Ruminant Nutrition: Methodology and Modeling.

This article presents abstracts of various papers related to the methodology and modeling of ruminant nutrition, that were presented during the symposium held on July 26, 2005, Cincinnati, Ohio, which was organized by the American Dairy Science Association, the American Society of Animal Science and the Canadian Society of Animal Science. One of the papers presented is "Influence of Fermentation Method on NDF Degradation Parameter Estimates," by D. Bossen, D. R. Mertens and M.R. Weisbjerg. Effect of three methods of fermentation on degradation parameters was studied using feeds ground to different sizes. Corn silage, grass silage, barley grain, sugar beet pulp, and rape seed cake were ground using a shear mill. Another paper discussed is "Measurement of Volatile Fatty Acid Interconversion As a Means to Study the Role of Thermodynamics in the Control of Fermentation," by E. Ungerfeld, B. Bequette, S. Owens and R. Kohn. The molar ratios of volatile fatty acids observed in the rumen may result in part from thermodynamic constraints on rumen fermentation. If certain pathway branches become infeasible because of the buildup of end products, fermentation may shift momentarily to other pathways, keeping the profile of end products in equilibrium.