Pain in Pig Production: Text Mining Analysis of the Scientific Literature

Public’s concern about poor animal welfare provided by intensive farming systems has increased over the last decades. This study reviewed the interest of the scientific research on the pain issue in pig production to assess if the societal instances may be a driving force for the research activity. A literature search protocol was set up to identify the peer-reviewed papers published between 1970 and 2017 that covered the topic of ‘pain in pigs’ using Scopus®, database of Elsevier©. One hundred and thirty papers were selected and they were mainly focused on the practice of castration (64%) followed by tail docking (24%). The scientific community first focused on these painful practices as a way to improve production efficiency and quality issues while more recently, due to the increased pressure by the public opinion, turned its interest towards the search of alternative solutions. A text mining analysis on the abstract of the selected papers clearly indicated the effort of the research to explore solutions to alleviate pain. Evocative words of this target were the selected terms ‘pharmacological analgesic’ and ‘anaesthetic treatments’. The text mining highlighted vocalizations as the main pain indicators in pigs as this term was frequently associated to ‘acute stress’. Ethical issues were a minor research topic in the scientific literature on pig breeding but in the short run, they are supposed to become a major subject to justify the acceptance of the modern production systems at the eyes of the consumers.