Introduction:

Given its importance in evaluating the digestibility of ruminant foods for ruminants, the paper aimed to bring information on some general aspects of the in vitro gas production technique and refers to the uses that are given to it.

Development:

The origins of the technique date back to the work in 1979. Since then there have been changes in the way it is applied, maintaining the essence of measuring the gas production that occurs when the sample is inoculated with rumen fluid, feces or enzymes in a buffered mineral medium based on bicarbonates that releases an amount of gas proportional to the volatile fatty acids produced. The way in which the amount of gas is measured has changed till the now mainly used transducers that are coupled to computers. The technique has been used for multiple studies that were reviewed, as well as some works dedicated to its improvement based on difficulties that arose.

Conclusions:

It is concluded that the in vitro gas production technique is probably the most versatile tool for measuring digestibility; it presents didactic and accessible procedures; entails fewer costs and also represents a more compatible alternative for animal welfare legislation, by using voided feces as inoculum and that still needs more to be done in order to achieve better precision and accuracy, and the possible application in other fields of animal food evaluation.