Neonatal survival: contributions from behavioural studies in sheep

Abstract

Newborn lambs need milk and immunological protection shortly after birth, and early interactions between the mother and the young are critical in this respect. The Merino ewe in the extensive conditions of Australia often has the reputation of being a poor mother. Attempts to improve the reproductive performance of these sheep must overcome this handicap. Observations at lambing highlight the importance of the birth site as the location where the bonding process takes place. Mother-young bonding and lamb survival are maximised by management practices that increase the time spent at the birth site by the ewe after parturition and ensure that the appropriate interactions occur between the ewe and her lamb(s) on the birth site. Optimal feeding strategies during the various stages of pregnancy and at lambing not only improve the birth weight of the lamb and the condition of the ewe at lambing, they also influence the quality of maternal behaviour. Bonding, and consequently survival, of twins can be considerably improved if mothers remain on the birth site for a minimum of 6 h. Good nutrition during late pregnancy also increases the production of colostrum by the ewe. Maternal behaviour also depends on the emotivity of the animal. Although emotivity and its selection in sheep have not been part of practical animal management on a wide scale, there is increasing evidence to implicate emotivity with production characteristics. Behavioural interactions that take place between the lamb and the ewe in the very first hours following birth are important for the development of a bond with the mother and the future of the neonate. Two major factors contribute to the formation of this early bonding: postnatal vocal communication and sucking. From the few data available, it would appear early bonding to the mother is important for lamb survival. In Merinos, twin lambs that survive beyond the first week of life are those that have established most rapidly a bond with their dam in the first 12 h after birth. Under extensive conditions, the cohesion of the mother-young unit is obviously a major element of the welfare of the neonate: inadequate maternal care leads invariably to early death.