Preliminary study to automatically train growing pigs to use a toilet

Cleaner pig pens with less fouling by urine and faeces are associated with lower ammonia emissions and improved hygiene and indoor air quality. This study aimed to train and encourage pigs to urinate in a designated small area, called the pig toilet, to achieve a cleaner pen. The toilet was designed to automatically train pigs with a food reward following urination inside the toilet, using a liquid-volume sensor installed beneath the toilet floor. A total of 24 pigs aged 12 weeks were trained for 4 weeks in four experimental pens with outdoor access. Two pens had an open, easily accessible toilet, and two pens had a closed toilet with partitions. All toilets were located indoors. After the training period, video recordings of each pen were analysed for 7 days. On day 4 of the observation period, the pigs were given access to the outdoor run. In total, 1 040 excretion events were identified and analysed. The results showed that the open toilet had a higher percentage of urinations (79 vs 54%) and defaecations (44 vs 17%) inside the toilet compared with the closed toilet. However, the closed toilet provided more protection during reward provision with a lower number of displacements. Opening the outdoor run shifted most excretions to the outdoor area. Only two pigs showed signs of having learned to use the toilet for urination to obtain a food reward. Most pigs did not seem to learn to use the toilet, though some learned to obtain rewards without prior excretion (i.e. to cheat the system). This study showed indications that the pigs can be trained automatically to use a toilet. Therefore, the toilet design requires improvement for easy accessibility and to reduce agonistic interactions, and the reward provision should be reliable for the individuals that performed the desired response.