Diets with more than 30 g K/kg DM have previously been associated with hypomagnesaemia in grazing cattle, and to test
whether such diets lead to mineral disorders in sheep, the absorption ofMgand other elementswas investigated using experimental
diets to whichKC1had been added to provide 27, 29, 32 or 34 g K/kgDM.The apparent absorption, balance and apparent retention
of Mg, and to a lesser extent Ca, were reduced for sheep offered the diets with 32 or 34 g K/kg DM. The absorption and retention
of K, Na, P, Zn, Pb and Cd was not affected by treatment. The blood intracellular Ca concentration was reduced by the diets
with 29, 32 or 34 g K/kg DM, compared to the diet with 27 g K/kg DM, but the concentration of other elements was unaffected.
Blood plasma Ca concentration was increased at the highest level of K inclusion, providing evidence of mild hyperkalaemia
and the involvement of Ca homeostatic mechanisms. It is concluded that Mg absorption by sheep will be impaired if the diet
contains more than 30 g K/kg DM, equivalent to an intake of approximately 13 g K/d, but that a high K diet may be beneficial
before parturition to accustom the sheep to Ca mobilization before lactation.
© 2005 Elsevier B.V. All rights reserved.
Mg absorption , Ca mobilization , sheep , k , Hypomagnesaemia