INFLUENCE OF VERTICAL VIBRATION ON HEART-RATE OF PIGS

Pigs with a body weight between 15 and 20 kg were vibrated in the vert ical direction for 1 h at 2, 8, and 18 Hz, in combination with root me an square (RMS) acceleration magnitudes of 1 or 3 m/s(2). Welfare and stress were quantified by comparing heart rate characteristics during a control period (2200 to 0600) before vibration exposure and during v ibration (1000 to 1100). The level of maximum heart rate and number of ventricular ectopic beats during vibration at 2 and 8 Hz in combinati on with a RMS acceleration of 3 m/s(2) indicated a larger fear respons e than at 1 m/s(2). Isocomfort contours based on mean heart rate durin g vibration showed the greatest specific sensitivity of the pigs to vi bration at a frequency of 8 and 18 Hz, especially in combination with a RMS acceleration of 3 m/s(2). During transport, RMS acceleration sho uld be less than 3 m/s(2) to protect pigs' welfare. Rigs were more sen sitive to acceleration than to frequencies within the range of treatme nts in this investigation. Although the response of the pigs in this e xperiment fit within the model concept for adult humans and for domest ic fowl, changes in heart rate are dependent on body weight.