Effects of the following treatments on abomasal and duodenal myoelectric activity in yearling cattle were studied: 2 ml of 0.9% sodium chloride solution (NACL); 0.07 mg of bethanechol (BET)/kg of body weight; 0.1 mg of metoclopramide (MET)/kg; and 0.07 mg of bethanechol and 0.1 mg of metoclopramide (BETMET)/kg. All treatments were administered SC during the early part of phase I of the migrating myoelectric complex Myoelectric signals were recorded for 4 hours after administration of the treatments from 1 electrode in the antrum and 3 electrodes in the duodenum. For the antral spike rate (ASR), there was no significant difference among treatments during the first hour, but the ASR was significantly (P < 0.05) greater during hours 2 to 4 after treatment with BETMET, compared with ASR for MET alone. The duodenal spike rate (DSR) was significantly (P < 0.05) greater during the first hour after administration of BETMET than after the other treatments. After administration of BET, DSR was significantly (P < 0.05) greater than after MET or NACL. There was no difference in DSR after MET, compared with DSR after NACL. There was no significant difference in DSR among treatments during the second and third hours. The total antegrade propagating spike (TAPS) count was greater after administration of BETMET in all hours, compared with the other treatments. The ratio of TAPS to total spikes on the orad-most duodenal electrode was significantly (P < 0.05) greater after BETMET during hours 1 and 2.

The reticulum and adjacent organs were mined ultrasonographically in 51 cows by use of a 3.5-Mhz linear transducer applied to the ventral aspect of the thorax over the sixth and seventh intercostal spaces. Examination included assessment of the contour of the reticulum, of reticular contractions, and of the organs adjacent to the reticulum. The normal reticulum appeared as a half-moonshaped structure with a smooth contour; it contracted at regular intervals and was situated immediately adjacent to the diaphragm and ventral portion of the abdominal wall when relaxed. Contents of the reticulum could not normally be imaged because of its partly gaseous composition. The ruminoreticular groove, craniodorsal blind sac of the rumen, and the ventral sac of the rumen were observed caudally. The distal aspect of the spleen and parts of the omasum, abomasum, and liver could be imaged. Reticular motility was characterized by a biphasic contraction pattern. Four biphasic reticular contractions usually were observed during a 4-minute period. During the first (incomplete) contraction, the reticulum contracted by a mean of 7.2 +/- 2.30 cm. There was then low-grade, incomplete relaxation of the reticulum, followed immediately by the second reticular contraction, during which the reticulum usually disappeared from the 17.5-cm-deep screen. The reticulum then reappeared in its normal position. The first reticular contraction lasted a mean of 2.6 +/- 0.33 seconds and the second contraction lasted 3.9 +/- 0.55 seconds. The mean interval between 2 biphasic contractions was 44.9 +/- 10.53 seconds. The speed of the first reticular contraction was 5.4 +/- 1.32 cm/s. Ultrasonography was useful for assessing the contour and motility of the reticulum.

Effects of the following treatments on abomasal and duodenal myoelectric activity in yearling cattle were studied: 2 ml of 0.9% sodium chloride solution (NACL); 0.07 mg of bethanechol (BET)/kg of body weight; 0.1 mg of metoclopramide (MET)/kg; and 0.07 mg of bethanechol and 0.1 mg of metoclopramide (BETMET)/kg. All treatments were administered SC during the early part of phase I of the migrating myoelectric complex Myoelectric signals were recorded for 4 hours after administration of the treatments from 1 electrode in the antrum and 3 electrodes in the duodenum. For the antral spike rate (ASR), there was no significant difference among treatments during the first hour, but the ASR was significantly (P < 0.05) greater during hours 2 to 4 after treatment with BETMET, compared with ASR for MET alone. The duodenal spike rate (DSR) was significantly (P < 0.05) greater during the first hour after administration of BETMET than after the other treatments. After administration of BET, DSR was significantly (P < 0.05) greater than after MET or NACL. There was no difference in DSR after MET, compared with DSR after NACL. There was no significant difference in DSR among treatments during the second and third hours. The total antegrade propagating spike (TAPS) count was greater after administration of BETMET in all hours, compared with the other treatments. The ratio of TAPS to total spikes on the orad-most duodenal electrode was significantly (P < 0.05) greater after BETMET during hours 1 and 2.