Data on the chemical composition and gas production from some indigenous fodder plants from Yucatán and Quintana Roo are shown in order to demonstrate the potential of these species as supplements for livestock However, contents of polyphenols but above all, their reactivity, present a serious constraint on their use in large proportions. Gas production techniques seem to be a good assay for estimating the reactivity of phenolic compounds since the closed environment used in the technique might exacerbate the negative effects of the reactive fraction of polyphenols on microbial population and enzymes.