A SURVEY OF THE SELENIUM STATUS OF BEEF-COWS IN ALBERTA

An epidemiological survey was conducted in Alberta to measure the sele nium status in blood of beef cows during the fall and to determine the risk of selenium deficiency among specific geographic regions of Albe rta. Three census divisions of Alberta based on the Statistics Canada Census of Agriculture were chosen as the study areas for the project. Soils and plants in area A (Edmonton area) and area B (Calgary area) w ere known to be deficient in selenium, while soils and plants in area C (southeast corner of Alberta) were known to have adequate levels of selenium. Blood samples were collected from 335 cows on 29 farms from the 3 study areas. These samples were collected from cows that had rec ently been removed from pasture in October and November 1992. Answers to a short questionnaire pertaining to various herd characteristics an d management practices were also obtained for each herd. The average v alue of selenium for all cows sampled was 2.20 mu mol/L. The average v alue of selenium of cows in areas A and B was 1.93 mu mol/L. The avera ge value of selenium of cows in area C was significantly (P < 0.05) hi gher at 2.70 mu mol/L. Nine percent of the cows in the study were cons idered marginal or deficient in selenium (< 1.27 mu mol/L selenium). N erds located in area C, herds that were provided with supplemental fee d on pasture, and herds that were pregnancy checked had higher average herd selenium values than did other herds. Cow-calf producers located in areas with selenium-deficient soils should pay particular attentio n to selenium supplementation for their cows. Some of the negative ''g eographic'' effects on selenium values can be overcome by more progres sive management practices,