Predicting in vivo production of volatile fatty acids in the rumen from dietary characteristics by meta-analysis: description of available data

摘要

Volatile fatty acids (VFA) produced in the rumen represent 40% to 70% of digestible energy intake in ruminants (France and Dijkstra, 2005), and yet their composition is poorly described by existing rumen models (Offner and Sauvant, 2004). The estimation of the quantitative supply of individual VFA to intermediary metabolism thus remains a key question in ruminant nutrition. Several authors measured in vivo production rate of individual VFA in the rumen, using mainly isotope dilution, which is recognised as the more reliable method (France and Dijkstra, 2005). By applying a meta-analysis approach to these data, we aim to produce quantitative information on (i) the effects of intake and dietary composition on the individual VFA production rates in therumen (VEA-PR); (ii) the partition of fermented energy between VFA, heat and gas productions, and their relation with microbial synthesis. The present paper describes the available data and presents preliminary results on the effects of the amount of organic matter digested in the rumen (OMDR) and concentrate level.