The invention relates to a method and apparatus for non-invasive determination of motility, motility change and/or degree of motility change of the gastrointestinal tract or a specific part thereof of conscious animals, by selectively detecting and analyzing myoelectric signals. The method and apparatus of the invention are suitable, for the first time, for simultaneous and specific non-invasive detection of changes in the motility of various parts of the gastrointestinal tract - such as stomach, small intestine and colon - of the monitored animal. The method and apparatus of the present invention can be used, inter alia, to detect and monitor a stress condition, to investigate the rate of feed utilization, and to investigate the effect of active substances, feed ingredients and stress on the feed utilization rate. The process and apparatus of the present invention are suitable for controlling and improving the husbandry and breeding conditions of farmed animals.