Editor's Note: The following excerpt from the November 2012 Miner Institute Farm Report was written by Rick Grant, president of the W.H. Miner Agricultural Research Institute in Chazy, N.Y.

"At the recent Cornell Nutrition Conference there was considerable discussion of our (in)ability to accurately predict rumen fiber digestion. In this era of high-priced grain and feeding higher-forage diets, our ability to predict forage digestibility and cow response is more crucial than ever.

An important, and often overlooked, component of fiber digestion is the interaction between larger and smaller particles within the rumen. Greater than 50% of NDF particles in the rumen are below the critical size for escape – in other words, they are sequestered within the rumen digesta mat by larger particles. This allows for more complete fiber digestion and greater energy available to the cow.

Our current nutrition models do not account for sequestration and selective retention of feed particles. They assume that all particles have the same probability of escape — which is simply not true."