• Department of General Psychology, Heinrich-Heine-University, Düsseldorf, Germany. Musial@uni-duesseldorf.de

The long-term observation of ingestive and excretory behaviors in freely ambulating and non socially isolated pigs is an important tool in the investigation of the physiological determinants of these behaviors. A computer-controlled laboratory setup for the recording of feeding, drinking, and defecation behavior in minipigs was developed, allowing for the observation of two pigs at a time for weeks. Four minipigs (29-52 kg) were conditioned to operate feeders with a precise food release per response and were then fed ad lib. The animals had up to 50% of their daily energy intake during the night. Meal size and time spent eating was highly correlated, meal size and the preprandial intermeal interval was moderately correlated, whereas meal size and the postprandial intermeal interval was not. Feeding facilitated defecation, supporting the assumption that the gastrocolonic response is present in the pig. The system has been shown to be highly reliable and valid, and thus provides an excellent tool for the investigation of the rhythmicity of ingestive and excretory behaviors in minipigs.