MINERAL ELEMENTS FROM PASTURE FOR GRAZING SHEEP

Pasture was harvested monthly from sheeptrack and slope on a hillside set-stocked with sheep. The elements determined and the ranges of the monthly site averages for the macroelements (%DM) are: organic N(2.0-5.0), Ca(0.2-0.7), Mg(0.1-0.24), P(0.2- 0.4). Na(0.07-0.22). K(1.2-3.0), Cl(0.6-1.2), Si(0.5-1.5), and for trace elements (mg kg-') Fe(400-3000), Mn( 110-430), Zn(25-70) and Cu(.5-10). The concentrations of all elements except Cl and Cu showed marked seasonal trends and varied up to twofold at a site. The Ca, Mg, P and Na requirements of grazing sheep for maintenance, pregnancy, lactation and growth were obtained from previous metabolism studies. For example, the macroelement requirements of sheep for lactation are two to four times above that for maintenance. For the hill country pasture studied, we,conclude that the sheep's requirements for P(1.3-5.4g per day) was more than adequately met, those for Ca (1.5-6g per day) and Mg(0.9-2.9g per day) were just met during June and July when the concentrations of Ca(0.2%) and Mg(0.11%) were at their lowest. The Na requirement (0.75-2.18 per day) was not met during June and July when the pasture Na concentration was 0.07%.