Selenium concentration in the blood of ruminants grazing in Northern New South Wales. 1. Analysis of samples collected in the National Brucellosis Eradication Scheme

Abstract

Bovine blood samples collected for the Brucellosis Eradication Scheme were analysed for selenium as a means of surveying the selenium status of grazing cattle in 10 Pastures Protection Board areas of northern New South Wales. Sources of error were also examined. The average standard deviation of repeat samplings from the same farm was ¦0.019¦g selenium ml-1 and the seasonal variation in blood selenium concentration appeared to be relatively small. Relationships were calculated for predicting the selenium concentration in bovine plasma and liver, and in ovine whole blood, plasma and liver, from the selenium concentration of bovine blood; they were used to extend the survey results to grazing sheep. Samples were collected from 794 farms, and there were significant differences between Pastures Protection Board areas. Cattle in the Glen Innes and Armidale areas had the lowest selenium status with 26 and 14% respectively of herds having blood selenium concentrations = 0.02 ¦g selenium ml-1.