**3. Results**

The influence of DD on behavioral signs, clinical symptoms, reticulo-ruminal contraction and blood plasma cortisol, and CA level was investigated. Before the physiological experimentation, no alteration was observed neither in the physiological behavior of two animals, simultaneously tested in individual cages, nor in the motoric and behavioral response to environmental factors. The mean cardiac frequency was 75.2 (±5.11) and the number of breathing was 35.6·min−1 (±4.21), and the reticulo-ruminal frequency was 6.45 ± 0.75 c × 5 min−1 in 30 min, before DD. After the implantation of an empty rubber balloon into the duodenum, the observed changes were NS in animal behavior or in the heart beat (70.5 beats·min−1 (±8.2)), respiration frequency (42.1 ± 6.35·min−1, **Table 1**) and reticulo-ruminal contractions (6.12 ± 0.28 c·5 min−1). Five-minute duodenal distension induced highly statistically significant alterations in the behavioral signs of animals [10].
