The Responsiveness of Newly Born Clun Forest Lambs To Odour Sources in the Ewe

Two groups of newly born lambs, twelve ("suckled" lambs) having been fed by the mother and aged between 3 and 21 h, and twelve ("unsuckled" lambs) taken at birth with minimal olfactory experience of the dam, were tested with the smell of three substances taken from the mother and three taken from an alien ewe. The substances were inguinal wax, wool and milk. Changes in heart and breathing rates and in behavioural activity were used as indices of the lambs' response. Results showed that lambs in both groups responded most markedly to the smell of wax. Behavioural responses consisted of head movements, oral activity and bleats and in unsuckled lambs were given significantly more to the smell of maternal, than of alien wax. Unsuckled lambs responded more to all six odour sources than did suckled lambs. In unsuckled lambs the rate of breathing rose significantly during stimulation with the smell of maternal wax and this response was also significantly different from that given by unsuckled lambs to alien wax. In suckled, but not unsuckled, lambs there was a significant rise in the heart rate during and after stimulation with maternal wax, but not in response to any other odour source. Results are discussed in terms of "teat-seeking" behaviour in newly born lambs and the question whether the unsuckled lambs' capacity to discriminate their own mother's from alien wax depends on prenatal olfactory experience.