Dietary potassium bicarbonate and potassium citrate have a greater inhibitory effect than does potassium chloride on magnesium absorption in wethers

We addressed the question whether the type of anion in potassium salts affe cts magnesium absorption and the transmural potential difference by using w ethers (n = 8) fed a control diet and diets supplemented with equimolar amo unts of KHCO3, KCI or K-citrate according to a Latin-square design. The con trol diet contained 10.9 g K/kg dry matter and the high K diets contained 4 1.3 g K/kg dry matter. Compared with the control diet, KHCO3 and K-citrate significantly reduced apparent Mg absorption by 9.5 and 6.5%, respectively. Supplemental KCI tended to reduce (P = 0.070) group mean magnesium absorpt ion by 5.5%. Consumption of supplemental KHCO3 and K-citrate produced a sig nificant increase in the transmural potential difference (serosal side = po sitive) by 17.1 and 20.7 mV, respectively, whereas the addition of KCl to t he diet did not. The individual values for the four diets tended to show a negative correlation (r = -0.336, n = 32, P = 0.060) between the transmural potential difference and apparent magnesium absorption. We conclude that d ifferent potassium sails have different effects on magnesium absorption in ruminants as caused by different effects on the transmural potential differ ence.