S. Hansen and E. von Borell

Institute for Animal Breeding and Husbandry with Veterinary Clinic, Martin-Luther-University Halle-Wittenberg, Germany

Heart rate variability (HRV), defined as the amount of heart rate fluctuations around the mean heart rate, gives information about the sympathetic-parasympathetic autonomic balance. In general, high HRV refers to relaxed body functions, whereas low HRV refers to physical or psychological strain.

The new non-invasive heart rate monitor Vantage NV (Polar Electro Oy, Finland) provides the opportunity to measure interbeat intervals, which are necessary for calculating the HRV. The Vantage NV has wireless coded transmission of data, which allows to use the system simultaneously in group-housed pigs. To protect heart rate monitors from damage, we used modified motorcycle belts.

Because of the strong influence of the behavioural activity on HRV, the heart rate data need to be directly related to specific behavioural patterns. Therefore we compared the intra- and interindividual HRV when animals were in recumbency. In order to reduce the amount of time for reading video tapes, we used The Observer (Noldus Information Technology b.v., The Netherlands) to estimate the individual range of heart rate for various behavioural patterns. Then we calculated the individual threshold under which the animal is definitely in recumbency and subsequently assessed HRV by time domain and frequency domain analysis. Based on this method we will investigate whether HRV is a good indicator for psychological strain under different social situations and housing conditions in pigs.

Paper presented at Measuring Behavior '96, International Workshop on Methods and Techniques in Behavioral Research, 16-18 October 1996, Utrecht, The Netherlands