Fig. 1.
Lateral cranial abdominal radiography of the 15 days old pilot calf (head oriented to the right) after administration of 100 ml of barium sulphate contrast using an oesophageal tube (A) and after consuming 4 l of contrast milk (BaSO4) (B). Note that the rumen (white arrow) and reticulum (black arrow) can be differentiated from the abomasum. Some barium sulphate contrast has passed to the small intestine.
On each of the three test days, continuous live behavioural observations were carried out in each calf during 2 h starting immediately after the test meal, to reveal signs of abdominal pain or discomfort according to a predefined ethogram (Table 2). The ethogram was based on Bourne [19]. All behavioural observations were carried out by the same observer (1st author, ethologist and researcher with experience from behavioural observations and pain assessment in animals). For practical reasons, the observer could not be blinded to the performance of the calves during trials.