Duration of parturition in ewes and its consequences on behavioural traits in mother-lamb bond

Doctoral thesis abstract

Resumo

Lamb mortality within the first 72 hours of life greatly affects sheep breeding, especially in extensive rearing, resulting in important economic losses and involving animal welfare. Prolonged fetal expulsion phase can influence maternal behaviour, and the extended period of hypoxia during birth can also affect the behaviour of the neonate. Limited information exists regarding the necessary duration of the fetal expulsion phase for these changes in maternal behaviour to occur or for the resulting hypoxia from prolonged delivery to either be reversed or cause sequelae that affect lamb viability. Behavioural disturbances of both the mother and the neonate prevent establishing a proper mother-lamb bond. This thesis aims to investigate the required time for the duration of the fetal expulsion phase to have consequences on both maternal and offspring behaviour. For early detection of foetal hypoxia, the effectiveness of a non-invasive and easy-to-use tool, a pulse oximeter, was evaluated and compared with venous blood gas analysis. The prolonged duration of parturition affected the behaviour of both dams and lambs, disrupting the mother-lamb bond and leading to a higher percentage of abandonment. A linear correlation between the duration of delivery and poor maternal behaviour was observed in primiparous ewes, but not in multiparous ones. The pulse oximeter successfully detected lambs with low oxygenation at birth, which would allow to establish therapeutic or management measures to improve survival. Reducing the duration of the foetal expulsion phase through programmed parturition assistance improved maternal behaviour and lamb vigour in primiparous ewes, enabling the establishment of an appropriate mother-lamb bond and potentially enhancing neonatal survival.