PREFERENCES FOR SIBLING OR MOTHER IN DALESBRED AND JACOB TWIN LAMBS

Shillito Walser, E., Hague, P. and Yeomans, M., 1983. Preferences for sibling or mother in Dalesbred and Jacob twin lambs. Appl. Anim. Ethol., 9: 289–297. Twin lambs of Jacob and Dalesbred breeds (12 and 13 pairs, respectively) were tested in a T maze and given the choice of running to (1) a sibling or an alien lamb, and (2) a sibling or dam. Lambs were tested 3 times before, and twice after, enforced weaning at 80 days. The choices made by the lambs and the time spent at each choice were recorded. Three-week-old Jacob (but not Dalesbred) lambs, and all older lambs, chose to run to the sibling first more than to the alien lamb. Eighty-two percent of Dalesbred lambs, before weaning, chose to go to their dam first rather than the sibling, but Jacob lambs before weaning, and all lambs after weaning, showed no significant preference for dam or sibling. Lambs which ran to the sibling first often moved over to the ewe, but fewer lambs moved from ewe to sibling. All lambs stayed near to the sibling for a longer time than near to the alien lamb. Before weaning, the lambs of both breeds spent a longer time near their dam than near the sibling. After enforced weaning, the Dalesbred lambs still did this but the Jacobs spent longer with their siblings. Short tests allowing ewe and lambs to meet showed that more of the Dalesbred than Jacob lambs tried to suck from their dams over 7 weeks after weaning. The variation between breeds and the strength of the ewe—lamb bond compared with the sibling bond is discussed in relation to cohesion of social grouping in sheep.