Serum selenium concentrations in neonatal calves: Influence of postnatal selenium injection and health status

Background Selenium supply plays a major role in calf rearing, as a deficiency can lead to health problems, economic loss, and even death. Therefore, postnatal selenium injections are often administered as a preventive measure. Objective In this study, we examined the serum selenium concentrations of healthy and sick calves within the first days of life. Further, serum concentrations after injection with selenium were determined. Animals and procedure Serum selenium concentrations from 75 calves were measured until the 10th d of life and the differences between sick and healthy calves were investigated. The variations in selenium concentration were analyzed 3 and 6 d after subcutaneous injection of 5.5 mg sodium selenite in 32 calves. To compare serum concentrations between healthy and sick calves, an independent samples t-test was used. For unequal variances, the Satterthwaite method was used; and for equal variances, the pooled sample variance was used. To analyze the statistical differences between the concentrations at different time points, the data were log-transformed and the Bonferroni correction was used. Results The mean initial selenium concentration was 46 6 37 mg/L. There was no statistically significant difference (P = 0.60) between sick (46 6 34 mg/L) and healthy (46 6 47 mg/L) calves. Serum selenium concentrations 3 and 6 d after injection of calves over 3 samples were 62 6 19 mg/L and 50 6 13 mg/L, respectively. Calves with an initial serum concentration of $ 72 mg/L showed a decrease of serum selenium concentration despite the injection. Conclusion and clinical relevance Newborn calves showed a high variation in selenium concentration that was not influenced by health status. A single injection of 5.5 mg of sodium selenite did increase the selenium concentration in calves with selenium undersupply. After injection, none of the calves showed serum concentrations above the reference range for adult cattle. Therefore, the indication for a selenium injection can be interpreted generously if selenium undersupply is suspected