Yeasts as Dietary Additives to Manipulate Ruminal Fermentation: Effect on Nutrient Utilization and Productive Performance of Ruminants

There is considerable interest in the use of microbial additives such as yeasts in the nutrition of ruminants. The prohibition of the antibiotics as growth promoters in animal feeds increased the interest to investigate the effects of yeasts as natural additives on the gastrointestinal ecosystem and animal productive behavior. The effect of yeast-based preparations on the rumen environment and on the growth performance of ruminants has been well documented and has generated considerable scientific attention in the last two decades. However, the precise action modes by which the yeast cultures improve nutrient utilization and livestock production are still under study. Therefore, the objective of this chapter is to deepen into the action mechanisms of the yeasts at the ruminal level and at the productive level for their use as additives in animal feeding