Calcium mobilisation in hypomagnesaemic cattle

Intravenous infusions of EDTA solution (4.7 per cent w/v) were used to induce hypocalcaemia in six steers and six non-pregnant lactating Friesian cows, once when they were normomagnesaemic and once when they were hypomagnesaemic (less than 0.85 mmol Mg per litre) and their rates of calcium mobilisation have been measured. The mean rates of calcium mobilisation by the normo- and hypomagnesaemic steers were 0.32 mmol/min and 0.21 mmol/min respectively (P less than 0.005) and the mean calcium mobilisation rates of the cows were 0.41 mmol/min and 0.26 mmol/min respectively (P less than 0.02). It is concluded that hypomagnesaemia reduced the calcium mobilisation rate in both steers and non-pregnant lactating cows.