[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.

Microbial transformation of hydroxy metabolites of 1-oxohexyl derivatives of theobromine by Cunninghamella echinulata NRRL 1384

AIM

The biotransformation of pentoxifylline (PTX), propentofylline (PPT) and their racemic hydroxy metabolites ((+/-)-OHPTX and (+/-)-OHPPT) by using the fungus Cunninghamella echinulata NRRL 1384.

METHODS AND RESULTS

A fungus Cunninghamella echinulata NRRL 1384 was used to catalyse the (S)-selective oxidation of the racemic hydroxy metabolites: (+/-)-OHPTX and (+/-)-OHPPT and for reduction of PTX and PPT. The first oxidation step appears to be selective and relatively fast while the second reduction step is slower and more selective with PTX. Modifications involving supplementing the bioconversion with glucose give yields and enantiomeric excess (ee) values similar to those obtained without glucose.

CONCLUSIONS

The bioconversion of (+/-)-OHPTX gave an (R)-enantiomer (LSF-lisofylline) with a higher enantiopurity (maximum approximately 93% ee) compared to the bioconversion of (+/-)-OHPPT, when the maximum ee value for (R)-OHPPT was recorded at 83%.

SIGNIFICANCE AND IMPACT OF THE STUDY

The conversion of (+/-)-OHPTX and (+/-)-OHPPT using Cunninghamella echinulata can be recognized as a process, which may be recommended as an alternative to the methods used to obtain (R)-OHPTX and (R)-OHPPT.