2.2. The test procedure
The study was performed as an open, non-randomized trial with a within patient 3-level RSP design [17]. On test days 3, 5 and 7 (days after arrival to the test facility), the calves' morning meal was replaced by milk containing the barium sulphate contrast (BaSO4) (Bracco, MIXOBAR® COLON (1 g/ml)) at a ratio of 6:1. The small aperture teat used allowed drinking at approximately 1.5 l/min. To standardize the rate of intake, the same rubber teat was used for all test sequences and all calves. Abdominal radiographs of the standing calves were taken before, during and immediately after administration of the barium sulphate contrast