A Theoretical Rumen Fermentation Balance

Abstract

Summary Certain assumptions are made which permit the calculation of the amounts of CO 2 and CH 4 produced in the rumen which correspond to a given molar distribution of volatile fatty acids present in rumen fluid. This calculation allows the development of a theoretical fermentation balance for a given molar distribution of volatile fatty acids. For a molar distribution of 65 acetate: 20 propionate: 15 butyrate, the following balance is calculated: 57.5 \( C 6 H 12 O 6 \) → 65  acetate + 20  propionate + 15  butyrate + 60  CO 2 + 35  CH 4 + 25  H 2 O The assumptions upon which the calculations are based are discussed, such as considering volatile fatty acids, CO 2 and CH 4 , as sole fermentation products and using the empirical formula C 6 H 12 O 6 to represent fermentation substrate. An attempt is made to evaluate the fermentation balance in terms of known experimental data which bear on product-substrate relationships. Values predicted from the theoretical equation are of the same order of magnitude as experimental values. Application of the balance is made to amplify the interpretation of experimental data concerned with variations in the molar distribution of fatty acids on various dietary regimes. It is proposed that the fermentation balance is useful for interpreting certain quantitative aspects of ruminant nutrition in terms of the quantitative aspects of the rumen microbial fermentation.