Maternal selectivity suppression through peripheral anosmia affects neither overall nursing frequency and duration, nor lactation performance in ewes.

The effects of prepartum peripheral anosmia on nursing activity, milk production and growth of the lambs, were assessed by comparing intact (n=10) and anosmic (n=10) multiparous Columbia and Rambouillet ewes and their single lamb during the first 2 months of lactation. Intact mothers only nursed their own lamb (98%) while most of the nursing activity in anosmic mothers concerned alien lambs (78%). On the other hand, the total duration and the frequencies of nursing did not differ significantly between groups (P>0.05). Nevertheless, the total percentage of nursing of own lamb by anosmic mothers (22%) was higher than expected at random (10%). Milk production or lambs' weights did not differ between groups. We conclude that prepartum anosmia resulted in the failure of ewes to develop true selective nursing up to the 8th week of lactation, although some preferential mother-young relationship yet developed. On the other hand, it did not affect significantly overall nursing activity.

Do ewes recognize their lambs within the first day postpartum without the help of olfactory cues?

Two studies were carried out to test the ability of Préalpes du Sud x Lacaune (Study 1) and Rambouillet ewes (Study 2) to recognize their lambs during the first 24 h postpartum. Ewes were given the choice between their own and an alien lamb of approximately the same age, in a triangular pen of 10 m×10 m×10 m. A lamb was placed in each of the two corners while the mother was released from the third corner. Direct access to the lambs was prevented by an open barrier located at 1 m from the pens in which the lambs were kept. Ewes were studied at 8 h (n=10, 12), 12 h (n=20, 10) and 24 h postpartum (n=29, 9; Study 1 and Study 2 respectively). Tests lasted 3 and 5 min in Study 1 and 2, respectively. Although the first choice of the ewes did not differ from random, in both studies mothers spent significantly more time near their own lamb than near the alien. In both breeds a significant preference for the own lamb was already present at 8 h (P<0.05). We conclude that ewes are very likely to recognize their lamb without the aid of olfactory cues as early as 8 h postpartum, which is much sooner than thought from previous studies.