Hypomagnesaemia in housed suckling cows

Clinical cases of hypomagnesaemic tetany were seen over two years during the winter housing period on a Charolais farm. This farm served as the model for the study of the incidence of certain factors linked to hypomagnesaemia in housed suckling cows and provided a scheme for an appropriate means of management. After analysis of the ration, the feed was changed such that 1.5 kg of concentrated carbohydrate, 30 g of NaCl and 10 g of MgO were added to the hay ration distributed as sole feed. Blood-electrolyte concentrations were measured in eight healthy cows during the relevant period and one month after correction of the feed. A significant increase in blood-magnesium concentration (and calcium concentration) was seen and no new clinical cases were observed. To correct hypomagnesaemia during periods of excess K in the forage, provision of Mg as a sole treatment may be insufficient. The role of Ca, P, energy and nitrogen must be evaluated.