Role of live yeasts in rumen ecosystem.

For many years, ruminant nutritionists and microbiologists have been interested in manipulating the microbial ecosystem of the rumen to improve production efficiency by domestic ruminants. Antibiotic ionophores have been used successfully for this purpose. However, the use of antibiotics in animal feeds has been banned in the European Union since January 2006 due to the risk of spreading antibiotic resistance.