Importance of the characteristics of the young in the manifestation and establishment of maternal behaviour in sheep.

The role played by the lamb in the regulation of maternal behaviour of the ewe around parturition was investigated in three experiments. In the first, the spontaneous manifestation of that behaviour was observed in parturient ewes when their lambs were swapped with either newborn or 12 to 24-hr old alien lambs. The ewes were undisturbed, or only slightly so, when their lambs were exchanged for alien newborn. In contrast, very obvious and significant differences were observed when swapping involved 12 to 24-hr old lambs. In the second experiment, ewes totally separated from their lambs at birth and for 12 hrs accepted a newborn alien lamb more readily than their own 12-hr old lamb at the time of reunion. In the third experiment, ewes were maintained in partial contact with their lambs for 12 hrs and maternal behaviour was tested at that time. The ewes remained maternal up to the time of testing only if they could smell their lambs. It was concluded that some characteristics of the newborn lamb are necessary for the development of adequate maternal behaviour.