Breed differences in the expression of maternal care at parturition persist throughout the lactation period in sheep

Maternal care plays an important role in the survival of offspring in mammals. In the ewe initial maternal care is expressed by nurturing the young and formation of an exclusive olfactory bond with the lamb. After the neonatal period, maternal care is associated with co-operation with sucking interactions, maintenance of a close ewe–lamb relationship, communication with lambs, vigilance and a tendency to seek absent lambs. Two breeds of ewe, Suffolk and Scottish Blackface, have previously been shown to differ in their expression of early maternal care, and in lamb survival. It was hypothesised that these differences in the expression of maternal behaviour would persist throughout the lactation period and continue to be expressed in other aspects of maternal care. The maternal behaviour of 32 primiparous ewes (18 Suffolk, 14 Blackface) was observed from birth until weaning at 12 weeks of age. As shown previously, Blackface ewes spent more time grooming their lambs than Suffolk ewes (P < 0.001), and were more cooperative with the early sucking behaviour of their offspring (P < 0.01). Blackface ewes were significantly closer to their lambs from birth and throughout the lactation period (P < 0.05). There were no significant differences between breeds in maternal vocal communication with their lambs, however, Blackface ewes were significantly more vigilant (head alert) than Suffolk ewes from week 4 of lactation onwards (P < 0.01). The lambs of Suffolk ewes had a significantly higher frequency of sucking bouts (P < 0.05) than lambs of Blackface ewes in the first weeks of lactation. However, Blackface ewes accepted a greater proportion of lamb sucking attempts than Suffolk ewes (P < 0.01), and these sucking bouts were longer than with Suffolk ewes (P < 0.05). The results therefore show that differences in the expression of maternal care seen in the initial post partum period in sheep persist throughout lactation, and would be expected to contribute to lamb survival.