Use of the monofrequency forced oscillation technique to measure changes in upper airway resistance in Friesian and blue Belgian calves.

Monofrequency forced oscillometry (MFO) using a sinusoidal test signal of one frequency (10 Hz) was compared with the classical pulmonary function technique (using an oesophageal balloon with airflow measurements) in two breeds of cattle which differ in their respiratory physiology, particularly to assess changes in upper airway resistance. Six healthy male Friesian calves (mean [SD] bodyweight 131 [12] kg) and six healthy male blue Belgian calves (mean [SD] bodyweight 137 [13] kg) were examined successively with their heads either in a normal position or held vertically, using a cross-over study design. In the normal position, higher resistances, a higher respiratory impedance, and lower values of the dynamic lung compliance (Cdyn) were measured in the blue Belgian than in the Friesian calves. In the vertical head position, total pulmonary resistance (RL) increased and Cdyn decreased significantly (P < 0.05). The changes in MFO-derived parameters were in accordance with the changes in classical parameters, and for both methods, the percentage changes were markedly higher in the blue Belgian calves.