Selenium supplementation by addition of sodium selenate with silage additive

An ensiling experiment was conducted to assess the possibility for increasing the selenium content in grass silage by using a selenium-enriched silage additive, and to determine possible changes in the form of selenium during ensiling. Prewilted and precision-chopped silage was prepared from the second cut of timothy – meadow fescue sward in southern Finland. The additive treatments (6 g kg -1 ) were: control without additive, water containing 50 mg sodium selenate kg -1 , and formic acid-based additive containing 10, 50 or 500 mg sodium selenate kg -1 . The selenium content of the control silage was low (0.069 mg kg -1 dry matter) whereas the selenium content of the other silages was in line with the dose level of selenium delivered in the additive. The added selenate was detected only as selenate in the silages. Addition of sodium selenate to silage additive provided a controlled way to add selenium to the diet of forage-fed animals.