COBALT DEFICIENCY IN THE KAIWERA DISTRICT, EASTERN SOUTHLAND

Abstract

SolIs and pastures were sampled at 96 sites in the Kaiwera district, an area having 12 soil types typical of eastern Southland and South Otago. Analyses indicated that ill-thrift in lambs could be due to low cobalt (Co) Intake. Upland (>300 m a.s.1.) topsoils had lower EDTA extractable Co than lowland topsoils and analysis of soil profile samples indicated that Co had been leached from upper horlzons of upland soils. Upland pastures contained much less Co than lowland pastures and Co concentration was much lower in February than in October. Sheep grazing on upland pasture had very low vitamin B 12 status from October to June and this coincided with low pasture Co concentration Sheep grazing on lowland pasture had adequate vitamin B l2, although pasture Co concentration fell to below 0.06 mg/kg for a short period in summer. We conclude that sheep grazed on upland pastures for long periods need supplementary Co or vitamin B 12 or need to be rotattonally grazed on lowland pasture to build up adequate reserves of vitamin 8, 2 Keywords: ill-thrift. sheep, vitamin B,2, pasture cobalt, seasonal variation