The relationship between the sow and piglets - how piglets recognize their mother's vocalizations

The ability to recognize mothers voice is important for offspring in many animal species. This thesis reviews the knowledge on maternal behaviour in domestic pigs and focuses on its important prerequisite which is the recognition between mother and her offspring. Domestic pig (Sus scrofa domestica) is chosen as a very good model species. Maternal behaviour of pigs did not change much due to domestication or inetnsive farming. Maternal behaviour including nursing behaviour should prevent monpolization of resources by stronger piglets. Therefore, maternal behaviour has interesting aspects: long udder massage, attraction of piglets with vocalization and announcment of milk ejection with short period of milk ejection. Maternal behaviour in pigs involves a complex of many interesting phenomena like: synchronization of nursings, non-nutritive nursings, potential for allo-suckling, parent-offspring conflict, specific initiation and termination of nursing and rich olfactoric, acoustic, and tactile signalling. Pig belongs to social animals in which communication needs to be complex, especially acoustic communication. Naturally, recognition of individuals is crucial in groups and this is true for recognition between mother and offspring. The acoustic recognition can be studied by three appraches. 1) Observing of natural behaviour, 2) Playback experiments (habituation, preference and comparison) and 3) Analysis of voice and searching for individual traits in voice. It is expected, that piglets should recognize mother as soon as possible. Sow should recognize piglets after rejoining her group. Results of the studies reviewed in this thesis seem to confirm these assumption. Piglets recognize their mother 36h after parturition by voice. Sows can recognize the smell of own piglets soon after parturition but not by voice. Identification based on voice seems to appear later at about 10 days after parturition, but it is not very strong. Other studies identified potential cues to identity in calls of sows as well as in calls of piglets