Ultrasonography of the reticulum, rumen, omasum and abomasum before, during and after ingestion of hay and grass silage in 10 calves

The reticulum, rumen, omasum and abomasum were assessed via ultrasonography in 10 healthy female calves before, during and 2 h after feeding hay and grass silage. The evaluations were made using an ultrasound machine with a 5.0 MHz linear transducer. The reticulum could be visualized before feeding in all the calves. Its appearance and pattern of contractions were similar to those in adult cattle, although the amplitude (5.2 ± 1.06 cm) and velocity (3.5 ± 1.42 cm/s) of the first contraction were markedly less than in adult cattle. The position and size of the entire rumen including the dorsal and ventral sacs and the ruminal contents were assessed. Except for its smaller size, the ultrasonographic appearance of the omasum of calves was similar to that of adult cattle. 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. Compared with its appearance before feeding, the ultrasonographic appearance of the rumen, omasum and abomasum did not change during or after feeding. Ultrasonography is an ideal imaging tool for evaluating the reticulum, rumen, omasum and abomasum before, during and after feeding in calves.