The Efficacy of Hay from Selenized Soil as a Source of Selenium in Ruminant Nutrition

Abstract

This paper describes three different experiments where hay from fields fertilized with selenium (Se-hay) were fed to sheep on an otherwise low selenium diet, and to fattening bulls and dairy cows on an adequate selenium diet. The effect was compared with feeding a basic diet alone or supplemented with inorganic or organic selenium. The sheep were given a supplement of approximately 300 μg Se/day, for a period of ten weeks, either as Se-hay, seleno-methionine or sodium selenite. The fattening bulls were given either 5 kg Se-hay/day or a supplement of 3 mg Se/day as sodium selenite for six weeks. The dairy cows were given 4 kg Se-hay/day (half of the roughage portion) for nine weeks. Selenium levels were monitored during the experimental periods in blood and milk, and also in certain organs of the animals after slaughter at the end of the experiment. Furthermore, glutathione peroxidase activity were also monitored in blood and certain organs. All methods of selenium supplementation resulted in an increase to desired selenium levels in blood and tissues. These three experiments showed that selenium from selenium fortified hay was almost equivalent to seleno-methionine, and superior to sodium selenite in raising the selenium levels in whole blood and organs of sheep. All three regimens were equivalent in raising the glutathione peroxidase activity. In fattening bulls, Se-hay was superior to sodium selenite in raising the selenium levels in whole blood and organs. In dairy cows, the supplement of Se-hay resulted in a slight increase in blood selenium and a significant rise in milk selenium.

Key Words:

• selenium fertilizers
• organic/inorganic selenium
• ruminants
• selenized hay
• blood and tissue concentrations