Manipulation of the Rumen Microbial Environment to Improve Performance of Beef Cattle

It is well known that rumen fermentation processes play a key role in ruminant nutrition, as it is this distinctive symbiotic feature between the host and the rumen microflora that lends the ruminant animal several advantages in digestive and metabolic processes over non-ruminants. The extent of complexity of interactions between diverse groups of microorganisms which inhabit the rumen is such that, even nowadays, some pathways and microorganisms involved are unknown. The possibility of controlling some of the metabolic processes in the rumen with the objective of achieving more efficient nutrient utilization has been an appealing concept to both nutritionists and rumen microbiologists. As a result of several decades of continuous research on ruminal fermentation, metabolism, and microbiology, the rumen is one of the most extensively studied microbial ecosystems. General objectives of ruminal fermentation manipulation can be summarized as follows (Nagaraja et al., 1997):