Effects of early post-partum separation on maintenance of maternal responsiveness and selectivity in parturient ewes

Abstract

The aim of this experiment was to study the effects of various durations of mother-young separation following a period of post-partum contact on the maintenance of maternal responsiveness and selectivity in sheep. The hypothesis that the recognition of the young results from ‘maternal labelling’, particularly by the intake of mother's milk, was also tested. After testing selectivity of ewes at the end of the first 4 h post-partum contact, mothers were separated from their lamb for 6, 12, 24 or 36 h. During this time, each lamb was allowed to suckle every 4 h from an alien mother. At the end of the separation a second selectivity test was performed with the mother's own lamb, the alien lamb which had suckled the tested mother and an alien lamb, introduced separately. Results showed that (i) maternal responsiveness was maintained for the first 24 h of separation but for 36% of mothers, maternal behavior had faded after 36 h; (ii) maintenance of selectivity decreased more rapidly as after 24 h of separation 45% of mothers accepted alien lambs; (iii) labelling transmitted through milk intake did not seem to influence lamb recognition. Selective mothers rejected the alien lamb regardless of whether it had been fed by the tested ewe. Conversely non-selective ewes did not accept preferentially one type of lamb.