Transportation can result in increased stress for pigs, which has been related to economic losses. The effect of supplementing feed or water with tryptophan, vitamin E or a herbal product (Sedafit) on the behaviour and physiology or pigs during simulated transportation (vibration) was studied. Water supplemented with tryptophan caused pigs to lie down more during the second hour of vibration. Compared to the control group, both during and after the stress of simulated transport, an increase in vitamin E in the feed caused a decrease in the peak heart rate, ventricular ectopic beats and ST elevation. Similarly, water supplemented with Sedafit resulted in smaller increases in the measured heart variables compared to the control group (before and after the stressor). Tryptophan calmed the pigs, such that they spent more time lying. Vitamin E and Sedafit had sedative and antianxiety effects based on the decrease in relative changes of some heart rate variables during and after vibration.