Bloat in cattle. XVII. A technique for recording pressure changes in the reticulo-rumen of cattle, using small electrical pressure transducers and a four-channel recorder.

Summary A small pressure transducer of the differential transformer type and a stable, sensitive, carrier-amplifier for use with it are described. An apparatus has been constructed consisting of four such units, together with their power-supply, the output being displayed by a modified Sanborn 4-channel heated-stylus recorder. Techniques are given for registering pressures in different regions of the reticulo-rumen of cattle having rumen fistulae. The transducers are located internally at the points from which the recording is being made, thus avoiding the errors inherent in external measurement through pressure-conducting systems. The equipment is versatile and can be used to record any physiological variable which may be expressed as a change of pressure, resistance, or displacement. Examples of such applications are given, while the Appendix describes a suitable pressure chamber for use with the transducer.