Use of isolated ruminal epithelial cells in the study of rumen metabolism.

A comprehensive understanding of ruminal development and metabolism has not yet been achieved. The study of rumen epithelial metabolism during development can facilitate the development of feeding strategies for developing pre-ruminant animals and mature animals. Understanding the effect of the physical form and nutrient composition of the diet on the ruminal epithelium will lead to changes in dietary regimens that exploit beneficial tissue responses. Characterization of the ontogenic shifts in ruminal metabolism, in association with the description of physical changes, has established more discrete periods during the development of the ruminal epithelium for future studies to be conducted. Isolated ruminal epithelial cells, specifically cells of the strata basale and spinosum, have been used for metabolic studies of rumen epithelial energy metabolism. Because the ruminal epithelium is a major producer of ketone bodies in the fed ruminant animal, it is integral to the energy metabolism of the whole animal. Arguably, whole tissue slices may provide better estimations of actual tissue performance; however, the benefits gained by maintaining tissue integrity are offset because of the high variability in tissue composition due to dietary influences. Use of enriched cell populations is ideal for short-term incubations and provides high cell yields with limited delay following removal of the tissue from the animal. Although the ruminal cell isolation system is continuously undergoing refinement, enriched cell cultures have provided realistic results with respect to known responses in vivo.