Ultrasonography of the reticulum, rumen, omasum, and abomasum in 10 calves before, during, and after ingestion of milk.

The reticulum, rumen, omasum, and abomasum were assessed via ultrasonography before, during, and 15, 30, and 120 minutes after feeding milk to 10 healthy calves. The ultrasonographic examinations were conducted using a 5.0 MHz linear transducer. Loops were recorded on video for further evaluation. The reticulum could be visualised before feeding in seven calves. Its appearance and pattern of contractions were similar to those in adult cattle, although the amplitude (1.7 ± 0.75 cm) and velocity (2.7 ± 1.34 cm/s) of the first contraction were smaller than in adult cattle. The reticulum could not be visualised in any of the calves during feeding as it was displaced cranially and laterally and therefore being obscured by the lungs as the abomasum expanded with the ingested milk. 2 hours post ingestion it remained obscured in 5 individual and was visualized again the other 5. The position and size of the entire rumen including the dorsal and ventral sacs and the ruminal contents were assessed. There were no changes in the ultrasonographic appearance of the rumen during or after feeding. Except for its smaller size, the ultrasonographic appearance of the omasum of calves was similar to that of adult cattle. Milk flow through the omasum could not be seen in any of the calves, and there were no changes in the appearance of the omasum during and after feeding. The abomasum was seen to the left and right of the ventral midline before feeding in all calves; it occupied considerably more space on the left than the right. The flow of milk into the abomasum and milk clotting, which occurred 15 minutes after feeding, could be seen in all calves. The milk clots started to slowly disintegrate 30 minutes after the start of feeding, and by 2 hours post feeding, this process was greatly advanced but remained incomplete. Ultrasonography is an ideal tool for the evaluation of the reticulum, rumen, omasum, and abomasum before, during, and after the ingestion of milk in calves.