Trace mineral concentrations in Canadian beef calves at weaning.

Objective: To describe the copper and selenium statuses of beef calves at weaning.

Animal: Calves ( = 1998) were sampled from 106 Canadian cow-calf herds in the fall of 2021.

Procedure: Serum samples from calves were tested for copper, selenium, and molybdenum concentrations.

Results: Although the percentages of calves classified as selenium deficient (< 0.025 ppm) were relatively low (0.5% western Canada, 3% eastern Canada), 53% of calves from western Canada and 77% of calves from eastern Canada were classified as having less than adequate selenium concentrations (< 0.08 ppm). Copper deficiency (< 0.5 ppm) was common in calves from both western (17%) and eastern (14%) Canada. High molybdenum concentrations (> 0.10 ppm) were identified in 6% of calves from western Canada and 7% of calves from eastern Canada.

Conclusion: Selenium concentrations were higher in calves from western Canada than from those in eastern Canada ( < 0.001). Copper and molybdenum concentrations were not significantly different between western and eastern Canada. Less-than-adequate serum copper was the most common deficiency identified in Canadian beef calves at weaning.

Clinical Relevance: Trace minerals are important for immune system function in calves at weaning. Selenium concentrations in calves at weaning were lower than in cows from the same herds collected at pregnancy testing 2 y earlier. Copper deficiency was also identified, though less frequently than for mature cows. Supplementation programs for calves should be customized based on testing and recognize both regional and age differences in risk.