Studies on the balance and digestibility of organic matter and minerals were carried out on 32 young Black-and-White bulls, divided into 8 groups, fed maize silage with rapeseed oil meal. Control group did not receive any mineral supplement while the rations of the experimental animals were supplemented with sodium phosphate and either limestone or local dolomites (Skalpasz or Dolopasz). Both control and experimental rations were fed either unsupplemented or supplemented with zinc oxide. The addition of zinc oxide and the Skalpasz dolomite raised organic matter and fibre digestibility as well as nitrogen retention. The addition of sodium phosphate and dolomites increased (P≤0.01) the absorption of Ca, Mg and P. During the 180 day period of fattening 120 young bulls with a initial weight of 220 kg, daily live weight gains of the animals receiving dolomite-supplemented rations were 11 and 15% higher than in the control group.