Temporal changes in the neonatal recognition cue of Dohne Merino lambs (Ovis aries).

The strong bond that is formed between ewe and lamb after parturition is important for lamb survival. Evidence exists that the ewe mainly employs olfactory recognition cues to distinguish her lamb from other lambs in the flock. We have found that volatile organic compounds in the wool of Merino lambs that presumably constitute the neonatal recognition cue in sheep undergo temporal changes, at least during the first 100 days of their lives. To compensate for changes in the composition of the recognition cue, ewes are compelled to sample the changing effluvia of lambs to refresh their memories of their lambs' odor in order to preserve the exclusive olfactory attachment to their lambs. These changes could be the reason for the well-known regular sniffing of ewes at their lambs. Parallel changes in the effluvia of twin lambs ensure the retention of the previously observed intratwin similarity of the recognition cues of twin lambs. The coherent manner in which these changes take place probably contributes to the cohesion in a flock of sheep.