The Solid-State Fermentation (SSF) of fibrous residues is one of the most promising techniques for animal feeding production through biotechnological via. In Cuba, from rustic fermentations, several product of great utility have been obtained such as Saccharina, the Sacchamaiz and Sacchaboniato. This study is methodological and presents a general review on the present situation of mathematical modeling of the SSF. The use of this tool to describe the rustic fermentation of fibrous substrates on slid state is included. For that, the equations of balance and energy have been taken into consideration, as well as a logistic equation to describe the microbial growth in these processes. Mathematical