A multi element supplement for grazing sheep. I. Intake, mineral status and production responses

Abstract

The safety and effectiveness of a loose mineral lick containing all known essential elements was investigated in an experiment in which 96 Merino weaner wethers grazed subterranean clover/grass pastures during summer and autumn. The treatments were no supplement or mineral mix ad libitum; there were four plots of 12 sheep per treatment. The mean intake was 29 ¦ 1 g/head per day of the mix and those offered the minerals had blood concentrations of P, S, Se and vitamin BIZ in the normal range. Unsupplemented Control sheep had blood concentrations of P, S and Se in the deficient range for all or part of the experimental period. There was an estimated 1.6-fold range in mineral intake between sheep, and none refused the mix. Concentrations of Cu, Cd and F in tissues and bone of sheep offered the mineral mix were within accepted safety margins. The mineral lick increased live weights by 4.5 kg during summer (P < 0 - 05), increased clean fleece weight by 240 g (9%), (P < 0.01), and increased wool staple strength by 15 N/kt (40%), (P < 0.01). The pasture concentrations of most macro elements decreased between November and March, respective concentrations being (g/kg DM): K, 17- 7 and 1.9; Na, 4-0 and 0.31; S, 1.6 and 0.9; N, 12.9 and 10; P, 1-95 and 1-08; Ca, 7-86 and 9-75; Mg, 2.29 and 1-38. Changes in trace element concentrations were small, the respective values being (mg/kg): Cu, 9.7 and 10-3; Mn, 47 and 67; Fe, 56 and 323; Zn, 20 and 20; Mo, 0-2 and 0.35; and Se, 0.015 and 0.032. The loose mineral lick was a safe and effective means of supplying macro and trace elements to grazing sheep during summer.