Postnatal maternal behaviour expression depends on lambing difficulty in Merino ewes

Dystocia, a prolonged or non-progressive birth event, is the main contributor to lamb mortality in Australia and across the world. Dystocia can cause neonatal hypoxia, central nervous system (CNS) damage leading to increased risk of starvation, exposure and mismothering, and death. These prolonged birth events can also cause fatigue, injury and death in the ewe. Dystocia may interrupt the expression of maternal behaviour and the strength of the ewe-lamb bond, and consequently lamb survival. This study focused on the effect of dystocia on ewe behaviour in the 2 h post-lambing. A total of 18 ewes were chosen for continuous behaviour annotation and analysis (dystocic (n = 9) and eutocic (n = 9)) based on the quality of video recordings, length of stage 2 parturition and classification by a single experienced observer. Dystocic ewes showed significantly lower expression of maternal behaviours and a significantly greater expression of avoidance behaviours compared to eutocic ewes. Additionally, dystocic ewes performed fewer behaviours in total compared to eutocic ewes. Dystocia can significantly affect the quality and quantity of ewe maternal behaviour expression, leading to increased avoidance of the lamb, increased risk of maternal disinterest, and increased risk of death for the lamb. If dystocic events can be identified quickly and accurately, measures can be taken to ensure the ewe and lamb recover successfully.