Influence of olfactory substances on the heart rate and lying behaviour of pigs during transport simulation
This study investigated the effect of olfactory substances on the heart rate and lying behaviour of pigs during transport simulation. Five treatments were tested through the application of each substance to pigs' snouts with a paintbrush. These consisted of: 1) control treatment (wiping
without product); 2) 2 ml of a synthetic, maternal-like pheromone; 3) 5 ml of a synthetic, maternal-like pheromone; 4) a commercial, non-relevant odour and 5) 2 ml of a placebo (solvent of the synthetic pheromone without active ingredients). In total, 90 pigs took part in this study and each
treatment was tested on a group of three pigs with six replicates per treatment. Pigs were vibrated in the vertical direction in a transport simulator with a frequency of 8 Hz and an acceleration of 3 m s–2. Cardiac activity and lying behaviour during vibration were quantified.
The effect of vibration was found to be statistically significant, ie causing an increase in heart rate and numbers of ventricular ectopic beats (VEB). Both 2 and 5 ml of synthetic pheromone were generally found to decrease the minimum, mean, and peak heart rate values in comparison with the
other treatments (in particular the control and the non-relevant odour group) but only minimum heart rate reached statistical significance. However, the number of VEBs was highest for these two synthetic pheromone groups during vibration. No dose-dependent synthetic pheromone effects were
found and there were no differences in the amount of time pigs spent lying. The use of olfactory substances may support pigs' ability to cope with real transport conditions thereby improving their welfare.