The objective of this study was to evaluate the performance and net requirements for calcium (Ca), phosphorus (P), magnesium (Mg), potassium (K) and sodium (Na) in Dorper × Santa Ines F1 crossbred lambs under different grazing times and supplement levels. We used 36 uncastrated male lambs with initial body weights (BW) of 15.5 ± 1.9 kg. Twelve animals were used as a reference group, and the remaining 24 animals were divided into three treatments according to grazing time and supplement level: 9 h × 1.2% BW, 6 h × 0.84% BW and 3 h × 0.48% BW. There were increases in the final BW, average daily gain (ADG) and dry matter intake (DMI) of pasture (p < .05) in lambs that grazed longer (9 h × 1.2% BW). Feed efficiency (G/F ratio) was similar between the 9 h × 1.2% BW and 6 h × 0.84% BW groups and both the groups were greater than the 3 h × 0.48% BW. However, there was a reduction in the DMI of concentrate, total DMI, and Ca, P, Mg and K intake (p < .05) for lambs that grazed longer. However, pasture DMI and sodium intake increased (p < .05) in animals that grazed for less time (3 h). The chemical composition of the empty bodies in DM, fat, ash, Ca and P showed the greatest values (p < .05) in groups with animals grazing 9 h with a supplement level of 1.2% BW. Net maintenance requirements were 0.101–0.202 g Ca/day, 0.204–0.408 g P/day, 0.053–0.105 g Mg/day, 0.386–0.771 g K/day and 0.105–0.211 g Na/day for crossbred lambs between 15 and 30 kg BW. For the same group, net requirements to gain 100/200 g/day BW were 1.171/2.341–1.667/3.333 g Ca/day, 0.694/1.398–0.998/1.995 g P/day, 0.027/0.054–0.032/0.063 g Mg/day, 0.098/0.195–0.091/0.182 g K/day and 0.315/0.629–0.311/0.621 g Na/day. Lambs grazing longer (9 h × 1.2% BW) displayed increased ADG and concentrate intake and reduced forage intake, which increased intake and body retention of Ca, P, Mg and K.