B/C/D: Note that radiopaque material is present in the abomasum and no visualization of the rumen. D: The lateral abdominal radiographs of standing calves are acquired using horizontal beam. The fluid level refers to an interface between fluid and gas (gas-fluid interface, white arrow) in the stomach. In addition to the gas-fluid interface there are occasionally visible fluid–fluid interfaces (black arrow). The double interface ismost likely due to radiographs taken immediately after the calves stopped drinking, before the fluid finds its true level, causing layering of the fluid.