Only the inorganic selenium salts sodium selenite were available at a cost permitting their use in animal feed. Because selenium is an essential element, sodium selenite is an ingredient in some food supplements.
selenium can be toxic in high doses.
NOTE ::: Huge Differences between Sodium Selenite and Sodium Selenate ?
Sodium selenate is a common ingredient in some insecticides used against mites, aphids, and mealybugs. For most insects, a dose of 10 mg/kg is enough to be fatal. It is also used in some fungicides.
According to AAFCO, the maximum amount of selenium used in a dog food should not exceed 2.0 mg/kg on a dry matter basis — or about 18 times the recommended minimum of 0.11 mg/kg.
And on a caloric basis, the maximum suggested selenium content is 0.57 mg per 1000 calories of food — which is about 19 times the minimum 0.03 mg for the mineral.
Although AAFCO sets a maximum for most minerals, the National Research Council has yet to determine the safe upper limit for many inorganic nutrients — including selenium.
