The objective of this study was to determine whether intestinal blood flow can be measured adequately in group-housed animals using the recently developed Physiogear (TM) I wireless flowmeter. We used the weaner pig as one of many possible animal models. Four 7-kg piglets were instrumented with a 3-mm flowprobe around the superior mesenteric artery (SMA) and SMA flow was measured pre- and post-weaning. During measurements, behavior was recorded. The piglets did not show any abnormal behavior and were not restrained by the flowmeter. Severe reductions (> 75%) in SMA flow coincided with nursing (pre-weaning) and aggressive behavior (post-weaning) and were only short-lived. Our results demonstrate that the Physiogear (TM) I flowmeter can be used to measure flow in group-housed animals without any human contact, providing the opportunity to relate flow measurements to undisturbed animal behavior. (c) 2007 Elsevier B.V. All rights reserved.