[Repeated drenching of calves - -Ultra-sonographic findings of the -reticulum and abomasum and -short-term -effects on pH and -D-lactate in rumen fluid and blood].

INTRODUCTION An oesophageal tube feeder was used to administer milk to six clinically healthy calves every 12 hours for a total of three feedings. The calves were seven to nine days of age, and each feeding consisted of a volume of milk that was 6 % of the body weight of the calves. The reticulum and abomasum were scanned ultrasonographically before, during and after drenching. Blood samples for D-lactate determination and venous blood gas analysis were collected at -12, 0 (first drenching), 6, 12 (second drenching), 18, 24 (third drenching), 30 and 36 hours. Ruminal fluid was collected for measurement of pH and D-lactate concentration at -12 and 36 hours. Based on simultaneous ultrasonographic examinations of the reticulum and abomasum, some of the force-fed milk flowed into the reticulum and some directly into the abomasum; both organs contained milk immediately after drenching. Drenching led to ruminal acidosis evidenced by a significant decrease in median pH from 7,0 (6,0 - 7,0) to 4,5 (3,0 - 5,0) and a 93-fold increase in median D-lactate concentration from 0,39 (0,14 - 1,33) to 36,3 (17,9 - 53,3) mmol/l but it did not cause metabolic acidosis. Based on these findings, we concluded that milk administered to calves via an oesophageal tube feeder flows into the reticulum and abomasum simultaneously and three force feedings 12 hours apart cause acute ruminal acidosis, which was not accompanied by metabolic acidosis in the short term.