Technical note: A device for obtaining time-integrated samples of ruminal fluid

A device was adapted to allow for time-integrated sampling of fluid from th e rumen via a cannula. The sampler consisted of a cup-shaped ceramic filter positioned in the ventral rumen of a cannulated cow and attached to a tube through which fluid entering the filter was removed continuously using a p eristaltic pump. Rate of ruminal fluid removal using the device was monitor ed over two 36-h periods (at 6-h intervals) and was not affected (P > .05) by time, indicating that the system was not susceptible to clogging during this period. Two cows having ad libitum access to a totally mixed ration we re used in a split-block design to evaluate the utility of the system for o btaining time-integrated samples of ruminal fluid. Ruminal fluid VFA concen tration and pattern in samples collected in two replicated 8-h periods by t he time-integrated sampler (at 1-h intervals) were compared with composite samples collected using a conventional suction-strainer device (at 30-min i ntervals). Each 8-h collection period started 2 h before or 6 h after feedi ng. Results indicated that total VFA concentration was not affected (P > .0 5) by the sampling method. Volatile fatty acid patterns were likewise unaff ected (P > .05) except that acetate was 2.5% higher (P < .05) in samples co llected 2 h before feeding and valerate was 5% higher (P < .05) in samples collected 6 h after feeding by the suction-strainer device. Although signif icant, these differences were not considered physiologically important. We concluded that use of the ceramic filter improved the sampling of ruminal f luid by simplifying the technique and allowing time-integrated samples to b e obtained.