EFFECT OF CONTROLLED-RELEASE SELENIUM GRANULES APPLIED WITH FERTILISER ON BLOOD LEVELS OF GRAZING SHEEP

Abstract

Two sheep grazing trials, at Awarua, Southland. and at Wairakei, central North Island, on selenium (&)-deficient and Se-retentive soils under a rainfall of about 1000 mm were used to test the duration of effectiveness of a mixture of standard and controlled-release Selcote Se granules applied at 0.5 kg/ha each. Selenium concentrations in blood of ewes and lambs were maintained above deficiency levels for 2 years in both trials. Peak values were observed or inferred from both rapid-release and slow-release granules. The pattern of pasture Se was consistent with blood Se values where sampling was sufficiently intensive to allow for the low rate of granule application. Keywords: Pasture, ewes, lambs, yellow-brown pumice soils, lowland yellow-brown earths, Selcote.