DEVELOPMENT OF A NEW RESPIRATION RATE MONITOR FOR CATTLE

Abstract

Studies were conducted investigating bioenergetic responses of growing cattle to heat challenges usingrespiration rate as one of the primary measures. Respiration rate (RR) was measured using monitors designed fromcommercially available thin-film pressure sensors and a small battery powered micro-computer. The monitors weredesigned, fabricated, and tested to provide continuous records as a basis for evaluating stress responses associated withenvironmental conditions. This article provides details about the monitors and the suitability of obtained records as anindicator of stress, based on measures obtained in environmental chambers during constant and simulated heat waveconditions as well as a field study. Representative data from two laboratory studies indicated an association of RR andambient temperature (P < 0.01) with diurnal changes being evident in the cyclic test and step changes being evident inthe constant ambient temperature tests. A two to three breaths per minute (BPM) rate of change of RR with respect toambient temperature (C) was observed for steers in the laboratory studies. The field study revealed a striking response ofRR to the ambient temperature (6.6 BPM/C rate of change) for a steer that had direct solar load (no-shade) compared toa 1.6 BPM/C rate of change in the shade.