A preliminary re-assessment of the requirements for major minerals by growing pigs

Forty-two mineral balances were measured in 50 kg pigs fed various diets, including barley, maize or potato, and used to examine the presumption that the current recommended dietary requirements for the major minerals, especially phosphorus, are essential to the well-being of the pig. All the diets contained similar levels of all the mineral elements, except potassium which was higher in the diets containing potato. The concentrations/kg dry matter were 11.0 g calcium, 6.9 g phosphorus, 0.96 g sodium, 1.5 g magnesium and 5.4 g potassium or 14.0 g potassium in the diets containing potato. The apparent digestibility coefficients were calcium 0.39, phosphorus 0.46, sodium 0.72, magnesium 0.26 and potassium 0.70 or 0.80 and the gross efficiencies with which the ingested elements were retained were calcium 0.36, phosphorus 0.25, sodium 0.32, magnesium 0.07 and potassium 0.22 or 0.16. The low efficiencies of utilisation of the digested minerals, especially phosphorus (0.53), suggested that a reduction in dietary phosphorus levels may be justified in terms of reducing the pollution of the environment with phosphorus caused by the application of pig slurry.