Dietary selenate versus selenite for cattle, sheep, and horses.

The research paper talks about a comparative study done on the effectiveness of sodium selenate and sodium selenite as dietary supplements for the purpose of increasing selenium concentration in dairy cattle, sheep, and horses.

Research Background

• Around 0.3 mg selenium (Se) per kg of diet is currently allowed by FDA regulations as an additive for chickens, turkeys, ducks, swine, sheep, and cattle. But indications from field reports suggested that this allowed level might not be sufficient for ruminants in every case.
• Sodium selenite, a common supplement of selenium, is known to be quickly absorbed to particles or reduced to elemental selenium or selenides in acid, anaerobic environments. Therefore, it’s necessary to test whether other selenium supplements, in this case, sodium selenate, could offer better bioavailability.

Research Design and Method

• The research was conducted using dairy cattle, sheep and horses that were given a diet of sodium selenate. The intention was to find out if this would result in higher selenium concentrations than sodium selenite.
• A two week period without any selenium supplementation happened first. This was then followed by 49 or 56 days of selenium supplementation at a measure of .3 mg/kg of dietary dry matter (DM).

Observation and Analysis

• Serum selenium concentrations and glutathione peroxidase (GSHPx), an antioxidant enzyme that requires selenium, activities were monitored and measured both initially and periodically throughout the study.
• The observed data revealed no significant difference between the two selenium supplement forms in terms of their effects on sheep and horses. However, in dairy cattle, a small statistical advantage was found for sodium selenate in boosting serum selenium concentration.
• Selenium levels in the skeletal muscle and liver of sheep showed no discernible difference between both selenium forms.
• Over time, the concentration of serum selenium increased, but GSHPx did not. Further, .3 mg of additional selenium per kilogram of dietary DM from either source, i.e., sodium selenate or sodium selenite effectively maintained normal serum selenium levels in all three groups: sheep, dairy cattle, and horses.