Na intake increased the percentage of Mg excreted in feces. Both elevated K and K-Na depressed (P less than .10) urinary Mg excretion, primarily a reflection of depressed Mg absorption in animals fed these diets. Apparent K absorption and retention increased when animals were supplemented with K. Addition of Na to the diet did not alter absorption or retention of K. Apparent K and Na availability increased when K and Na supplements were included in the diet. This increased availability resulted from increased total absorbed K and Na compared with a fixed endogenous excretion. Calcium balance in lambs was not affected by addition of K or Na. Lambs were able to absorb enough Mg from their respective diet to maintain normal serum Mg levels. Addition of Na to a diet high in K did not enhance Mg absorption in lambs.
D000821:Animal Feed; D000818:Animals; D001682:Biological Availability; D008274:Magnesium / Q000378:metabolism* / Q000652:urine; D008297:Male; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology*; D012756:Sheep / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology*
D012964:Sodium; D008274:Magnesium; D011188:Potassium